Document Rad7mk6gjg3gVzbrm4qOv0L67

HEMATOLOm VOL. XIX. NO. 4, OCTOBE- __ N e w Approaches in Chronic Granulocytic Leukemia-Origin, Prognosis, and Treatment John M. Gddman and D a d s t Lu A SERIESof remarkable discoveries has-contributed in the last 20 yr toour understanding of the nature of chronic granulocytic leukemia (CGL)-notable landmarks have been the discovery of the Philadelphia chromosome, the recognition of the translocation t(9;22). the realization that CGL is a panmyelopathy involving all cell lines in the myeloid series. and the finding that a- minority of transformations have biastcells with a lymphoid phenotype. For the patient with CCL, however. the progress has been less impressive. Drugs that controlled to some extent the myeloproliferation were available at the beginning of the century, and the use of radie therapy when it became available in 1902 was an important funher devclopmcnt. In 1952 the inrroduction of busu lfan revolutionized treatment and it was indeed some ycars before it was fully realized that busulfan was in a sense a nixed blessing-the very ease of its administration directed attention away from the fact that urvival of patients treated with busulfan was rolonged only very modeslly. Subsequent attempts to improve survival by the usc of other cvtoioxic drugs, alone or in combination. have it in general &en valuable. Many aspects of the etiology, epidemiology. cytogenetics. clinical features and hematology of 7L have been ably reviewed in the last few 3 r s ~ ~ ~ . m1o3.1.19~ uIn this short paper we will limit our attention to three arcas in which new i-Corrnation has accumulated very recently: the t dencc for the clonal origin of CGL. the attempts to predict the duration of the chronic phase and of survival, and the nrwer approachcs t i reatrnent of paticnts in chronlc phase and in tr Isformation. CLONAL ORIGIN OF CGL Cytogenetic and Enzymologic Data for Unicellular Origin In 1960 Nowell and Hungerford described an abnormai small chromosome in patients with CGL."This abnormality is now known to arise as a result of translocation of a variable quantity of genetic material from the long arm of one of the 22 chromosomes to another site. In perhaps 90% of patients the material is translocated on to the long arm of chromosome9and the translocation is then referred to as t(9q+; 22q-).% Although originally thought to be confined to cells of the granulocytic series. the Ph' chromosome has since &en identified in cells of erythroid, rnegakaryoblastic, monocytic, cosine philic and probably also basophiIic line- '''a g e .l'"~w'~'*'. It is regularly absent in divid- ing marrow fibroblasts. in somatic cells and in most peripheral blood lymphocytes stimulated to divide by phytohcmagglutinin."~'~''zOl ne report suggested that it was present in T-lymphocytes (or their precursors).' but we studied a 13-yr-old boy who had had CGL since the age of 7 without finding any Ph'-positive T-cells in the peripheral -~ From thr MRC Lrukarmra Untr. Hammwsmrrlr Hosptral and Royal Parrgrodnarr Urdrcal School. M o a . UK (D? Goldman) and Thr Propb's Hospital and lnrri~urrof Hrmatology. Brijing Mrdrral Colltgr, Brrpng f h k i n g ) . China {Or h!. Supporlcd in pari by the Lrukatmia Research Fund. Address reprint rtqursrs IO Or John M Goldman. MRC Lrukatmra Unit, Royal Postgraduate Mrdical School. Ducane Road. London Wt2 OHS.England. C) I982 by Grunr & Sirairon. Inc. 0037-1 9 6 J / 8 2 / 1 9 0 4 ~ l S 0D2ol0 -. .- 242 blood.'% Conversely the simultaneous application of immunoftuorcscencetechniques and cytogenetics showed that substantial proportions of B-lymphocytes may be Ph'-positive' and B- lymphoid cell lines bearing the Phi chromosome have been established from a patient with CGL.'' Such evidence suggests that the Ph' abnormality may originate in a single pluripotential stem e l l . In patients in whom the two 22 chromosomes can be distinguished one from the other the finding that the Ph' chromosome always involves the same member of the pair further supports the concept that the Phi abnormality has developed originally in asingle progenitor or stem ~ X I I . ~ Further evidence in favor of the uniceflular or clonal origin of CGL comes from the elegant studies of Fialkow and his co-workers. They made use of the observation that individual somatic cells of black female patients heterorygous for the twa enzymes of glucose-6-phusphate dehydrogenase (G6PD) contain only either enzyme type A or enzyme type 8. Studies in a small serics of women have uniformly shown that leukemic cells and their progenyxontain exclu- sively enzyme type A or enzyme type B but not both. This finding suggests that the CGL is derived from a single hemopoietic stem cell of one or other enzyme type."*" One such patient treated with cytotoxic drugs has achieved a true remission. Her marrow was restored to Phinegative status; at that time the marrow contained presumably normal myeloid cells that were of bath enzyme types."' Other cytogenetic evidence also favors the clonal origin of CGL. In one patient whose somatic cells showed him to be a sex chromosome mosaic (XY/XXY) only the 46, XY clone showed the Ph' chromosome." A similar patient was reported by Moore and his colleagues": a boy with CGL proved to be a constitutional mosaic with 46. XY/47. XYY chromosomes in skin, blood and marrow. In ihc chronic phase a third cell line, 46. XY. Ph' prcdominatcd in the marrow and was identiticd also in transformation. Finally. onc inusi considcr ihc cvidcncc that .some paticnts w i t h CGI. cntcr 3 phasc of trans- formation in uhich tlic b l ~ s tcclls havc prcdominantly lymphoid char~ctcrist~csS.'uch lyniphoid blast cclls contain trrminal dcoxynuclcoridyl t r a n ~ f c r a s c " ~a'n~d~ somctimcs cytoplasmic im- -OMAN AN munoglobulin"*"that suggests features in c mon with an early progenitor of B-ccll lineage one reponed case the blast cells had immunotc cal feature of T-ctlk.'" The finding that SI lymphoid transformations involve Ph'-postr progenitor cells adds further weight to the ar; ment that CGL starts in a cell with both myel( and lymphoid potential. in other words, a plu potential hemopoieticstem cell." Significanceof Ph'-Negative Myeloid Cells in Patients with Phl-Positive C G ~ In the majority of patients with CGL, 100%( marrow metaphases show the Phi chromosorr and the anomaly persists throughout the cours of the disease. A small proportion, perhaps la than 8% have a similar disease in which the Ph chromosome is never detected. Most suci patients with Ph'-negative d i ~ have~a leuke mia that is hemtologicalIy distinct from Ph'. positive CGL and could perhaps kbetter classi- fiedas "chronic myeloid lwkuniZ'*' It is gener- ally agreed that the survival of patients with Ph'-negativc CGL is inferior to that of patients with Ph'-positive disease."