Chronic myeloid leukemia in first chronic phase not responding to ...

Bone Marrow Transplantation, (1999) 24, 259–264  1999 Stockton Press All rights reserved 0268–3369/99 $12.00 http://www.stockton-press.co.uk/bmt

Chronic myeloid leukemia in first chronic phase not responding to ␣-interferon: outcome and prognostic factors after autologous transplantation J-M Boiron1, J-Y Cahn2, G Meloni3, C Carlo-Stella4, G Bandini5, O Reman6, N Milpied7, J Apperley8, J Reiffers1 for the EBMT Working Party on Chronic Leukemias ˆ ´ ˆ ´ ˆ Service des Maladies du Sang, Hopital Haut-Leveque, CHU Bordeaux; 2Service d’Hematologie Clinique, Hopital Jean Minjoz, 3 Besanc¸on, France; Universita degli studi ‘La Sapienza’, Dipartimento di Biopatologia Umana, Sezione Hematologia, Rome; 4 Universita degli studi di Parma Cattedra di Ematologia, Centro di Midollo Osseo, Parma; 5Universita degli studi di Bologna, Instituto di Ematologia ‘Lorenzo e Ariosto Seragnoli’, Policlinico s Orsola, Bologna, Italia; 6Service d’He´matologie Clinique, CHU ´ ˆ Caen, Caen; 7Service d’Hematologie, CHU Nantes Hotel Dieu, Nantes, France; and 8Department of Hematology, Imperial College at Hammersmith Hospital, London, UK 1

Summary: We report the data obtained from the European Bone Marrow Transplant Registry for patients with CML who received autologous transplantation (AT) in chronic phase (CP) because ␣-IFN was ineffective. Forty-one CML patients (median age: 40.5 years; median Sokal index: 0.78) were included in this study. Bone marrow (16 cases) or blood (25 cases) progenitor cells were collected at diagnosis in 19 patients, during stable chronic phase or while the patient had cytogenetic (Cy) or complete hematologic response (CHR) in the other 22, and were manipulated ex vivo in 10 cases. The conditioning regimen consisted of busulfan associated with other chemotherapeutic regimens in 36 cases. Two patients died from interstitial pneumonitis (one case) and hemorrhage (one case). From the date of AT, the estimated probability of survival for the 41 patients was 84 ⴞ 13% and 51 ⴞ 29% at 2 and 4 years, respectively. Considering the 39 evaluable patients, the actuarial probability of achieving CHR, major and complete CyR 2 years after AT was 92 ⴞ 9%, 46 ⴞ 17%, and 30 ⴞ 15%, respectively. The Sokal score at diagnosis and the achievement of hematologic response after transplant were of prognostic importance. We suggest that a significant proportion of CML patients not responding to ␣-IFN may benefit from AT. Keywords: autologous transplantation; CML; interferon

Chronic myeloid leukemia is a clonal myeloproliferative disorder characterized by a cytogenetic abnormality corresponding to a reciprocal translocation between chromosomes 9 and 22 (Philadelphia chromosome). Recombinant alpha-interferon (␣-IFN) and allogeneic transplantation are the two therapeutic strategies which are routinely used in most cases.1 Allogeneic transplantation is usually restricted ˆ Correspondence: J-M Boiron, Service des Maladies du Sang, Hopital ´ ˆ Haut-Leveque, Avenue Magellan, CHU Bordeaux, 33604 Pessac, France Received 29 July 1998; accepted 17 February 1999

