Complete Cytogenetic Response Rates Research Articles

Results of ponatinib as frontline therapy for chronic myeloid leukemia in chronic phase.

Ponatinib is a third-generation BCR::ABL1 tyrosine kinase inhibitor (TKI) with robust activity in Philadelphia chromosome-positive leukemias. Herein, we report the long-term follow-up of the phase 2 trial of ponatinib in chronic myeloid leukemia in chronic phase. Patients received ponatinib 30 to 45 mg/day. The primary end point was the rate of 6-month complete cytogenetic response (CCyR). The study was held in June 2014 because of the risk of cardiovascular toxicity, requiring patients to change TKI. Fifty-one patients were treated with ponatinib (median dose, 45 mg/day). Median age was 48 years (range, 21-75); 30 (59%) had baseline cardiovascular comorbidities. Median treatment duration was 13 months (range, 2-25). Fourteen patients (28%) discontinued ponatinib because of toxicities, 36 (71%) after the Food and Drug Administration warning/study closure, and one for noncompliance. Dasatinib was the most frequently chosen second-line TKI (n=34; 66%). Among 46 patients evaluable at 6 months, 44 (96%) achieved CCyR, 37 (80%) major molecular response, 28 (61%) MR4, and 21 (46%) MR4.5. The cumulative 6-month rates of CCyR, major molecular response, MR4, and MR4.5 were 96%, 78%, 50%, and 36%, respectively. Durable MR4 ≥24 or ≥60 months was observed in 67% and 51% of patients, respectively. The 24-month event-free survival rate was 97%. After a median follow-up of 128 months, the 10-year overall survival rate was 90%. Eight patients (16%) had serious grade 2 to 3 cardiovascular adverse events, leading to permanent discontinuation in five (10%). Ponatinib yielded high cytogenetic and molecular responses in newly diagnosed chronic myeloid leukemia in chronic phase. Its use in the frontline setting is hindered by arterio-/vaso-occlusive and other severe toxicities.

Efficacy and safety of bosutinib in patients treated with prior imatinib and/or dasatinib and/or nilotinib: Subgroup analyses from the phase 4 BYOND study

The BYOND study evaluated the efficacy and safety of bosutinib 500 mg once daily in patients with chronic myeloid leukemia (CML) resistant/intolerant to prior tyrosine kinase inhibitors (TKIs). These post-hoc analyses assessed the efficacy and safety of bosutinib by resistance or intolerance to prior TKIs (imatinib-resistant vs dasatinib/nilotinib-resistant vs TKI-intolerant), and cross-intolerance between bosutinib and prior TKIs (imatinib, dasatinib, nilotinib), in patients with Philadelphia chromosome–positive chronic phase CML. Data are reported after ≥3 years’ follow-up. Of 156 patients with Philadelphia chromosome–positive chronic phase CML, 53 were imatinib-resistant, 29 dasatinib/nilotinib-resistant, and 74 intolerant to all prior TKIs; cumulative complete cytogenetic response rates at any time were 83.7%, 61.5%, and 86.8%, and cumulative major molecular response rates at any time were 72.9%, 40.7%, and 82.4%, respectively. Of 141, 95, and 79 patients who received prior imatinib, dasatinib, and nilotinib, 64 (45.4%), 71 (74.7%), and 60 (75.9%) discontinued the respective TKI due to intolerance; of these, 2 (3.1%), 5 (7.0%), and 0 had cross-intolerance with bosutinib. The response rates observed in TKI-resistant and TKI-intolerant patients, and low cross-intolerance between bosutinib and prior TKIs, further support bosutinib use for patients with Philadelphia chromosome–positive chronic phase CML resistant/intolerant to prior TKIs. Trial registrationClinicalTrials.gov: NCT02228382

Update of Olverembatinib (HQP1351) Overcoming Ponatinib and/or Asciminib Resistance in Patients (Pts) with Heavily Pretreated/Refractory Chronic Myeloid Leukemia (CML) and Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia (Ph + ALL)