*"lOC'U ln occasional cases. however, the leukemia is hematologically indistinguishable from classical CGL and differs only in lacking the Ph' the sur- vival of such patients may k no dimerent from survival of patients with Phi-positive disease. There are other patients in whom Ph'-positive and Ph'-negative metaphases coexist when the disease is first diagnosed. Rarely. such mom- icisrn may be recognizcd even bcfore the leuke- mia is clearly cstablishcd or when the leukocyte count is still comparativcly low." Mort often. the patient already has pronounced Icukocytosis and perhaps symptomatic disease. The frequcncy with which some Ph'-ncgative incraphasz are identified in patients wit h Ph'-positive disease must depend to somc cxtrcnt on [he number of metaphases analyzed: >*mePhl-ncgjlive cclls have bccn found in 64.(11 p:rticnts in one serics."' in 29% o r c x c s in I sccoiid scrics"' and in 5 1'5 of cascs in a third.:' In ttrc majority of cases in which Ph'-ncgativc n ~ ~ ~ t a p h a shcasve bccn observed in Sokal's scrisb. less than 2 yr have ehpscd from diagnosis a i i d the author concludcd t h J t the probability u t finding Ph'-ncgative mitoscs was invcrscly rc1.iic.d to the duration of thc CGL."' In another scrics of paticnts the finding of Ph'-lwsitivc/Ph'-nc~ntivcmosaicism indicated a rchtivcly prolongcd duration of chronic phase disase'' but in earlier and later studies no such survival advaniagc could be dcmonstra tcd. ".I In 1964 Spccd and Lawlcr rcportcd brief details of a patient with CGL who was trcated with busulfan and sustained a period of bone marrow hypoplasia; subsequently his marrow was found to be Phi-negaiivc."' Thereafter a number of similar patients was reported whose marrows. Ph'-positive at diagnosis. showed a majority or virtually all mitoses to bc Phinegative after treatment with busulfan ihat had produced variable periods of hypopla~ia.''.~~" In some reports the patienu had teen treated with amounts of busulfan that were excessive by conventional standards, but in other cases the hypoplasia had followed administration of quite small dascsof the drug."'Such obseivations were interpreted as compatible with the hypothesis that Ph"-negative. and presumably normal, hernopoietic stem cell: were prcstnt in the marrow, albeit their proliferation suppressed. in the majority of cases of CGL at diagnosis. Appropriate therapy might then selectively suppress the Ph'-positive clone and permit the marrow to be rcpopulatcd by normal hemopoietic cells." This possible approach to therapy appeared to have particular appeal because some of t h a e patients who survived periods of marrow hypoplasia and showed Phi-negative metaphases had I n onevery long s u r v i v a ~ s . ~ . 9 . ~ b . J 7 . ~ ~ . 7 9 . ~ i ~ . l ~ 7 remarkablc example a 42-yr-old woman was treated with busulfan (185 mg) in 1956 (before the Ph' chromsome had been recognized). In 1964 her marrow was Ph'-negativc but later in the year it became Ph'-positive: she then received further treatment with busulfan ( I 10 mg) and her marrow was restored to Phi-ncgativity. Thus, her first true remission may be presumed to have lasted 7 yr'b; her second remission continued and had lasted 11years at the time of the morc recent report.' More often, the treatment has Icd to a stable pattcrn where both Phl-positive and Phinegative cells were present for long pcriods in the marrow in approximatety constant proportions.'.'' Such "stable mosaicism" alter treatment with busulfan might be explained by posrulating that busulfan caused a mutation or other -. 243 sublethal damage in the Ph'-positivc clone whereby thesc cells lost their proliferative advantage." A murine model of chronic hypoplastic marrow failure following treatment with busulfan was developed by Morlcy and might parallel in the mouse the cffccu of busulfan in selected cases in man." These observations has led Sandbcrg to p r e pox a scheme of "staging" for patients with Ph'-positivc CGL based on cytogenetic findings? * Stage I-The presence of only cytogenetically normal marrow metaphases (only achieved on rare occasions following treatment) Stage II-Cytogenctically normal cells OQ. exist with Ph'-pc#itive cells Stage 111-All marrow metaphaw are Ph'positive Stage IV-All marrow metaphases are Ph'positive but some cells have additional chromosomal anomalies Stage V-AI1 metaphases show the Phi change plus additional chromosomal anomalies Most patients with CGLare in Stage 111 when the disease is diagnosed. Clearly, Stage I is achieved only after "successful" therapy and might correlate with prolonged survival. Whether Stage I1 recognized before tratment or achieved after administration of cytotoxic drugs is of benefit to the patient remains an open question. Is the Ph' Chromosomal Anomaly Primary OT Secondary in CGL? It was assumed for some years after its discovery that the acquisition by a hemopoietic stem cell of the Phi chromosome anomaly represented the primary event in the pathogenesis of CGL. and such may indeed be the case. Certainly the Phi chromosome is almost universally present, usually in 100% of marrow metaphases. very early in the clinical evolution of CGL.L' Recent evidence, however, casts some doubt on the conclusion that the acquisition of a Phi chromosome is always the seminal event. There are a number of individual reports in which the patient's marrow is apparently entirely Ph'-negative at diagnosis. but Ph'-positive cells are identified during subsequent follow-up (Table 1). Of course. if the number of metaphases analyzed originally is ! -NS Not ri8i.d n rw. cacp-ovmsqnurocyrccW~--dvmrcgh.u. -Cm-61- &mC QMWbWlC WmU--b(ard D O f l d a W l O t h . MPO My.