to the 15–20% of patients who both are under 50 years of age and have an HLA-matched donor. Recombinant ␣interferon is considered a better treatment than hydroxyurea or busulfan,2,3 but only the 20–30% of patients who have a cytogenetic response to ␣-IFN seem to have a substantially prolonged survival.4 For the patients who do not respond to ␣-IFN and who cannot benefit from allogeneic transplantation, alternative treatments have to be proposed. One major rationale for using autologous transplantation (AT) is that normal progenitors are present in the bone marrow (BM) and blood of CML patients5,6 and that most of the immature cells capable of long-term hematopoietic reconstitution do not belong to the leukemic clone.7 Autologous transplantation was first used for patients with advanced disease. Although most are restored to chronic phase (CP) and more interestingly, the re-emergence of Philadelphia-negative hematopoiesis is observed in some cases, the duration of the second CP is usually short, not exceeding 6 months.8,9 More recently, AT was performed in some patients during CP; the results were encouraging enough to lead some investigators to propose AT for patients who did not respond to ␣-IFN and who could not benefit from allogeneic transplantation.8 In addition, in vivo and ex vivo purging techniques designed to eradicate Philadelphia-positive leukemic progenitors from the autologous products have been developed. They include the incubation of hematopoietic progenitors with different reagents such as gamma-IFN,10 cyclophosphamide derivatives11 or antisense oligonucleotides12,13 and long-term culture techniques.14 In vivo purging using intensive chemotherapy followed by the use of hematopoietic growth factors has also been proposed.15 The influence of AT with either purged or unpurged progenitors on the survival of CML patients is unknown, as no prospective study has compared the survival of patients treated with either AT or standard treatment in CML. However, the rate of cytogenetic response observed after AT compares favorably with that seen after ␣-IFN.8 In this paper, we have retrospectively analyzed the patients registered with the European Bone Marrow Transplant Registry (EBMTR) who underwent AT for CML in first CP because they were unresponsive to ␣-IFN. These results suggest that AT is able to restore ␣-IFN sensitivity

Autologous transplantation for CML in chronic phase J-M Boiron et al

260

in a substantial proportion of patients who do not respond to this treatment.

Patients and methods Patients Of the 55 patients who were reported to the EBMTR and who underwent AT for CML between 1986 and 1995, we selected 41 who were in first CP and were considered to be resistant after more than 3 months of ␣-IFN treatment. The other 14 patients were excluded because they were in accelerated phase (six patients), were autografted despite response to ␣-IFN or chemotherapy (four patients), or had received IFN for less than 3 months (four patients). All 41 patients were in first CP at the time of AT and had failed to achieve or maintain hematologic or cytogenetic response. The median age at diagnosis was 40.5 years (range 16–61). The median Sokal index at diagnosis was 0.78 (range 0.45– 1.5, n = 38). Twenty-one patients were in the low-risk group, 12 patients in the intermediate-risk group and five patients in the high-risk group. In three cases, the Sokal score was not available. The different treatments used in addition to ␣-IFN before AT were: hydroxyurea (17 cases), busulfan (one case) and aracytine (four cases). Intensive chemotherapy was used in seven patients: two courses of DAT chemotherapy were used in one patient, the ICE regimen was used in two patients, and high-dose melphalan and the ROAP regimen were used in one patient each. The chemotherapy was unknown in two patients. Autografting procedure For AT, the origin of progenitors was BM (16 cases) or peripheral blood (25 cases). The cells were unmanipulated in 31 cases (BM: 11 cases, blood: 20 cases); ie blood progenitors had been collected during the recovery phase of high-dose chemotherapy in five cases and bone marrow was treated with mafosfamide or using the long-term culture technique in five others. The conditioning regimen consisted of busulfan (4 mg/kg/day, 4 days) associated with either melphalan alone (140 mg/m2)16 (29 cases), or cyclophosphamide alone (120 mg/kg, one case) or both (melphalan 90 mg/m2 and cyclophosphamide 120 mg/kg, four cases). The BAVC regimen11 was used in three other cases and combined melphalan and cyclophosphamide in one case. The conditioning regimen was unknown in three cases. ␣-IFN was used after AT in 29 cases. The duration between AT and the beginning of ␣-IFN treatment and initial dosage of ␣-IFN were not standardized, as these patients had been treated in different institutions. Response criteria and statistical analysis Complete hematologic response (CHR), cytogenetic response (CyR), major, minor and complete CyR (CCR) were defined as described elsewhere.17 Patients were subclassified into four groups according to their pattern of ␣-