Background Olverembatinib, a novel, potent BCR::ABL1 tyrosine kinase inhibitor (TKI), shows strong antitumor activity in pts with CML and Ph + ALL. Here, we report on the safety, efficacy, and pharmacokinetic (PK) profiles of olverembatinib in pts with CML (all phases) and Ph + ALL outside of China, particularly in pts previously treated with ponatinib and/or asciminib. Methods Olverembatinib was administered orally once every other day (QOD) in continuous 28-day cycles. In the monotherapy cohort, pts were enrolled after treatment failure on at least 2 prior TKIs and randomized to olverembatinib QOD 30, 40, or 50 mg. In the combination cohort, pts with Ph + B-cell precursor (BCP) ALL or lymphoid CML-BP (CML-LBP) resistant to at least 1 TKI were enrolled and received olverembatinib (30 or 40 mg) QOD in combination with blinatumomab. Results As of June 30, 2023, 76 pts were enrolled, including 57 with CML-CP and 19 with advanced Ph + leukemia. The median (range) age was 54.5 (21-80) years, and 56.6% of pts were male. In all, 11 (14.5%), 23 (30.3%), and 39 (51.3%) pts had received 2, 3, and ≥ 4 prior TKIs, respectively. A total of 52.6% of pts were previously treated with ponatinib, of whom 67.5% were resistant and 25.0% intolerant to the drug, and 7.5% experienced treatment failure for other reasons. A total of 27.6% of pts were previously treated with asciminib, of whom 71.4% were resistant and 19.1% intolerant to the agent, and 9.5% experienced treatment failure for other reasons. At baseline, 32% of pts had T315I mutations, 38% hypertension, and 17.1% other cardiovascular comorbidities. Median (range) treatment duration was 24.1 (0-134) weeks, and PK profiles were similar to historical PK data on Chinese pts. Twelve pts with CML-CP and 7 with advanced Ph + leukemia discontinued treatment: 4 because of AEs, 7 disease progression, and 8 other reasons. A total of 54 of 65 (83.1%) pts who received ≥ 1 dose of olverembatinib experienced any-grade TRAEs. Grade ≥ 3 AEs occurring in ≥ 3 pts (≥ 4.6% incidence) included thrombocytopenia (17%); neutropenia (13.8%); elevated blood creatine phosphokinase (13.8%); leukopenia (7.7%); and anemia and elevated lipase (4.6% each). Ten (15.4%) pts experienced olverembatinib treatment-related serious AEs, of which each were experienced by 1 (1.5%) pt. Two (3.1%) pts discontinued the study because of TRAEs. No TRAE-associated deaths were reported. Olverembatinib showed sustained antileukemic activity in pts with CML and Ph + ALL (Table 1). Among 50 efficacy-evaluable pts with CML-CP, the rate of complete cytogenetic response (CCyR) was 57% (25/44) and major molecular response (MMR) 43% (21/49). Efficacy improved over time; the MMR rate in pts with CML-CP treated for 6 months was 66% and 88% in pts treated for 12 months. Among pts whose disease failed ≥ 4 prior TKIs, CCyR and MMR rates were 57% (13/23) and 42% (11/26), respectively. In pts with CML-CP harboring the T315I mutation, rates of CCyR and MMR were 60% (9/15) and 44% (7/16), respectively, and 55% (16/29) and 42% (14/33) in pts without the T315I mutation. Among evaluable ponatinib-failed pts, 8/15 (53%) achieved CCyR and 6/16 (38%) MMR. Among pts who failed asciminib therapy, 3/7 (43%) achieved CCyR and 3/8 (38%) MMR. Of 8 pts with CML-CP who had prior exposure to both ponatinib and asciminib, 2 (25%) achieved MMR. At 24 months, PFS was 75% (95% CI, 56.1-86.7) and OS was 97.6% (95% CI, 90.8-99.4). Thirteen pts with advanced Ph + leukemia were efficacy-evaluable, of whom 3 (23%) achieved MMR; only 1 of 3 pts with the T315I mutation achieved MMR; the other 2 were also resistant to ponatinib treatment. The median (95% CI) PFS of efficacy-evaluable pts with advanced leukemia was 12.7 (4-19.5) months. In the combination cohort, 2 pts with Ph + BCP ALL received olverembatinib 30 mg QOD with blinatumomab; both achieved CCyR and 1 achieved a negative MRD status after 1 treatment cycle. Conclusions Olverembatinib alone or combined with blinatumomab was efficacious and well tolerated in pts with heavily pretreated CML or Ph + ALL . Olverembatinib monotherapy was potent in pts who were either resistant or intolerant to ponatinib and/or asciminib, regardless of T315I mutation status. Olverembatinib may provide an effective new treatment option for pts after failure of 2 or more TKIs. Internal study identifier: HQP1351-CU101. Clinicaltrials.gov identifier: NCT04260022.

Deep and Durable Cytogenetic and Molecular Responses with Pemigatinib in Myeloid/Lymphoid Neoplasms with Fibroblast Growth Factor Receptor 1 Rearrangement: The Fight-203 Study

