Document LpbqMOjNZDd47qrQ4xErVEp8Q

, I HE SEIV E S G U X D JOURNAL OF SIEDICISE JUIY 3. 1986 I The New England ACUTE LEUKEMIA AND CELLDIFFERENTIATION i Journal of Medicine Owned and Published bv the A c c u b i u u m c evidence for a unicellular (clonal) Shssachusetu Medrcal Souctv origin of leukemia, based on the studies of Fialkow Barbara A. Rocketr. 1I.D. Prtndrnr and coworken employing isozymes of the X-linked gene, glucose-&phosphate dehydrogenase (GGPD),as LViIIiarn 11. .\lcDcrrnott. Jr., M.D. Charles s. Arnoroslno,Jr. markers,' combined with evidence from rigor- Errrurrtn Z'U P r ~ l d r n t E r r c v I l U t Stntlnn ous karyotyping,' leaves little doubt that acute non- T H E COMMlmE ON PCBUCATIONS OF THE hlASACHUSEm .\IEDICAL SOCIETY Jarna F. McDonough, X D . . Charman Henrv H. Banks, M.D. Samuel p. Solish, M.D. Fmnk E. Bisbv. Jr., M.D. Samuel K. Stewart, M.D. Valene L. hlunn Roben E. Tranquada, M.D. Jolin I . Sandson. M.D. P e T I$Iva'd-man7 11.D. lymphocytic leukemia (AYLL)c,hronic myelogenous leukemia. and acute lymphoblastic leukemia originate in the transformation and subsequent clonal expan- a hematopoietic precursor, often (at least in the leukcmius) a precursor with multipotent de- Capabilities. The goal of antileukemic clear enough: to destroy the trans- Arnold S. Rclrnan, 1l.D.. EDITOR Marcia Angell, M.D., SENIOR DLPC'NEDITOR Edwin W. Salzrnan. S1.D.. DLPLTYEDITOR Gregory D. Curfrnan. M.D., DEPL-TYEDITOR .. ASSOCIATE EDITORS Jane F. Desforqa. M.D. Norman K. Hollenberg, M.D., Ph.D. Ronald .\. >lait. 1I.D. Slorron S. Swanz, M.D. Franklin H. Epstcin, S1.D. Fmncis D. Moore, MD., Boor REVIEW EDITOR ' John c. Bailar. 111. h[.D., srAnsnc%LCOSSCLTAXT John K. Iglehan. SPECIALCORRESPOSDENT Emily S. Boro, DIRECTOORF .\IASCSCRIPTEDITING .\larlene A. Thavcr. EDITORIAL OrrtcE S~ASACER Stephen E. Cinto, MANAGER OF EDITORIAL PRODUCTION EDITORIAL BOARD Euqene Braunwald. M.D. Samuel A. L a r . S1.D.. Ph.D. .\ram V. Chobanian. .M.D. Robert j.Slaver. M.D. Theodore Colton, Sc.D. Kenneth SlcIntosh, M.D. Richard H. Egdahl, M.D. Da\id G.Sathan, M.D. John T. Harringron. M.D. Lawrence G . Raisz, SLD. Homayoun Kazcmi. hf .D. Kenneth J. Rothrnan, Dr.P.H. Thomas J. Ryan, 1I.D. formed blastic clone and encourag-e rep-op.ulation by residual normal precursors. Common sense dictates that the disappearance of leukemic blast cells from blood and marrow and the reemergence of adequate numbers of functioning erythrocytes, platelets, and granulocytes constitu te irreducible evidence of theiapeuric success. whether short-lived, prolonged, or even permanent. Reports of chemotherapy-induced remissions of =\SLL accompanied by disappearance of the chromosomal markers of the malignant clone and reappearance of functionally normal blood cells of polyclonal oris$' reinforce the wisdom of the common-sense tiew. Yet, some disquieting evidence has also accumulated. Two years ago in these pages, Fialkow and his colleagues3 described a patient with ANLL. a chromosomal abnormalitv, and enzymatic evidence of cionality of the leukemic blasts, in whom complete remission was characterized by a normal karyotype but persistent evidence for a clonal origin of the repopulating normal blood cells. This strongly suggests tirat a leukemogenic clonal population of Frederick Bowva. 111, DIRECTOR OF PCBUSHISC OPERAlY0N.S Ann Rcinke Strong, DEPUTYDIRECTOR Ronald H. Brown, ~ ~ A N A G EORF .bVERT:SlsC 8c .\IARKET!NG tVilliani H. Paigc. MANAGER OF PRODUCTIOS & DISTRIBLTION blood precursors can generate apparently normal progeny, IS well as senre as a source of an overtly leukemic. chromosomally abnormal blast-cell popuiation. Yet. the implications of this observation re- Piorrrcnvr authors should coruulr "Informatiun rbr Authors." which a p pears in the fint issue of every volume and mav k obtained lrom the Joama1 office. A n n c r u with original material arc accepted Cor consideration with the understanding that. except for abstncu. no part o i the data h u been pub. lirhcd. or d l k submitted for publication clsovherc. before appearing hcrc. Yo PAST d this publication may be reproduced or tnnsmiited in any form without wnttm permission. SIATLRIApLrinted in the / a dis covered bv c-opvnqht. The /amrnuf doer not hold itselCmporuible for sucnnencs made bv any contnbutor. S T A m r * n or OpinlON exprCaed in the jommol reflect the views of the author(s) and d o not rrpment ollicial policy o i the hlassacliusetis Medical Socicrv unless so s t a i d . N o n w should be srnt at least 30 drvr before publication date. ALTwouon a11advenainq material accepted is rxpectcd to conlorm IO cihical medical standards, &cccptanccdoer nor implv riidoncmcnt bv the journal. Rrrutws: Reprints are available in minimum quantities of50. To order. please coiitilct the Busiiinr Office a i the addrns pmvided below. Sumcair rion Pnicu: CSA: 5 6 0 per w a r I intrrns. residents L35 per vrac \iudentr L'u)pcrvear). Outride USA (US.lundsoi~ki$. 73 prr irar iintcrns. midents $55 per war: students Sf5 per v c I r i . Rrmit pa\mrnis and correrpondcncr IU S E J N Subxnbcr Sewice Uept.. I c w ) >lain 31.. \Valtham, AI:\ U''2S+-0&)3. Please include current mailinq l a b 1 rriih rcnmrl order. EDITOSIALO m m : I O Shattuck SI.. Boston. At.\ 021 15. mained uncertain; is this a rare event or the common underlying biologic pattern in ANLL? Much of the uncertainty is dispelled by a report in this issue of the Journal, by Fearon et ai.: which provides further compelling evidence for the developmental capabilities of clonal leukemogenic blood-cell precursors, this time has& on recombinant-DNA techniques. The new genetic tool provided by D N A r t striction-fragment-length polymorphism,' which has been so powerful in mapping the human genome and detecting elusive senetic traits, has been brought to bear decisively on the somatic-cell genetics of leukemic cells. Restriction-fragment-length polymorphisms arc produced by small local variations in DNA. sequence in the vicinity of identifiable genetic loci; these 1-arkitions are recognized because they change the size of DSA fragments generated bv the cleavage of DSA by restriction enzymes. which have very specific base-pair sequences as their cutting-site tar- I , ' '.' I EDITORIALS 51 yets. A ratnction-fragment-length polymorphism is Gassed, like any other genetic feature, in Setm-line and 1 somatic cells; heterozygosity can be detected, and the :- analysis is independent of the actual esprcssion of any particular gene; In any population of nucleated j. cells, whether di\*iding or quiescent, the rcstriction- fragment-length polymorphism will bc revealed to the investigator armed with the appropriate molecular probes. To detect donalitv in leukemic blast cells and the normal blood cells of patients with ANLL, whether at diagnosis or during remission, Fearon et ai. used molecular techniques and restriction-fragment-length polymorphisms according to three strateges: ( I ) to detect X-linked markers entirely analogous to the G6PD isozymes studied by Fialkow et al., but without the need to detect expression of an enzymatic gene product; (2) to detect clonal aneupioidies, but without the need for a dividing ctll population to generate visible chromosomes: and (3) to detect the immunoglobulin gene rearrangement that normally occurs early during E-cell differentiation and that for unknown reasons may occasionally occur during the evolution of a myeloid leukemia clone. Three major conclusions can be drawn from these studies. First of d1. clonalitv in at least a large majority of cases of A S L L seems certain: 7 of 10 patients who were heterozygous for the X-linked restrictionfragment-length polymorphism locus had the telltale ionoclonal pattern. Second, clones of leukemic pre,ursors seem quite frequently capable of sustaining apparently normal differentiation to mature granulocytes during active disease; five of six patients evaluated according to one or another of the three strategies had this phenomenon. Third, in elegant confirmation , of Fialkow's prediction. 3 of 13 evaluablr patients had i evidence that their remission-stage granulocyte popui lations were of clonal origin and presumably (al- though not proved) of the same clone as the blasts of j their active-stage disease. : Taken together. these studies. the work with G6PD isozvmes, and the results of karyotype analysis begin i to point out a more comples pathophysiology for t AKLL than might have been supposed. A s proposed 1 by both Fialkow and Fearon et al., emergence of a t clone of hematopoietic preleukemic precursors capa- I ble of essentially normal differentiation, but with i variable levels of proliferative advantage over normal } precursors, may constitute an early event in leukemo- i? genesis. Such a stage could be hematolo+dly unde- ii tectable except by anaiysis of clonality. Oi-ert blastic disease would supen-enc with a second somatic genetIC event. perhaps sipnalcd by a chromosomal abnor- f mality. Successful chemotherapy may suppress the I blast population 1and the chromosomal marker), leav- . ing both the clonal preleukemic cell lineage and nor- mal precursors. in \-anable proportions, to reemerge I hematologically normal blood-ceil elements. 1 Exciting questions and uncertainties remain. LVould it be clinically usehi. d it were actually possibic. to be able :o dciect the presence of a hcmatoloqcaily normal it but preleukemic clonal population? At present there seems littie likelihood chat such a population could be detected before the onset of overt hematoiogc disease. either blastic leukemia or dyshematopoiesis (such as - -refractory anemia). Bur a remission-stage clonal popula- tion is fair game for detection by using if necessary additional geneac markers for donalicy. Could the behavior of such a clone and irs potential, on the one hand, to support normal hematopoiesis or, on the other, to allow the reemergence of blastic leukemia in relapse be modified by therapeutic intervention? It is clear from studies with experimental leukemia cell lines of both murine and human rigi in^,^ that both chemical cyto- differentiation agents and naturai growth factors can modify the expression of developmental potential. The possible role of simultaneous and sequential combinations of cytocidal chemotherapy and cytodifferentiation agents must surely be considered in the light of these findings, as must the future role of ablative therapy followed by bone marrow transplantation. Whatever the practicai outcome, the studies. provide powerful new -insights into the natural history of a hematologic neoplasm insights that may apply equally to nonhematopoietic cancers. Memonal Sloan-Keaennn I Cancer Ccuta New York. NY 10021 RICHARD A. RIFIUNDh, 1.D. REFERENCES I. Fidkow PI. Sinpu JW, Adamson 1W. n ai. Acuu nonlynphocyfic leukc- mir: hecaogerrity of stem cell ongin. Blood 1981:571068-73. 2. Pepnon MG.lassonRA. Golomb HM. Clinicalsignificance of chromosome paturns ID malipmu diseases from molecula to man. In: Rowky JD. Ultmann JE.&.Chromoromtr and cancer hwnmolecule, 10 man. New Yak: Academic F'res.5. 1983311-31. 3. Jacobson RJ. Temple MJ.Sinpa JW. RaskindW. h e l l J. Fdkow PJ. A c l o d compleu mission m a purent with acuu nonlymphocyrr leukemia onginuing in a multipount stem cell. N Enel J Mcd 1984: 3101513-7. 4. Fearon ER. Burke PI, Schiffer CA.Zchnbuvr 5A. Vopcls~rnB. Diffclmiiauon of leukcma cells to pdvmorphonuclar leukocytes in patients with acute nonlvmphocyuc ieukemu. N En@ J Mcd 1986 315:15-24. 5. Boatein 0. Whiu RL. SkolNck M. Davis RW. Conwnrnion of a generic linkdnc nup in m a using marctionfngmcnc kngth polymorphisms. Am 1 Hum GeM 1980: 32314-31. 6. Rifkind R4.ShcffcryM. Mukr PA, Induced differemmion of murine en*mlcukcmra cells: cellular and moleculu maharurms. In: Klein G. Wcinhouse S. cdc. Advances in cancer ICICIICII.Vol. 41. Orlando. Ha.:Academic Press. 1984:IJPW. 7. Collins SJ. Bodner A. Tinp R. Cdlo RC. Induction of morphological and functional differcniiaiion of h u m pmmyclayfic leukemia cells tHL-60) by compoundswhich induce diffemtuaon o i munnc leukcma cells. Inr J Cam c u 1980. 25213-8. ADVANCES IN CORNEAL TRANSPLANTATION DISEASE of the cornea is the most common cause or blindness in the world.' The cornea is the normally transparent anterior structure of the eye that functions similarly to the lens of a camera and has the appearance of a watch crystal. The normal cornea is a layered. avascular structure in which an outer epithelium and an inner endothelium surround the central stroma. T h e stroma imparts its opticai properties to VOL. XI, NO. 2 - A P R I L 1975 Current Concepts in Chronic Myelogenous Leukemia By P. A. Stryckmans ASOU.; 5-Y R LEUKEMIA-FREE SURVIVAL and possible cure rate can be expected in children with acute lymphocytic leukemia treated with the best treatment schedules available This is not the case for chronic my- elogenous leukemia in which the median duration of survival is still of the order of 3-3.5 yr, which is almost the same as for the patients with no treatment. de- scribed by Minot in 1924.IM Most reviews dedicated to the treatment of chronic myelogenous leukemia in recent years have emphasized this point. I t must be recognized that. on the other hand. many important new facets of the disease. related to its pathogenesis. are continuously described. New forms of treatment such as more aggressive chemotherapy. maneuvers to decrease physically the total mass of myeloid cells (early splenectomy and leukapheresis) and others to increase the immunologic defense of the patient have been proposed in the last few years. Whether these new approaches will significantly improve t h e survival of the patients is not clear yet, but the new experimental facts certainly constitute a logical and ethical basis for the use of more aggressive therapeutic procedures in a disease still rapidly fatal. The basic concepts and some of the emerging concepts will be discussed first, and the classical and the more recent therapeutic procedures will be re- viewed thereafter. Only the classical Ph '-positive CM L will be considered in this article because the evaluation of new therapeutic procedures is ciisicr in this form of the disease than in the Ph '-negative form. The reasons therefore are: that the Phi-positive C M L is more frequent. that it represents probably a nosologic entity distinct from the Phi-negative CM L' and finally that eradicu- tion of the disease by therapy may be indicated by disappearance of the marker. THE PERSISTENCE OF REGULATORY M E C H A N I S M S FOR MYELOPOIESIS IN CML Although Ph '-negative myeloid cell lines have been so far described in only a few patients with Ph '-positivc C M L.20.4Y"'~Rit' i s concrivablc that they do exist in all these patients. I f so, they probably represent what i h left of the normal nonleukemic population. -- . Friitti r/w .Sc*rvtc.c* clr Mi&c~ttrc* Iiirt*rttc* rr c / ' l t ~ ~ ~ ~ , . \ r ~ ~ c rCr 'rliit~iityi trr rlc I'lnrrirrrr J i h v Horddv. L'rnrre drs Tuitriwrs de. l'Uttiwr.rti+ Lihrc Jc. Llric.vrllc*s.tlrii.w4.