Clinical Significance of ABCB1 in Acute Myeloid Leukemia: A Comprehensive Study.

ABCB1 is a member of the ATP binding cassette transporter family and high ABCB1 activity is considered as a poor prognostic factor in acute myeloid leukemia (AML) treated with intensive chemotherapy, its direct relation with drug resistance remains unclear. We evaluated ABCB1 activity in relation with clinical parameters and treatment response to standard chemotherapy in 321 patients with de novo AML. We assessed multiple clinical relationships of ABCB1 activity-ex vivo drug resistance, gene expression, and the ABCB1 inhibitor quinine were evaluated. ABCB1 activity was observed in 58% of AML and was linked to low white blood cell count, high expression of CD34, absence of FLT3-ITD, and absence of mutant NPM1. Moreover, ABCB1 activity was associated with worse overall- and event-free survival. However, ABCB1 activity did not directly lead to ex vivo drug resistance to anthracyclines. We found that ABCB1 was highly correlated with gene expressions of BAALC, CD34, CD200, and CD7, indicating that ABCB1 expression maybe a passenger characteristic of high-risk AML. Furthermore, ABCB1 was inversely correlated to HOX cluster genes and CD33. Thus, low ABCB1 AML patients benefited specifically from anti-CD33 treatment by gemtuzumab ozogamicin in addition to standard chemotherapy. We showed prognostic importance of ABCB1 gene expression, protein expression, and activity. Furthermore, ABCB1 was not directly linked to drug resistance, ABCB1 inhibition did not improve outcome of high ABCB1 AML patients and thus high ABCB1 may represent a passenger characteristic of high-risk AML.

Pomalidomide, cyclophosphamide, and dexamethasone for relapsed multiple myeloma.

It is important to have an effective therapy for patients with multiple myeloma (MM) at first relapse, particularly if an autologous stem cell transplant (ASCT) is considered at this stage. This multicenter, phase 2 trial evaluated the efficacy and safety of weekly oral pomalidomide-cyclophosphamide-dexamethasone (PCD) in patients with MM in first relapse after treatment with lenalidomide-bortezomib-dexamethasone (RVD). All patients had received RVD as induction and consolidation therapy, plus lenalidomide maintenance for 1 year (arm A). Half had also received an ASCT after induction (arm B). At MM relapse, all patients received 4 oral cycles of pomalidomide 4 mg (days 1-21), cyclophosphamide 300 mg (days 1, 8, 15, and 22), and dexamethasone 40 mg (days 1-4 and days 15-18 of a 28-day cycle; PCD). Responding patients in arm A underwent ASCT and received 2 additional cycles of PCD, whereas those in arm B received 5 cycles of PCD. All patients received pomalidomide-dexamethasone maintenance until disease progression. Primary end point was partial remission or better after the initial 4 cycles of PCD. Responses were obtained in 82/97 (85%) patients evaluated: complete remission (n = 1; 1%), very good partial remission (n = 32; 33%), and partial remission (n = 49; 51%). Three patients (3%) had stable disease, and 6 (6%) had disease progression (6 response failures). Forty-five (94%) of the 48 patients in arm A underwent planned ASCT. PCD was effective therapy after first relapse with RVD. After 4 cycles, the rate of partial remission or better was 85%, and 94% of planned ASCTs were performed. Toxicity was mostly hematologic and manageable. This trial was registered at www.clinicaltrials.gov as #NCT02244125.

Salvage therapy post pomalidomide-based regimen in relapsed/refractory myeloma.

The combination of pomalidomide and low-dose dexamethasone (Pom-Dex) has proved effective and safe in patients with end-stage relapsed/refractory multiple myeloma (RRMM), otherwise characterized by a very poor outcome. MM remains an incurable disease with unavoidable relapses, and the outcome after pomalidomide is still dismal. However, some patients demonstrate prolonged survival even beyond pomalidomide therapy.We sought to analyze the treatment of RRMM patients following Pom-Dex therapy and the response and survival after this next treatment line.We studied 134 patients treated with Pom-Dex until progression across two IFM studies. Seventy percent of these patients received further therapy after Pom-Dex. Among the treated patients, one third responded and one third maintained stable disease. The median OS for treated patients was 12 months (6.5;17), with 22 and 12.5% of patients surviving beyond 2 and 3 years, respectively. The factors associated with a better outcome were exposure to a triplet-based regimen containing a novel agent, response to therapy, absence of adverse cytogenetic, and a longer time from diagnosis to post pomalidomide therapy.This study suggests that patients relapsing after Pom-Dex therapy can still benefit from a further line of treatment. A subset of these treated patients even displayed a prolonged OS, while the prognosis remained very poor without treatment. An active approach could therefore be recommended even in this adverse situation, however guided by the patients' prognosis factors.

