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Accelerated phase (AP) CML at onset and have poorer prognosis than CP-CML. We hypothesize that off-license use of second generation TKI (TKI2) as front-line therapy might counterbalance this poor prognosis, with limited toxicity. In "real-life" conditions, newly diagnosed patients meeting the ELN cytological criteria for AP-CML or harboring ACA and treated with first-line TKI2 were included in this retrospective multicenter observational study. We enrolled 69 patients [69.5 % male, median age 49.5 years, median follow-up 43.5 months], segregated into hematologic AP [HEM-AP (n = 32)] and cytogenetically defined AP [ACA-AP (n = 37)]. Hematologic parameters were worse in HEM-AP [spleen size (p = 0.014), PB basophils (p < .001), PB blasts (p < .001), PB blasts+promyelocytes (p < .001), low hemoglobin levels (p < .001)]. Dasatinib was initiated in 56 % patients in HEM-AP and in 27 % in ACA-AP, nilotinib in 44 % and 73 % respectively. Response and survival do not differ, regardless of the TKI2: 81 % vs 84.3 % patients achieved CHR, 88 % vs 84 % CCyR, 73 % vs 75 % MMR respectively. The estimated 5-year PFS 91.5 % (95%CI: 84.51-99.06 %) and 5-year OS 96.84 % (95%CI: 92.61-100 %). Only BM blasts (p < 0.001) and BM blasts+promyelocytes (p < 0.001) at diagnosis negatively influenced OS. TKI2 as front-line therapy in newly diagnosed AP-CML induce excellent responses and survival, and counterbalance the negative impact of advanced disease phase., Competing Interests: Declaration of Competing Interest Marie Balsat: Speaker for Novartis, Pfizer, Jazz pharmaceuticals, Amgen, Incyte Biosciences. Vincent Alcazer has nothing to disclose. Gabriel Etienne speaker for consultant for Novartis, BMS, Pfizer and Incyte Pharma and has given some lectures for BMS, Incyte Pharma, Pfizer and Novartis. He has received research grants from Novartis and BMS. Françoise Huguet: Speaker’s bureau for Novartis, Incyte Biosciences, Pfizer. Board entity for Novartis, Incyte Biosciences, Pfizer. Marc Berger institutional research grants from Novartis, Pfizer and Incyte Biosciences. Board entity for Novartis. Emilie Cayssials speaker for Incyte Biosciences. Aude Charbonnier speaker for Incyte biosciences, Novartis and Pfizer, board entity for Incyte biosciences, Novartis and Pfizer. Martine Escoffre-Barbe has nothing to disclose. Hyacinthe Johnson-Ansah board entity for Novartis. Laurence Legros speaker for Novartis, Incyte Biosciences and Pfizer, research grant from Incyte Biosciences. Lydia Roy board entity for Pfizer, Novartis. Speaker for Pfizer, Novartis. BMS. Research fundings from Bristol Myers Squibb, Pfizer and Novartis. Alain Delmer has nothing to disclose regarding this study. Jean-Christophe Ianotto has nothing to disclose. Corentin Orvain speaker for Novartis and Incyte Biosciences. Fabrice Larosa has nothing to disclose. Mathieu Meunier has nothing to disclose. Shanti Amé has nothing to disclose. Annalisa Andreoli has nothing to disclose. Pascale Cony-Makhoul speaker for Pfizer, Novartis Pharma and Incyte, institutional grant from Pfizer. Stéphane Morisset has nothing to disclose. Isabelle Tigaud has nothing to disclose. François-Xavier Mahon consultant for Novartis, speaker for Novartis. Delphine Rea is a consultant for Novartis, and board entity for BMS, Pfizer and Incyte Biosciences. Franck Emmanuel Nicolini: Speaker’s bureau for Novartis, Incyte Biosciences. Board’s entity for Incyte Biosciences, Pfizer and Novartis. Research fundings from Novartis and Incyte Biosciences Europe. Consultant for Sun Pharma Ltd, Novartis., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Objective: Chronic myeloid leukemia (CML) is a disease caused by the acquisition of BCR-ABL1 fusion in hematopoietic stem cells. In this study, we focus on the oncofetal ENOX2 protein as a potential secretable biomarker in CML., Materials and Methods: We used cell culture, western blot, quantitative RT-PCR, ELISA, transcriptome analyses, and bioinformatics techniques to investigate ENOX2 mRNA and protein expression., Results: Western blot analyses of UT-7 and TET-inducible Ba/F3 cell lines demonstrated the upregulation of the ENOX2 protein. BCR-ABL1 was found to induce ENOX2 overexpression in a kinase-dependent manner. We confirmed increased ENOX2 mRNA expression in a cohort of CML patients at diagnosis. In a series of CML patients, ELISA assays showed a highly significant increase of ENOX2 protein levels in the plasma of patients with CML compared to controls. Reanalyzing the transcriptomic dataset confirmed ENOX2 mRNA overexpression in the chronic phase of the disease. Bioinformatic analyses identified several genes whose mRNA expressions were positively correlated with ENOX2 in the context of BCR-ABL1 . Some of them encode proteins involved in cellular functions compatible with the growth deregulation observed in CML., Conclusion: Our results highlight the upregulation of a secreted redox protein in a BCR-ABL1 -dependent manner in CML. The data presented here suggest that ENOX2 , through its transcriptional mechanism, plays a significant role in BCR-ABL1 leukemogenesis., Competing Interests: Conflict of Interest: No conflict of interest was declared by the authors., (©Copyright 2023 by Turkish Society of Hematology | Turkish Journal of Hematology, Published by Galenos Publishing House)