Introduction:Myeloid/lymphoid neoplasmswith fibroblast growth factor receptor 1 rearrangement (MLN FGFR1) are aggressive hematologic neoplasms caused by various reciprocal translocations involving chromosome band 8p11, resulting in tyrosine kinase fusion genes (eg, ZMYM2::FGFR1 from t[8;13][p11;q12] or BCR::FGFR1 from t[8;22][p11;q11]) and constitutive FGFR1 activationand downstream signaling. Pemigatinib is a potent and selective oral inhibitor of FGFR1-3 approved for the treatment of adults with relapsed or refractory MLN FGFR1. Efficacy and safety data for 41 patients with MLN FGFR1 in the ongoing FIGHT-203 study of pemigatinib were previously reported. Median daily pemigatinib dose was 9.5 mg; treatment-emergent adverse events led to dose interruptions in 66% of patients. Rates of complete response (CR) among the 38 patients evaluable for clinical response and rates of complete cytogenetic response (CCyR) for the 40 patients evaluable for cytogenetic response were 74% and 70%, respectively. CR and CCyR occurred in >80% of patients with chronic phase disease and in >50% of patients with blast phase disease. Here we present an analysis of centralized fluorescence in situ hybridization (FISH) evaluation of bone marrow (BM) cells and serial characterization of levels of FGFR1 fusion transcripts in this same cohort. Methods: FIGHT-203 (NCT03011372) is an ongoing open-label, multicenter, phase 2 study evaluating pemigatinib in patients ≥18 years old with MLN FGFR1 and ≥1 prior therapy. The starting dose was pemigatinib 13.5 mg daily (2 weeks on, 1 week off). Following protocol amendments, patients without prior therapy were eligible to enroll, and the dosing regimen was changed to a continuous schedule. Patients were censored for cytogenetic and molecular follow-up at the time of transplantation. CCyR was defined as 0 metaphases positive for the respective reciprocal translocation in ≥20 evaluated BM metaphases on local and/or central karyotyping or 0 cells (or not exceeding the lower level of detection of the probe) with the FGFR1 rearrangement in ≥200 BM cells on local and/or central break-apart FISH assays (central FISH prioritized). As part of the translational research plan, fusion partner genes were identified with next-generation sequencing (NGS; FusionPlex, Archer, Boulder, CO, USA) and targeted PCR profiling of RNA extracted from whole blood; droplet digital PCR (ddPCR) assays were developed to monitor the frequencies of specific FGFR1 fusion transcripts in RNA extracted from whole blood samples (estimated limit of detection, 0.05 copies/μL). Results: As of June 30, 2021, 39 of 41 enrolled and treated patients were evaluable for translational analyses. Among the 39 patients with whole blood samples, FGFR1 fusion partner genes identified on translational testing were ZMYM2 (n=17), BCR (n=11), FGFR1OP (n=4), TPR (n=3), TRIM24 (n=2), and C14orf93, CCDC6, CNTRL and ETV6 (n=1 each). Two of 39 patients had 2 fusions detected ( ZMYM2 and BCR, n=1; ZMYM2 and TPR, n=1). C14orf93, CCDC6 and ETV6 have not been previously identified as FGFR1 fusion partner genes. Central FISH assessment of BM cells confirmed FGFR1-aberrantcells were reduced to undetectable levels in responding patients but rebounded in some patients during periods of treatment interruption (Figure A). Serial ddPCR of whole blood samples demonstrated marked reductions in FGFR1 fusion transcripts for the 34 patients with ≥3 measures while on treatment (Figure B). Among patients with CR, 81.0% had a >2-log reduction and 47.6% had a >3-log reduction in detectable FGFR1 fusion transcripts. Smaller reductions in FGFR1 fusion transcripts were observed in patients with stable disease. Changes in FGFR1 fusion transcripts correlated with FGFR1 FISH results (Pearson coefficient = 0.81) and reflected changes in treatment intensity. Conclusion:Several new FGFR1 fusion partner genes, including C14orf93, CCDC6, and ETV6 were identified with NGS and PCR profiling. Pemigatinib treatment resulted in marked decreases in the percentages of cells with the FGFR1 rearrangement on FISH, as well as 2-3 log reductions in FGFR1 fusion transcripts in patients with MLN FGFR1. Further investigations are ongoing to determine the relationship between pemigatinib dose intensity and the depth and durability of molecular response.

Flumatinib Versus Nilotinib for Newly Diagnosed Chronic Phase Chronic Myeloid Leukemia

Introduction Tyrosine kinase inhibitors (TKIs) have considerably improved the long-term clinical outcomes in patients with chronic phase chronic myeloid leukemia (CML-CP). Most of these patients receive 1 st generation TKI imatinib as first-line therapy; however, an increasing number of patients are now receiving 2 nd generation TKIs as first-line therapy, because of the more potent BCR-ABL1 inhibition with proven efficacy in patients resistant or intolerant to imatinib. Flumatinib is a novel 2 nd generation BCR-ABL1 TKI with promising efficacy and manageable safety in newly diagnosed CML-CP. Compared to imatinib, patients treated with flumatinib have achieved significantly higher rates of 12-month major molecular response (MMR) and complete cytogenetic response were observed in patients with CML-CP and that too within a shorter time duration. Though there have been many studies comparing 2 nd generation TKIs vs imatinib in CML-CP, studies comparing clinical outcomes between different 2 nd generation TKIs are scarce. Here, we report the real-world effectiveness and safety of flumatinib and nilotinib in patients with newly diagnosed CML-CP. Methods In this study, adult patients (≥18 years old) with newly diagnosed Philadelphia chromosome-positive (Ph+) CML-CP who received either 300 mg nilotinib twice daily or 600 mg flumatinib once daily, were included, with a follow-up duration of roughly 3 years (NCT04739826). The primary endpoint was the rate of MMR at 12 months as defined by European LeukemiaNet 2020 recommendations (BCR-ABL1 transcript level ≤0.1% in peripheral blood on RT-PCR assay on International Scale [IS]).The secondary endpoints were the rate of early molecular response (EMR) at 3 months (BCR-ABL1 IS ≤10%), the rate of molecular response at 6 months (BCR-ABL1 IS ≤ 1%) and safety (adverse events [AEs] reports in accordance to Common Terminology Criteria for Adverse Events, version 4.03). Results A total of 446 patients were enrolled in the study between November 2020 and August 2022, of which 150 and 296 patients were enrolled in nilotinib and flumatinib groups, respectively. The baseline characteristics were comparable between the two groups (Table 1). No significant difference in the rate of MMR was observed at 12 months between nilotinib and flumatinib (78% vs 80%; P=0.68) . Similarly, no significant difference was observed in the rate of EMR at 3 months (85% vs 89%; P=0.26) and the rate of optimal molecular response at 6 months (93% vs 92%; P=0.70; BCR-ABL1 is ≤1%) between the two groups. The overall safety profile was similar between the two groups. However, hyperbilirubinemia (47% vs 7%), increased ALT (33% vs 12%), increased AST (24% vs 9%), rash (30% vs 18%) and anemia (19% vs 10%) were more frequent in nilotinib group than flumatinib group, whereas diarrhea was lower in nilotinib than flumatinib (2.7% vs 8.8%). The incidence rate of grade 3-4 AEs were reported to be 13% in nilotinib group and 10% in flumatinib group. The safety of flumatinib was more favorable compared to nilotinib in terms of hepatic toxicities, skin toxicities, etc. (Figure 1). Conclusion The efficacy of flumatinib is comparable to nilotinib in Chinese patients with newly diagnosed Ph+ CML-CP. The overall incidences of grade 3-4 AEs were also accessible for the two drugs, nevertheless, a few AEs inclusively hepatic toxicity, anemia and skin toxicity were remarkably lower with flumatinib intervention.