\. IIv1,qiiini. Supported in parr 6,s /he fonds Canrerolugiqur de la Caissc GGneralc J Lpurgnr e*[ dr Xrirurri, de Belgiyur and by rhr Lady Tala foundarton. @ 1971 by Cmne & Sirairon. lnc. S.minan in Hematology. Vol. 11, No. 2 (April). 1974 101 - F- 102 P. A. STRYCKMANS 'I'Iiccdwiciiis proIiI'cr;ilivc :itIv;iiit;igc 01. IIic PI1 '-poai[ivc cell lincs ~ o t l l dhc iiihcrciit to the cell or rchlcd ( c ) I'cciIIxick l~lcd\;\i\isi\1.a!',lie accolltl I 1 c ~ a ~ t h l l i t y would be realized if the normal -ell line were dcprcsscJ because i t s nocn1;Il sensitivity to regulatory mechanisms which would not afect. to the same extent. thc Ph '-positivc ccils. In f x t . this Ph '-positive cell line produces large numbers ol' rii;iliirc cclls which, clircclly o r ii~tiircctly.b y I;.cti-h;ick clfcct could dcprcas the Ph '-ncgalivc cclls iiiorc t h a i i thc l'h '-posiitivc cclls. 'I.his Iiypolhcxis i i ~ ~ p l i c ~ partial retention of normal homeostatic control. Granulopoiesis has bccn proposed as a negative feed-back system containing a time delay and therel'ore may show oscillations under appropriate circumstances.lo5 The cyclic oscillations of the granulocytes blood level which occurs in CM L or during chemotherapy given at a constant doselS suggest therefore that a homeostatic control is still acting on myeloid cell proliferation in CM L. A humoral factor has been proposed for the homeostatic control of granulopoiesis operating in normal individualss0 and the colony-stimulating factor (CSF) found in serum and urine which brings about differentiation of myeloid precursors cells in vitro, could very well be the humoral factor responsible Tor the regulatory mechanism operating in vivo.'o*'02 Gatti et al.51found an inverse relationship between the level of CSF and the peripheral c o u n t in their patient with CML who had oscillating leukocyte counts. This is an additional argu- ment for the persistence of some regulatory mechanisms in CML. Two characteristics of the leukocyte oscillations seen in C M L should be pointed out; the great amplitude of individual cycles (some exceeding lOO,OOO/ cu mm) and the length of the cycles: 30.40.50. 1 IO.iob 66."' and 72 days.s' These amplitudes and cycle lengths are considerably greater than those found in cyclic neutropenia and normal individuals.lo5Cronkite and Vincent" found that tke cycle length of 20 days sccn in normal individuals and in cyclic neutropenia fitted what we know of humans on the time for a stein cell to produce polymorphonuclear cells (PMN). This time is normally around IO days. Such a delay of 10 days from maximal signal from the blood (the level of PMN) to maximum response from bone marrow will produce oscillations o f 2 x IO days. Therefore the observation o f long oscillation periods in C M L suggest that i n this disease more time may be needed to produce a mature PMN. One possible explanation for this long delay could be an increased number of successive divisions, which, in turn, could explain the great amplitude of the oscillations. On the other hand, the high amplitude of oscillation could also result from an abnormal sensitivity of the Ph '-positive stem cells to the regulation system. How this fits with the observation of high levels of colony-stimulating activity found in the urine of CM L patients'*' is not yet clear. THE TRANSIT TIME IN THE BLOOD OF POLYMORPHONUCLEAR CELLS (PMN) IN CHRONIC MYELOGENOUS LEUKEMIA A remarkable observation was the fact that the transit time of P M N of C M L in the blood is considerably longer than in normal individuals during the active phase of the disease and tends to become normal when the blood leukocyte count decreases as a consequence of treatment.'.4'."2 I n order to reduce the artifacts due to the presence, in t h e blood. of immature myeloid cells in the determination of the of the P M N ,irradiation of t h e labeled cells when the blood contained a large proportion of myelocytes was performed to stop the CHROf m;i I II c1lr;Il 'I.,,: ( conti nor ncylo.\ C l l ' r111 l'h incre a goc blooc Th be d these the c: has k the S: of CI the s Pede (LAI that than abili! were rrup vitro IO rn. Tk chro: delet it prc 22 ar - CML the : othe: havc amo: posit mal This abnc acq u scrib sister KMANS Id be Ibility 3 r i iI ~ xtent, nbers :press nplies 7 prordore scilla- 0,106.1s3 that 'J. pnufactor yeloid )le Tor nverse mien1 argu- Jld be o.ooo/ These cyclic iat the openia lymorday of ximum Therein this iossible :cessive lations. rom an system. activity T1 ,r C M L e active ukocyte .he artithe dehen the ;top the CHRONIC MYELOGENOUS LEUKEMIA 103 maturation of these cells into labeled PMN.4SThis technique has given more accur:ile v;il~issTor the TI,>of I'MN in CMI.. Around 210.000 WHC/cu n i m . ;I l,,?ol'26 h r was found. instead 016.4 hr ;ISfur norm;il subjects. This study thus confirmed that the PMN ol' C M L had a longer transit time in the blood than normal PMN. This prolonged transit time, although it potentiated the leukocytosis once it had developed, was of secondary importance in the pathogenesis of the increased number of blood PMN. The conclusion is that the increased number o f PMN in CML is due to an increased production. This would suggest t h a t thc chances are small of inducing a good remission only by removing the excess o f myeloid cells in the peripheral blood. F U N C T I O N A L CAPACITY OF POLYMORPHONUCLEAR CELLS (PMN) The prolonged transit time of PMN of CM I- in the blood has been shown to be due to cellular rather than to extracellular I h c t o r ~ . ~T*h' ~is suggests that these cells may be deficient and may not function normally. As a matter of fact. the capacity of CM L mature neutrophils to egress from the blood to the tissues has been found to be decreased in CML.'.'20 By means of plastic chambers at the site of mechanical abrasion, a defect i n cell migration was found in all stages of CM L. I t was inversely correlated with the clinical state.' Moreover. once at the site of inflammation, the PMN of C M L may be less active than Pedersen and Hay hoe"' have compared leukocyte alkaline phosphatase activity (LAP) and phagocytic capacity in P M N from C M L patients and have observed that the cells with demonstrable enzyme content were more active phagocytes than the LAP negative ones. This is in agreement with an improved phagocytic ability found during remission." However. although deficient, PMN of CM L were found useful in the treatment of severe infections in neutropenic non-CML recipients.37This suggests that their decreased functional capacity observed in vitro may be due to their immaturity but thai with time. in vivo. they are able to mature into normally functioning cells. THE PHILADELPHIA CHROMOSOME The Philadelphia or P h ' chromosome. discovered in 1960,'0nis still the only chromosomal marker consistently found in a human neoplasm. It represents a deletion of the long arm of chromosome ZZ."."' It has been shown recently that it probably results from a translocation betueen the long arm of chroniosonie 22 and the long arm of chromosome 9.Iz6It persists throughout the course of C M L both in relapse and during remi~sion."".~"The myeloid, erythroid and the megakaryocytic cell lines presumably have the marker.~zg~'~*w'h5e' reas other have cells the a such noma as ly. sCkiMn..Lc-e_,il.sl~la-yp,mpaprheonctlyyteas a n nd -ac bone marrow quired disease fibroblasts" d o since concorda not nce among identical twins is exceptional. I n only one pair did both twins have Ph'- positive CML."' I n the other pairs. there was no Ph' chromosome in the nor- mal twins whose leukemic twins showed typ~calPh'-positive CML.'Z*54.55.M.67 This strongly supports the postulate that the f'h' chromosome is an acquired abnormality rather than a hereditary defect 01' the chromosome. It seems to be acquired long before the appearance of clinicill symptonis as in a patient de- scribed by Canellosl' in whose marrow cells rhe Phl chromosome was con- sistently detected for almost 6 yr in the absence of hematologic disease. 104 P. A. STRYCKMANS All 1 1 1 o~hs~cr~v;itions ;Ire con1p;itihlc wit11 tllc coilccpt tIt;it ~ r : l d i ~ ; i l i ~~ ~l i'1 the Phi-positive cells could be a way 10 eradicate the diseasc. Howvcr. the Philadelphia chromosome is said to be ncithcr constant nor specilic for C M L. As a matter of fact. i t is found in approximately 8 5 " , ol` the u s e s o f C M L . and. on the other hand, it has been described occasionally i n all sorts of myelopro- liferative disorders. It should be stressed however [hiit several ~ t ~ d i e s " ~ ' ~ ' ' ~ ~ ' ' have indicated [hat the clinical features of thc Phi-negative cases are some- what different from those of Ph `-positivecases. The Ph `-negative cases are more frequent in infancy and in the older adults, they have usually enlarged lymph nodes and lower leukocyte and platelet counts. They respond poorly to treat- ment, they transform earlier and have a much shorter median survival than the Phi-positive cases. The Phl-negative cases therefore probably represent a nosologic entity distinct from a classical C M L associated with the Phi chromosome."~149~'5~ On the other hand, a low percentage of Ph'-like chromosomes have been found in occasional cases of acute myeloblastic leukemia,81*H.i'i.ieHrythro- le~kemia.".~t'hrombocytopenia,'" p~lycythernia.~'myelofibrosis,77~i5asgno- genic myeloid metaplasia,4' untreated pernicious anemia." For several reasons. all these observations d o not rule out with certainty the possibility that the Ph' is still specific of CML. First, most o f these diseases share clinical features with CML and therefore some of these cases may have been particular forms or phases of a true CML mistakenly labeled: secondly, most of these data should be reviewed today since they were obtained between 1965 and 1970, at the time when the more accurate banding techniques were not then available; thirdly, because these cases may have been C M L in their preclinical stage since we know that the Phl chromosome may be present many years before the clinical onset of CML." The finding that the Ph` is probably constant and specific for C M L reinforces the idea that its eradication may be of therapeutic value in this disease. A crucial finding which has important therapeutic implications is that al- though in most cases of CML. all or practically all cells in the bone marrow have the Ph' chromosome, Phi-negative myeloid cells also exist. Occasionally. in a few patients who had been intensively treated or at least deeply myelo- depressed, clearly Phl-negative myeloid cells have been seen in VIVO.".`~.~~.'~ The existence of Phl-negative myeloid cells in Phi-positive C M L was confirmed on bone marrow grown in vitro. This technique allows observation, in bone marrow cultured in a petri dish of many granulocytic colonies each arising from a single granulocyte precursor. I t was found that all metaphases from a single colony were either Ph '-positive o r Ph `-negative suggesting that leukemic and normal cells may coexist in CML.20 - THE CLONAL ORIGIN OF CML The Phl chromosome being acquired and limited to the myeloid. erythroid, and megakaryocytic series, strongly suggests but does not prove however that the disease is originated from one single transformed cell. G 6 P D heterozygote patients with C M L provide an additional strong hrgument for the theory of the clonal origin of CML. G6PD heterozygotes have two distinct populations of cells: one producing the type A isoenzyme only and the other the type B iso- ct c I. c I' h: ! di or fir th or dr pa ce Stl cr: in( (3 la: tic rn w: in. m. ce P3 fo a1 co of m m IC TI ( <- 4' RYCKMANS ation of :vcr, thc ir CML. I L . and. yelopro- &s38.14P.I 55 'C someare more d lymph to treatval than iresent a the Phl ive been crythrosa agnoreasons, L the Ph' features ar forms ese data 1970, at ,vailable; age since :fore the Lant and :r apeutic that almarrow sionally, y rnyelo- ,.4l.49.85.l50 o n firmed in bone h arising s from a I e u k e inic ry t h r o id, ever that :rozygote lry of the ations of DC B iso- CHRONIC MYELOGENOUS LEUKEMIA 105 enzyme only. I t was found that when these patients w h o have type A and type B enzynic-prciducing fibrob1:~sts. gct CM I-. that ilicir red cclls and granulocytes had cithcr typc A or type B enzyme but not both.'