Superior rates of deep molecular response (DMR) have been reported with the combination of tyrosine kinase inhibitors and pegylated-interferon-alpha (Peg-IFN) in patients with newly diagnosed chronic phase-chronic myeloid leukaemia (CP-CML). In this setting, this study investigated the efficacy and safety of dasatinib combined to Peg-IFN-α2b (Dasa-PegIFN, NCT01872442). A total of 79 patients (age ≤65 years) started dasatinib; 61 were eligible for Peg-IFNα-2b add-on therapy at month 3 for a maximum 21-months duration. Dasatinib was continued thereafter. The primary endpoint was the cumulative rate of molecular response 4.5 log (MR 4.5 ) by 12 months. The results are reported for the 5-year duration of the study. Grade 3 neutropenia was frequent with the combination but did not induce severe infection (one of grade 3). Other adverse events were generally low grade (4% of grade 3-4) and expected. Seventy-nine per cent and 61% of patients continued the Peg-IFN until months 12 and 24, respectively. Overall, at these time points, MR 4.5 rates were 25% and 38%, respectively. Thereafter, 32% and 46% of patients achieved a sustained (≥2 years) MR 4.5 or MR 4 , respectively. This work established the feasibility and high rates of achievement of early and sustained DMR (a prerequisite for treatment-free-remission) with dasatinib and Peg-IFNα-2b combination as initial therapy., (© 2022 British Society for Haematology and John Wiley & Sons Ltd.)

Discontinuation of tyrosine kinase inhibitors in chronic phase chronic myeloid leukemia is feasible in clinical practice based on recently published international recommendations. Nevertheless, factors predictive of molecular recurrence have not been fully elucidated and long-term follow-up of patients enrolled in clinical studies are required in order to update knowledge on discontinuation attempts particularly in terms of the safety and durability of treatment-free remission (TFR). In the current study, we updated results from the STIM2 study in the light of the consensual criterion of molecular recurrence reported in different international recommendations. Among the 199 patients included in the perprotocol study, 108 patients lost a major molecular response. With a median follow-up of 40.8 months (5.5-111 months), the probability of treatment-free remission was 43.4% [36.3-50.4] at 5 years, 40.9% [32.8-47.3] at 7 years and 34.5% [25.6- 43.3] at 9 years. Molecular recurrence occurred between 0 to 6 months, 6 to 24 months and after 24 months in 75 patients (69%), 15 patients (14%) and 18 patients (17%), respectively. Notably, the kinetics of molecular recurrence differed significantly between these three subgroups with a median time from loss of MR4 (BCR::ABL1 IS≤0.01%) to loss of major molecular response of 1, 7 and 22 months, respectively. Predictive factors of molecular recurrence differed according to the time of occurrence of the molecular recurrence. Durations of imatinib treatment and deep molecular response as well as BCR::ABL1/ABL1 levels at cessation of tyrosine kinase inhibitor treatment, as quantified by reverse transcriptase droplet digital polymerase chain reaction, are involved in molecular recurrence occurring up to 24 months but not beyond. (ClinicalTrial. gov Identifier NCT#0134373).