Bortezomib, Doxorubicin, Cyclophosphamide, Dexamethasone Induction Followed by Stem Cell Transplantation for Primary Plasma Cell Leukemia: A Prospective Phase II Study of the Intergroupe Francophone du Myélome.

PURPOSE: Primary plasma cell leukemia (pPCL) is a rare and aggressive malignancy with a poor prognosis. With conventional chemotherapy, patients typically die within 1 year. In all but one of the retrospective studies reported to date, bortezomib and lenalidomide seem to improve survival. We conducted a prospective phase II trial in patients with pPCL to assess the efficacy of an alternate regimen that combines standard chemotherapy, a proteasome inhibitor, and high-dose melphalan and autologous stem cell transplantation (HDM/ASCT) followed by either allogeneic transplantation or bortezomib/lenalidomide maintenance. PATIENTS AND METHODS: Patients 70 years old and younger with newly diagnosed pPCL received four alternating cycles of bortezomib, dexamethasone plus doxorubicin or cyclophosphamide. Peripheral blood stem cells were collected from responding patients with < 1% of circulating plasma cells before HDM/ASCT. As consolidation, young patients received a reduced-intensity conditioning allograft, whereas the remaining patients underwent a second HDM/ASCT followed by 1 year of bortezomib, lenalidomide, dexamethasone. The primary end point was progression-free survival (PFS). RESULTS: Forty patients (median age, 57 years; range, 27 to 71 years) were enrolled. The median follow-up was 28.7 months. In the intention-to-treat analysis, the median PFS and overall survival were 15.1 (95% CI, 8.4; -) and 36.3 (95% CI, 25.6; -) months, respectively. The overall response rate to induction was 69%. One patient underwent a syngeneic allograft and 25 HDM/ASCT (16 of whom subsequently received a reduced-intensity conditioning allograft and seven a second ASCT followed by maintenance). CONCLUSION: In this prospective trial in patients with pPCL, we show that bortezomib, dexamethasone plus doxorubicin or cyclophosphamide induction followed by transplantation induces high response rates and appears to significantly improve PFS.

VTD is superior to VCD prior to intensive therapy in multiple myeloma: results of the prospective IFM2013-04 trial.

The Intergroupe Francophone du Myélome conducted a randomized trial to compare bortezomib-thalidomide-dexamethasone (VTD) with bortezomib-cyclophosphamide-dexamethasone (VCD) as induction before high-dose therapy and autologous stem cell transplantation (ASCT) in patients with newly diagnosed multiple myeloma. Overall, a total of 340 patients were centrally randomly assigned to receive VTD or VCD. After 4 cycles, on an intent-to-treat basis, 66.3% of the patients in the VTD arm achieved at least a very good partial response (primary end point) vs 56.2% in the VCD arm (P = .05). In addition, the overall response rate was significantly higher in the VTD arm (92.3% vs 83.4% in the VCD arm; P = .01). Hematologic toxicity was higher in the VCD arm, with significantly increased rates of grade 3 and 4 anemia, thrombocytopenia, and neutropenia. On the other hand, the rate of peripheral neuropathy (PN) was significantly higher in the VTD arm. With the exception of hematologic adverse events and PN, other grade 3 or 4 toxicities were rare, with no significant differences between the VTD and VCD arms. Our data support the preferential use of VTD rather than VCD in preparation for ASCT. This trial was registered at www.clinicaltrials.gov as #NCT01564537 and at EudraCT as #2013-003174-27.

Pomalidomide plus low-dose dexamethasone in multiple myeloma with deletion 17p and/or translocation (4;14): IFM 2010-02 trial results.