.w The single enzyme phenotypes in leukemic cells of C M L most probably reflect a clonal origin of the disease. Studies on experimental animals indicate that the concept of clonal origin is not inconlpatible with a viral origin of CM L which is suggested by the finding of revcrsc transcriptase associatcd with 70 S-UNA in the leukocytes of three CM L patients.b Nevertheless, one observation exists which does not support that CML is originated from one single cell. It concerns a patient with Klinefelter's syndrome and CML who had a sex chromosome mosaicism of the X Y / X X Y pattern in the blood cells and was found to have the Phlchromosome in some cells of both cell PROLIFERATION OF MYELOID CELLS IN CML As it was indicated in a previous paragraph. there is good evidence from studies on P M N blood transit times that the production of these cells is in- creased. This may be due either ( I ) to an increased rate of cell division, (2) to an increased number of successive divisions in the recognizable myeloid cells, (3) to an increased number of myeloid precursors at the stern cell level. The first possibility can easily be tested by measurement of the 'H-thymidine labeling indices. providing the duration of DNA synthesis is known. The duration of D N A synthesis during the chronic phase of the disease, whether it was measured by the double labeling technique'" or by the stathmokinetic method,2 was found io be in the normal range of 10-15 hr.lu This information made it interesting to compare the labeling index of the myeloid cells in C M L and normal individuals. The labeling index of the proliferating bone marrow myeloid cells taken as a whole was of the order of 23% in 12 studies on nine C M L patients in the chronic phase of the disease. Le.. in the order of what was found in normal indi~iduals."~Thivsalue was the same whether the patient had a high number of leukocytes/cu rnm of blood or 3 nearly normal number as a consequence of treatment (Fig. I ) . When only the granulated precursors (pro- a $100 f $c 1 2 ;V 60} Fig. 1. Ordinate: the percentage of 'HTdR Iqbeled pyeloblasts, promyelocytes, end myelocytes in the .,marrow of nine CML patients. Ab- scissa: the blood leukocyte counts. The bone marrow of three patients (e, and A) was examined twice, at different WBC levels. : 1 p e0.05 WEC / mm3 x 10-3 104 P. A. STRYCKMANS myelocytes + myelocytes) were examined I'or thcir Iahcliiig indcx. thc inc;ii1 value was of thc same order of magnitude, i.e.. 24.7 in seven C M L patients.' I n contrast. when the niyeloblasts i n the bone marrow ol'thest: p'I* t 'imts were ex- amincd separatcly. at thc onset of the disease they showed a mean labeling index of 16.9. a valuc considcr:ibly Iowcr than i n normal individuuls but of the same order of magnitude as in blastic transl'ormation2 and only slightly higher than in bliists of acute myeloblastic Thus C M L myeloblasts. from t h r clinical onset ol' rhc disease on. seem 10 hch;rvc ;IS the hlrist cells of acute myeloblastic leukemia. I t is s t i l l n o t clcar. howcvcr. whcthcr the I;ibclin_c index o f t h e myeloblasts remains low when a remission with a normal spleen and a normal blood picture have been obtained. The ;inswer. 10 this would tell us whether the decreased labeling index is directly related to the disease or rather indirectly related through the effect of homeostatic mechanisms probably still operating in this disease. The answer to this question will have considerable implications for the treatment of the chronic phase o f C M L . These observations do not support the hypothesis of an increased rate ol' cell production in the recognizable myeloid cells. The second possibility. namely an increased number of successive divisions in I 1 R I/ T2, I' 5 D 1, L 1: 'I i b i / i A M J J A 5 0 N 0 J F M A M J J A 5 0 'N 0 J F M A M J J A 195L 1955 1956 Fig. 2. Four increases of the number of total (0) or only irnmarure ( e ) myeloid cells/cu mm of blood after discontinuation of busulfan during periods with no mointenonrc treatment. The doubling times ( 1 2 ) got progressively shorter. The l a s t before death under blastic transformation was 5 days. The T p were always shorter far immature myeloid cells than for the total of mature and immature. CHRONIC 1 thc rccog long pcr: tions oft ditional increase uously, L' the last 2 cells. Th, sivc cou course o total ma faster, ir. observai marrow ma t u rat could be would e precursc This c die in t t cent o f ; ment fo than AF principi of the c the bias Sever blastic : ( I ) mye abnorrr of the I blood.a In 18 of initi: with a r sis late of mye -?ittrib u was an concer; tion ex sequen is SU@ blastic patient 4 RYCKMANS le mean ',:I t ien I s. wsrs exlabeling ~t of t h e y higher 10bI as1s. or labeling rl spleen ould tell sease or irobably siderable :rvations in in the ,isions in .U MJJA 56 IS/CU mm of ni. The dourmotion wos mature and CHRONIC MYELOGENOUS LEUKEMIA 107 the recognizable myeloid cells, could be suggested. ;ISexplained above. by the long period o f the oscil1:Irions sccn in the p;itients w h o cxhihiicd cyclic v;iri;t- ticins ol'ilistr Icukocytc counts. tiowever. ;ISBrcsciani': has pointed out. a n additional division would increase the number of cells produced. but in order to increasc i t continuously. i h c nunibcr o f divisions should also incrcasc c o n t i n uously, a modification which seems unlikely. For the resons explained below. the lasi aliernalive is the most probahlc naniely an increased pool o f precursor cclls. Thc I'act that the immaiurc niycloid cells i i i ihc blood bctwccii two S U ~ C C S sive courses of busulfan increase progressively faster and Cdster after each course of myleran up to the blastic transformation (Fig. 2). suggests that the total mass of immature myeloid cells in the body also increases faster and faster. in view of the traffic existing between marrow. blood, and spleen. This observation and the fact that no real change of the labeling index in the bone marrow occurs during the course of the disease (Fig. I). suggest a progressive maturation defect of the self-perpetuating precursors. The consequence 0 1 this could be a n exponential expansion of the precursor compartment which i n turn would explain a more and more rapid increase of the number of recognizable precursors in the blood after discontinuation of busulfan.'" THE BLASTIC TRANSFORMATION OR BLAST-CELL CRISIS This event is the main threat of CML.Sixty to seventy per cent of the pat.i,e/ni .,ts die in this stage of the disease which is clinically and hcrnatoto&df$ rem%iscent o f acute myelobiastic leukemia (AML).'OThere is almost no effective treat- ment for this complication once it has arisen; it is more resistant to therapy than AML. Prevention of this acute phase of t h e disease should therefore be the principal aim o f all our efforts. However, so far most of our classical treatments of the chronic phase of C M L have failed in delaying significantly the onset of the blast crisis. Several modifications which have been found to precede and herald the blastic transformation could shed some light on the pathogenesis of this event: ( I ) myelofibrosis i n the bone marrow biopsy:56 (2) ;idditioniil chromosomal abnorm;iliiics o n top o f t h c I ' h ' , ' .V ..I I .I-1..1.%..7.1,l.l7.1 I*J.I.IV,l~I (3) ;I markcd incrc:isc of the LAP;57(4) a short doubling lime of the immature myeloid cells in the bh o d .x.'7.'45 I n 181 patients with CML, myelofibrosis was found in seven patients at time of initial diagnosis of CML.s6 Four of them died from blastic transformation with 3 mean survival of 8.8 mo. Thirty-two patients who developed myelofibro- __sis late in the course of CML had a mean survival of 4.9... mo a I_ f t.e-r the diagnosis of myelofibrosis was e s t a b l i s h e d . ~ ~ g . . ~ f . : t h ethme,.cause ofdeath could b3 attributed to blastic t r a ~ ~ o r m a i ~ r r ; . ~th~us~s~trepssoesrtthat myelofibrosis was an ominous prognostic sign. T h i s observation raises an important question concerning the pathogenesis of blastic transformation name&. is this complica- tion exclusively related 10 a modification of the leukemic cells o r also the con- sequence of chanses in the microenvironment of these cells? The last possibility is suggested by reports on exceptional cases such as the five cases i n whom blastic transformation started with destructive-lytic lesions in the bones." the patients with typical blood and marrow features of thc chronic phase in whom 108 P. A. STRYCKMANS hl;lstic transformation w a s seen o n l y in lymph nodes ( t w o patients) or in the ccrchr~)spill:ilIILlid (two p:I[icnts)" :Inti the patient in whonl h h t i c transl'ormation started in a post-t rauni aI ic hc*:l;itoma.1') The Phl anomaly persists during the blastic transformation. hut all sorls 0 1 additional chromosomal abnormalities appear on top of it in about t*'o thirds o f the I nc~ses.22.J11.~~.71.8~.111.1)o.137.14~,IJI.IJ~ most cases, abnormalities O( several autosomes ilre seen often associated with t h e appearance of aneuploidy. Hyperploidy represents the most frequent linding but hypoploidy may ;~lsohc seen. The appearance of two or more Phi chromosonles either heralds or ac- companies the development of the blastic I t may appear a consid- erable period of time before the blastic phase develops.35 Serial investigations have provided evidence that progression of the disease is accompanied by a karyotype evolution which leads to chromosome complements with increasing numbers o f numerical a b n ~ r m a l i t i e s . ~ ~ "I~t "h'a~s been proposed that the nondiploid cells differentiate less successfully than diploid Phl-positive cells."'This will result in a more dedifferentiated appearance of the marrow and is supported, not only by the increased proportion of myeloblasts in the marrow and the blood. but also by findings suggesting disorganized differentiation with nucleo-cytoplasmic asynchrony. namely, premature devel- opment of PASw and Sudan black B'42positivity as well as peroxidase activity9' in blast crisis myeloblasts. Serial caryotypes during chemotherapic treatment of the blast crisis have demonstrated the heterogeneity of the leukemic cell population. Several leukemic clones could he recognized which responded differently to chemotherapy since some decreased as a consequence of treatment while othcrs were recorded for the first time after ~ h e m o l h e r a p y . "T~he cell line not seen before treatment may have been dormant and therefore resistant to therapy. This ob- servation supports the idea to treat intensively CM L in the chronic phase since it suggests that if a Ph'-negative cell line in a dormant state exists in all C M L patients. an assumption for which we have arguments, it may survive to the tredtment better than the Ph'-positive cells and. by proliferation, become predominant thereafter. An important question which is intimately related to the treatment of CM,t i; and which has been extensively-discussed in the last few years is whether CML $Iin its chronic phase is a true leukemia or rathcr a preleukemic condition. In dther words. is the acute blastic transfo fiih "built into" the disease from the very beginning79or is it rather an additional evenills which does not necessarily occur but has o n l y a high risk to occur in a disease characterized by a chromosomal abnormality and therefore predisposing IO leukemia.'" The fact . that the development of cytologic and PAS anomalies in the myeloblasts late in thc discrlsc is positively correlated with karyotype,alterations and the Fact that thc Icukocy~calkaliiic phospliatasc dccrcasc sccn carly in the disease. may be due to incomplete maturation of granulocytic end-cclls on carly rclcasc I'roni the bone marrow rather than to a maturation defect."* have been argued for the theory of C M L being a preleukemic state."" However, strong arguments exist for the opposite theory of C M L being leukemic from the very beginning. One is the correlation found by Bergsagel between the duration of remission CHRONI follou other c;lcll c in IO cells ; r busulf up to for mc i t s on! was nc evolut the di: 1 _- dl h -m U -JI I u u -'0 0 0 1. E -Q1 .C- -m 3 v .L- U 0 L 3 I m E -E 0 -5 07 5 il 3 0 0 Fig. numb deter! joins rhortc CKMANS in the forma- orts 01' ) thirds ,ies of Iploidy. also be , or acconsid- disease compleas been dipioid :e of the :lobi ;ISLS Pganized e develict ivit y 92 sis have Several chemoiers wcrc n before This obase since all C M L ve to the ome pre- o1'CML her C M L dition. In :ase from 101 neceslzcd bv 3 ' The I'act >lasts late d the pact ease, may IC;ISC froin irgiied Ibr arguments bcgi n 11i 11g. remission CHRONIC MYELOGENOUS LEUKEMIA 109 followins the first course o f busulfan and total survival from diagnosis.' Another is ihc f x r th;it thc douhling time (T,) of t h e white blood cells d t c r c:icIi c'oursc ol'husull';iii W;IS l.oiiiicl 10gci slioricr wiili iiiiic." I n thc s;iiiic line,'.'' iii IO oul 01' I2 c;iscs 01' CMI.. ilic 'I-? 01' the iiuiiibcr ol' iiiiiiiniurc myeloid cells in t h e blood between successive courses of intermittent treatment with busulfan and/or '2P has been found to become progressively shorter with time. up to the blastic transformation (Fig. 3). In one additional patient followed for more than IO yr and still in the chronic phase of her disease 20 yr after its onset. ;L very slow shortening of the TI could b e seen. The shortening of T? was not found to be related to t h e treatment but appeared rather as the natural .)voIutioii of the disease. I t strongly suggests that. at the time of diagnosis. the disease was already progressing towards its terminal phase. This concept is r '72' / Mo:lths bofore doath Fig. 3. Shows for 12 patients deceased the correlation between the doubling time (1,) of the number of immature myeloid cells/cu m m of blood ( i n ordinate) and the time at which this was determined before death ( i n abscissa). A different symbol i s vsed for each patient, and each line joins the rutcessive estimations of 1, for each patient. The eight cases whose 1, became shorter than I 2 days a l l died within a year (dotted square). 