RNA splicing factors are frequently altered in cancer and can act as both oncoproteins and tumour suppressors. They have been found mutated or deregulated, justifying the growing interest in the targeting of splicing catalysis, splicing regulatory proteins, and/or specific, key altered splicing events. We recently showed that the DNA methylation alterations of CD34 + CD15 - chronic myeloid leukaemia (CML) cells affect, among others, alternative splicing genes, suggesting that spliceosome actors might be altered in chronic-phase (CP)-CML. We investigated the expression of 12 spliceosome genes known to be oncogenes or tumour suppressor genes in primary CP-CML CD34 + cells at diagnosis ( n = 15). We found that CP-CML CD34 + cells had a distinct splicing signature profile as compared with healthy donor CD34 + cells or whole CP-CML cells, suggesting: (i) a spliceosome deregulation from the diagnosis time and (ii) an intraclonal heterogeneity. We could identify three profile types, but there was no relationship with a patient's characteristics. By incubating cells with TKI and/or a spliceosome-targeted drug (TG003), we showed that CP-CML CD34 + cells are both BCR::ABL and spliceosome dependent, with the combination of the two drugs showing an additive effect while sparing healthy donors cells. Our results suggest that the spliceosome may be a new potential target for the treatment of CML.

The registered dose for imatinib is 400 mg/d, despite high inter-patient variability in imatinib plasmatic exposure. Therapeutic drug monitoring (TDM) is routinely used to maximize a drug’s efficacy or tolerance. We decided to conduct a prospective randomized trial (OPTIM-imatinib trial) to assess the value of TDM in patients with chronic phase chronic myelogenous treated with imatinib as first-line therapy (NCT02896842). Eligible patients started imatinib at 400 mg daily, followed by imatinib [C]min assessment. Patients considered underdosed ([C]min < 1000 ng/mL) were randomized in a dose-increase strategy aiming to reach the threshold of 1000 ng/mL (TDM arm) versus standard imatinib management (control arm). Patients with [C]min levels ≥ 1000 ng/mL were treated following current European Leukemia Net recommendations (observational arm). The primary endpoint was the rate of major molecular response (MMR, BCR::ABL1IS ≤ 0.1%) at 12 months. Out of 133 evaluable patients on imatinib 400 mg daily, 86 patients had a [C]min < 1000 ng/mL and were randomized. The TDM strategy resulted in a significant increase in [C]min values with a mean imatinib daily dose of 603 mg daily. Patients included in the TDM arm had a 12-month MMR rate of 67% (95% CI, 51−81) compared to 39% (95% CI, 24−55) for the control arm (p = 0.017). This early advantage persisted over the 3-year study period, in which we considered imatinib cessation as a censoring event. Imatinib TDM was feasible and significantly improved the 12-month MMR rate. This early advantage may be beneficial for patients without easy access to second-line TKIs.

The STI571 prospective randomised trial (SPIRIT) French trial is a four-arm study comparing imatinib (IM) 400 mg versus IM 600 mg, IM 400 mg + cytarabine (AraC), and IM 400 mg + pegylated interferon alpha2a (PegIFN-α2a) for the front-line treatment of chronic-phase chronic myeloid leukaemia (CML). Long-term analyses included overall and progression-free survival, molecular responses to treatment, and severe adverse events. Starting in 2003, the trial included 787 evaluable patients. The median overall follow-up of the patients was 13.5 years (range 3 months to 16.7 years). Based on intention-to-treat analyses, at 15 years, overall and progression-free survival were similar across arms: 85%, 83%, 80%, and 82% and 84%, 87%, 79%, and 79% for the IM 400 mg (N = 223), IM 600 mg (N = 171), IM 400 mg + AraC (N = 172), and IM 400 mg + PegIFN-α2a (N = 221) arms, respectively. The rate of major molecular response at 12 months and deep molecular response (MR4) over time were significantly higher with the combination IM 400 mg + PegIFN-α2a than with IM 400 mg: p = 0.0001 and p = 0.0035, respectively. Progression to advanced phases and secondary malignancies were the most frequent causes of death. Toxicity was the main reason for stopping AraC or PegIFN-α2a treatment., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited part of Springer Nature.)