(aOldrlUbWe-. AWL - A M a y . ( a 6 W n n u . small (as was the case in the report by Lisker et ai.)," it remains possible that a Phl-positive !ine was present a b initio but was simply not identified. In other cases a Ph'-positive line was identified originally at diagnosis but disappeared subsequently in the patient's clinical course (Table I). One such patient was studied with particular care by Hagemeijcr and his colleagues." A 19-yr-old boy presented with typical Ph'-positive CCL. He was treated intermittently over four years with busulfan; his blood and marrow stilt showed a picture consistent with CGL but cytogenetic analysis of blood. marrow. and spleen cells was normal. During two separate episodes of blast-cell transformation, he had a hyperdipioid karyotype without evidence of the Ph' chrornsome. Another paticnt described by Chcssells and her collcagues is of interest.20 A 5-yr-old boy prescntcd with classic Ph'-positive CGL in chronic phase. The disease was controlled initially with busulfan. but some months later blast-ccll transformation supcrvcncd; at this timc thc blast cclls were Phl-negative. Thcsc various clinical reports are difiicult to rcconcile with thc conccpt of CGL as a monoclonal disusc i n which thc ncoplastic clonr. marked by rhc Ph' chromo- some. cocxists with 3 population ol strictly nor- mal cclls. thc prolifcration of which is usually cfTcctively supprcsscd. Further study of t h r paticn! with CGL and constitutional mosaicism originally dcscribcd by Sfoorc et al."."' has yicldcd intriguing results. Though initially blastic transformation was rec- ognized in t h e 46. XX. Ph' cell l i n c h e r in the evolution of the disease a major aneuploid 46. XYY, -C,Ph' line was identified. One possible explanation for this curious sequence of events is that both lines of' the mosaic were involved early by the leukemic process, the Phl anomaly being acquired or cxprtssed in the X Y Y line only late in the diseasc. Y Fialkow and his colleagues have recently reported thc combined use of cytogenetic analy- sis and assay of cellular G6PD with valuable results." Thcy were nblc to infcct with EB virus B-lymphocyics collccted from a patient with C C L who \$:ISheterozygous for the two enzymes of G6PO and to establish from different lym- phoid progcnttor cells n scries of short-term cell lincs of undstubtcd E-ccll lincage. Some of thcse lincs were Phl-positive but the majority were Ph'-negativc. The Phl-positive lincs were a k o f thc w m c GbPD phcnotypc 11sihc paticnt's my- cloid Icukc1iiia (typc 8); amongst the Ph'- ncgativr l h c \ vomc wcrc of type A and othcrs of typc E. Of [tic Phl-ncgittivc lines only thosc of GhPD typc I3 Iud karyotypic abnormiilitics: thc G6PD type \ lincs wcrc ;111 csscntiallv normal. Thc authors cuncludcd thdt thcir studics ucrc compaiiblc 11 1 1 h multi-stcp origin of CGL--a ncoplastic ccll linc occurring first 3s A result ol a hcritablc chaiigc in a singlc pluripotcntid stem ccll and thc I)!\c'hromosornc appearing thcreaf- tcr. I f this ir lndecd thc universal vqucncc of Y 24 I m mine thc duration of the chronic phase or of I1 survival in a given paticnt are not undcrstood, but it may reasonably bc postulatcd that they include at least somc mcasure of thc ratc of progrcssion or "tempo" of thc diseasc. some mcasurc of the point in its progression at which the disease is diagnosed and other unspecified facton."' An assessment that takes acwunt in individual 4+- 1- patients of "static" features at diagnosis may reflect the stage to which the disease has pro- gressed but may provide no measure d the disease tempo. Conversely, m~surcmenotf "dynamic" features such as change in feukocyte numbers following treatment or cytokineticdata may give some evidence of the discax tempo but may not accurately reflect the point in its pro= -gression at which the discve is diagnosed. The ideal procedure for assessing prognosis should reflect both these as- of a patient's disase. A possible solution to this problem will kdiscuuad later. events, it seems probable that the acquisition of the Ph' anomaly confers on that clone of cells (in most cases) a proliferative advantage over both normal and Phl-negative neoplastic hemopoietic stem cells. This hypothesis is shown schematically in Fig. 1. PROGNOSTIC FEATURES IN CGC For some years. writcrs have studied personal series of paticnts with CGL and have sought like a holy grail a feature or a constellation of features that would help to predict prognosisthe duration of the chronic phase or the duration of survival-in an individual patient. Results of such analysts have in general been confusing, and features that appeared in one study to have definite prognostic significance have frequently failed to gain confirmation in other studies. This result can only mean either that the originai positive findings rcachcd conventional Icvcls of statistical significance only by chance or that different series of paticnts are genuincly different. In either case, the valuc of the original findings is reduced. In more gencral tcrms. ihc attcmpt to identify a feature or features charactcriting a paticnt at diagnosis that corrclates well with survival may be conceptually wrong. The fcaturcs that deter- A further problem related to the question of predicting the duration of the chronic phase or of survival requires mention. It has been suggested that the chronic phase of CGL might better be desaibai as a 'jxe-leulttmic" amtiition that pre disposes to but does not inevitably terminate in blastic transformation." The observation that transition to a more aggressive phase of the disease is usually accompanied by evidence of cytogenetic evolution has been interpreted as support for this concept. AfternaIivcly, it is plausible that even in chronic phase the disease is already truly leukemic and is progressing inexorably towards a terminal blastic transforma- tion.'" Evidence for kinetic changer occurring progressively during the course of chronic phase disease. referred to below. is compatible with this interprela tion. Whichever view more correctIy describes the natural history of CGL. one can recognize two different categories of prognostic features. On the one hand, there is a reasonably well defined series of features which, occurring during the course of the chronic phase, appear to prcdict poor subsequent survival but are in fact early signs of transformation.'