1 IO P. A. STRYCKMANS compatible wiih the finding t h u t . at the very beginning ol' thc discasc. the ! 'H-thymidine labelin_eindex o f the myeloblasts was considerably lower than in normal myeloblasts and ;1s low as it is seen in acule transformation or in acute myeloblastic leukemia.* T h e s ~findingsstronply support the hypothesis that the blastic crisis is the fully expressed end of a continuous process which i s pro- 1gressina. more or less rapidly. from the very beginning of the disease and is not all'cctcd by o u r actual trcatincnts. ..t' -3 THE TREATMENT OF CHRONIC M Y E L O G E N O U S LEUKEMIA large number of drugs have been found to have sonic activity in C M L . All these studies were different in their aims ilnd methods and will therefore be classilicd ;ISIbllows: ( I ) The studies which indicate that a drug is able to induce i\ remission (decrease of WBC. spleen, and platelets and eventual increase of hemoglobin). The drugs only studied in this way are the following: nitrogen uracil m u ~ t a r d . ' ~ 'vinblastine,b' t h i o g ~ a n i n e .T~E~M.I2' m e l p h a l a r ~ , 'C~ ~ol- cemid.gOetc. (2) The studies in which a drug in its capacity to induce remissions was com- pared to a reference drug (usually busulran) in ;I randomized way for a limited period of time. Such studies have shown that 6M P.M chlorambucil"X and cyclo- phosphamidemare less active than mylerari in inducing a remission. (3) The studics in which one mode of treatment was given over most or a l l the duration of the disease. These studics makc it possiblc to cvaluatc lhc mcdi;in survival of the patients so treated. Splenic irradiation.'" '2P,124busulfan.'"'" h y d r o x y ~ r e a , 'a~nd dibromomannitoI2' have been studied in this way (Table 1). (4) Only rare studies of this type exist. The M RC study compared on a ran- dom basis, the median survival obtained with t w o ditferent modes of treatment namely busulfan and splenic irradiation'" (Table I). BUSULFAN (MYLERAN) Busulfan has been considered up to now as probably the best treatment available in CML.48This view may be challenged, n o w that new approaches Table 1. Survival of Patients Treated for CMl Treatment None '2P Busulfon Busulfan Splenic irrodiotion Number of Patients 52 118 30 48 54 Median Survwal (4 31 32 42 40 28 Survival From - EO EO 6T 61 Oibrornornonnitol 73 Hydroxyurea 10 Hydroxyurea 43 -(+ or splenectomy) +Chemo. immunotherapy 15' ~-~~ EO. erwnared onset; BT, beginning of treatment; 0.diagnosis 'Selected portents 43 50 39.6 > 84 D D - - Ret. 104 124 58 - 100 100 28 76 132 13c CP to V;i de Ck to r;l IC; su CC' th cc sr IIt tf re le SI' or cl, tlfr VI A tr P IT lt 0 1C P ti 4 \4 n G F IC r 1 \: c- RYCKMANS m e . the r th;in in in acute , that the h is prose and is in CML. :refore be remission Ioglob i 11). n ustard,'' 1,133 Col- was com. a limited and cyclo- t or all the he median S U Ifan .5B*lw (Table 1). I on a ran- .treatment t rea tmen t approaches Ref. I04 124 58 100 100 28 76 132 136 CHRONIC MYELOGENOUS LEUKEMIA 111 to trcatmcnt of CM L secin promising. The method o f administration. the adv:iiit:igcs and t.hc haz:irds 01' rnylcr;ln iii CM I_. which have been rc1ii:lrkably clchcribcd h y <;;illon iii ;I 1969 issuc oi' this jotirii;iI." havc practically not chanscd since then. Thcrcl'orc. iii;ijor points only will be stressed hcrc. Thc individual daily dose seems more important in terms of toxicity than the total dose. The daily dose should not cxcccd 6 mg or even 4 wig.'' Siiicc the rate of fall is dose related. with these relatively low doses, the decreiisc o f the leukocytc count in t h c blood is slow and wcckly blood controls are therefore sullicicnt to adapt the dose and avoid ovcrdos;lgc. The dccrcasc oI' the leukocyte count is generally a good indicator o f the therapeutic effect of the drug since this decrease is usually accompanied by a decrease o f the size of spleen and by correction of anemia. A decrease o f the leukocyte count without effect on thc spleen or without correction of the anemia ottcn announces blastic transforma- tion. The leukocyte count still increases during thc first IO 15 days o f the treatrnenl." This occurs in most patients and should not be considered as resistance to the drug and the daily dose should t h u s not be increased. The leukocyte count may continue to fall more than 1 mo after treatment has been stopped. Therefore, busulfan should be stopped around 15.OOO/cu m m and not only when a normal leukocyte count has been reached. When a normal leukocyte count is reached. no more immature myeloid cells are generally seen in the blood. A t that time. smears of blood Lind marrow may be undistinguishable from normal, ;1 result rarely obtained with other chemotherapeutic agents. When the platelet count falls below the limits of normal during treatment. vigilance is required since persistent thrombocytopenia and irreversible marrow aplasia have been encountered in these cases when treatment was continued. A trend for platelets to decrease faster than expected may herald blastic transformation. In most cases. at least in the beginning of the disease, the anemia is completely corrected by the intake of busulfan. Transfusion is not part of the treatment and should be given only in exceptional cases of severe anemia. As for the platelets. a tendency for red cells to fall. should make one suspect either overdosage or blastic transformation. Busulfan appears to be as eflective as irradiation o t the spleen in its capacity to shrink the spleen and to maintain i t in a state of regression for long periods. Itn Whether a maintenance treatment with myleran should be given or whether the treatment should be discontinued when the leukocytes are nearly normal is a question which has never been definitely settled. The possibility to re-treat with busulfan with the same efficacy several times over many years is an argu- ment for intermittent treatment. I n this case. the patient may not be treated until the WBC reaches 50,000 or even 1OO.OOO/cu mm. since the majority of patients start to complain of fatigue, perspiration, and headache only at these levels of WBC. Evidence has been p u t forward for a. better maintenance of normal or subnormal levels of henioglobin in the case of continuous therapy.'# However. no controlled study answered the question in terms of survival. A n y way, either type of treatment seems compatible with a long survival: Galton'" describes a case surviving more than 13 y r on almost continuous therapy -. . '1 - r I I ? P. A. STRYCKMANS \vhcrc:lx otic o l " t i u r p;liictiis trc;itcd inlcrnlittcnlly w i i h husull';in only. is still i n the chronic phase ol` her discasc ;il`tcr 20 yr. Whcll rcsisIatlcc to husull.at1 is . .;IC h icvcd scvc r;i I oih cr dr u 2s (d i hro ni oma 11 11i ioI, h yd ro x y u rc;i. m clph :Ila n CIC. have still been fouild active. Only a few controlled studies exist in which busulfiin has been compared wilh other sorts of treatment. The classical study which was conducted by the Medi- cal Research has very clearly demonstrated the superiority Of busulfan over splenic irradiation. This was true for quality of remission 2nd for survival. Another randomized study h a s showti cIc:irly thc superiority of busulfan over cyclophosphilmide in its ability 10 normalize or 10 dccrcasc thc leukocyte count, to normalize t h e platelet count. to increase the hemoglobin. to reduce the spleen, and to improve the performance status of the patient." Cyclophosphamide was also considerably less active in maintaining the remis- sion. Moreover. eariy development of resistance was seen with cyclophos- phamide. Busulfan was also found superior to 6-MP for the over-all control of C M L during a 12-wk course of studybJand considerably superior to chloram- bucil as evaluated after a period of 12 wk."* Among the several toxic effects of busulfan, the bone marrow depression is certainly the most constant one. In most patients, this toxic effect seems dose- related and can thus be avoided if the daily dose is maintained low and is reduced in time. It has been pointed o ~ t ~ . ~tha~t a~ fe~w ~pat*ien~ts ~ap'pe~ar ' much more sensitive than the others and are brought into deep marrow aplasia very rapidly, usually, with doses well tolerated by the large majority of patients. The mortality o f these cases was high. Interestingly. survivors seemed to have long remissions some lasting one or several years. Whether busulfan should be administered deliberately at a dose inducing aplasia in order to obtain longer remissions has been questioned several times.".'*1 Rare forms of busulfan toxicity include: skin germinal cell a t r ~ p h y , 'fe~tal m a l f ~ r m a t i o n s . ~a'nd ;I wasting syndrome.86The most dangerous of these rather rare complications is probably the "busulfan lune syndrome."88~"0.1T" his is seen in patient o n busulfan therapy generally for more than 1 year or m u c h longer. The clinical picture is characterized by progressive dyspnea. cough, fever, weakness. and bilateral crepitations in the lungs. The chest x-rays show characteristic widespread mottling. .A needle biopsy of the lung is useful for diflereniial diagnosis with miliary tubcrculosis. mycotic infection, leukemic infiltration, etc. Pulnionary function studies show an alveolar capillary block. Cessation of the drug led to progressivc clinical and radiologic improvement in some cases." Some cases responded to large doses of prednisone.'I0 Most cases developed progressively increasing dyspnea and died.a*lwHistology of the lungs shows cellular atypia, fibrinous edema, hyaline membranes and interstitial and intraalveolar fibr~sis..'~I.t~'should be nolcd that kinyonc of these arc frequently secn in symptomless CM I. patients whether they wcrc trciitcd with iiiylcran or not."' The ccllulnr atypi:i of lonp- term adrninistrarion of busulfiin are not restricted t o lung; gencralkcd nuclear abnormalities have been reported." DIBROMOMANNITOL (DMB) Dibromomannitol. a polyalcohol derivative synthesized in 1961, was found to he active in the treatment of C M L but to have no advantages over busulfan. C T c` rt f, a 9 d C b e ir a a I: h c u v C T t I: s b 8 L 2 t . is still in usull;in is ~ l l ~ l i cl .tc.) Tared with the Medi:riority ol on and for xiority of :crease the :rnoglobin, e patient.70 the remiscyclophos.all control .o chloram- :pression is ,eems doselow and is :nts appear row aplasia of patients. led to have lfan should otain longer mentation,6 rorne.86The le "busulfan py generally acterized by ttions in the g. A needle tuberculosis. studies show ssive clinical ded to large sing dyspnea nous edema, I t should be :ML patients ypia of longilized nuclear 11. was found ]vet busulfan. _- CHRONIC MYELOGENOUS LEUKtMlA I13 The daily dose in most clinical studies on C M L patients was 250 mg/day decreasing to 250 mg every 2 or 3 days. Given in this way. partial or complete rciii issions were ohl;i i iicrl in CAY!,', XO";, oI' c:~scs~"~""..~~~iln~st.c;id oI' X",, SO",, rcspcinsc rate I'or husulfiin. The Icukocytcs tend 10dccrcasc from the bcginnlny as opposed to busull';in whicli c;iuscs ;in iilcrcasc (or IO IS days. Thc tlmc rcquired to normalize the WBC depends on the daily dose. Using the dose indicalcd, 80% of the patients werc in remission within 3 m o of treatment. Only 13% though achieved a complete remission, i.e., normalization of cell blood parameters and complete regression of splenomegaly.'6 The beneficial effect on anemia was dilferently appreciated in the different studies. DBM given in doses over 5 mg/kg per day causes considerable and long-lastins _eranuloand thrombocytopenias. Neither erythropoiesis nor lymphopoiesis are severely affected. The toxicity appears to be restricted to the hemopoietic system. The gastrointestinal side-effects are rather insignificant. Complete remissions may last 1-9 mo. In a retrospective study the Dibromomannitol Co-operative Study Group" has shown that the median survival of a group of 122 patients treated with DBM was 43.3 m o or 3.6 yr. The median survival of the 73 patients treated with DBM only was not significantly different from the one of the 49 patients who received DBM for more than half the duration of the disease. This is of the same order of magnitude as that obtained by busulfan in other studies. The 2 5 x survival is at 62 mo for DBM: perhaps somewhat better than for all the other groups (48 mo). The analysis of the causes of death in this group indicated that the blast crisis occurred with the same frequency as in the other studies, i.e., 68.70/, and more probably 74.87; depending on the definition of blast crisis. As in other series. death due to marrow toxicity was not negligible: 8.4% of the cases. HYDROXYUREA Hydroxyurea. synthesized a century ago, is a cell cycle-phase-specific agent: a specific inhibitor of D N A synthesis. Since more than 90% is excreted within 12 hr.' it was recommended to give the drug every 12 hr. Given to hematologically normal individuals. it causes several hematologic anomalies such as anemia, neutropenia, thrombocytopenia, megaloblastosis. Howell-Jolly bodies, macrocytes, and hypersegmented P M N .74 A clinical study was performed on 20 cases of CML76who received 50 mg/ kg/day in two divided doses until the WBC was below 1O.OOO/cu mm. The WBC was rapidly normalized within a week o r two in all of the cases. A n increase in hemoglobin to more than 12 g/lOO ml occurred in the 12 of the 16 patients with anemia. Splenomegaly which was present in the 20 patients was reduced by more than 90% in 18. In the 1 I instances of thrombocytosis, a reduction of platelets to normal values occurred following the decrease of WBC. These excellent results were obtained despite the fact that ten patients were no longer responsive to busull'an. The bone marrow returned to a near normal differential count in all patients studied serially unless myelofibrosis had developed. Subsequently, a maintenance dose of approximately 20 mg/kg/day was employed. This dose was found to produce a continuing suppression of the WBC. The median duration of improvement was 41 mo. and t h e median sur- - - I I4 P. A. S~RYCWMANS viva1 from diagnosis to death was 50 n l o for tcn patients w h o hiid not hiid prev ioLISch emot h er;i py . I n another study."' lower doses were given: IN0 2500 mg/day for induction. A complete remission. i.e.. a complete disappearance of all blood and marrow signs of C M L (except the chromoson1rIl abnormality). as it is often obtained with busulfan. was only rarely seen. I n [act. in 43 cases SO lreated. a "complete remission" was observed only once. Another ditTerence with busulfan. probably related to the previous one. was that a rapid increase of the WBC was observed as soon as HU was stopped. The median survival (40 mo) appeared similar to that obtained by the other classical treatmenls. I t should be pointed out that this last study does not allow a precise evaluation of the antileukemic activity of H U . since for 15 of these patients. the treatment consisted of splenectomy I'ollowcd by H U and repeated Icukaphcresis. However. this study probably indicates that when a complete remission or nearly normal whitecell count is not maintained most of the time. the results are not worse in terms of survival. An important information which has 10 be kept in mind when usins H U is that. in certain patients. even when the dose is kept constant. cyclic oscillations of the leukocyte count may be observed.'