Phase 2 Study of Dasatinib with and without Venetoclax in Patients with Early Chronic Phase Chronic Myeloid Leukemia (ECP-CML)

Background Treatment-free remission (TFR) is a therapeutic goal for patients with ECP-CML once patients maintain a deep molecular remission (DMR) on tyrosine kinase inhibitors (TKIs). Only a fraction of patients (pts) achieved sustained (3+ years) molecular remission with 4.0- to 4.5-log reduction (MR4.5). Preclinical studies showed that BCL-2 is a key survival factor for CML stem/progenitor cells. Therefore, the combination of TKIs and venetoclax, targeting BCR::ABL1 and BCL-2, has the potential to significantly improve DMR and subsequently the rates of TFR. The aim of this study is to evaluate the safety and efficacy of the combination. Methods Patients with ECP-CML or accelerated phase (AP; defined by clonal evolution only) were eligible; pts with < 1 month of prior TKI therapy were eligible. Pts received single-agent dasatinib 50 mg/d for the first 3 months. From Month 4 and onwards, venetoclax was administered from Days 1 to 14 each month concomitantly with dasatinib for a total of 3 years. The first 16 patients received venetoclax 200 mg/d, with a rapid ramp-up starting 50 mg on Day 1, then 100 mg on Day 2, then 200 mg daily on Day 3 and onwards. Due to neutropenia observed with continuous dose of venetoclax 200 mg/d, the protocol was ameded: from patient #17 and onwards, venetoclax was administered at 200 mg/d for 14 days per month and upon achievement of MR4.5, venetoclax was reduced to 100 mg/d for 7 days per month. After 3 years of combination, patients received single-agent dasatinib. TFR was offered after ≥ 3 years of DMR. The primary endpoint was the rate of major molecular response (MMR) by 12 months of the combination. The secondary endpoints were the 12-month rate of MR4.5 and the cumulative overall rate of MR4.5; the rates of MR4.5 at 6-, 12-, 18-, 24, and 36-months of the combination; the proportion of patients with sustained MR4.5 of 3 years and more; the TFR rate; overall survival; and the safety of the combination. Cumulative response rates were calculated with treatment failure as a competing event. Failure-free survival (FFS) was calculated from the initiation of therapy to loss of major cytogenetic response (MCyR), transformation to AP or blast phase, discontinuation of therapy for any reason except of TFR, or death. Results Sixty-five pts were enrolled and treated between April 2018 and August 2021. The median age at treatment initation was 46 years (range, 23-73) and 57% of the pts were females. Twenty-one (32%) pts had splenomegaly, 46 (71%) had low Sokal risk disease and 3 (5%) had high Sokal risk disease (Table 1). By 12 months of the combination, 85% of the pts had achieved MMR or deeper response. The median time to MMR, MR4, and MR4.5 were 6.2 months, 13 months, and 23.9 months from the time of TKI start, respectively. After a median follow-up of 25.7 months (range, 8.7-48.1), two pts discontinued therapy due to adverse events (GI intolerance, and pleural effusion); the 2 -year FFS was 96%. One pt switched TKI therapy due to the lack of 18-month complete cytogenetic response (CCyR); no loss of CCyR, transformation, or death was observed. We then compared the outcomes with the combination to the outcomes of 85 pts treated with single-agent dasatinib. From the start of TKI therapy, the 12-month cumulative MMR rates were 78% and 79% in the dasatinib single-agent and dasatinib + venetoclax groups, respectively. The cumulative 24-month rates of CCyR, MMR, MR4, and MR4.5 are summarized in Table 2. In the dasatinib single-agent group, 3 pts switched TKI therapy due to the lack of 12-month MCyR, 18-month CCyR, and the acquisition of ABL1 mutation (1 each); 3 pts switched TKI therapy due to loss of CCyR; 2 pts died during therapy (deaths unrelated to CML). Within one year of therapy, the incidence of grade 1/2 neutropenia (absolute neutrophil count, below lower range of normal to 1,000 x10 9/L) was 21% and 52% in the dasatinib single agent and dasatinib + venetoclax groups, respectively ( P<0.001); the incidence of grade 3/4 neutropenia (absolute neutrophil count, below 1,000 x10 9/L) was 8% and 17%, respectively ( P<0.001). There was no incidence of neutropenic fever in the dasatinib + venetoclax. Conclusion The combination of dasatinib 50 mg/d and venetoclax is safe and effective in pts with ECP-CML. With a median follow-up of 2 years, the cumulative resposne of dasatinib + venetoclax is similar to that of dasatinib single-agent without adding significant toxicities. Further follow-up is needed for the evaluation of TFR.