.".''' 'These features include fever. refractory splenomegaly. nodular skin lesions. significant lymphadenopathy, lyric lcsions of bone, excess of blasts or blasts plus promyelocytes in the blood or the marrow, high neutrophil alkaline phosphaiasc and per- I -. haps marrow myelofibrosis. Cytogenetic evidence of clonal evolution or changing patterns of colony and cluster formation in agar culture of marrow are probably also in this category.'o.'s.'s Any of these features may in reality be better regarded as evidence that the initial events in transformation have already occurred and the relevant question relates only to the speed at which transformation will proceed thereafter. On the other hand. there are other features. some identifiable at diagnosis (static features) and others based on changes occurring during the first months or years after diagnosis (dynamic features). that do not definitely represent early transformation but may yet have prognostic significance. The possible prognostic features in this second category are reviewed briefly bclow. I Possible Prognostic Features Definable at Oiagnosis A@ In one large series. younger patients (less than 20 yr) survived significantly longer than older patients (more than 70):' The same trend was noted in other series."'-".'M Young patients survived longer also in the multicenter study organized in Italy' but age carried no prognostic weight in a recent report of patients treatcd in B~logna.~"In the majority of other reports the age of the patient did not appcar to influence prognosis. I ~.s.6s.tz.s?.llx Sex There was no difcrcnce in survival between m a l a and females in the series of patients reported by Minot ct al." and there was no influence of sex in series rcportcd recently from Italy. Spain and the United States.".50~'2' In almost every other series i n which sex was considered in relation to survival. howcver. rnalcs survived distinctly or significantly worsc than fcma /es.""l .LS.Io1.IO1.IIo I t seems fair to concludc that in general fcmalcs with CGL can cxpcct to live lonncr than rnalcs. Sj*ntpronr.rat Dia,qriori.c Will\ rcsprct I O ~ ~ ~ i i i p tri oi\~ ip;~ir~ticui3rly neccssary to d i [fcrcnt irr tc bct wccn clin ic;i1 fcalurcs that actually dcnote early transformation and those that corrclsic rncrely with cxtcnsivc chronic phasc discase. W i t h this proviso. J;icquil- ]at has rcportcd that patients with symptoms (including asthcnia. weight loss. bone pin. fever, night sweats and gastrointestinal disturbance) at diagnosis have significantly shorter survivals than those without symptoms." Bared on a series of 130patients. Haanen and Oehlen have confirmed that patients with weight loss or night sweats have poorer prognoses than those without such symptoms." Luvell has reported that patients with a bleeding tendency have poor progn~~es."Others. however, have found that asthenia and weight Iw lack prognosticrignifiunce. . Spleen Size at Diagnosis Measurement of spleen size is not particularly objective and writers have used various criteria to dowment splenomegaly. In the two Italian series and in the Chinese series. patients with splccns descending more than IS cm below the costal margin have survived for shorter periods than those with smaller spleens.'u'" la the Spanish series. an impalpable spleen has k e n a good prognostic feature"; in five other series patients with minor degrees of splenomegaly have survived longer than those with larger s p l ~ c n s . ' ~ ~ ~O~th~e'r~ r"e'ports have failed to show any efect of spleen size at diagnosis on survivs 1~59.64.82.104 Liver Sire at Diagnosis If thc measurement of spleen size at diagnosis is sonicwhat inexact. this applies even more to measurcmcnt of liver size. Frequently the organ is enliirged bui the consistency of the edge is such that if 1% difficult to fccl per abdomen. Neverthe-' less, piiticnts with a n impalpable or small (less than 0 cm bclow thc costal margin) liver have survived signific~ntlylonger than paticnts with a largcr livcr in thc scrics rcportcd from Italy and Spain." I:' Convcrscly, larpc liver size has carricd 3 poor prognosis in somc scries'O," bui the wu3ci.l t ion has nor bccn contirrncd by ot hers.'' "'* i . A * i t A d J a : ~ > ) I I I I I111 #iO,gtto.ri.c I n [tic t w o l t i i l i : i i i xrics p;lricnts irith prc- scntinp Icukocytc counki bclow 100 x lO*/l survived significmtly longcr than those with highcr Icukocytc cour~ts.~U" sing a cut-off p i n t at ZS b IOe/l. thc wmc superior survival for d patients with low leukocyte counts was noted in the series reported by hcquillat." Lcsvell also noted a favorable inthence of relatively low leukocyte counts," although in a German series paticnts with presenting leukocyte counts below 20 x lO*/l had short survivals." In line with thc possible k n t f i t of a low leukocyte count at diagnosis. a high leukocyte count ( = 3 0 0 x IO'/ 1) was found to predict short survival in one ~~rics.'"N' O etfcct of Ieukwyte Count on survival was noted in five other series."."'.'o~w.s: proporrion of Blasts and Promyeiocyirs in Blood and Marrow ai Diagnosis There secms to k no general agreement as to whether the proportion of blast-cells or blasts plus promyelocytcs has significance in determining prognosis in patients who are not in incipient transforrn;rtion. In five series a relatively high percentage of blast cells in the blood or the blood and marrow has correlated with poor prognosis.~uaw.~i.iaIn the Italian series patients with lcss than 1% of blasts in their blood, who surprisingly constituted 33% of patients. have had significantly longer sur~ivals'~t*h;e patients with fewer than 20% of granulated precursors (promyelocytcs and myelocytes) have also survived longer than those with more than 20%. On the other hand, no influenceof blast cell numbers at presentation has been noted in two other studics.'z'M Iimroglobin a: Presentation In some series patients with relatively lower hcmoglobin values had poorer survivals than thosc with higher va Iues. 'm.mw.bi~".l'o In other series no erect of hcmoglobin level on survival was discerned."""'M.'