-' I n one single cycle the WBC was found to vary from normal 10 15 or 80 or even 170,OOO/cu mm. The cyclic periods usually ranged from 30 10 50 days with considerable similarity in each individual. Similar oscillations with the same periodicity as the leukocyte count were observed for t h e platelet counts. The recognition of this phenomenon during H U treatment is of course o f great practical importance for the dosage regulation. Despite a mechanism of action apparently very different from the one of the other treatments effective in CML,the median survival obtained in these two studies appeared similar to that obtained by the other classical treatments. I t is clear that as all the other agents tested so far. on one hand, it does not prevent the development of myelofibrosis and blast crisis, and. on the other hand, it may be responsible for fatal bone marrow aplasia. Besides the bone marrow suppression. systemic reactions were seen. They consisted in mild anorexia and dermatologic alterations such ;IS partial ;ilopeciii. pigmentation. dry skin. atrophy of the skin and subcutaneous tissuc, nail changcs. a n d crythcnia of thc face and hands which occurred mainly with long-term continuous maintenance th erapy .l6 The mode of administration of H U has not been entirely examined and could probably be improved. For instance. there are studies on solid tumors. suggesting that larger doses (80 mg/kg) givcn every third day in ii single dose are better tolerated and might have greater antitumor ctTecLs!' SPLENIC IRRADIATION This method of treatment has been somewhat- abandoned at the moment. although it has been extensively used in the past. At a dose of 600- 1000 rads, it is elfective not only to shrink the spleen but also to normalize the peripheral blood and the bone marrow.*J Several observations give an explanation for the systemic effect of this local treatment. The myeloid meiaplasia seen in the spleen of these patients has suggested for a long time that an abundant cell production CKMANS i t had inducid :ind often ecated. 2 with ase of irvival ments. uation ilmenl Hownearly ire not ept in s kept 'I1 one r evcn s with same s. The great of the se two nts. It )t prehand, i;irrow ia and skin. of the :11ilTICC d and ~iiiors, c dose 1 :nt* alIS.it is I I)Iood o r the 5pleen I LIc t ion CHRONIC MYELOGENOUS LEUKEMIA 115 occurs in this organ. This impression was confirmed by kinetic studies conducted by Clarkson et al.'OJ who showed. using infusions of 'HTdR into the splenic artery, that the great majority of the immature myeloid cells in the blood of these p:itients originate in the spleen. However. splenectomy is not very efticient in decreasing the WBC. and the arrest of production in the spleen is probably not the only way of action of splenic irradiation. The obsrrvaiions mndc by Mt~xley'~a'nd Galbraith" may explain the normalization of blood and bone marrow after irradiation of the spleen only. These studies indicate that the immature myeloid cells in C M L circulate from blood to marrow. from blood to spleen and from spleen to marrow. However, they still do not give a complete explanation for the bone marrow aplasia sometimes observed after splenic irradiation.'" Such clinical observations would support the theory of the release into the circulation by the irradiated spleen cells of an inhibitor of the myeloid cell pr~liferation.~' Splenic irradiation is capable of maintaining a state of regression for long periods of several months. However, progressively, courses of radiotherapy using successively higher doses are required and cause less regression. Splenic irradiation ;is the sole form of treatment of CM L has been rather abandoned. This was due to the publication of the results of the controlled clinical trial by the Medical Research Council's Working Party for Therapeutic Trials in Leukemia conducted on 102 untreated C M L patients who were allocated a t random for treatment by either splenic x-irradiation or busulfan.Iu0 It has shown that busulfan was significantly better at obtaining and maintaining a higher level of hemoglobin concentration. Moreover, the median survival time was longer in the group allocated to myleran (170 wk) than in the group allocated to splenic irradiation (120 wk). The incidence of blast crisis being the same in both groups (7OUi;;). suggests that treatments may be different in their capacity to delay or to enhance the blast crisis. A n important conclusion from this clinical study is thus t h a t it seems possible by the treatment to influence the time of onset of the blast crisis. Splenic irradiation has, since then, no longer been used alone for the treatment of C M L. However, it remains a practical way to obtain 3 rapid decrease of the size of the spleen even in some cases resistant to myleran. EXTRACORPOREAL IRRADIATION OF THE BLOOO (ECIB) First described by Cronkite et al.2J*'3a' nd Thomas et al.,''' this technique permits the irradiation of the peripheral blood cells only. I t takes advantage of the radioresistance of the erythrocytes and in the case of C M L of the existence of a rapid traliic of myeloid cells existing between marrow and spleen via the blood. A chronic arteriovenous shunt inserted in the forearm is connected to an extracorporeal circuit at the time of irradiation. The blood then flows through a radialion source, and the system is built so that the amount of radialion (500 rads) rewivcd by a segment of blood as it passes completely through the irradiation one time (the transit dose) is sufficient to kill the cell. Only few patients wiih C M L were treated by this method. For instance two patients'" with 90.000 a n d 140,000 WBC and 36% and 14% immature white cells, respectively, were submitted to 2-4 h r ECIB sessions, respectively, 14 and 32 times. The re- - I I6 P. A STRYCKMANS suit of this treatment was a decrease of the WBC (to 21,000 and 12,000). a de- crease of the per cent of immature cells in the blood (to 242, and 3x1 and a considerable decrease of the size of the spleen in the second patient. Complete remissions were not obtained. Moreover, after cessation of ECIB, relapse of leukemic process occurred in a matter of days to several weeks. Whether this was due to increased cell production has not been elucidated. There are no studies on the proliferative capacity of the bone marrow cells before and after ECIB in C M L patients. However, studies on the bone marrow of patients with acute leukemia using tritiated thymidine labeling indices and mitotic indices before and after ECIB suggest that it may be increased as a consequence of the irradiation of the b l ~ o d . ~A~n. 'i~ncreased proliferative activity of the myeloid precursors in CML may explain the disappointing results obtained with this technique. Obviously, this form of therapy is not a cure for CM L and therefore in view of the existence of other much more convenient forms of treatment, its use should be restricted to very special cases such as pregnancy, a situation in which all chemotherapeutic agents should be suppressed' at least in the first months. LEUKAPHERESIS As a consequence of the rapid traffic of cells existing between marrow and spleen via a depletion of the blood should theoretically affect the bone marrow also. The continuous flow centrifuge (NCI-IBM Blood Cell Separator) has been used in C M L in order to investigate the possibility to use CML patients as granulocyte donors and the possibility to improve CML pa- tients by subtracting regularly large amounts of blood myeloid immature cells. The efficiency of leukocyte separation and collection was variable from patient to patient with median yields of 18%-53%." In 98 separate centrifugations corn- plettd in 12 CML patients, the average decrease of WBC expressed in per cent of the pretreatment value was only 16.5% (range 45 to 0). Moreover, in most patients, 2-3 days only were required for the WBC to return to baseline level. Since, moreover, red blood cells were always lost during continuous flow cen- trifugation and technical problems encountered i n more than 25% of the ses- sions, it appears that this technique is not very efficient and practical as the only treatment of all CML patients. The explanation for these disappointing results may be the same as the one suggested for ECIB. A complete evaluation of ths role of leukapheresis in the treatment of CML has still to be done since some patients appear to respond better than others. This was the case of a patient. described recently, in whom intensive leukapheresis (12 and 18 sessions) appeared able, by reducing to total amount of leukemic cells, to come back on two occasions to a previous, ap- parently more benign, stage of the disease.j' Whether the patient who exhibited this promising response to leukapheresis had a w r y peculiar form or a rather classical form of CML is important to know but stlll unsettled. SPLENECTOMY The constancy of splenomegaly in CM L has suggcsted for more than a century to remove the spleen as a therapeutic procedure. Thls was followed by an opera- - CHRONIC I ,_ tivc rnc i exist i n fection I the chr i either t I as CM therap! and 19r opera t i Great I in nine per forr therefo the trar been u leu koc; proved had a r( Thre fullyev has bee siderab therap! disease case), r tive rist In thes rhagic : in the c transfo rarely operari Spier the sub chronic pict u re to redL disease _the-spl reservc subline transfo spleen I trea tmt tensive to decr ready r YCKMANS ), a deI and a mplete ipse of ier this are no d after ts with indices :of the nyeloid th this erefore ent, its tion in he first )w and ict the ,d Cell to use 4L pa-e cells. patient IS com)er Cent n most e level. IW cenhe seshe only .he one in the espond l whom to total us, aphibited rather century opera- CHRONIC M Y E L O G E N O U S LEUKEMIA I17 tivc mortality of 25"/,i'J or more which was due partly to the difficulties still existing at that time for blood transfusions, anesthesia. and treatment of infections. Since splenectomy was. in most cases. performed in order to control the chronic phase of the disease and since it did not generally modify greatly either the blood picture or the late outcome of the disease. it fell into disrepute as C M L became easily controlled by progress in radiotherapy and chemo- therapy. Strumia"' reviewed 34 cases published in the literature between 1940 and 1964 iiicluding live ol' his own cases and round still a n operative and postoperative mortality of the order of 252, as it was during the period 1902- 1939. Great improvement was noticed in five patients out of 34, minor improvement in nine. It should be pointed out that, at that time. splenectomy was generally performed because of loss of control of the disease in its chronic phase and. therefore, on large spleens when the leukocyte count was highi0'.'*' and that the transient decrease following splenectomy in some of these cases could have been unrelated to splenectomy but rather due to undisturbed cycling of the leukocyte count. This explanation is certainly not valid in all the cases who improved after splenectomy. For instance, it seems improbable in a case26who had a remission lasting 8 mo. Three indications for splenectomy have been suggested but have not been fullyevaluated. Decreased platelet production due to busulfan in gne of them. I t has been shown on a small group of six patient5 that splenectomy may considerably improve throm bocytopenia consecutive to long-term pyleran therapy.'