IFN resistance (Table 1). Patients who achieved neither hematologic response (HR) nor cytogenetic response (CyR) were defined as having primary hematologic failure (group I). Patients who achieved HR without achieving CyR were defined as having primary cytogenetic failure (group II). Patients who achieved HR without CyR were defined as having secondary hematologic failure if CHR could not be maintained (group III). Those who achieved HR and CyR were considered to have secondary cytogenetic failure if they remained in CHR and if CyR could not be maintained (group IV). CyR after AT was evaluated within 45 days from AT in 22 patients (Figure 1). The patients who had a better hematologic or cytogenetic response anytime after AT than the best response obtained before AT were defined as ‘good’ responders to the procedure. The other patients were classified as ‘poor’ responders. Analysis of overall survival (OS), probability to achieve CHR or CyR was made by the Kaplan–Meier test on the SPSS software (Chicago, IL, USA). The patients who died less than 1 month after AT were not considered for the response analysis. Patients lost to follow-up were censored at the time of the last information for survival and response curves. For CHR or any CyR, the duration of response was censored at the time of death, relapse or subsequent transplantation. Results Response to ␣-IFN before AT The median duration between diagnosis and AT was 25.3 months (range: 4.3–84). The median duration of ␣-IFN treatment before AT was 16 months (range: 4–81). Table 1 shows the number of patients and the median duration of ␣-IFN treatment before AT in each of the four subgroups defined according to the previous response to ␣-IFN. The numbers of patients who received less than 1 year, between 1 and 2 years, between 2 and 4 years, and more than 4 years of ␣-IFN therapy before AT were 13, 13, 11 and 4, respectively. The median (range) duration of ␣-IFN treatment in the Sokal low, intermediate and high-risk groups were 23.5 (5.6–57.9), 17.3 (4.1–50.3) and 10.8 months (4– 81.7), respectively. Respectively two, one, and one patient received less than 6 months of ␣-IFN therapy before AT. Most patients were transplanted because they failed to achieve CyR after a median of 15.3 months of ␣-IFN treatment Table 1 Characteristics of the 41 patients according to response to ␣-IFN before AT Group

I II III IV

Patients

IFN treatment (months)

Definition

LR

IR

HR

n

median

range

PHF PCF SHF SCF

5 8 1 7

3 5 3 1

1 1 2 1

9 17 6 9

7.3 15.3 18 35.2

4–33.9 5.1–57.9 9.7–38 10.2–81.7

PHF = primary hematologic failure; PCF = primary cytogenetic failure; SHF = secondary hematologic failure; SCF = secondary cytogenetic failure; LR, IR, HR = Sokal low, intermediate and high risk patients.


261

39 evaluable patients

22+

10pts + (5CCR)

7 pts +

5 CyR (2 CCR)

3 pts - 10 pts +

3

2 1 CyR (1 CCR)

2 pts -

6

2 CyR (2 CCR)

3 3 CyR (2 CCR)

CyR within 45 days after AT

12 pts +

5

17-

Number of patients evaluable for CyR after AT

1 CyR

12 pts +

5 pts -

Number of patients evaluable for CyR at 6 months

7

0

CyR at 6 months

3 CyR (1 CCR)

-

Number of patients evaluable for CyR at 1 year

5

0

2 CyR (2 CCR)

-

0

1 CyR

2

Number of patients treated with interferon after AT

-

0

CyR at 1 year

-

Figure 1 Patients’ cytogenetic response to autologous transplant (AT) according to the status and ␣-IFN treatment after AT.

(group II). Of these 17 patients, only six had been treated with ␣-IFN for less than 1 year and two for less than 6 months. All patients transplanted for primary hematologic failure had received at least 3 months of ␣-IFN. For the seven patients who received intensive chemotherapy, one belonged to group I, three to group II, two to group III, and one to group IV. The exact dose of ␣-IFN delivered to the patients was not available from the registry. However, the maximal tolerated doses were used in 18/18 patients for whom this information was available. The exact duration between the end of IFN treatment and autografting was not known for all patients. However, when these data were identified (18 patients), IFN had been stopped a minimum of 1 month before grafting.

Polymorphonuclear neutrophil recovery (⬎0.5 G/l) occurred at a median of 18 days (range 9–71 days). Platelet recovery (⬎50 G/l) was seen at 21.5 days (range 7–145). Two patients died from interstitial pneumonitis at day 155 (group III, one case) and hemorrhage at day 19 (group II, one case). The former had been transplanted with peripheral blood progenitors collected at diagnosis and the latter received purged bone marrow progenitors.