*' Plotrfcr Count at Diagnosis The level of the platelet count at diagnosis has had prognostic significance in most reports. Though the level defining "high" platelet counts was quite variable, it was a gcneral finding that paticn~s with high counts had short survivajs.".Ll.77.W.l 24 Converscly, patients w i i h abnorm d l y low platelet counts also had a poor progno~is.~*l.%.iM.IlN24In two rcports no dctinite effect Of platelet count on survival could be detected.t'.'2 There seems general agrcemcnt -_:*. .that a persistent rise of platelet numbers refrac- 247 '.. tory to rhcrapy and falling numbers both herald transformat ion. Cy:ogene:icAnalysis 10 Predict Prognosis in CGL This subject has been extensively reviewed in recent years""' and results will be summarized here only briefly: ( I ) In almost all reports. patients with Phi- negative CGL survive less well than thase with Ph'-positive disease. in fact the presenct or absence of the Ph' chromosome is probably the single most important prognostic feature. (2) Patients with non-standard translocations (translocations other than t(9;22)) do ncll differ in survival from those with standard tnnrlocations."' (3) The survival of patients with abnormalities in addition to Ph' at diagnosis is not definitely shorter than when the Phi chromosome is the only abnormality. Those who acquire such additional abnormalities after diagnosis do. however. have shorter survivals. (4) In most reports, IOU of the Y-chromosomc leading to the Ph'-positive, XO myeloid line c a r r i a a relatively favorable prognosis'"''; not a11, however, agreen Prognostic Features DefinedAfter Initial Diagnosis Response of rhr Lcukotyte Count io Chemoihcrapy In early studies Galton noted that the rate at which the leukocyte count fell after beginning treatment was related to the daily dose of busul- fan.'* He also noted that the rate of fall differed in different patients and that the doubling time for the leukocyte count after each successive course of busulfan tended to shorten in an individual paticnt. These observations were extended . by Bergsagel who plotted the leukocyte a u n t doubling time after the first course of busulfan against the patients' survival and observed a significant correlation': a similar relationship bctwecn circulating immature myeloid cell numbcrs and survival h3s also been dcmonstrated.'Ib Cyrokinetic Studies Cytokinetic studies carried out on the blood and marrow of patients with CGL have recently been reviewed."' Using specific cytokinetic fea- _I __.. . 24. gum (mitotic index, stathmokinetic indcx fob some increase in marrow content of reticulin lowing vincristine in vivo and flash-labcling index with 'H-TdR). Baccarani and Killmann fibcrs at diagnosis and 39 of 181 patients developed fibrosis after diagnosis: the mean duration wererble to show that promyelocytes and myelo- of survival after rccognition of fibrosis in t h e cytes in CGL resemblcd normal progenitor cells paticnts was only 4.9 mo." In another mare but blast cells had a distinctly lower labcling recent but smaller series ofpatients the finding of index and resembled in this regard the blasts of myetofibrosis "warned of imminent de?th."'' fhe acute myelogenous leukemia rather than their amount of fibrosis was graded in serial biopsies normal counterpart.' These studies were inter- performcd in 45 patients by Claugh and her preted as evidence for the existence early in the colleagues." They established no definite oorre- disease of a minority of cells that might charac- lation between the amount of fibrosis and sur. terize subsequent transformation. Others have viva1 and noted that patients with major marrow suggested that the labeling index in vitro was fibrosis did not always have a rapidly fatal - related rather to the level of the leukocyte count course. Others also failed to find a melation . and was unlikely in itself to have prognostic betwecn myelofibrasis and survival in the first significance."' There was. however, a correlation three y e j n of the chronic phase but fibrosis was between high proportions of blasts plus promy- a poor prognostic feature in patients motc than elocytes with low mitotic indices and sur~iva1.'~ 45 mo aftcr diagnosis." Myelofibrosis is seen Though the authors suggested it, they did not with q u a l frequency in patients with lymphoid show in their study a separate influence of low and mycloid transformations." mitotic index and high proportion of blasts plus promyelocytes. Requirement for Treatment as a Prognostic Feature Cytogenetic Studies The finding that the leukocyte count doubling The majority of patients with Ph'-positive time after a single course of busulfan can k CGL have no other cytogenetic abnormalities correlated with survival' could be due to the lact &.- when first diagnosed. Perhaps 80% of patients in blast-cell lransformation have evidence of addi- that this measure reflects to some degree both the point in its evolution at which the disease is e tional cytogenetic change. and the Occurrencc of diagnosed and the tempo of disease in a given such change in patients still in apparcntly patient. Along similar lines, Haanen and his uncomplicated chronic phase disease has bccn colleagues note that splenomegaly or leukocyte held to indicate impending transformation. The sis that persists aftcr three months' treatment subject has been rcviewed by a number of writers with busulfan defines patients in a "poor-risk" in recent years'k".'oo and will not be referrcd to category.'b Wc identified 2S patients whose here in further detail. For the sake of this discus- chronic phase disease has lasted from 13 to 72 sion, the central question is really whether the mo and w h o have received treatment with busul- occurrence of further cytogenetic changc in chronic phase rcprcscnts thc carliai evidcncc of transformation or merely reflects a disease th31 is genetically unstable and thus more likely ih:in others to enter transforniation in thc near futurc. Myelofibrosis fan only within the first year of diagnosis. We found that ihc total dosc of busulfan administercd during this time was inversely relatcd to thc duration of chronic phase in individual patients:- and a n~~~thcrniiidccarlivation of the relationship gavc n highly significant correlation.':' When busu I fa rr-trcatcd pa ticnts arc included in i hc original conyxirison of busulfan and radio- I e. 1 i f I Marrow fibrosis is present 31 diagnosis in s w i c paticnts with C G L and dcvclops during rhc coursc of the chronic phase in oihcrs. A s to whcthcr the idcntiticntion of mild or rnodcrarc degrees of fibrosis indicaics impending transformation. opinions direr. I n rhc scrics rcportcd by Gralnick and his collctgucs. 