Front-Line Tyrosine Kinase Inhibitors in Pediatric Chronic Myeloid Leukemia: A Study on Efficacy and Safety.

We conducted a retrospective study on 51 pediatric patients with newly diagnosed chronic myeloid leukemia chronic phase or accelerated phase. The patients were classified into the IMA group (N = 33), treated with imatinib, and the DSA group (N = 18), treated with dasatinib, as front-line tyrosine kinase inhibitors (TKIs). At 12 months, the rates of complete cytogenetic response were similar between the IMA group (92.3%) and DSA group (100%) (p = 0.305). However, the rate of early molecular response was higher in the DSA group than in the IMA group (100.0% vs. 80.0%, p = 0.043). By 12 and 24 months, the DSA group showed faster and higher cumulative rates of both major (DSA group: 72.2% and 100%, respectively; IMA group: 41.2% and 68.7%, respectively; p = 0.002) and deep molecular responses (DSA group: 26.0% and 43.6%, respectively; IMA group: 13.8% and 17.5%, respectively; p = 0.004). Both TKIs were well tolerated. Although the height standard deviation scores decreased in both groups, the height decline was greater in the DSA group between one and two years from the start of TKI therapy. In this study, dasatinib achieved faster and higher molecular responses with an acceptable safety profile. Further follow-up is necessary to assess the long-term outcomes of TKI treatment in children.

Pemigatinib for the treatment of myeloid/lymphoid neoplasms with FGFR1 rearrangement

ABSTRACT Introduction Myeloid/lymphoid neoplasms with fibroblast growth factor receptor-1 (FGFR1) rearrangements (MLNFGFR1) are rare entities with aggressive features and poor prognosis. Presentation is heterogeneous, ranging from myeloproliferative neoplasms (with or without eosinophilia) to T-cell lymphoma and acute leukemia. Historical treatments have been guided by the presenting phenotype with induction chemotherapy frequently used. Pemigatinib is a FGFR1–3 tyrosine kinase inhibitor that has demonstrated high complete hematologic and cytogenetic response rates in MLNFGFR1. Areas covered We discuss the pathogenesis, presentation, and historical treatments for MLNFGFR1, in addition to clinical data using pemigatinib and other targeted therapies. Discussion of the mechanism of action and adverse events is also included. Expert opinion Pemigatinib represents a significant advance in the management of MLNFGFR1. High rates of complete hematologic and cytogenetic response have been observed. While direct comparative data are unavailable, outcomes appear favorable compared to conventional approaches. Long-term efficacy and tolerability are not yet known, and allogeneic hematopoietic stem cell transplant (alloHSCT) continues to be the treatment with the highest chance of long-term disease free survival in responding patients. Combinations of pemigatinib and chemotherapy, particularly for more aggressive phenotypes, warrant future investigation as does the use of pemigatinib maintenance following alloHSCT.

Comparison of Efficay and Safety of First-Line Drugs (Imatinib Vs Nilotinib) in Newly Diagnosed pts of Ch Myeloid Leukemia

Background: Tyrosine kinase inhibitors (TKI’s) revolutionized the treatment of chronic myeloid leukemia (CML). Aim: To compare the efficacy and safety between two Tyrosine Kinase Inhibitors among Pakistani population. Study Design: Randomized control trial. Methodology: Patients (n=124) were enrolled through simple random sampling. Prognostic scores were calculated for each patient. The institutional ethics committee of HFH approved this study protocol. Written informed consent was taken. Patients were randomly assigned to nilotinib 600 mg or imatinib 400 mg. The first analysis was done at 12 months of treatment. The second analysis was conducted after patients completed 24 months of therapy with TKIs. A consent form was signed by the participant before taking data. The basic end point was the rate of complete cytogenetic response (CCyR; 0% Ph+ metaphases by cytogenetics) at 12 months. Data was evaluated by using SPSS version 23. Chi-square test was applied with p-value of less than 0.05 was considered significant. Results: Nilotinib proved superior over imatinib in achieving complete cytogenetic response (94% vs 79%) with significant p-value. Both drugs showed similar risk profile to those from other international studies. Conclusion: It was concluded that Nilotinib proved clear benefit over imatinib in achieving higher rates of cytogenetic response in our study. The risk of events was comparable with imatinib and nilotinib; but each one showed different kinds of adverse events. Keywords: Chronic Myeloid Leukemia, Tyrosine Kinase Inhibitors and Cytogenetic Response.

Therapy for patients with chronic phase-chronic myeloid leukemia previously treated with ⩾2 tyrosine kinase inhibitors: a systematic literature review.