Purpose: Tyrosine kinase inhibitor (TKI) discontinuation is an emerging goal in chronic myelogenous leukemia (CML) management and several studies have demonstrated the feasibility of safely stopping imatinib. A sustained deep molecular response on long-term TKI is critical prior to attempting treatment-free remission. Reproducible results from several studies reported recently, failed to identify robust and reproducible predictive factors for the selection of the best candidates for successful TKI cessation., Patients and Methods: We conducted a prospective national phase II study evaluating the cessation of imatinib after at least 2 years of MR4.5 obtained on imatinib first-line in patients with chronic phase CML., Results: A total of 218 patients with de novo chronic phase CML were involved in the study. The median follow-up after imatinib cessation was 23.5 (1-64) months, 2 patients died from unrelated causes, and 107 experienced a confirmed increase in BCR-ABL1 levels defined as molecular recurrence. The molecular recurrence-free survival was 52% [95% confidence interval (CI), 45%-59%] at 6 months, and 50% (95% CI, 43%-57%) at 24 months. Droplet digital PCR (ddPCR) was used to evaluate more accurately low levels of BCR-ABL1 in 175 of 218 patients at imatinib cessation. To apply positive BCR-ABL1/ABL1 ratios on the international scale (IS), a conversion factor was calculated for ddPCR and the significant cut-off point was established at 0.0023% IS . In a multivariate analysis, the duration of TKI (≥74.8 months) and ddPCR (≥0.0023% IS ) were the two identified predictive factors of molecular recurrence, with P = 0.0366 (HR, 0.635; 95% CI, 0.415-0.972] and P = 0.008 (HR, 0.556; 95% CI, 0.360-0.858), respectively., Conclusions: We conclude that the duration of TKI and residual leukemic cell load as determined by ddPCR are key factors for predicting successful treatment-free remission for patients with de novo chronic phase CML. See related commentary by Yan et al., p. 6561 ., (©2019 American Association for Cancer Research.)

Aryl Hydrocarbon Receptor (AHR) is an ubiquitous basic helix-loop-helix transcription factor, which is ligand-activated and involved in numerous biological processes including cell division, cell quiescence and inflammation. It has been shown that AHR is involved in normal hematopoietic progenitor proliferation in human cells. In addition, loss of AHR in knockout mice is accompanied by a myeloproliferative syndrome-like disease, suggesting a role of AHR in hematopoietic stem cell (HSC) maintenance. To study the potential role of AHR pathway in CML progenitors and stem cells, we have first evaluated the expression of AHR in UT-7 cell line expressing BCR-ABL. AHR expression was highly reduced in UT-7 cell expressing BCR-ABL as compared to controls. AHR transcript levels, quantified in primary peripheral blood CML cells at diagnosis (n = 31 patients) were found to be significantly reduced compared to healthy controls (n = 15). The use of StemRegenin (SR1), an AHR antagonist, induced a marked expansion of total leukemic cells and leukemic CD34+ cells by about 4- and 10-fold respectively. SR1-treated CML CD34+ cells generated more colony-forming cells and long-term culture initiating cell (LTC-IC)-derived progenitors as compared to non-SR1-treated counterparts. Conversely, treatment of CML CD34+ cells with FICZ, a natural agonist of AHR, induced a 3-fold decrease in the number of CD34+ cells in culture after 7 days. Moreover, a 4-day FICZ treatment was sufficient to significantly reduce the clonogenic potential of CML CD34+ cells and this effect was synergized by Imatinib and Dasatinib treatments. Similarly, a 3-day FICZ treatment contributed to hinder significantly the number of LTC-IC-derived progenitors without synergistic effect with Imatinib. The analysis of molecular circuitry of AHR signaling in CML showed a transcriptional signature in CML derived CD34+ CD38- primitive cells with either low or high levels of AHR, with an upregulation of myeloid genes involved in differentiation in the "AHR low" fraction and an upregulation of genes involved in stem cell maintenance in the "AHR high" fraction. In conclusion, these findings demonstrate for the first time that down-regulation of AHR expression, a major cell cycle regulator, is involved in the myeloproliferative phenotype associated with CML. AHR agonists inhibit clonogenic and LTC-IC-derived progenitor growth and they could be used in leukemic stem cell targeting in CML., Competing Interests: The authors have declared that no competing interests exist.

Background: The ultimate goal of chronic myeloid leukemia management in the tyrosine kinase inhibitor (TKI) era for patients who obtain deep molecular responses is maintaining a durable off-treatment response after treatment discontinuation; this situation is called treatment-free remission (TFR). Knowledge accumulated during the last 10 years justifies moving TFR strategies from research to clinical practice., Methods: Twenty experts from the French Chronic Myeloid Leukemia Study Group (France Intergroupe des Leucémies Myéloïdes Chroniques), including 17 hematologists, 2 molecular biologists, and 1 cytogeneticist, critically reviewed published data with the goal of developing evidence-based recommendations for TKI discontinuation in clinical practice., Results: Clinically relevant questions were addressed, including the selection of candidate patients (with known prognostic factors for outcomes taken into account), detailed monitoring procedures during the treatment-free phase, a definition of relapse requiring therapy resumption, and monitoring after treatment reintroduction., Conclusions: This work presents consensus statements with the aim of guiding physicians and biologists by means of pragmatic recommendations for safe TKI discontinuation in daily practice. Cancer 2018;124:2956-63. © 2018 American Cancer Society., (© 2018 American Cancer Society.)