8 of 30 paticnts h;td t hcrnpy undcrtal.cn by thc Medical Rcscarch Council in t hr Unitcd Kingdomaowcrc analyzcd in [hc s31iic way, a simil;ir correlation was obscrvcd (Fig. 2). We havc a1.m idcntificd in our scrics I I paiicnrs with rclativcly long durations of chronic phase. continuing 47 to 136 mo aftcr diagnosis. These patients cithcr had very low ) i i 'I - -1 -Ii rquirements for busulfan or were untreated within the first year of diagnosis."' Thus the rcquircment for treatment reflected in the use of cytotoxic drugs can be an important prognostic fcaturc: t h e idca must be tested in other series of patients. TREATMENT OF CGL Many aspects of the treatment of CGL have wbeen comprehensively yQn.16.67.1 IJ.II5.11t e will reviewed in recent discuss here only the various attempts that have been made to elimi- nate the Ph'-positivc myeloid population by usc of cytotoxic drugs during the chronic phase and the place of autografting and allogeneic marrow transplantation in the management of patients in chronic phase and in transformation. Attempts to Eliminate the Ph'-Positive Myeloid Populatton During the Chrontc Phase Because it now secms likely ih3t residual Ph'-negative (and perhaps therefore normal) hemopoietic stem cells survive in the marrow of 249 most or 311 patients whcn CGL is d i a g n d and bccausc occasional paticnts whose marrows are Ph'-pozitivc at diagnosis but become largely Ph'nega tive after trca tment with busul fa n"'*''.l n have had unexwtedly long survivals. deliberate attcmptt have made to suppress the Ph'-poJitive population of cells in the hopc of permitting re-emergence of Phl-negative hemopoie- IOJl.JI.IO1.IW The interim r e s u b of the L-5 protocol used at thc Sloan-Kettering Institute in New York were publish4 in 1979." Thirtyseven patients with newly diagnosed CGL were treated first by splenic irradiation, then subjected to splenec- tomy and thereafter rccsked a variety d cyto- toxic drugs more commonly employed for patients with acute myeloid leukemia. The median survival for all 37 patients was 50 mo. slightly longer than that reponed in previous series. In 12 patienu there was a temporary reduction in the proportion of Ph'-positive mar- row metaphases LQ one-third or less of their initial value. These reductions lasted from I to43 mo. and the median sunival for these I2 patients. designated "responders" was signifi- cantly longer than the survival of the remaining 25 patients. Similar results were obtained in a subsquent protocol. designated L-15. in which additional cytotoxic drugs were introduced. Of 28 patients treated. 12 had marrow studies that showed Ph'-negative hemopoiesis but such cyto- genetic "rcmissions" tended to be short-lived." Broadly similar rcsuits have been reportcd for patients treated with cycle-activecytotoxic drugs at other ccntcrs. In Philadelphia 23 patients were treated with anbinosyl cytosine and i-thiogua- nine followed by splenectomy a d 6 (24%;) showed some reduction in the percentage of Phi-positive metaphases in the marrow.1o In another study also reported from Philadelphia patients were treated with the same drugs but without splenectomy. Two of 16 patients achieved Ph'-negative Twelve patients were trcatcd each with six courses of combination chcrnotherapy at the King's College Hospital in London."' In 6 the proportion of Ph'-positive marrow metaphases fell to 50% or lower and 4 patients had vdues less than 10%. The splenectomy included in most of these proto- cols may be an important component of this approach since the spleen may play a role in _.I +. c f ~ d l i u t i n gthe proliferation of Phl-poritive alh" Taken together, the resultr of t h e e studies pmvide s m n g support far the concept that some PhI-neg8tive stem cells 8re present when CGL h d i a g d and that suppression of the Ph'-. pmitive clone with cytotoxicdrugs u n ratare to tbe progeny of Phl-negative stem cells. albeit temporarily, a proliferative advantage. Unfonu- nmtely, one a n n o t conclude that such "respond- en." those patients whose mrrowsshow ttm- pmry reduction in proportion of Phl-paitive metaphucs. have in fact ken benvlited by the tmtmmt. It U.@ble t h t 8 m V e t n r t - mart merely h e l p to identify I subpopulation of. patients whose prognosis would in m y case have kur favorable. Further s t u d i a along t h e liner a n only k justified after due ansideration has k e n given to the toxicity of the and to the intcrferencc with the patients' life-style. 'O01: CT QCI 'I/ Auto&rtring for CGL in Tranrfamrth . Autologous hemopoieticstem cellsa n beused in the rrun~gemenot f CGL in transformation. Thu approach was pioneered by Buckner 8nd his c o l l u g u a in Seattle." Nuclated cellswere barvested from the patient's marrow at dugnosu of soon after. stored in liquid nitrogen and used when the patient entered blastic transformation . (0 reconstitute the bone marrow after treatment with high-dose cyclophosphamide and whole body irradiation (TBI). Two of the 7 patients treated in this way were rapidly restored to a hematologial picture consistent with chronic phase d i m . Engraftment was apparently facilitated in patients who received substantial quant i t i a of cryopwerved autologow blood dlr IS we11u marrow cells." &cruse we encountered techniul difficulties in harvesting a d q u a t c numbers of marrow cells and because we speculated that pluripotential stem d l s might. uniquely in CGL be present in the circulation in vast excess. we began at the Hammersmith Hospital to store nucleated cells collected from the blood of newly diagnosed patients: we abandoned collection of marrow cells. Subsequently. we showed that reconstituted blood cells alone would re-establish chronic phase hemopoiesis in patients in blastic transformation after treatment with chemotherapy or chemotherapy plus TBI." &tween July 1977 and June 1981 we treated 29 patients by thu approach: I7 patients lcotivcd only cytotoxic drugs before autografting 8nd 12 rccCived cyta toxic drugs plus TBI. Definite mad in m a t casu rapid re-cstablhhmcnt of chronic p b u e h e m poiesis occurred in 28 paticnu The median survival from date of t m n s f o m t i o n v u 20 w k which was significantly longer than the IO-wk median survival in a cantempony group of patients treated by chemotherapy along.