ATP-competitive tyrosine kinase inhibitors (TKIs) are the current standard of care for patients with chronic phase-chronic myeloid leukemia (CP-CML) in the first-line and second-line (2 L) setting. Treatment after 2 L is not clearly established. The objective of this study was to summarize the available evidence to compare the efficacy and safety of interventions in the treatment of CP-CML patients who had received ⩾2 prior TKIs. A systematic literature review was performed. A systematic literature review (SLR) of studies published until May 2021, reporting clinical outcomes in adult patients with CP-CML who had received ⩾ 2 prior TKIs was performed. Studies were identified through the database searches via Ovid platform (Embase, MEDLINE Epub Ahead of Print, In-Process and Other Non-Indexed Citations, and Cochrane Central Register of Controlled Trials), the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP), bibliographic search of relevant reviews, and proceedings from the previous 3 years of the key conferences in the field of oncology. Our search identified 38 relevant studies. Among the identified studies of the current third-line treatments, the major molecular response (MMR) rate for ponatinib was 19.0-66.7%, 23.3-25.5% for asciminib, 19.2% for omacetaxine, and 13.2% for bosutinib at 6 months. The complete cytogenetic response (CCyR) rate was 21.4-64.8% for ponatinib, 38.7-40.8% for asciminib, 18-24.2% for bosutinib, and 16.1% for omacetaxine at 6 months. The findings from current SLR demonstrated the lack of data for patients with CML treated with ⩾2 TKIs. TKIs such as asciminib, ponatinib, and bosutinib are valid options for those patients. Further research is needed to identify the best treatment option for patients with CML receiving later lines of therapy.

Comparative Characteristics of the Effectiveness of Tyrosine Kinase Inhibitors Vs Allogeneic Hematopoietic Stem Cell Transplantation in the Chronic Phase of Chronic Myeloid Leukemia

Background: Chronic myeloid leukemia (CML) patients (pts) with the resistance at least to two tyrosine kinase inhibitors (TKIs) should be considered as candidates for allogeneic hematopoietic stem cell transplantation (allo-HSCT). At the same time, the majority of pts in real clinical practice continue conservative third-line therapy with TKIs (TKI-3L). Aim: To compare the long-term results of TKI-3L vs allo-HSCT therapy in chronic phase (CP) CML. Methods: We have included 139 pts in CP CML from six centers in Saint Petersburg and Leningrad Region (males, n=66) in the multicenter retrospective study: 73 pts on TKI-3L and 66 pts after allo-HSCT. Me age in the whole group was 45(19-88) mos. Basic characteristics of patients according to groups are presented in the Table. At the start of TKI-3L there were 51/73(71%) pts with no cytogenetic response (CyR). The best baseline CyR was minimal or minor (mmCyR), partial (PCyR) in 12/73(16%), 10/73(13%) cases, respectively. In the group with allo-HSCT there were 62/66(93%) pts with no CyR. The best baseline CyR was PCyR in 3(5%) cases. Reasons for TKI-2L discontinuation were: resistance in 56/73(76%) or intolerance in 17/73(24%) cases respectively. Reasons for performing allo-HSCT were: resistance in 65/66(98%), including 6 interferon-resistant cases, or intolerance in 1/66(2%) cases respectively. Descriptive statistics were used for analysis, significance of differences between groups were estimated using chi-square test and Fisher's exact test. The rate of complete CyR (CCyR) (equal to BCR::ABL transcript level ≤1% by IS) were assessed. Overall (OS) and progression-free survival (PFS) were analyzed by Kaplan-Meier method. Log-rank test was used to assess the significance of differences in survival between patients' groups. Results: The Me duration of TKI-3L therapy was 14(1-120) mos, the Me time of follow-up (FU) from initiation of TKI-3L was 25(3-136) mos. The Me duration time of FU from allo-HSCT was 42(1-322) mos. CCyR and MMR were achieved in 22/73(30%) and 9/73(12%) pts respectively in TKI-3L group while CCyR and PCR-negativity were achieved in 53/66(80%) and 29/66(44%) pts respectively in the group after allo-HSCT (with p≤0,05 in CCyR and MR in both groups). Progression to acceleration phase or blast crisis (AP/BC) was observed in 13/73(17%) pts with the Me time to progression 17 mos in TKI-3L group and in 7/66(10%) pts with the Me time to progression 6 mos in allo-HSCT group, p=0,24 (See Fig. 1A). Death occurred in 19/73(26%), including five deaths from non-CML-related causes with Me time to death 17,2 mos in TKI-3L group and in 26/66(39%), including 17 transplant-related deaths and 6 CML-related with Me time to death 14 mos in allo-HSCT group, p=0,25 (See Fig. 1B). Estimated 1-year, 3-year and 5-year OS was 95%, 65% and 65% respectively in TKI-3L group as well as 90%, 65% and 60% respectively in allo-HSCT group. During FU time Me PFS and OS was not reached in both groups. In pts with any CyR at baseline in TKI-3L group with FU time 25(3-136) mos no pts progressed to AP/BC and only 2 CML-unrelated deaths occurred. At the last visit, TKI-3L therapy was continued in 13/73(18%) with Me FU time 7,5(4-99) mos. Most of them(n=10) with CCyR or better responses. TKI-3L discontinuation was mainly associated with resistance in 42/60(70%) pts. In allo-HSCT group 40/66(61%) pts alive with 21/40(53%) in stable PCR-negativity. Conclusion: In our observation OS and PFS was equal under TKI-3L or after allo-HSCT. No Pts with any CyR at baseline progressed and dead due to CML in TKI-3L group. Meanwhile less than one third pts and a few of them obtained CCyR and MMR, respectively, whereas the majority of pts after allo-HSCT reach CCyR and nearly half of them obtained PCR-negativity in this heavily pretreated group. Despite there are some biases (retrospective study, undirected comparison, in allo-HSCT group were included pts with any number TKIs or even without ones, much less FU time in the TKI-3L group), it seems that allo-HSCT is preferable option for pt after two second generation TKIs failure. Also in pts with any CyR after 2TKIs failure the use of TKI-3L therapy might be justified. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Asciminib (Scemblix): A third-line treatment option for chronic myeloid leukemia in chronic phase with or without T315I mutation.