Progenitor cells

Treatment and outcome after autologous transplant

The median duration between diagnosis and progenitor collection was 5.6 months (range 0–54.7). Autologous progenitors were collected at diagnosis in 19 patients, during stable chronic phase, or while the patient had CyR or CHR. Table 2 shows the type of progenitors used for AT in the

The median follow-up after AT for the 39 evaluable patients was 22.5 months (9.6–65.8). From the date of AT, the estimated probability of survival for the 41 patients was 84 ⫾ 13% and 51 ⫾ 29% at 2 and 4 years, respectively (Figure 2). After AT, three patients received only hydrox-

Table 2

1.00 0.90 0.80 0.70 0.60 0.50 0.40 0.30 0.20 0.10 0.00

Response at time of progenitor collection for the 41 patients

Response at time of progenitor collection

No purging

Purging In vitro

In vivo

Total

Diagnosis CP without response CHR CyR

18 4 4 5

— — 5 —

1 1 1 2

19 5 10 7

Total

31

5

5

41

different subgroups. The median numbers of CFU-GM and nucleated cells transplanted were 18.4 × 104/kg (0.08– 1266) and 4.98 × 108/kg (1–82), respectively. Toxicity

0

12

24

36

48

60

72

Months since ASCT

Figure 2 Probability of survival after autotransplant for the 41 patients.


262

yurea and seven received no treatment. Twenty-nine patients were treated with ␣-IFN beginning a median of 3.2 months (range 0.4–20) after AT. Eleven of these 21 patients evaluable for cytogenetic response at 6 months achieved CyR (52%). Two patients had received purged products (in vitro and in vivo: one each), and nine unpurged products. Patient response according to the status after AT and to ␣IFN treatment is indicated in Figure 1. Twenty-four of the 39 evaluable patients (61%) were ‘good’ responders (group I: 7/9; group II: 8/16; group III: 2/5; group IV: 7/9). In group I (primary hematologic failure), three patients experienced a CHR and four CyR (CCR: one patient); in group II (primary cytogenetic failure), one patient remained in CHR without treatment for 19 months and seven obtained CyR (CCR: four cases); in group III (secondary hematologic failure), one patient obtained CCR and one reverted to CHR; in group IV (secondary cytogenetic failure), seven patients reverted to CyR (CCR: four cases). Twenty of these 24 (83%) patients received IFN after AT. Fifteen patients (39%) were ‘poor’ responders (group I: 2/9; group II: 8/16; group III: 3/5; group IV: 2/9). Two patients were not evaluated (group I and III: one each) and were classified as poor responders. One patient (group II) had no response after AT although he was in CHR before. All other patients were in a similar situation after AT. Nine of these 15 patients (60%) received IFN after AT. Nine of the 39 evaluable patients had no cytogenetic analysis after AT. Ten of the 22 patients evaluable for cytogenetic response within 45 days after AT achieved CyR (45%). Six of these had received unpurged products and four purged products (in vitro: three patients, in vivo: one patient). Considering the 39 evaluable patients, the actuarial probability of achieving CHR, major CyR, and CCR 2 years after AT was 92 ⫾ 9%, 46 ⫾ 17% and 30 ⫾ 15% (Figure 3), respectively. As a whole, 14 achieved a major CyR at one time point after AT including nine (31%) who obtained CCR (unknown Sokal score at diagnosis: two patients; high: one patient; intermediate: one patient; low: five patients). From these nine patients, the median duration of ␣-IFN treatment before AT was 25 months (5.1–81.7). Only one had received less than 6 months of ␣-IFN treatment before AT. The median duration between AT and major CyR was 48 months (1–48). The median duration of major CyR and CCR was 29 (range 5–38, 14 patients) and 18.7 (range 2–36, 9 patients) months, respectively. The probabilities of a patient who achieved major CyR and 1.00 0.90 0.80 0.70 0.60 0.50 0.40 0.30 0.20 0.10 0.00

CHR

1.00 0.90 0.80 0.70 0.60 0.50 0.40 0.30 0.20 0.10 0.00

MCR: n = 14 CCR: n = 9

0

6

12

18

24

30

36

42

Figure 4 Probability of remaining in major CyR or CCR for the patients who achieved this result after transplant. Fourteen achieved a major CyR at one time point after AT including nine who obtained CCR.