Gamma-delta (γδ) T cells contribute to the innate immune response against cancer. In samples of 20 patients upon DLBCL diagnosis, we found that Vδ1 + T cells were the major γδ T cell subset in tumors and PBMCs of patients, while Vδ2 T cells were preponderant in PBMCs of healthy subjects. Interestingly, the germinal center (GC) subtype was associated with an increase in Vδ1 + T cells in tumors, whereas the non-GC subtype was associated with a lower frequency of γδ T cells. While circulating Vδ1 + T cells of patients or HSs mostly exhibited a naïve phenotype, the majority of tumor Vδ1 + T cells showed a central memory phenotype. Resident or circulating γδ T cells from patients were not functionally impaired since they produced high levels of IFN-γ. Collectively, our findings are in favor of γδ T cell activation in tumors and open new perspectives for their modulation in DLBCL immunotherapy.

STOP second generation (2G)-tyrosine kinase inhibitor (TKI) is a multicenter observational study designed to evaluate 2G-TKI discontinuation in chronic myeloid leukemia (CML). Patients receiving first-line or subsequent dasatinib or nilotinib who stopped therapy after at least 3 years of TKI treatment and in molecular response 4.5 (MR4.5) with undetectable BCR-ABL1 transcripts for the 2 preceding years at least were eligible for inclusion. This interim analysis reports outcomes of 60 patients with a minimum follow-up of 12 months (median 47, range: 12-65). Twenty-six patients (43.3%) experienced a molecular relapse defined as the loss of a major molecular response (MMR). Relapses occurred after a median time of 4 months (range: 1-38). Cumulative incidences of molecular relapse by 12 and 48 months were 35% (95% confidence interval [CI], 24.79% to 49.41%) and 44.76% (95% CI, 33.35% to 59.91%), respectively. Treatment-free remission (TFR) rates at 12 and 48 months were 63.33% (95% CI, 51.14% to 75.53%) and 53.57% (95% CI, 40.49% to 66.65%), respectively. In univariate analysis, prior suboptimal response or TKI resistance was the only baseline factor associated with significantly worse outcome. A landmark analysis demonstrated that loss of MR4.5 3 months after stopping TKI was predictive of failure to maintain MMR later on. During the treatment-free phase, no progression toward advanced phase CML occurred, and all relapsing patients regained MMR and MR4.5 after restarting therapy. In conclusion, discontinuation of first-line or subsequent 2G-TKI yields promising TFR rates without safety concerns. Further research is encouraged to better define conditions that will offer patients the highest chance to remain free from 2G-TKI therapy., (© 2017 by The American Society of Hematology.)

Background: There is increasing evidence that excessive blood transfusion may be associated with impaired survival or cardiovascular events. One way to reduce the number of red blood cells (RBCs) is to transfuse 1 unit (1RBC) instead of 2 units of RBCs (2RBC)., Study Design and Methods: Patients requiring blood transfusions in hematologic intensive care unit were included in a prospective study using a single RBC unit per transfusion and were compared with an historical cohort who received 2 RBC units per transfusion., Results: A total of 1323 units were transfused to 126 patients between 2013 and 2014. The 186 patients in the comparative cohort received a total of 1824 RBC units in a 2-RBC-unit policy between 2010 and 2012. The mean number of units was 7.35 (SD, 5.9 units; 95% confidence interval [CI], 6.5-8.2 units) in the 1RBC group and 8.14 units (SD, 6.2 units; 95% CI, 7.3-8.9 units) in the 2RBC group. The absolute mean difference was -0.79 (95% CI, -1.98 to 0.40; p = 0.09). In the 1RBC allogeneic hematopoietic stem cell transplantation (allo-HSCT) subgroup, a significant reduction in the number of RBC units transfused was observed in comparison with the historical 2RBC allo-HSCT group (5 units vs. 7.7 units; p = 0.01). No anemia-related side effects were reported. Overall survival did not differ between the two groups., Conclusion: The 1RBC transfusion policy made is feasible in patients with transient hematologic toxicity after chemotherapy. The number of units transfused between the two groups was not different. However, in the allo-HSCT group, the use of a single RBC unit reduced significantly RBC consumption. A randomized trial comparing the two strategies is planned with a medicoeconomic evaluation., (© 2016 AABB.)