To review the pharmacology, efficacy, safety, dosing and administration, and place in therapy of asciminib, an oral tyrosine kinase inhibitor (TKI) used as a third-line treatment option for Philadelphia chromosome-positive chronic myeloid leukemia (CML) in chronic phase. CML is a rare cancer caused by a chromosomal translocation that forms a fusion of the BCR and ABL1 genes on chromosomes 22 and 9. Until recently, patients for whom first-line treatment options failed were treated with TKIs that bind to the adenosine triphosphate-binding site on BCR-ABL1. However, because of similar mechanisms of action, there continues to be an unmet need in patients for whom at least 2 TKIs have failed or those with a T315I mutation unable to tolerate ponatinib. In October 2021, the Food and Drug Administration approved asciminib (Scemblix), the first TKI specifically targeting the ABL1 myristoyl pocket (STAMP) via allosteric binding, as a third-line option for patients with chronic-phase (CP)-CML. Asciminib received accelerated approval due to meeting its primary endpoint at week 24, demonstrating a major molecular response rate of 25.5% for patients on asciminib compared to 13.2% for those receiving bosutinib. In addition, patients on asciminib achieved a higher rate of complete cytogenetic response at 40.8% compared to a rate of 24.2% for bosutinib. Clinicians prescribing asciminib should monitor for increased levels of pancreatic enzymes, hypertension, cardiovascular toxicity including ischemic and thromboembolic conditions, and decreased numbers of neutrophils and platelets, as these may require treatment interruption, dose reduction, or treatment discontinuation. Asciminib is a unique targeted TKI that provides clinicians with an additional third-line and beyond treatment option for adults with CP-CML regardless of mutation status as well as a second TKI treatment option for patients harboring a T315I mutation.

CML-155 Prognostic Markers of the Effectiveness of Tyrosine Kinase Inhibitors in Third-Line Therapy of Chronic Phase Chronic Myeloid Leukemia Patients: Data From a Multicenter Study

Despite success in chronic myeloid leukemia (CML) treatment there are unmet needs third-line therapy. To determine the efficacy and factors influencing the long-term outcomes of third-line therapy with tyrosine kinase inhibitors (TKIs). Multicenter retrospective study was conducted in 2019. All adult 73 pts, including 26(35%), CML chronic phase (CP) pts treated with TKIs in third line (TKI-3L) without complete cytogenetic response (CCyR) at baseline were included in the study. The me duration of CML from diagnosis to baseline was 63(10-314) mos. The rate of CCyR (equal to BCR::ABL transcript level <1%) and overall survival (OS) were assessed. Univariate and multivariate logistic regression analyses assessed risk factors for CCyR achievement. For a scoring system, selection of predictors was performed using L2-regularization after standardization of quantitative variables. The me duration of TKI-3L therapy was 14(1-120) mos, the me time of follow-up from initiation of TKI-3L was 25(3-136) mos. CCyR was achieved in 22/73(30%) pts. Both in univariate and multivariate regression analysis factors influenced on CCyR achievement were absence of CCyR at baseline (OR 0.26[95% CI, 0.08-0.85]; p=0.0252), no CCyR on TKI-1L and TKI-2L (OR 0.21[95% CI, 0.04-0.99]; p=0.0502), as well as pt's age at baseline per every 10 years (OR 1.52[95% CI, 0.61-3.8]; p=0.369). Score system was set up based on these factors with scores 7, 8, 1 score per 10 years respectively. ROC analysis divided pts into three groups: low risk (score ≤9, n=22), intermediate-risk (score 10-15, n=27) and high risk (score ≥16, n=24). The low-risk group had a significantly higher rate of CCyR on TKI-3L compared to intermediate or high-risk groups (14/22[64%] vs 7/27[26%] vs 1/24[4%], p<0.05). There were 19(26%) deaths. Estimated 1-year and 5-year OS was 95% and 65% respectively. All CML-related deaths(n=14), as well as transformation to BC (n=13), occurred in intermediate- and high-risk groups. Nearly a third of pts obtained CCyR on TKI-3L in our study. Most pts were alive at 5 years. Younger pts with any CyR on previous TKIs and at baseline had favorable prognosis. The use of TKI-3L is justified in low-risk groups and may be used in transplant-eligible pts.

P719: EFFICACY AND SAFETY OF BOSUTINIB IN LATER-LINE PATIENTS WITH CHRONIC MYELOID LEUKEMIA: A SUB-ANALYSIS FROM THE PHASE 4 BYOND TRIAL