* In this study, splenectomy was performed in the chronic phase of the disease. Although the platelet count was generally very low (6000/cu m m in one case), no operative mortality was observed. There was an immediate postoperative rise in platelet count in all six patients which was sustained in five patients. I n these five patients with bleeding and thrombocytopenia. n o further hernorrhagic problems or platelet transfusions were required as long as they remained in the chronic phase of CML.Splenectomy as a part of the treatment of blastic transformation is a second possible indication. I t has been advocated only rarely. It was performed in eight cases in blastic transformation, caused no operative death. and apparently improved most patients.'j5 Splenectomy as prevention of blast crisis is the third possible indication still the subject of an unsettled debate. It consists of removing the spleen during the chronic phase of the disease when the size of the spleen and the hematologic picture have been normalized or almost by a conventional treatment, in order to reduce, as much as possible, the operative risk. Late in the course of the disease the surgical procedure is certainly more difficult. The rationale is that the spleen contains Ph'-positive cells."' and constitutes therefore a large reservoir of cells susceptible to transformation. As a matter of fact, abnormal sublines of Phi-positive cells have been found in the spleen at the time of blastic transforniaiion.i'Y:ind it is conceivable that this transformation may start in the spleen (cited by Galton"). Early splenectomy per se is certainly an inadequate treatment. I t is proposed as an adjuvant procedure in combination with an intensive chemotherapy in order to get rid of the Ph'-positive cell line or at least to decrease the number of abnormal myeloblasts seen in the bone marrow already at the time of diagnosis.' -. 118 P. A. STRYCKMANS Single cascs have already shown ux t h d t blast crisis may still occur after c:irly splcncctoiiiy . Moreover, no randomired study has SO far demonstrated that splsiicctomy pcrforiiicd i n thc chroriic p h ; w durins ;I period oi' remission is certainly a useful procedure in C M L . I n a clinical study pcrlbriiicd by I ~ c group of Villejuif, splenectomy was performed as soon ;IS the first remission had been obtained by chemotherapy."' This study suggests that the blast crisis may be delayed by splenectomy. since the median survival of 15 splenectomized patients (43 mo) was 6 mo longer than the niedinn survival of 25 patients who refused splenectomy (37 mo). However. the incidence of the blast crisis (13/ 15) was of the same order as in the reference patients (l9/24) and the morbidity. mainly venous thrombosis due io thrombocytosis. was not negligible. We also experienced this in one of our early CML w h o reached more than 2.000.000 platelets/cu mm. Finally, mortality in the last years, although in decrease. remains prohibitive as it can be seen in Table 2. Whether early splenectomy is a useful procedure for the patient in terms of survival cannot be settled from the available studies. Controlled clinical trials are needed to evaluate the effect of splenectomy performed early in CML. Such a trial is prr .mtly conducted by the Medical Research Council's Working Party on Leukemia in Adults and one has been started by the European Organization for Research and Treatment of Cancer (EORTC), but conclusive results have not yet been obtained. Studies on the usefulness of splenectomy in early C M L might have to be repealed i n association with direrent regimens of chemotherapy. PROPHYLACTIC TREATMENT OF THE BLASTIC T R A N S F O R M A T I O N OF CML The observation that a t the clinical onset of C M L the bone marrow already contains a population of abnormal myeloblasts having kinetic features highly reminiscent of those of the blasts of acute myeloblastic leukemia2 suggests the Authors Strumia 1940-1964 Meeker e l 01. 1967 SoLal et al. 1971 Conellos et al. 1972 Schwortrenberg et 01. 1973 Spiers 1973 Stryckmonset 01. 1973 Total 1967-1973 Table 2. Mortality of Splenectomy in CML ~ ~~~~~~~~~~ ~~~~~~~~ Operative OI fndicarions No. 01 Cases Pos4aparat~ve Death Evolution Ret. Resistance. severe paln Hypersplenivn. splenomegoly Hypersplen9sm. blast crisis Thrombocytopenio after busulfan Prevention of Bc in early CML Prevention of BC in early CMl Prcvenbon of BC in corly CML 34 15 17 6 18 (17) 3 8 (23%) 3 5 great improvemeni 9 minor improvement 8 improved I43 101 0 Immediate benefit 1/2 135 Losiing improvement 1/4 0 5 improved 14 3 (o?) 6 mo increased . median wrvival? 132 140 0 59 6(10%) Ct- P' rh th i( m tC ki A SI Si rr ti I: I, e 5 F \ f 2YCKMANS bur after mstrated :ill issioii J by the mission ast crisis :tom ized :nts who i (13/15) orbidity, We also !,000,000 'ease, re- terms of cat trials I L . Such ng Party inization ults have riy CML r chemo- : CML H already es highly ;gem the ~ Ref. 143 101 2 135 114 I4 132 140 CHRONIC MYELOGENOUS LEUKEMIA I19 prevention of their accumulation by destroying them as soon as possible during the chronic phase of the disease. Since busulfan appears to have more tendency 1h;tii the (11 her ;igcnls to produce 1ong-l;isting cytopcnias ;ind sincc, niorcovcr. 11 is not ;I cell cycle-pliusc spccilic: agent, i t docs not seem rc;isonablc 10 rccoiiimend its use at higher doses. I n the present state of o u r knowledge, it is logical to believe that the best chemotherapeutic regimens for acute myeloblastic leukemia could also be the best candidates for this prophylactic chemotherapy. Arabinosyl-cytosine is therefore probably a drug of first choice. There are data suggesting that this drug might act selectively on myeloblasts since it has been shown, in CML. to be more active on myeloblasts than on promyeiocytes and myelocytes.' There are presently several clinical studies going on in order to test the validity of this sort of chemotherapy for delaying the blast crisis. In the same line as studies carried out in acute lymphoblasticY6 and acute myeloblastic" leukemia, another approach has been to stimulate the immunologic defenses of the organism presumably against the leukemic blasts. Sokal et have recently published the results of a study of C M L patients w h o were subjected to repeated vaccination with BCG and allogeneic cultured cells. Fifteen patients with uncomplicated Phl-positive CM L were treated with conventional chemotherapy whenever it was found necessary and moreover, except forone receiving BCG alone, they were immunized with one o r both of t w o cultured cell lines mixed with BCG organisms. One o f the cell lines was established from the peripheral blood of a patient with acute myeloblastic leukemia, the other was established from the blood of a patient in blastic crisis of Phl-positive CM L. Most patients received their first three vaccinations at 3-6 wk-intervals. The interval was extended gradually so that they received three to four vaccinations per year when the niaintenance schedule was reached. These i 5 patients were compared to 28 unimmunized historical controls whose initial prognosis and chemotherapeutic management were comparable to those of the immunized patients. A survival curve for the immunized patients was constructed despite the fact that they entered the immunotherapy program at widely varying times after diagnosis (0.5-7 yr). The median survival of the immunized patients (more than 7 yr) was strikingly better than that of the selected controls (about 3.5 yr). This study certainly suggests a favorable effect ofimmunotherapy but does not prove it, firstly, because the treatment was not randomly assigned and, secondly, because immunized patients were admitted in the study any time after diagnosis which may have resulted in the selection of patients who survived longer than the average. A controlled trial on a random .basis has been started by the same group (personal communication). I f their init ia I rcsu Its :I rc confir iiicd 111;I11y q iicsIi o n s w o ii Id st i I I rcni;i i n 11n ;Inswcrcd . Is the mechanisni ol'action iinmunlogic? Il' so, is it a specilic or nonspecilic immunologic stimulation? What is the part played, respectively, by BCG and leukemic blasts? What are the hazards of BCG administration? ERADICATION OF THE LEUKEMIC CELLS This term will be used here indifferently for eradication of the Phl-positive cell line. There x c important I'acts which justil'y the coiiccpt ol'cradication. The first is that ail the chromosonial analyses ol' blast metaphases during I20 P. A. STRYCKMANS acute transl'ormation have shown the persistence 01' the Phl chromosome, implying t h a t it is always in this cell line that transformation will occur. The second fact is that in vitro studies clearly indicate the coexistence of Phi-positive and Ph'-negative myeloid cells in t h e bone marrow.mThe absence of Ph '-negative cells tis it is obsei ved i n most direct karyotype analyses. probnbly reflects the inhibition o f proliferation of these cells rather than the absence of these cells. The third Fdct is that in a few cases. as a consequence of chemotherapy. the Phl-negative cells became predominant in t h e bone marrow. In most cases it was unexpected and occurred as a consequence of a busulfan-induced aplasia. Finney'l has described a patient who, after a busulfan-induced bone marrow insufficiency. has had a remission lasting 10 yr. During this period o f time, seven chromosome studies on bone marrow cells have shown that 70%- loo?,, of thc mitoses were Ph'-ncgative. G a l t ~ n 'h~as recently reviewed several of his cases ol' C M L treated with busulllln w h o showed a preponderance ol' normal Ph'-negative cells with persistance of o n l y some Phi-positive cells. All these cases were found among patients whose bone marrow had become severely hypoplastic after treatment with busulfan. Within this subgroup, the few who showed regeneration o f apparently normal bone marrow with Ph '-negative cells and restoration of an apparently normal blood picture had received relatively small amounts of busull'an. treatnient having been discontinued or reduced rapidly because of an exceptional sensitivity to the drug. Maurice et aLW have reported a case of CML, who. after busulfan treatment, had severe pancytopenia for I yr and had still, 9 yr later, a completely normal hematologic status with Ph'-negative cells. This study was only very suggestive of eradication of the Ph'-positive cells since chromosomal analysis was not yet available at the time of diagnosis. It should be kept in mind that the long duration of a normal hematologic status only does not imply "cure" since relapses have been observed after more than 6 yr complete remission."' These clinical observations allow us t o draw two conclusions and to make certain working assumptions. Firstly, in some cases at least, preferential cytocidal effect can be obtained on the leukemic cells and it may be assumed that isnot intrinsic to the cell and specific to busulfan but. instead, a consequence of a greater proliferative x l i v i t y of the leukemic cells and therefore obtainable by other drugs. Secondly. these observations also indicate that the Ph '-positive cells have probably to be considerably decreased in number before the "normal" cell line is able to reappear. This second finding may be explained by a negative feed-back exerted by the abnormal cell line, on the normal cell line. The persistence of a regulatory mechanism i n CM L. strongly suggested by the cyclic oscillations of the leukocyte counts in CML. is compatible with this hypothesis. Thus, excellent arguments do exist to induce deliberately an intense marrow aplasia. I t should be of short duration to be a b l e t o give the patient the best supportive treatment available if necessary. Moreover, cycle phase-specific agents should probably be used in order to protect the "dormant" Phi-negative cells. Therefore, the long duration and the unpredictability of the aplasia induced by busulfan and the absence of cell cycle phase-specificity of this agent make it a bad candidate for this sort of eradication treatment. CHRi A Star oft of r ofc mal pati tho: sort- T si0n was erac Ph ' CUI1 m aJ mye mer: out m ;i r neg: pear N viva abl) mon in a bilit; find men by t t the r tom: TI restr inclL Fi L a no low COUI( I. i Leukc kineti( Invcs1 ~CKMANS ?e. im- :nce of lbsence probaabsence ,py, the cases it aplasia. marrow )f time, 100% of I of his nor ma I .I1 these severely 'ew who tive cells elatively reduced have pancytojc status m of the the time L normal Deen ob- to make tial cytomed that juence of inable by I -positive the "norined by a cell line. .ed by the with this an intense utient the se-specific !