The combination of pomalidomide and low-dose dexamethasone (Pom-Dex) can be safely administered to patients with end-stage relapsed/refractory multiple myeloma (RRMM). However, we observed a shorter median progression-free survival (PFS) and overall survival (OS) in these patients when characterized with adverse cytogenetics (deletion 17p and translocation [4;14]) in the Intergroupe Francophone Myélome (IFM) 2009-02 trial. We then sought to determine whether MM with adverse cytogenetics would benefit more from Pom-Dex if exposed earlier in the multicenter IFM 2010-02 trial. The intention-to-treat population included 50 patients, with a median age of 63 years (38% were ≥65 years). Interestingly, there was a striking difference in time to progression (TTP), duration of response, and overall response rate (ORR) according to the presence of del(17p) compared with t(4;14) (TTP, 7.3 vs 2.8 months; duration of response, 8.3 vs 2.4 months; and ORR, 32% vs 15%). OS was prolonged after Pom-Dex, particularly in t(4;14), given the short TTP, suggesting that patients were rescued at relapse with further lines of therapy. Pom-Dex, a doublet immunomodulatory drug-based regimen, is active and well tolerated in adverse cytogenetic patients with early RRMM, particularly in those with del(17p), who are characterized by a high and rapid development of a refractoriness state and known for their poor prognosis. Future studies will determine the underlying mechanisms of Pom-Dex activity in del(17p). This trial is registered at www.clinicaltrials.gov as #NCT01745640.

Age is a prognostic factor even among patients with multiple myeloma younger than 66 years treated with high-dose melphalan: the IFM experience on 2316 patients.

Age is a strong prognostic factor in multiple myeloma. The overall survival is shorter in patients older than 66 years, and even shorter in those older than 75 years. Whether age is also a prognostic parameter in patients younger than 66 years treated homogeneously with intensive approaches is unknown. To address this issue, we retrospectively analyzed a series of 2316 patients treated homogeneously with 3-4 cycles of induction chemotherapy followed by a high-dose melphalan course, without any consolidation or maintenance. We show that patients older than 60 years have a statistically significant shorter overall survival. The analysis of prognostic parameters did not show a higher incidence of high-risk cytogenetics, but a higher incidence of International Staging System (ISS) stages 2 and 3, mainly due to higher ß2-microglobulin levels. This study is the first to demonstrate the impact of age in the outcome of 'young' patients with multiple myeloma, and suggests that this parameter should be included in the stratification factors for future prospective clinical trials.

The translocation t(4;14) can be present only in minor subclones in multiple myeloma.

PURPOSE: Although the translocation t(4;14) is supposed to be a primary event in multiple myeloma, we have been surprised to observe that in large relapse series of patients, the t(4;14) can be observed only in subpopulations of plasma cells, in contrast to what is seen at diagnosis. This observation raised the question of possible subclones harboring the translocation that would be observable only at the time of relapse. EXPERIMENTAL DESIGN: To address this issue, we analyzed by FISH a cohort of 306 patients for whom we had at least two samples obtained at different disease phases. RESULTS: We observed a "gain" of the t(4;14) in 14 patients, and conversely, a "loss" of the translocation in 11 patients. Two hypotheses were raised: either an acquisition of the translocation during evolution or the existence of small t(4;14)-positive subclones at the time of diagnosis. To address this question, we had the opportunity to analyze two patients at the time of diagnosis by RT-PCR (reverse transcription-polymerase chain reaction) to look for the chimeric Eµ-MMSET transcript, and one patient positive at diagnosis, but negative at relapse. The samples were positive, supporting the second hypothesis. Furthermore, the IGH sequences of two patients who "lose" the t(4;14) were identical at diagnosis and relapse, confirming the existence of a common ancestral clone. CONCLUSION: Thus, the conclusion of this study is that the t(4;14) is not a primary event in multiple myeloma and that it can be present in silent subclones at diagnosis, but also at relapse.

Chromosomal abnormalities are major prognostic factors in elderly patients with multiple myeloma: the intergroupe francophone du myélome experience.

PURPOSE: Chromosomal abnormalities, especially t(4;14) and del(17p), are major prognostic factors in patients with multiple myeloma (MM). However, this has been especially demonstrated in patients age < 66 years treated with intensive approaches. The goal of this study was to address this issue in elderly patients treated with conventional-dose chemotherapy. PATIENTS AND METHODS: To answer this important question, we retrospectively analyzed a series of 1,890 patients (median age, 72 years; range, 66 to 94 years), including 1,095 with updated data on treatment modalities and survival. RESULTS: This large study first showed that the incidence of t(4;14) was not uniform over age, with a marked decrease in the oldest patients. Second, it showed that both t(4;14) and del(17p) retained their prognostic value in elderly patients treated with melphalan and prednisone-based chemotherapy. CONCLUSION: t(4;14) and del(17p) are major prognostic factors in elderly patients with MM, both for progression-free and overall survival, indicating that these two abnormalities should be investigated at diagnosis of MM, regardless of age.

Safety of thalidomide in newly diagnosed elderly myeloma patients: a meta-analysis of data from individual patients in six randomized trials.