CCR remaining in major CyR and CCR at 1 year were 43 ⫾ 18% and 32 ⫾ 17%, respectively (Figure 4). Fourteen of the 21 patients (66%) with low-risk CML had a ‘good’ response, including 16 who achieved CHR, 10 of whom achieved CyR. Five of these patients achieved complete cytogenetic response. Eighteen patients are alive with a median follow-up of 21.8 months (range 0.6–62.8). Thirteen are in CHR, six in CyR and three in CCR. Six of the 12 patients with intermediate-risk CML had a ‘good’ response with three achieving complete cytogenetic response. Two of the five patients with high-risk CML had a good response but no patient achieved complete cytogenetic response. Prognostic factors The following parameters were studied by univariate analysis: Sokal score at diagnosis, presence of a response before AT (ie classification in group I, II, III or IV), duration of ␣-IFN treatment before AT, duration between diagnosis and AT, use of a purging procedure, use of ␣-IFN after AT and achievement of a response (hematologic or cytogenetical) after AT. The most significant prognostic factors are shown in Table 3. Obtaining a cytogenetic response at one time point before AT had no statistical influence on survival in this study. In line with this observation, the different subgroups (defined in Table 1) in which the patient could be classified before transplant (ie the type of resistance to ␣-IFN) were not found to be of clinical significance. The patients who had CyR at one time point after AT did not experience a better survival than the others. Table 3 Prognostic factors of survival after autologous transplant for chronic myelogenous leukemia in chronic phase not responding to interferon

MCR

CCR 0

3

6

9

12

15

18

21

24

Months since ASCT (patients censored at the following transplant) Figure 3 Probability of obtaining hematologic and cytogenetic responses in the 39 evaluable patients.

48

Months since ASCT (patients censored at the following transplant)

Factors

Survival

Sokal score at diagnosis Higha vs low or intermediate risk Hematologic response before AT Use of a purging techniquea Hematologic response after AT IFN treatment after AT

0.009 0.02 0.08 0.0001 0.02 0.0001

a

Unfavorable effect.


Discussion This study confirms the feasibility of AT for CML patients in CP who are not responders to ␣-IFN. These results were obtained from a large cohort of 41 patients who had all received ␣-IFN and were truly resistant to this treatment. They strongly suggest that a significant proportion (at least one third) of CML patients not responding to ␣-IFN may benefit from AT. The best results were obtained for patients with the lowest tumor mass at diagnosis. Like other registry studies, this study has several drawbacks. Although allogeneic transplantation would probably have been suggested for the patients if they had had an HLA-compatible donor, these data were not available for all patients. The higher proportion of low-risk patients in this study may be explained by the different therapeutic choices for higher-risk patients in the different institutions involved in the study: front-line autologous transplant or MUD transplant. Although no uniform guidelines were followed for the pre-transplant ␣-IFN treatment, we assume that the maximal tolerated dose of ␣-IFN was used before concluding that it was inefficient. This was true in 18 of 18 patients for whom these data were available. The influence of the type of response before transplant seems low, as if resistance to ␣-IFN therapy had become the major characteristic of the disease, independently of tumor mass at diagnosis. Therefore, our subclassification of patients in four subgroups according to type of ␣-IFN resistance could be mainly descriptive. However, it would be interesting to test its value in larger series of patients with no response to ␣-IFN. First-line treatments, conditioning regimens and graft products (BM vs blood products, purge vs unpurged) are all variables and no conclusion can be drawn from this study regarding the strategies used. The negative influence of the purging techniques may be the result of a selection bias. Conversely, ␣-IFN may have been used in selected patients whose condition was better than that of those who did not receive it. This may explain the good prognostic influence observed. The lack of prognostic significance of cytogenetic response after transplant may be due to the low number of patients studied and to the lack of recommendations for the frequency of cytogenetic studies in the follow-up. Given these possible biases, we did not perform a multivariate analysis of these prognostic factors. Despite these limitations, our results are encouraging and very similar to previously published data. They may be explained by a growth advantage of normal progenitors during hematopoietic recovery and by a restoration of a balance between immunocompetent cells able to control leukemic growth soon after transplant, leading to a better action of ␣-IFN. In the most recent update of the patients who received AT at the Hammersmith Hospital, 21 patients were studied. They received AT with unmanipulated blood progenitors between 1984 and 1992. The median time between diagnosis and AT was shorter than in our study (median 18 months, range 2–67) and few patients were treated with ␣-IFN either before or after AT. Half of them had blood cells collected at diagnosis. No early deaths were seen. Interestingly, 11/16 evaluable patients had Ph-negative marrow metaphases 6 months after AT and the overall survival was 56% at 5 years.18–20 In three papers describing