* We noted that patients treated by chemotherapy &fore autografting fared better than th& w received chemotherapy plus TB1 (Fig. 3). It is possible to draw some general c o n d u s k _ about the piace of autografting in the ment of patients in transformation. Hemopoietic3 ;- rtconstitution is highly predictable and seems - not to be a problem. Unfortunately, the value of the technique is strictly limited by the relative resistance to therapy of the transformed popula- - tion of cells and their propensity to reappear in the marrow and blood in mast casu within 3 4 . mo of autografting. It is worth noting that OCQ- ,';sional patients have. however. had second chronic phases lasting more than a For '.. -.patients whose transformation has. recurred. _ .a 4& 5 Uro m t M U T OC CQ. -- I-.,.-2s r u t w f t i n g hr been attempted on a second or a third oaarion with some succus. At p e n t it seem reasonable to recommend that a quantity Of blood 1euk-a should be c o l l ~ t e d and stored from every new patient with CGL ..., k f o r e treatment is started. The questions ofhow 1 " 01when. or indeed whether, to use the stored cells *': a n ktackled a t a later date. e. A major conceptual objection to autografting ir the fact that hemopoieticstem cells collected in c.. the chronic p h u c be it from the blood or from *&- the marrow, are d l presumably Ph'-poritive. -$ Howcvcr. this may nol necessarily be to if stem &b arc harvested after the patient has k e n + t m t e d with cytotoxic A recent report dacribod a patient whose manow, 3'.initially Pt+-pitivt, was restored to ~ht-negr- tivity bytreatment with highdost cyclophosphamide." Blood stem cells were then collected and *&.&. ,cryopratr~ed. When Ph'-positive transformation occurred, the patient was treated with high- dose busulfan and cyclophosphamide, followed .- by transfusion of autologous stem cells. Herno- .~ poisir was reestablished with Ph'-negative myeloid cells. lf one assumes for the sake of argu'- mcnt that the cytogenetically normal cells in this ** patient were not leukemic, the sequence of events &.*. ruggsts 8 new wry in which autografting with circulating stem cells might be exploited in the *.f.-.i.. future. .A- .- BO^ M ~ OTWranspiantation 9 n e successful transplantation of bone mar- $$ row collected from a normal donor could in $' thcory cure a patient with CGL. Cure would, f however. be more difficult if constitutional or e marrow microenvironmental facton play a role in the pathogenesis of the leukemia-hitherto .8 ufonrrathoelvreadnqupeasttiieonnts.foSrutuchnactoenesnidoeurgahtiotonshaapvaerta, a bematologically nomu1 genetically identical twin the major problem may be simply the design of a regimen of chemondiotherapy preceding the syngeneic transplantation that will permanently w a d i a t e the Ph'-positive myeloid cell line. A larger number of patients is likeiy to have HLAidentical sibs, and allogeneic marrow iransplantation may then be undertaken. in such uses the problem of eradicating the leukemia is a m - s.pounded by the dangers inherent in transplantation of HLA-matched non-identical marrow. 2Sl principally those of gnft-venw-host disuse (GVHD) and interstitial pneumonitis. Syngeneic Marrow Transpianlatior! Results of treating patienu with CGL in transformation by chemoradiot h m p y followed by transplantation of normal marrow from idart i u l twins are not encouraging. ODly 2 d 10 patienuso treated inScrtdcremrindi*eand the single knpterm survivor b 7 1 mo) may have been transplanted in adcrated pbuc nthtr than frank transformation Of CGLn As with autografting in tnnsformrtion, the main pmb lem appears to be the extreme mistanae d the transformed clone of cellsto h i g b d a e &anom- diothurpy; momover the padeat is dtca ia poor clinical andition when the p d u e ir Wtaken. The \ut of syngeneic m a m transplantation for patients still in the chronic phase d CGL u much more promising. In 1979 the Seattle group reported preliminary results of t r a t i n g 4 paticnu with Ph'-positive CGL with dimctbyl bruulfrn. cyclophosphamide. a d TBI follorcd by transfusion of twin marrow?' On follow-up the 4 patients were hematolagically normal with- out Phl-positive marrow metaphases. Subsequently. a further 8 patients w e n treated by transplantation of syngeneic bone manow. Of all 12 patients transplanted, the most recent report noted that one subsequently died of interstitial pneumonitis and another entered blastic transformation and died; two other patients relaprcd with cytogcrrctic but not clinical e*idcnce of CGL. Eight patimu remainedappmntfy free of all evidence of leukemia at follow-up timer rang- ing from 21 to 65 mo pt-transplant.u Similar experfence with a smaller number of patients has been gained at other centen. At the Hammenmith Hospital we treated two patients, one in uncomplicated chronic p b u e and the other in early accelerated phase, with cheme radiot herapy followed by syngeneic r m m transplantation." Both patients are alive and well 30 and 33 mo. respectively. after transplantation: both have only cytogenetically normal cells identifiable in the bone marrow. Two other patients with CGL in chronic phase w e n truted with twin marrow transplantation in Paris." In one case the transplant w8s complicated by I clinical picture closcly resembling GVHD but '. i the patient recovered and both patients were well CGI, no recurrenee of Phi-positive ha- at the time of the report." It thus appun that for the patient in chronic merapham after transplanution has yet & reported in any of thcsc series. No recunncr br phase, syngeneic marrow transplantation has the Ph'-pitive marrow m e t a p h u a a f t u tnnsphn- capacity either to cure or at l a s t to prolong the trtion has yet been reported in any of thae duration of life. Conversely. for the patient series. already in transformation the p d u r e offers At praent. allogeneic transplantation is avail- little benefit. able only for the relatively young pstient (usually under the age Of 40) who has an HU-idcntial Allogeneic Morrow Transplanmion For the patient with CGL in transformation who has an HLA-idential sib. the results of allogeneic transplantation are generally poor. At the time of their most recent report. 