Treatment with melphalan-prednisone-thalidomide improves the outcome of patients with multiple myeloma and is now considered a standard of care for patients not eligible for transplantation. However, this treatment is a major source of morbidity. A meta-analysis of data from individual patients (n=1680) in six randomized trials was performed, comparing the effects of melphalan-prednisone-thalidomide versus melphalan-prednisone. The main objective was to estimate the risk of serious adverse events and their impact on outcome. The primary endpoints were the 2-year cumulative incidence of grade 3-4 hematologic and non-hematologic toxicities. At least 75% of the grade 3-4 toxicities occurred during the first 6 months of treatment in both treatment groups. The cumulative incidence of grade 3-4 hematologic toxicities was higher in the melphalan-prednisone-thalidomide group than in the melphalan-prednisone group (28% versus 22%; HR 1.32, 95% CI 1.05-1.66) as was the cumulative incidence of non-hematologic toxicities (39% versus 17%, HR 2.78, 95% CI 2.21-3.50). Grade 3-4 non-hematologic toxicities were significantly increased in patients with poor Performance Status. Occurrence of grade 3-4 non-hematologic toxicities had a negative impact on both progression-free survival (HR 1.24, 95% CI 1.07-1.45) and overall survival, (HR 1.23, 95% CI 1.03-1.47). Besides toxicities, progression-free and overall survival were also negatively affected by advanced International Staging System stage, high creatinine levels and poor Performance Status. Age had a negative impact on survival as well. Although melphalan-prednisone-thalidomide improved outcome, it increased toxicities, especially non-hematologic ones. Serious non-hematologic toxicities, older age, poor Performance Status, and high creatinine levels negatively affected survival.

Long-term analysis of the IFM 99 trials for myeloma: cytogenetic abnormalities [t(4;14), del(17p), 1q gains] play a major role in defining long-term survival.

PURPOSE: In multiple myeloma, many prognostic parameters have been proposed. However, all of these predict shorter survival. To identify patients with a longer life expectancy, we updated the data of patients treated in the IFM (Intergroupe Francophone du Myelome) 99-02 and 99-04 trials. PATIENTS AND METHODS: A series of 520 patients was analyzed. Median follow-up was 90.5 months. To perform a comprehensive analysis of the major prognostic factors, we reanalyzed all patients for 1q gains [in addition to updating del(13), t(4;14), and del(17p) analyses]. RESULTS: It was possible to identify a subgroup of patients (representing 20% of total patients) with an 8-year survival of 75%. These patients were defined by the absence of t(4;14), del(17p), and 1q gain and ß(2)-microglobulin less than 5.5 mg/L. CONCLUSION: We propose that all patients with newly diagnosed multiple myeloma be evaluated for these three chromosomal changes, not only to define high-risk patients but also to identify those with a longer life expectancy.

Bortezomib plus dexamethasone versus reduced-dose bortezomib, thalidomide plus dexamethasone as induction treatment before autologous stem cell transplantation in newly diagnosed multiple myeloma.

The Intergroupe Francophone du Myelome conducted a randomized trial to compare bortezomib-dexamethasone (VD) as induction before high-dose therapy (HDT) and autologous stem cell transplantation (ASCT) to a combination consisting of reduced doses of bortezomib and thalidomide plus dexamethasone (vtD) in patients with multiple myeloma. Overall, a total of 199 patients were centrally randomly assigned to receive VD or vtD. After 4 cycles, the complete response (CR) rate was the same in both groups (13% in the vtD arm, 12% in the VD arm, P = .74). However, the CR plus very good partial response (VGPR) rate was significantly higher in the vtD arm (49% vs 36%, P = .05). After ASCT, the CR plus VGPR rate was significantly higher in the vtD arm (74% vs 58%, P = .02). The reduced doses of bortezomib and thalidomide translated into a reduced incidence of peripheral neuropathy (PN): grade ≥ 2 PN were reported in 34% in the VD arm versus 14% in the vtD arm (P = .001). vtD, including reduced doses of bortezomib and thalidomide, yields higher VGPR rates compared with VD and can be considered a new effective triplet combination before HDT/ASCT.

Bortezomib plus dexamethasone induction improves outcome of patients with t(4;14) myeloma but not outcome of patients with del(17p).