autologous transplants using in vitro manipulated cells, early death was seen in 16 to 50% of late CP patients. Transient CyR was observed within 2 months after AT in 83 to 100% of the remaining evaluable patients. ␣-IFN treatment was necessary in 30 and 75% of evaluable patients in two studies and was not given in the third. By no means all the patients in these series received ␣-IFN before AT.10,11,14 In another study, 33 patients who were previously treated with ␣-IFN entered a program of highdose chemotherapy followed by G-CSF and blood progenitor collection. A low proportion (39%) of patients with CML in CP were eligible for AT (Ph-negative blood products and suitable levels of progenitors). 53% were given ␣-IFN post-AT. Two patients were Ph-negative at the time of the report.15 After the use of similar in vivo purging techniques, 10 patients in late CP received AT at the MD Anderson Hospital. One patient died of graft failure, one needed infusion of a back-up transplant and nine were alive at the time of the report.21 In another study, AT (purged or unpurged) used in 22 patients resistant or intolerant to ␣IFN was followed by a median survival of 34 months. There were two graft failures and one early death. Eleven patients had a CyR after AT. ␣-IFN treatment after AT was given in three of 22 CP patients.22 In summary, we show in this study that one third of patients in CP after a median of 2 years of ␣-IFN treatment can achieve CCR after AT. In addition, we suggest that ␣IFN following AT may be beneficial in maintaining a CyR obtained after AT, or in patients who do not immediately respond to AT. This has to be compared to the results obtained when ␣-IFN is given for a protracted period without response.23 The use of AT at an earlier stage of the disease may further enhance our results and it might be tempting to use early indicators of IFN resistance to decide when to suggest AT.23,24 This question has to be evaluated in the prospective randomized studies currently in progress in Europe. Acknowledgements ´ Other participants: M Michallet (Service d’Hematologie, Hopital ´ E Herriot, Place d’Arsonval, 69437 Lyon cedex 03), Dr Granena (I Catala Oncologia, Servei d’Hematologia Clinica, Hospital Duran i Reynals, l’Hospitalet di Llubregat 08907 Barcelona), Dr Jouet (Nice), Dr De Laurenzi, Dr Carreras (Hospital Clinic i Provincial de Barcelona Villaroel, 170–08036 Barcelona), and Ray Cooke for linguistic advice.

References 1 Kantarjian HM, O’Brien S, Anderlini P, Talpaz M. Treatment of chronic myelogenous leukemia: current status and investigational options. Blood 1996; 87: 3069–3081. 2 Hehlmann R, Heimpel H, Hasford J et al. Randomized comparison of busulfan and hydroxyurea in chronic myelogenous leukemia: prolongation of survival by hydroxyurea. Blood 1993; 82: 398–407. 3 The Italian Cooperative Study Group on Chronic Myelogenous Leukemia. Interferon-alfa-2a as compared with conventional chemotherapy for the treatment of chronic myeloid leukemia. New Engl J Med 1994; 330: 820–825.