28 patients in aplastic. accelerated or frank blastic p h a w of CGL had been treated in Suttlc.w Three patients were alive at times ranging from 18 to 37 mo after transplantation. It is of interest that one of these survivors is a woman who was transplanted at the age of 50. the SUCCQS achieved with allogeneic trans- brother or sister. Even then the risks remain considerable. The especitl b r d r arc GVHD and interstitial pneumonitis. One hopes, how- ever, that increased undvrunding of the pathogenesis ol t h e e two major oornpiiationr will lead to multura that went tban. At ~ o m c time in the future it may k pardbk to o f k marrow transplantation to older p a h u with CGL and to thotc who. lacking HU-identical sibs. can only be transplanted with aurmw fmm mismatched relations or matched uarclrted d e nom plantation of patients with acute leukemia in remission and the observation that syngeneic coruaustous transplantation for patients in the chronic phase Though there is pcrJuarivcevidence to support of CGL a n suppress the Ph'-positive clone of the concept that Phl-positiv; CGL b a clonal cells at least for some y u n has led a number of disease derived originally from 8single ancestral groups to explore the possibility of treating stem cell, the assumption that all Ph'-negative patients by allogeneic transplantation before the marrow cells in a patient with Phi-positive dis- r onset of transformation. Again. the Seattle group ease are necessarily normal is no longer tenable. .L has pioneered this approach. A Cyr-old boy with It is probable, however. that some Phl-negative Ph'-negative chronic myeloid leukcmi8 was suc- and truly normal hemopoietic stem 4 1 s do sur- ctufully treated by transplrnution of marrow from his histocompatible brother.'"' Of 10 other vive in the marrow of the newly d i a g n d patient with CGL, pauibly such residual normal . patients with Ph'-positive CGL transplanted in stem e l l s are gradually destroyed by chemotha- the chronic phase, 4 died of tnnsplant-related complications but 6 survive at follow-up times aW* In assessing the prognostic value of clin ranging from I3 to 37 mo: t h e patients are all and hematological feacures defined at diagn clinically well.aa At the Hammmmith Haspi- (or soon after), one must first exclude fcatu tal 12 patients in the chronic phase of C G L were that indicate that the disease is already in treated with cyclophosphamide at high dosage or established transformation. -?he remainin and fractioned TBI (total IO00 or 1200 cGy) 'prognostic fe3turcs' can then k divided into followed by transplantation of marrow from static features that reflect the extent of disease HLA-identical sibs; 2 patients died of infection and dynamic f w t u r u which reflect its tempo; and GVHD but IO survive at follow-up times someof the latter may only be measurable after a ranging from I to 14 rno." Similar results with period of observation or after initial treatment. smaller numbers of patients have k e n reported These two categories of prognostic features must from Los Angeles. Toronto, Minneapolis and to some extent be interdependent. but this Basel.'"" Though the duration of follow-up is approach may heip to discriminate between still short in most casu and some patients may odvoncd disease that is not necessarily aggra- ultimately relapse initially with cytogenetic and sive and aggressive disease that m y or may not tubsqucntly with hematological evidence of be advanced. Though there is no general agree- 213 mcni about thc prognostic valuc of individual re;ltura, possibly significant st;ttic fcaiurcs include the pticnt's sex. splccn s i x . livcr sizc. hemoglobin. lcukocyrc count. plotclct count. thc proportion ofimm3tufc prnnulocytcs in thc blood or marrow, and the prcscncc or ;ihscncc of ihc Phi chromwmc. Possibly significant dynamic f a l u r e s include the doubling iimc of thc lcukocyic counl. thc response of thc Icukwytc count to chemotherapy and its ratc of risc thcrcaftcr. thc mitotic index ofthc blast ccllr and ihc acquisition of cytogenetic changes in addition to t h c Phi chromosome. Occasional padcnls trcalcd with busulfan have had true "cylogenetic"remisGons and some of t h e patients have been long-term survivors. Altcrnpts. howcver. to reproduce such clinical bcncfit roulincly with combinations of cytotoxic drugs havc in gcncrd been disappointing. Rcsulis of syngcncic nimow tmnsplanlation suggcst that most pticnts in the chronic phase bcncfit from such rrcatmcnt and some m y perhaps be cured. Prclirninary results of allogcncic marrow transplantation for patients still in thc chronic phase of CGL suggCSt onc poyiblc ave- nue for progress in thc current dcude. ACKNOWLEDGMENT We arc very grateful to Rof- David Gaiton rho r a d the manusccnpt and nude valuable mmmcnu; hc ab0 mrdc availableh e n u t d q i cdata on paticnlr treated i n the M1Research Council study" amparins h u l f a a with rdia therapy. We must thank a b Proraror J e p b sdul rbac constructive criticism id. we hope. 10 an i m p m d manuscrip. REFERENCES I. b c c r n n i M. Killmann S: Cytokinetic studies in chronic myeloid leukaemia: Evidence for early presence of abnormal myeloblrsts. %and J Haematol9:183-292. I972 2. B a c a n n i M. R u ~ e r o0. Tura S;Therapy of chronic myelaid leukmi. (CML): Interim report on protocols CML/73 a d CML/74. Boll 1st Sieroter Milan 57218-288. I978 3. Barr RD.wall I:Preliminary evidence for the common oriBin of a Iympha-myeloidcomplex in man. A a a Hacmatol (&ucc) W.29-35.1978 4. Barton JC. Conrad ME: Current status of blastic tranrformrih in ch'ronic myelogenous leukemia. Am J 0Wl428l-291. I978 njamin 0, Djaldetti M. 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