PURPOSE: Cytogenetics is an important prognostic parameter in multiple myeloma (MM). Patients presenting with either t(4;14) or del(17p) are known to have a short event-free survival (EFS) and overall survival (OS). Some preliminary data suggest that bortezomib is able to overcome these prognostic parameters. PATIENTS AND METHODS: A series of 507 patients with newly diagnosed MM who received four cycles of bortezomib-dexamethasone induction therapy before high-dose melphalan were analyzed for both t(4;14) and del(17p). RESULTS: We found that both t(4;14) and del(17p) remain prognostic parameters, even in the context of bortezomib treatment. However, it is important to note that bortezomib significantly improves the prognosis (in terms of both EFS and OS) of patients with t(4;14), compared with patients treated with vincristine, doxorubicin, and dexamethasone induction therapy. In contrast, no improvement was observed for del(17p) patients. CONCLUSION: Short-term bortezomib induction improves outcome of patients with t(4;14) but not the outcome of patients with del(17p). However, both abnormalities remain prognostic factors predicting both EFS and OS despite bortezomib induction.

Genetic abnormalities and survival in multiple myeloma: the experience of the Intergroupe Francophone du Myélome.

Acquired genomic aberrations have been shown to significantly impact survival in several hematologic malignancies. We analyzed the prognostic value of the most frequent chromosomal changes in a large series of patients with newly diagnosed symptomatic myeloma prospectively enrolled in homogeneous therapeutic trials. All the 1064 patients enrolled in the IFM99 trials conducted by the Intergroupe Francophone du Myélome benefited from an interphase fluorescence in situ hybridization analysis performed on purified bone marrow plasma cells. They were systematically screened for the following genomic aberrations: del(13), t(11;14), t(4;14), hyperdiploidy, MYC translocations, and del(17p). Chromosomal changes were observed in 90% of the patients. The del(13), t(11;14), t(4;14), hyperdiploidy, MYC translocations, and del(17p) were present in 48%, 21%, 14%, 39%, 13%, and 11% of the patients, respectively. After a median follow-up of 41 months, univariate statistical analyses revealed that del(13), t(4;14), nonhyperdiploidy, and del(17p) negatively impacted both the event-free survival and the overall survival, whereas t(11;14) and MYC translocations did not influence the prognosis. Multivariate analyses on 513 patients annotated for all the parameters showed that only t(4;14) and del(17p) retained prognostic value for both the event-free and overall survivals. When compared with the currently used International Staging System, this prognostic model compares favorably. In myeloma, the genomic aberrations t(4;14) and del(17p), together with beta2-microglobulin level, are important independent predictors of survival. These findings have implications for the design of risk-adapted treatment strategies.

Dexamethasone-based regimens versus melphalan-prednisone for elderly multiple myeloma patients ineligible for high-dose therapy.

Dexamethasone alone increases life expectancy in patients with relapsed multiple myeloma (MM); however, no large randomized study has compared dexamethasone and dexamethasone-based regimens with standard melphalan-prednisone in newly diagnosed MM patients ineligible for high-dose therapy. In the Intergroupe Francophone du Myélome (IFM) 95-01 trial, 488 patients aged 65 to 75 years were randomized between 4 regimens of treatment: melphalan-prednisone, dexamethasone alone, melphalan-dexamethasone, and dexamethasone-interferon alpha. Response rates at 6 months (except for complete response) were significantly higher among patients receiving melphalan-dexamethasone, and progression-free survival was significantly better among patients receiving melphalan (P < .001, for both comparisons), but there was no difference in overall survival between the 4 treatment groups. Moreover, the morbidity associated with dexamethasone-based regimens was significantly higher than with melphalan-prednisone, especially for severe pyogenic infections in the melphalan-dexamethasone arm and hemorrhage, severe diabetes, and gastrointestinal and psychiatric complications in the dexamethasone arms. Overall, these results indicated that dexamethasone should not be routinely recommended as first-line treatment in elderly patients with MM. In the context of the IFM 95-01 trial, the standard melphalan-prednisone remained the best treatment choice when efficacy and patient comfort were both considered. These results might be useful in the context of future combinations with innovative drugs.

Karyotypic abnormalities in myelofibrosis following polycythemia vera.