263


264

4 Kantarjian HM, Smith TL, O’Brien S et al. Prolonged survival in chronic myelogenous leukemia after cytogenetic response to interferon-␣ therapy. Ann Intern Med 1995; 122: 254–261. 5 Dube ID, Kalousek DK, Coulombel L et al. Cytogenetic studies of early myeloid progenitor compartments in Ph1-positive chronic myelogenous leukemia. II. Long-term culture reveals the persistence of Ph1-negative progenitors in treated as well as newly diagnosed patients. Blood 1984; 63: 1172–1177. 6 Jazwiec B, Mahon F-X, Pigneux A et al. 5-Fluorouracil-resistant CD34+ cell population from peripheral blood of chronic myelogenous leukemia patients contains BCR-ABL negative progenitor cells. Exp Hematol 1995; 23: 1509–1514. 7 Coulombel L, Kalousek DK, Eaves CJ et al. Long-term marrow culture reveals chromosomally normal hematopoietic progenitor cells in patients with Philadelphia chromosome-positive chronic myelogenous leukemia. New Engl J Med 1983; 308: 1493–1498. 8 Reiffers J, Goldman J, Meloni G et al. Autologous stem cell transplantation in chronic myelogenous leukemia: a retrospective analysis of the European Group for Bone Marrow Transplantation. Bone Marrow Transplant 1994; 14: 407–410. 9 Haines ME, Goldman J, Worsley AM et al. Chemotherapy and autografting for chronic granulocytic leukemia in transformation: probable prolongation of survival for some patients. Br J Haematol 1984; 58: 711–721. 10 McGlave PB, Arthur D, Miller WJ et al. Autologous transplantation for CML using marrow treated ex vivo with recombinant human interferon gamma. Bone Marrow Transplant 1990; 6: 115–120. 11 Carlo-Stella C, Mangoni L, Almici C et al. Autologous transplant for chronic myelogenous leukemia using marrow treated ex vivo with mafosfamide. Bone Marrow Transplant 1994; 14: 425–432. 12 Gewirtz AM. Oligodeoxynucleotide-based therapeutics for human leukemias. Stem Cells 1993; 11 (Suppl. 3): 96–103. 13 de Fabritiis P, Petti MC, Montefusco E et al. BCR-ABL antisense oligodeoxynucleotide in vitro purging and autologous bone marrow transplantation for patients with chronic myelogenous leukemia in advanced phase. Blood 1998; 91: 3156– 3162. 14 Barnett MJ, Eaves CJ, Phillips GL et al. Autografting with cultured marrow in chronic myeloid leukemia: results of a pilot study. Blood 1994; 84: 724–732.

15 Carella AM, Chimirri F, Podesta M et al. High-dose chemoradiotherapy followed by autologous Philadelphia chromosome-negative blood progenitor cell transplantation in patients with chronic myelogenous leukemia. Bone Marrow Transplant 1996; 17: 201–205. 16 Cony-Makhoul P, Marit G, Boiron J-M et al. Busulphan and melphalan prior to autologous transplantation for myeloid malignancies. Bone Marrow Transplant 1995; 16: 69–71. 17 Talpaz M, Kantarjian HM, McCredie KB et al. Hematologic remission and cytogenetic improvement induced by recombinant human interferon ␣-A in chronic myelogenous leukemia. New Engl J Med 1986; 314: 1065–1069. 18 Brito-Babapulle F, Bowcock SJ, Marcus RE et al. Autografting for patients with chronic myeloid leukemia in chronic phase: peripheral blood stem cells may have a finite capacity for maintaining haemopoiesis. Br J Haematol 1989; 73: 76– 81. 19 Hoyle C, Gray R, Goldman J. Autografting for patients with chronic myelogenous leukemia in chronic phase. Br J Haematol 1994; 86: 76–81. 20 Mughal T, Hoyle C, Goldman J. Autografting for patients with chronic myeloid leukemia – The Hammersmith experience. Stem Cells 1993; 11 (Suppl. 3): 20–22. 21 Talpaz M, Kantarjian H, Liang J et al. Percentage of Philadelphia chromosome (Ph)-negative and Ph-positive cells found after autologous transplantation for chronic myelogenous leukemia depends on percentage of diploid cells induced by conventional-dose chemotherapy before collection of autologous cells. Blood 1995; 85: 3257–3263. 22 Khouri IF, Kantarjian HM, Talpaz M et al. Results with highdose chemotherapy and unpurged autologous stem cell transplantation in 73 patients with chronic myelogenous leukemia: the MD Anderson experience. Bone Marrow Transplant 1996; 17: 775–779. 23 Sacchi S, Kantarjian HM, Smith TL et al. Early treatment decisions with interferon-alfa in early chronic-phase chronic myelogenous leukemia. J Clin Oncol 1998; 16: 882–889. ` 24 Mahon FX, Faberes C, Boiron JM et al. High response rate using recombinant alpha interferon in patients with newly diagnosed chronic myeloid leukemia (CML): analysis of predictive factors. Blood 1996; 88 (Suppl. 1): 638a.