-negative 3plasia inthis agent CHRONIC MYELOGENOUS LEUKEMIA 121 A prospective study based on this concept of therapy of CML has been started in a n attempt to determine i f intensive treatment might alter the course of the disease by elimination of the leukemic stemline." The regimen consisted of radiotherapy of the spleen followed by splenectomy, then an intensive course of chemotherapy with arabinosylcytosine and thioguanine, and usually further maintenance therapy with various chemotherapeutic agents. In eight of the patients studied. two showed disappearancc of the Phl chromossme. I n one of those. i t reappeared in 0 wk whcrc:ts the second W;IS still I'rcc 01' the chromosome abnormality more than 2 yr after its disappearance. The information available indicates clearly that the Ph'-negative cells occasionally seen in Ph'-positive patients must have been present before treatment was begun, although they could not be found in chromosome analyses. Since eradication has so far been rather exceptional, it raises the questions whether Ph '-negative myeloid stem cells are present in all the cases of CML. The difficulty of obtaining iI Ph I-ngativc bonc inarrow by chcmothcrnpy in the grcat majority of the cases. does not exclude the universal presence of Ph '-negative myeloid cells in CML. This difficulty could only reflect the inability of our treatments to affect preferentially the Ph'-positive cells.49 I f this is the case, it holds out the hope that with better Chemotherapy the return to a Ph '-negative bone marrow is possible in all the patients. Unfortunately. so far the return to a Ph '- negative state usuaily was neither complete nor permanent; nevertheless, it appeared to be associated with a long s ~ r v i v a l . ~ ' * ~ ~ . ~ ~ . ~ SUMMARY None of the classical treatments have so far significantly increased the survival of CML patients. This general statement includes all the treatments suit- ably tested, namely, "P, splenic irradiation, busulfan, hydroxyurea, or dibro- momannitol. However, there is no doubt that all these treatments have all, each in a difTcrcrcnt way, improved thc quality of thc survival. Moreover, thc possibility to choose among several treatments makes it more and more possible to find in individual cases, with toxicity or resistance, another more suitable treatment. Other therapeutic procedures which are not able to control the disease by themselves have to be evaluated for their capacity. as adjuvant. to improve the results obtained by chemotherapy. These procedures include early splenectomy, extracorporeal irradiation of the blood, leukapheresis, etc. The therapeutic erect of immunotherapy, which appeared in humans to be restricted to acute myeloblastic and lymphoblastic leukemia, could perhaps include CM L. This deserves additional evaluation. Finally. the few patients in whom intensive chemotherapy was able to induce a normal hematologic state with disappearancc of thc Ph I-positivc cell line allow us to hope that, with better drug administration schedules. such results could be obtained on more patients and maintained indefinitely. REFERENCES 1 . Athens JW,Raab SO. Haab OP. CI al: Leukokinetic sludics. X . Blood granulocyte kinetics in chronic myelocytic leukemia. J Clin Invest 44:765. IYOS 2. Baccarani M. Killmann SA: Cytokinettc studies in chronic myeloid leukaemia: Evidence for early presence of abnormal myeloblasts. S w n d J Haematol Y:283. 1972 I 2 2 P. A. STRYCKMANS 3 . H;iccar;ini M. S;intucci M A . Zacc;iri;i A . et ai: Kinerics 0 1 graiiulacyte precursors in chronic niyclciid Icuhcinia: The clTcct 0 1 arabinosyl cytosine. Second Mcetii~g0 1 the Europ a n and African Division of the International Society of H;iem:itology. Prague. Augus! IY73. p 89. 4. Banerjee TK. Hansjocrg S. Holland Jl-: Comparative studies on localized leukocyte mobiliz;ction iii patients with chronic m y c l & l leukemia. Cancer 29:637. 1972 5. Barr R D . Fialkow P: Clonal origin of chronic myclricyric leukemia. N tingl J Mcd 28Y:307. 1Y73 6. Baxt W. Hehlmann R. Spicgelman S: Human leukaemic cells contain reverse transcriptase associated with high molecular weight virus- related RNA. Nature [New Biol] 240:72. I972 7. Becklotf GL, Lerner HJ. Frost 0. et al: Hydroxyureii (NSC 32065) in biologic fluids: 0osc-concciitr3tic)ii rclatioitship. C:inrcr Chcmothcr Rep 48:57. 1965 8. Bergsagel D E T h e chronic leukemias: A review or disease manifestations a n d the aims ortherapy. C a n Med Assoc J Yh:16lS. 1967 9. Bernard J. Mathe G . Najcdn Y: Traitemcnt d e 50 IeucCmies myiloides chroniques par Misulban. Scm Hop Paris 313083. 1955 IO. Bernard J. Seligmann M, Kvicala R: La transformation aigut de la leucemie myiloidc chronique. Rev Fr Etud Clin Biol4:1024. 1959 I I. Braiidt L: Phagocytic activity of ncutro- philic leukocytes in chronic myeloid leukemia. Scand J Hacmatol [Supply]2 3 . 1967 12. Brcsciani F Cell proliferation in cancer. Eur J C;inccr 4:243. 196% 13. Buckiicr D. G r a w I<(;. liiscl K J . CI :iI: Lcukapheresis by continuous flow centrilugation in patients with chronic myelocytic leu- -kemia. Blood 33:353. I969 14. Cancllos G P . Nordlvnd J. Carbone PP: Splenectomy for thrombocytopenia in chronic -granulocytic leukemia. Cancer 29660. 1972 I S . Canellos GP. Whang-Pcng J: Philadelphia-chromosome-positive prclcukaemic state. Lancet 2: 1221. 1972 16. Casazrr A R , Cahn EL, Carbone PP: Preliminar! studies with dibromomannitol (NSC-94 Ilk)) iii p;iricnts with chronic myclogenous kiihci1li:l. Cmccr Chcinothcr Kcp 5 I : Y I , 1967 17. C;lr;oldi G. Yam LT. Mitus WJ. ct al: Chromowimal studies in erythroleukemia and chronic e:ythremic myelosis. Blood 31:202. 19om I x. ~JSt,lldi(j 1.. sr;ip"ll <iL. l~~lllilpicL~~ll:i 8. ct Ail;llyse des ;~n~imalicschronitiw- nliqucs d a m I'airCinic pcrnicieusc. Nouv Rev I-r Iieiiiatol Y:7hY. IYOY 19. Chan BWB. Hayhoe FGJ.Bullimore JA: Erect or extra corporeal irradiation of the hood on bone nlarrow activity in acutc Icukae- mia. Nature 22 1:972. IYbY 20. Chcrvenik PA. Ellis LD. Pan SI-.et ill: Hutnan leukemic cells: In vitro growth ol colonies containing the Philadelphia (l'h') chromosome. Science 174:1134. I971 Z I . Chicapo Conference. Standardi7;ction in huin:iii cytcipciictics. T h e N:itic)ild l.t)ui\d:ititil1 March ol' Dimes. IY66 22. Court Brown W M . Tough IM: Cytoge- netic studies in chronic myeloid leukemia. Adv Cancer Res 735I. 1963 23. Cronkite EP: Extracorporeal irradia- tion o l the blood a n d lymph in the treatment of leukemia a n d for immunosuppression. Ann Intern Med 67:415.1907 24. Croiikitc IY. Vinccnt I'C: Gruitilo- poicsis. Scr Hacmatol 2:3, 1969 25. Crowther D. Powles RL, Batcman CJT. et 11: Management or adult acute myelogenous leukaemia. Br M e d J 1:131. 1973 26. Cutting HO: .The effect of splenectomy in chronic granulocytic leukemia. Arch Intern M c d 120356. 1967 27. Diamond L. Anderson MM. McCready SR: Transplacental transmission of busulrdn (mylrran) in a mother with leukemia. Produc- tion or lct:il rn;ilformation and cvtomeply. Pediatrics 25:15. 1960 28. Dibromomannitol Cooperative Study Group. Survival of chronic myeloid leukemia p:i~iciiIs treated by dihromom;iiinitol. Eur J C'aiiccr 9 : 5 8 ? . 1973 29. D c G r o u c h y J. De Nava C. Cantti JM. et al: Models for clonal evolutions: A study of chronic myelogenous leukemia. Am J Hum Genet 18:4(15.1966 30. Djaldetti M. Padeh B. Pinkhas J. et al: Prolonged remission in chronic myeloid leuke- mia after one course of busulfan. Blood 27: 103. I966 3 I . Dourdn L. Onesti G.Woodliff HJ: Cyto- genetic studies in chronic granulocytic leu- kaemia. Ausi A n n M e d 1652.1967 32. Dougan L, Scott ID. WoodlifTHJ: A pair of twins. m c 01- whom has chronic gr:iiiulocytic -leukemia. J MeJ Genet 3:217. 1 Y 6 h 33. Duvall CP, Carbone fJP. Bell W K . ct aI: Chronic myelocytic leukemia with two Phila- delphia chromosomes and prominent peripheral lymphadenopathy. Blood 29:642. 1967 CHROI. 34. EJTeci on ck Chernt 35. rnoson 36. cycle e blood Haem . 37. Leuko fused illye I o 1 2tt Fhilac tive c t Med 7 -49. term . Med 1 40. Clona in ma 1967 41. et al: negat: remis: Haen: 42. dencc lar ne 43. ch rur: metar 44. scquc chr o I; J Y5:: 45. lopol, Brl t 46. loid I 1 47. - lcuke Ag. myelt 1969 49. in:n 1 I-ilth Padu. 50. al: ( ICKMANS ll;lplcclil~i hromoso- ,lIlV Hcv more JA: I of t h e e leukae- iF. et 11: owih ~ l ' ia (Ph') u i i o n in undation Cytope- cukemia. i rVdd iprcalment on. Ann Sranulo- Ian CJT. lopenous ,nectomy h Intern icCready busulfan Producmcgaly. Study cukemia . Eur J ntu JM. study of J Hum J, et al: d leukeI 27:103. J: Cytoqic leu- 1: A p:iir rulocytic R. et al: o Philacripheral CHRONIC MYELOGENOUS LEUKEMIA 123 .I4 !.cLh;irdi 5. Scllci C . Ilorv;~rli 11'. et ai: Icukocyttisis .iiiJ idciiiical twitis dixordaiicc. I-3lcci 0 1 I .h-dihrotno- I .s-dideo~v-I)-nr;innitol Proceedings Anit 1'cdi;itrics SOL. Mcctiiig. t i i i kdiriwic pr:iiiiiIoc\tic 1cuLc.iiii;i. <':iirccr Ail:iiilic < ' i t \ N1. M:iy 1')70. p SO C~liciiit~tlicIr< q i J3:57. 1'Ni.I 51. Ciatti A H . K~ihinsonW h . Dciii;irtl AS. ci 35. Engel E. McKee LC: Double Ph' chro- ai: Cyclic leukocytosis in chronic myelogenous mosomes in leukaemia. Lancet 2 3 3 7 . I966 leukenria: New perspectives on pathogenesis 36. Ernsi P. Andcrsen J. Killmann. SA: Cell a n d therapy. Blood41:771. 1973 cycle cfTect of exlracorporeal irradiation of the 52. Gavosto F. Pileri A. Bachi C. et a(: Pro- hlood in acuie myeloid 1eukcmi;i. Sc;ind J 1ifcr;ition :ind nr:iiur:ition defect iii ;icuic leu- ll;iciii:iiad X 21. 1')71 ti;iciiii;i cclls. N;iiurc 2W:'J2. IWJ 37. Eyre H J . Chisicin IM. Perry S. et al: 53. <ice'IS.Dowlinp M0. Clarkson BD. CI Leukocyte transl'usions: Function of trans- ai: Blastic transformation occurring in extra- fused granulocytes from donors with chronic medullary sites in controlled chronic myeloge- myelocytic leukemia. Blood 36~432,1970 nous leukemia (CML). Proceedings of the Am 2 Ezdinli EZ. Sokal JE. Crosswhite L: Assoc for Cancer Research. April 1973. Ab- P h i l a d c l ~ h i a - c h r c i i n ~ ~ s ~ ~ i n e - p o;stn~dt i v-cneea- S I I J C I 2 I7 live chronic granulocyiic leukemia. Ann Interi: 54. G o h K. Swisher SN: Ideniical twins and Med 72: 175. 1970 chronic myelocytic leukemia. Arch Intern Med 4.Feingold ML. Koss LG: EtTects o f long- 119475. 1965 terni adminisirillion of busullan. Arch Intern 55. G o h K. Swishcr S N . Herman EC Jr: Med 124:66. IY6Y Chronic myelocytic leukemia and identical 40. 1.i;ilkow PI. Garller SM. Yoshida A: twins. Additional evidence of the Philadelphia Clonal origin of chronic myelocytic leukemia chromosome as postzygotic abnormality. Arch in man. Proc Nail Acad Sci (Wash) 58:1468, Intern Med 12021-1, 1967 I967 A 6 . Gralnick HR. H a r b o r J. Vogel C: Myelo- 41. Finney K. Mcl>onal G A . Baikie AG. librosis in chronic granulocytic leukemia. CI al: Chronic granulocytic leukemia with Ph'- Blood 37:152. IY71 nqdtive cells in bone marrow and a ten-year 57. Hammouda F. Quaglino D, Hayhoe remission after busulfan hypoplasia. Br J FGJ: Blast crisis in chronic granulocytic leu- Haematol23:283. 1972 kemia. Cytochemical. cytogenetic and auto- 42. Ford CE. Clarke CM: Cytogenetic cvi- radiographic studies in 4 cases. Er Med J dence of clonal proliferation in primary reiicu- 1:1275. 1964 lar neoplasms. Can Cancer Conf 5: 129. 1969 58. H a u t A. Abotr WS. Wintrobe MM. ei 43. Forresier RH. Louro JM: Philadelphia al: Busulfm in the treatment of chronic inyelo- chromosome abnormality in agnogenic myeloid cytic leukemia. The ctrect of long term inter- -metaplasia. Ann Intern Med 64:622. IY66 44. Galbrnith RR: Studies on the longevity. mittent therapy. Blood 17:l. 1961 59. Heard BE. Cooke RA: Busulfan lung. scqucsiraiions and release o i the Icukocyics in Thor:ix 13:IK7. 19OS chronic myelogenous leukemia. Can Med Assoc J Y5:51 I . 1966 60. Heckner F: Iaolysiccharide in Blul- und Knockenmarks- Zcllen. Zyto- und Histochemie 45. Galbraith PR. A b u . Z a h r a HT: G r a n u - in der Hiimlrtoloeie Neutes Freiburger Sym- lopoiesis in chronic granulocytic Icukcmi;i. posium. Berlin. 1963. p 408 Br J Haemaiol22:135. 1972 61. Hill J M . Locb E: Trcatincnr 01' leukemia. 46. Galton DAG: Myleran in chronic mye- lymphoma and other malignant neoplasms with loid leukemia. Lancet 1:208. 1953 vinblastine. Cancer Chemothcr Rep 15:41. I961 47. Galton DAG: Treatment of the chronic 62. Holland J F . Glidewell 0: Oncologists' leukemias. Br Med Bull 15:79. 1959 reply: Survival expectancy in acuie lympho- A 8 . Galton DAG: Chemotherapy of chronic cytic leukemia. N Engl J Mcd 287:76Y. 1972 myclocylic \eiikemi:i. Semin Hem:tttil ( ~ 3 2 3 . 63. Hoichkiss DJ.. Rlock MI+: lilkct o l I 'JWJ splciiic irr:idi;iii~iii oii ~ystctiiicIieiii;iit~pti~csi~. JU. Ci;ilii)n IMG: .Iliyroid Iiiiiiours. Iyiiipho- Arch Iiit Mcd I09:Ot~S.I M 2 mas granulocytic leukemia. Proceedings of the 64. Huguley C M Jr. G r i u l c J. Rundles RW. Fifth Padua Seminar o n Clinical Oncology. et al: Southeastern Canc. Chemother. Coop. Padua: &cin Medical Books. October 1972. Study Group: Comparison of 6-mercaptopurine 50. Gatti RA. Dcinard HS. Nesbit ME. et a n d busulfan in chronic granulocytic leukemia. a 1 Chronic myelogenous leukemia; cyclic Blood 21:89. 1963 I24 P. A. STRYCKMANS 65. H u ~ t uHO. Aur KJA. Verzosa MS. et 11: Prevention of central nervous system leukemia by trradiiiion. Cancer 32:585. 1973 66. Jackson EW. Norris I-D. Klauber MK: Childhood leukemia in California-born twins. Cancxr 23:Y 13. IYOY 67. Jacobs EM. Luce JK. Cailleau R: Chromosome abnormalities in human cancer. Report of a patient with chronic myelocytic Ieukemia and his non leukemic monozygotic twin. Cancer 19:86Y, 1966 68. Jeanmart 1.Klastersky J. Verhest A. et al: Les pneumopathies diffuses au cours d e la chimiotherapie par le busulfan e t la blcomycine. J Belge Radio1 55:425. 1972 69. Karnofsky DA: Summary of results obtained with nitrogen mustard in the treatment of neoplastic disease. Ann N Y Acdd Sci 68: 899. 1958 70. KaUng DT. Close HP. Whittington KM. CI ;ti: Conipsrison of h u s u l h and cyclophosph:iiiiidc in the trciltiiictit 0 1 chroiiic myelocytic leukemia. Cancer 27:608. IY71 71. Kemp NH,StatTord JL.Tanner R: Chromosome studit. during cwly and tcrniinal chronic nrycloid 1eukacmi;l. l3r M c J J 11:1010. 1Y64 72. Kenis Y, Dustin P Jr. Henry JA. et al: Action du Myleran dans 22 cas de leuckmic myiloidc chronique. Rev F r Etud Clin Biol 1:435, 1956 73. Kenis Y. Koulisher L: Etude clinique et cytogcnetique d e 21 patients atteints de leuc h i c mycloide chronique. Eur J Cancer 333, 1967 74. Kennedy BJ. Yarbro JW: Metabolic a n d therapeutic etrects of hydroxyurea in chronic myeloid leukemia. J A M A 195:1038. 1966 75. Kennedy BJ: Cyclic leukocyte oscillations in chronic myelogenous leukemia during hydroxyurea therapy. Blood 35751. 1970 76. Kennedy BJ: Hydroxyurea therapy in chronic myelogenous leukemia. Canccr 29: 1052, 1972 77. Khan M H . Martin H: Multiple chromosomal abcrrations in a c a w 0 1 in;ilign:int myclosclerosis. Acta Harmalol (Basel) 3Y:29Y. l Y 6 X 78. Killmann SA, Cronkite EP. Robertson JS. et al: Estimation of phases of the life cycle of leukemic cells from labeling in human beings in vivo with tritiated thymidine. Lab Invest 12:671. 