Polycythemia vera (PV) is a chronic myeloproliferative disease characterized by an increase of total red cell volume; in 10% to 15% of cases, bone marrow fibrosis complicates the course of the disease after several years, resulting in a hematologic picture mimicking myelofibrosis with myelocytic metaplasia (MMM). This condition is known as post polycythemic myelofibrosis (PPMF). Among 30 patients with PPMF followed in Northern France, 27 (90%) expressed one or two abnormal clones in myelocytic cell cultures. Of these, 19 (70%) had partial or complete trisomy 1q. This common anomaly either resulted from unbalanced translocations with acrocentric chromosomes, that is, 13, 14, and 15, or other chromosomes, that is, 1, 6, 7, 9, 16, 19, and Y, or from partial or total duplication of long arm of chromosome 1. A single patient had an isochromosome 1q leading to tetrasomy 1q. In all cases, a common trisomic region spanning 1q21 to 1q32 has been identified. Given that most patients had previously received chemotherapy or radio-phosphorus to control the polycythemic phase of their disease, this study illustrates the increased frequency of cytogenetic abnormalities after such treatments: 90% versus 50% in de novo MMM. Moreover, karyotype can be used to distinguish PPMF-where trisomy 1q is the main anomaly-from primary MMM where trisomy 1q is rare and deletions 13q or 20q are far more common. Whether trisomy 1q is or is not a secondary event remains a matter of debate, as well as the role of cytotoxic treatments.

Effects of long-term intravenous ibandronate therapy on skeletal-related events, survival, and bone resorption markers in patients with advanced multiple myeloma.

PURPOSE: Bisphosphonates have been found to reduce the incidence of skeletal-related events (SREs) in patients with multiple myeloma. This is the first double-blind, randomized, placebo-controlled study to assess the efficacy of ibandronate, a third-generation amino-bisphosphonate, in preventing SREs in advanced-stage multiple myeloma patients. PATIENTS AND METHODS: Patients with multiple myeloma stage II or III were randomly assigned to receive either ibandronate 2 mg or placebo as a monthly intravenous (IV) bolus injection for 12 to 24 months in addition to conventional chemotherapy. SREs such as peripheral pathologic or vertebral fractures, hypercalcemia, severe bone pain, and bone radiotherapy or surgery were analyzed. Bone-turnover markers were also studied. Finally, post hoc analyses of bone morbidity and survival were performed. RESULTS: Ninety-nine patients per treatment group were assessable for efficacy analysis. The occurrence of SRE per patient year and the time to first SRE were not significantly different between the two treatment groups. In overall evaluation, no differences were found between the treatment groups regarding bone pain, analgesic drug use, quality of life, and median survival (33.1 v 28.2 months, respectively). Explorative post hoc analyses revealed that ibandronate patients with strongly suppressed bone-turnover markers (> or = 30% and > or = 50% mean reduction of serum osteocalcin and urinary C-terminal telopeptides) developed significantly less bone morbidity. Ibandronate was tolerated well during as many as 25 therapy cycles. CONCLUSION: Monthly injections of ibandronate 2 mg IV neither reduced bone morbidity nor prolonged survival in the overall population of stage II/III multiple myeloma patients.

Alpha-interferon in combination with cytarabine in children with Philadelphia chromosome-positive chronic myeloid leukemia.

BACKGROUND: Philadelphia chromosome-positive chronic myelogenous leukemia (CML) is a rare disease in children, and the optimal therapy is not clearly defined in these patients when a human leukocyte antigen-identical donor is not available. The present work focuses on the therapeutic efficacy and the toxicity of interferon (IFN) alpha 2b in combination with cytosine arabinosine (Ara-C) in patients younger than age 18 years enrolled in the randomized trial CML 91, which compared the efficacy of IFN and cytosine arabinoside (Ara-C) with IFN alone in 810 patients with CML in the chronic phase. PATIENTS AND METHODS: Twelve patients younger than age 18 years were enrolled in the randomized trial CML 91. Hydroxyurea and IFN (5 million units/m2, once a day) were given as initial treatment in all patients. After randomization, six patients received IFN (5 million units/m2, once per day) and Ara-C (20 mg/m2 for 10 days each month) (IFN plus Ara-C group), and six patients received IFN alone (5 million units/m2 once per day) (IFN group). RESULTS: Six months after the beginning of the treatment, a complete hematologic response was obtained in all the patients in the IFN plus Ara-C group and in four patients in the IFN group. A major cytogenetic response was observed in three patients in the IFN plus Ara-C group and in two patients in the IFN group. Five patients from the IFN group who crossed over to receive Ara-C did not experience additional hematologic toxicity. Three patients in the IFN plus Ara-C group and two from the IFN group are alive, in major cytogenetic response, with a follow-up of 18 to 48 months. CONCLUSION: The combination of IFN and Ara-C induces complete hematologic and major cytogenetic responses and is well tolerated in patients younger than age 18 years with CML. This combination may offer an alternative to bone marrow transplantation in children in the chronic phase of CML without a histocompatible donor.