In acute myeloid leukemia (AML), new prognostic tools are needed to assess the risk of relapse. Hematogones (HGs) are normal B-lymphocyte precursors that increase in hematological diseases and may influence remission duration in AML. HG detection was prospectively investigated in 262 AML patients to determine its prognostic value. Flow cytometric HG detection was performed in bone marrow aspiration after intensive chemotherapy at the time of hematological recovery. Patients with HGs in bone marrow samples had a significantly better relapse-free survival (RFS) and overall survival (OS) than patients without HGs (P = 0.0021, and P = 0.0016). Detectable HGs independently predicted RFS (HR = 0.61, 95%CI: 0.42 - 0.89, P = 0.012) and OS (HR = 0.59, 95%CI: 0.38 - 0.92, 0.019) controlling for age, ELN classification, the number of chemotherapy cycles to achieve CR, performance status, secondary AML and flow cytometric minimal residual disease (MRD). In intensively treated AML, individual determination of HGs could be useful to stratify the optimal risk-adapted therapeutic strategy after induction chemotherapy. Am. J. Hematol. 91:566-570, 2016. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)

Tyrosine kinase inhibitors targeting the BCR-ABL oncoprotein represent an outstanding progress in chronic myeloid leukemia and long-term progression-free survival has become a reality for a majority of patients. However, tyrosine kinase inhibitors may at best chronicize rather than cure the disease thus current recommendation is to pursue treatment indefinitely. As a consequence, high quality treatment and care must integrate optimal disease control and treatment tolerability. Tyrosine kinase inhibitors have an overall favorable safety profile in clinical practice since most adverse events are mild to moderate in intensity. However, recent evidence has emerged that new generation tyrosine kinase inhibitors may sometimes damage vital organs and if not adequately managed, morbidity and mortality may increase. The 2nd generation tyrosine kinase inhibitor nilotinib is licensed for the treatment of chronic myeloid leukemia with resistance or intolerance to imatinib and newly diagnosed chronic phase-chronic myeloid leukemia. Nilotinib represents an important therapeutic option but it is associated with an increased risk of cardiovascular events. The purpose of this article by the France Intergroupe des Leucémies Myéloïdes Chroniques is to provide an overview of nilotinib efficacy and cardiovascular safety profile and to propose practical recommendations with the goal to minimize the risk and severity of cardiovascular events in nilotinib-treated patients., (Copyright © 2015 Société Française du Cancer. Published by Elsevier Masson SAS. All rights reserved.)

Background: The pegylated form of interferon-α-2a (PegIFNa2a) in combination with imatinib has demonstrated a molecular improvement in patients with chronic-phase chronic myeloid leukemia. However, to the authors' knowledge, the appropriate dose of PegIFNa2a has not been established to date., Methods: In the French SPIRIT trial, the authors compared 2 initial doses of PegIFNa2a, taking into account an amendment that recommended reducing that dose from 90 μg/week to 45 μg/week because of toxicities. Accordingly, 2 subgroups of patients were identified: the PegIFN90 group (171 patients who were treated with the 90-μg/week dose) and the PegIFN45 group (50 patients who were treated with the 45-μg/week dose). Both groups were compared for toxicity and efficacy., Results: PegIFNa2a at a dose of 90 μg/week resulted in a rate of 54% of grade 3 to 4 hematologic toxicity compared with 27% with the dose of 45 μg/week (P < .001), leading to discontinuation rates of 40% and 10%, respectively, before 6 months. The dose reduction did not significantly affect the efficacy of the combination. By 12 months, the cumulative molecular response rates (ie, BCR-ABL/abl ≤ 0.01 [IS: molecular responses graded as molecular response 4 (MR4)]) were 14% and 25%, respectively, for the subgroup treated with imatinib at a dose of 400 mg and the PegIFN90 subgroup. After the amendment, the MR4 rates were 10% and 28%, respectively, for the subgroup treated with imatinib at the 400-mg dose and PegIFN45 subgroup (P < .0001)., Conclusions: The results of the current study demonstrate that in combination with imatinib, the efficient dose of PegIFNa2a appears to be 45 μg/week. Society., (© 2013 American Cancer Society.)