1963 79. Killmann SA: Chronic myelogenous leukemia: Preleukemia or leukemia'! Proceedings of an International Symposium. Tura S. Baccarani M (ed) Edirione di Haematologica: Pavia 1972. 80. King Sintth EA. Morley A: Computer stimulation of granulopoiesis: Normal . and impaired granulopoiesis. Blood 36:2.(4. 1970 XI. Kiossoglou KA. Mitus WJ. Dameshek W: Chromosomal aberrations in acute leukenii:i. Blood 26610. I965 d 2 . Kirschner KH. Esterly JK: Pulmonary lesions associated with busulfan therapy of chronic myelogenous leukemia. Cancer 27: 1074. IY71 83. Koulischer 1. Fruhling J. Henry J: Observations cytogcnctiques d a m la maladie d e Vaquez. E u r J Cancer 3:193, 1967 84. KrakofflH. Ellison RR. Tan CTC: Clinical evaluation of thioguanosine. Cancer Res 21:lOlS. 1961 85. Krakoff IH. Dowling MD. Gee T. et al: A perspective of intensive trealment aiming at prolonged control and/or eradication of chronic granulocytic leukemia. Thyroid Tumtiiirs I.ymphom;is Griinulocytic I.eukcmia. I'rocccdiiips ~ilt`h c Sccuiid I'aduii Sctiiiti;ir OII Clinical Oncology. October 1972. Padua. Piccin Medical Books. 1973. p I13 A 6 . Kyle R A . Schwartz RS. Olincr HL. IS :tI: A sytidroine rcscmbling d r c n a l cortical unsutiiciency associated with long term busulfan (Myleran) therapy. Blood 18:497, 1959 87. Lawler SO. Galton 0: Chromosome changes in the terminal stages of chronic granulocytic leukemia. Acta Med Scand (Suppl) 179:312. 1966 88. Leake E. Smith WG. Woodliff HJ: Diffuse interstitial pulmonary fibrosis after busulfan therapy. Lancet 2:432. 1963 89. Lerner HJ. Beckloff GL: Hydroxyurea administered intermittently. J A M A 192:l 168, I965 90. Lessmann EM. Sokal JE: A colchicine derivative in therapy of chronic myelocytic leukemia. J A M A 175:741, 1961 91. Litter W A , K a y JM. Hasleton PS. et al: Busulfan lung. Thorax 24:639, 1969 92. Lortholary P. Lejeune F. Tanzer J. et al: Etude cytochimique des leucohlastes au cours d e l:i tr:insl`ormation aigue d c l;i IcucCmic mydoide chronique. Presuc: Mcd 71:1237. 1966 93. Manistis A K . Amsel S. Mitus WJ: Chro- mosome pattern of bone marrow fibroblasts in patients with chronic granulocytic leukaemia. Nature ( L o n d o n ) 2221278. 1969 94. Mastrangelo R.Zuelzer WW. Thompson R: T h e significance of the Ph' chromosome in acute myeloblastic leukemia: Serial cytogenetic studies in a critical case. Pediatrics 40834. I967 95. M a t h e G.Schneider M. Cattan A. et al: 4. STRYCKMANS ( A: Computer Normal and 36:254. 1970 WJ. Danicshek 111 ;ic1itc Icuiu- IR: Pulmonary 'an therapy ol' a. Cancer 27: J. Henry J: Ins la maladie I967 Tan CTC: Clinic. Cancer Res 1. Gee T. et 31: ment riming at eradication of . Thyroid Tu- !tic Leukemia. Iua Scminar on , Padua. Piccin llincr I4 I-. ct 11: cortical un- , term bUSUlfdn I. 1959 Chromosome :CS of chronic d Scand (Suppl) iodliff HJ: DifIsis after busul- : Hydroxyurea , M A 192:1168, i: A colchicine myelocytic leu- ,leton PS. et al: 369 Tanzer J. et ak 8~:~swasu cows IC la leuckmic I 74: 1237. 1966 litus WJ: Chrow fibroblasts in ytic leukaemia. i W . Thompson chroniosome in rial cytogenetic diatrics 401134. :attan A. et al: CHRONIC MYELOGENOUS LEUKEMIA I25 Essai de iraitement de la IeucCmie mycloide chroniquc pat le dibroniomannitol. Presse M c d 72:1135. 196-4 96. Msthe G . hmiel JI.. Schw;trrenhcrg I.. ct ;il: h c t i v c i i i i i i i i i i i ~ ~ l h e rl~oirr ~:ictile lyiiiphtl- bl;isiic Icukacinia. Lancet I:OY7. 196Y 91. M a w A M . kisher V: ('h;ir:ictcristics of cell prolikration i n lour patients with untreated acute leukemia. Blood 211:421. 1966 98. Maurice PA. Williner E. Gindrat JJ, et al: EtTect of splenic X-irradiation on bone marrow function. 11. Experimental studies in patients with chronic myelocytic leukaemia. Br J Haematol 17543. 1969 99. Maurice PA. Alberto P. Ferrier S. r t ai: IsucCmic myilocytairc uhroniquc: "GuCrison" apparcnte depuis plus de 9 ans. consecutive 1 une hypoplasie medullaire therapcutique. Schweiz Med Wochenschr 101:1781. 1971 100. Medical Research Council's Working Party for Therapeutic Trials in Leukaemia. Chronic granulocytic Icukacmix Coinparison of radiotherapy and busulfan therapy. Br M e d J 1:201. 1968 101. Meeker W U . Jr. del'crio JM. (irticc JT. et 11: The rolc 01' splcncctorny in ni:ilignani lymphoma and leukemia. Surg Clin N o r t h A m 47:1163. 1967 102. Metcall D: The colony stimulating fac- tor (CSF). Aust J Exp Biol Med Sci 50547. 1972 103. Miller RW: Relation between cancer and congenital defects i n man. N Engl J M c d 275:87. 1966 104. Minot GR. Buckman JE. lsaacs R: Chronic myelogenous leukemia: Age incidence: duration and benefit derived. J A M A 821486. I924 105. Morley AA: A neutrophil cycle i n healthy individuals. Lancet 2:1220. 1966 106. Morley AA. Baikic AC. Galton D A G : Cyclic IeucocytosIs as evidence for retention of normal homeostatic control in chronic granulocytic leukaemia. Lancet 2: 1320. 1967 107. Moxlcy JII. l'crry S. Wciss <ill,et d: Return of leucocylcs to the bone marrow i n chronic myelogenous leukaemia. Nature (London) 2011: I28I . 1965 108. Nowell PC. Hungerlord DA: A minute chromosome in human granulocyiic leukemia. Science 132: 1497. 1960 109. Ogawa M. Fried J. Sakai Y. el 31: Studies of cellular proliferation in human leukemia. v i . The proliferative activity, genera- tion time and emergence time 01' neutrophilic granulocytes in chronic granulocytic leukemia. Cancer IS:IO31. 1970 I IO. Oliiier H. Schwiriz R. Kuhio t-, Inter- stili;il pulniori;iry librosis lollowing busullan therapy. A m J Med 31:134. 1Y61 I I I. Oiicsti I). Wooillill I I J : rhc lJhil;iclel- plii:i cliroiiiosoiiic i r i ;I piticiit will1 .icutc Icu- kcniia. Med J Ausr 1:544. IY70 I 12, I'aris Coni'crcncc. St:ciid;irdiratim in human cytogenetics. The national boundation March of Dimes. 1972 113. Pedersen E. videback A: Several cell lines with abnormal karyotypes in a patient with chronic myelogenous leukaemia. Scand J Hacmatol 1:129. 1964 114. Pcdcrsen E: Karyotypes profiles in chronic myelogenous leulmnia. Influence o f t h w i p y and progression ol'discase. Acta Ptthol Microbiol Scand 67:463. 1966 115. Pedersen E, Hayhouc FGJ: Relation be- tween phagocytic activity and alkaline phos- phatise content of neutrophils in chronic myeloid leukaemia. Br J Harmatol 21:257. 1971 116. I'cderscn B. Iiayhoc t-GJ: Cellular changes in chronic myeloid leukaemia. Br J Haeniatol21:251, 1971 117. l'edcrscn U. Kil1iii;lnii SA: Lrukacmic suhclocics i n chronic myelogenous leukemia. Acta Med Scand 190:61. 1971 118. Pedersen 6:The blastic crisis of chronic myeloid leukaemia: Acute transformation ol a preleukaemic condition? Br J Haematol 25: 141, I973 119. Penny R. Gslton DAG: Studies on neutrophil function. 11. Pathological aspects. Br J Haematol 12:633. 1966 120. Perilie PE, Finch SC: The local exudative cellular response i n leukemia. J Clin Invest 391353. 1963 121. Perreiu P. Gardais J: La survie de la leucemie myiloide chronique a p r b aplasie par misulhan. Scm Hop Paris I ?:964,1969 122. Perry S. Moxley J I i 111, Weiss GH, et al: Studies o f leukocyte kinetics by liquid scintillation counting in normal individuals and in patients with chronic myelocytic Icukei s i i : ~ . J C h i liivcst 4% 13811. laX>8 123. Ranianan CV. 1sr:icls MCG: Treatment of chronic myeloid leukemi;i with dibroniomannitol. Lancet 2:125. 1969 124. Reinhird EH. Ned! CL. Samples DM: Rudioactive phosphorus 111 [he treatment of chronic myelocytic leuliem1;i over a period of 15 years. Ann Intern Mcd 50.932. I959 125. Robinson WA. PiLc BL: Leukopoietic activity i n human urine. Thc granulocytic leukemia. N Engl J Mrd 282:1291. 1970 126. Rowley JD: A ncu <onsistent chromosomal abnormality in chroiiw mvelogenous leu- - I I26 P. A. STRYCKMANS kcnii;i identilied hy quinacrine Ruorescencc ;rnd 143. Strumia M M . Strumia PV. Basscrt D: (;iciiis:i s1;iiiIiilg. N;i!tirc. 242:L'H). I972 Splenectomy in leukcmia: Hematologic ;ind 127. Kundlcs K W . Coolir;id I:V. Will;ird cliilic;tl cll'ccts o i l ?a p:iliciils iiild rcvicw 0 1 N L Summary o l results obtained with T E M . 2W published cases. Cancer Kcs 26:5IY. 1900 A n n N Y Acad sci 68:926. 19515 144. Stryckmans P. Cronkite EP. Fache J. l2X. Rundles RW. Grizzle J. Bell W N . et ai: et al: Deoxyribonucleic acid synthesis tinie of Southcjstern Cant Chemother C o r p Study crythropoictic a n d granulopoktic cells in Group: Comparison of Chlorambucil a n d human beings. Nature ( L o n d o n ) 21 1:717, 1966 Myleran in chronic lymphocytic and granu- 145. Stryckmans P. Manastrr 1. Pcltzer T. et locytic leukemia. Ani J Med 27:424. 1959 129. Sandberg A h . Ishihura T. Crosswhite al: Cell prolil'eration in chronic myeloid leu- kemia. in Grigoletto t: (cd): Thyroid Tumors LH. et al: Cornparison of chromosome con- Lymphomas Granulocytic Leukemia. Padua. stitution in chronic myelocytic leukemia a n d Piccin Medical Books. 1972. p 99 other myeloproliferative disorders. Blood 2 0 -146. Tjio JH. Curbone PP. Whang J. et 11: 393. 1962 The Philadelphia chromosome and chronic .- 130. Sandberg AA. Hossfeld OK: Chromo- myelogenous leukemia. J Natl Cancer lnst 36: somal ahnormalilies in human neoplasia. A n n K c v Mcd 21:379. lY70 131. Schilfcr LM, Chaniina A D . Crtiiikitc EP. et ai: Extracorporeal irradiation of the 567. 1966 147. T h o m a s ED.Epstcin RB. Eschbach J W J r . c i ;il: Trc:itiiicnt o C Icukcnii;i hy cxIr:icorporc;il irr;idi;itioit. N Engl J Mcd ?7?:h, blood. Semin Hematol3:154, 1966 132. Schwarzenberp L. Mathe G. Pouillart P. et al: Hydroxyurea. leucopheresis a n d splenectomy in chronic myeloid leukaemia at the problastic phase. Br Med J 1:700. 1973 I965 148. Tokuhata GK, Neely C L , Williams DL: Chronic myelocytic leukemia in identical twins and a sibling. Blood 31:216. 1968 149. Tough IM, C o u r t Brown W M . Baikir 133. Seeler RA. Hahn KO: Chronic pranu- AG. et al: Cytogenetic studies in chronic locytic leukemia r a p o n d i n g to Mclphalan. inyeloid leukaemia a n d acute leukaemia asso- Cancer 27284. IY71 ciated with mongolism. Lancet 1:41 I . 1961 134. Smalley RV, Wall RL: T w o cases of 150. Tough IM, Jacobs PA. Court Browii busulfan toxicity. A n n Intern M c d 64: 154. 1966 W M . e t al: Cytogenetic studies on booc-mar- 135, Sokal JE. Elias EG, Mittelman A: row in chronic myeloid leukaemia. Lancet I: Splenectomy in chronic myelocytic leukemia (CML) and related states. Proc Am Assoc Cancer Res IZAbstract 37, 1971 844. 1963 151. Trujillo JM. Fernandez MN. Schullcn- bergcr C. et ai: Cytogenetic contributions to 136. Sokal JE. Aungst C W , Grace JJ: Im- the study or human leukemias. Leukeinia munotherapy in well-controlled chronic myelo- Lymphoma Fourteenth Annual Clinical Con- cytic leukemia. N Y State J Med 73:1180. 1973 ference o n Cancer 1969 a t the University of .137. Speed DE. Lawler SO: Chronic granu- Texas M D Anderson Hospital a n d Tumor Insti- locytic leukaemia. the chromosomes and the tute. Houston. Texas. Chicago. Year Book. disease. Lancet 1:403. 1964 1970. pp 105- I22 138. Spiers ASD, Baikie AG: Chronic granu- 152. Vincent PC. Cronkite PC. Greenberg locytic leukaemia: Dcmonstration oC the ML. ct ;iI: Leukocyte kinetics in chronic Pliilalelphia chroniosomc in culturc o l spleen myeloid IcuL.cnria. I. D N A synthesis tiiiic in cclls. Nature ?OX:407, I'lbf, hlood ;Inil iii;Irrow inyelocy tcs. I3lood 33:X4 3. 13Y. Spiers ASD, Eaikic AG: Cytogenetic IWI9 evolution and clonal proliferation in acute 153. Vodopick H , R u p p EM. Edwards CI.. transformation of chronic granulocytic leu- et ai: Spontaneous cyclic leukocytosis and kaemia. Br J Cancer 22192, 1968 thrombocytosis in. chronic granulocytic leu- 140. Spiers ASD: Surgery in milnagcment ol kemia. N Engl J M e d 2156:284. 1972 patients with Icuk:ienii;i. Hr Mcd J 3:528. 1473 154. Whang J. Frci E Ill. Tjio JH. ct al: 141. Staeubcr PG, Gerhartz H. Liss E: I)ic The distrihution ol' the I'hil:idclphi:i chroino- Chcmoiherapic Lcukamie-Kranker mit Myclobromol. Vcrh Dtsch Gcr Inn Mcd 71:733. 1965 142. Storti E. Pcrugini S Cytochemical re- searches on the lipids of the hematic cells with particular attention to t h o x or acute leukosis. some in patients with chronic myclopcnouh Icukemia. Blood 22664. 1963 155. Whang- Peng J. Canellos GP. Carbone PP. et al: Clinical implications of cytogenetic variairts in chronic myelocytic leukemia (CM L). Acta Haemaiol 5:321, l Y S l Blood 32755. I968 CHRONI 156. ' T. CI a1 cyiic ICI occurrci 1970 157. MCG: with Ur STRYCKMANS I , Basscrt D: ;ttologic and nd review of i:519. 1966 EP. Fachc J. hesir time of :tic cells i n .211:717, 1966 Peltzer T. et myeloid leuyroid Tumors cmia. Padua. 'hang J. et al: and chronic anccr lnst 30: Eschbach JW mia by extraJ M e d 273:6. . Williams DL: identicdl twins n WM, Baikie ics in chronic cukacmia asso141 I . 1961 , Court Brown i on bonc-rnar:mia. Lancet I: MN. Schullen:oniributions 10 iias. Leukemia I Clinical Cone University oF ind Tumor Insli;o. Year Book. PC. Greenberg tics in chronic ynthcsis time in s. Blood 33~843. M. Edwards CL. d w c y t o s i s 2nd granulocytic leu1972 , Tjio JH. et al: tdelphia chromomyelogenous leu- 110s GP. Carbonc ns or cytogenetic leukemia (CML). CHRONIC MYELOGENOUS (EUKEMtA 127 156. Whang-Peng J, Henderson ES. Knutscn T. ct ill: Cyiogenciic siudics in iicuic myclaC ~ I I CIcukcini;i with spcciiil eiiiphasis on tlic occurrence of Ph' chromosome. Blood 3 6 ~ 4 8 . lY70 157. Wilkinson JF, Bourne MS. lsracls MCG: Treatment of lcukacmlas and reticuloses with Uracil mustard. Br Mcd J 1:1563. 1963 158. Wolf U. Mcrwcr H. Bockclmann W: Chromasomc-nuniersuchunpn bel chronischiiiycloischcr Lcuklniie. Kliii Wochenschr 44: 12. 19M 159. WoodlifT HJ. Onesti P. Dougan L: Karyotypes in thrombocythaemia. Lancet I: 114. 1967