Background: Bosutinib is approved for patients with Philadelphia chromosome-positive chronic myeloid leukemia (CML) resistant or intolerant to prior therapy and newly diagnosed patients in chronic phase. The efficacy and safety of bosutinib in patients with CML resistant or intolerant to prior tyrosine kinase inhibitors (TKIs) was evaluated in the phase 4 BYOND trial (NCT02228382; Gambacorti-Passerini et al, Blood, 2021). Aims: The efficacy and safety of bosutinib in resistant and intolerant patients with CML treated with 2 (3L) and 3 (4L) prior TKIs was characterized. Methods: The BYOND trial included 163 patients with CML resistant or intolerant to prior TKIs. A sub-analysis of 48 patients treated with 2 (3L) and 3 (4L) prior TKIs, categorized by resistance or intolerance to the last received TKI, was performed. This sub-analysis is based on the final November 23, 2020 database lock. Results: There were 18 and 30 patients resistant or intolerant to the last received TKI who entered the study without complete cytogenetic response (CCyR) or major molecular response (MMR), respectively. Median (range) treatment duration was 10.6 months (1.6–48.5) vs 28.3 months (0.2–48.6) and median (range) dose intensity was 447.1 mg/d (131.3–520.4) vs 288.8 mg/d (79.7–500.0) for resistant vs intolerant patients. Prior TKIs included imatinib (88.9% vs 100.0%), dasatinib (88.9% vs 83.3%), and nilotinib (66.7% vs 63.3%) for resistant vs intolerant patients. Overall, 61.1% vs 66.7% of resistant vs intolerant patients discontinued bosutinib, mostly commonly due to adverse events (AEs) in 27.8% vs 16.7% patients; 16.7% vs 6.7% discontinued bosutinib due to insufficient clinical response. Rates of CCyR and MMR are shown in the Table. Among responders (resistant vs intolerant patients), median (range) time to CCyR was 5.1 months (2.8–8.8) vs 3.0 months (2.7–6.1); median (range) time to MMR was 5.8 months (2.8–9.4) vs 3.2 months (2.8–9.3). In resistant vs intolerant patients, any grade treatment-emergent AEs (TEAEs) were reported by 100.0% vs 96.7% patients; grade 3/4 TEAEs were reported by 72.2% vs 83.3% patients. Grade 3/4 TEAEs >10% in resistant patients were thrombocytopenia (22.2%) and neutropenia (11.1%), and in intolerant patients were increased alanine aminotransferase (26.7%), diarrhea (23.3%), pleural effusion (13.3%), and rash (13.3%). Image:Summary/Conclusion: This sub-analysis of resistant and intolerant patients without baseline CCyR or MMR shows bosutinib was active in heavily pretreated patients with resistance or intolerance to the last received TKI. Despite a difference between resistant and intolerant patients with CML, efficacy outcomes, though lower than the overall BYOND population, are encouraging, and safety was generally consistent with previous reports.

A retrospective observational research study to describe the real-world use of bosutinib in patients with chronic myeloid leukemia in the United Kingdom and the Netherlands.

ObjectivesTo describe the real‐world effectiveness and safety of bosutinib in patients with chronic myeloid leukemia (CML).MethodsThis was a multi‐center, retrospective, non‐interventional chart review study conducted in 10 hospitals in the United Kingdom and the Netherlands.ResultsEighty‐seven patients were included. Bosutinib was the third‐line tyrosine kinase inhibitor (TKI) in 33 (38%) and fourth‐line in 44 (51%) patients. Median treatment duration was 15.6 months. Among 84 patients in chronic phase (CP) at baseline, 26 (31%) switched to bosutinib due to resistance and 57 (68%) due to intolerance to prior TKIs. Cumulative complete cytogenetic and major molecular response rates in CP patients were 67% and 55%, respectively. After a median follow‐up of 21.5 months, nine (11%) patients in CP died; estimated overall survival rates at 1 and 2 years postbosutinib initiation were 95% and 91%, respectively. Overall, 33/87 (38%) patients discontinued bosutinib due to either lack of efficacy/disease progression (17%), adverse events (14%), death (2%), or other reasons (5%). Eighty‐two (94%) patients experienced ≥1 adverse event possibly related to bosutinib, most commonly diarrhea (52%).ConclusionsBosutinib used in routine clinical practice in heavily pretreated patients with CML is an effective treatment for patients in CP and is generally tolerable.

Safety and Efficacy of Elective Switch from Nilotinib to Imatinib in Newly Diagnosed Chronic Phase Chronic Myeloid Leukemia

The treatment of newly diagnosed chronic phase chronic myeloid leukemia (CML) with nilotinib has resulted in a higher rate of major molecular (MMR) and complete cytogenetic response (CCyR) at 12 months compared to imatinib but at a higher cumulative cost and increased risk of serious adverse events. To maintain long-term efficacy and minimize both toxicity and costs, we aimed at evaluating in a prospective single-center trial the efficacy and safety of a response-directed switch from nilotinib to imatinib after 12 months in patients newly diagnosed with chronic phase CML. Thirteen adult patients were enrolled. Twelve patients started on nilotinib 300 mg twice daily. Eleven patients completed one year of nilotinib and were switched to imatinib 400 mg daily as per protocol. At 3 months, all patients achieved a complete hematologic response, with 7 (58%) patients had early molecular response. At 12 months, all patients achieved CCyR, of whom 5 (42%) and 4 (33%) patients achieved MMR and MR4.5, respectively. Three (27%) patients switched back to nilotinib after 18, 24, and 51 months respectively: 1 patient because of loss of CCyR after 18 months, and 2 patients because of imatinib intolerance. At last follow-up, all patients (n = 12) were alive and in MMR, 6 (50%) of them in continuous MR4.5. These findings suggest that response directed switch from nilotinib to imatinib at 12 months is capable of maintaining long-term response, with manageable side effects. This approach warrants further exploration with larger prospective trials. Clinical trial registration: Clinicaltrials.gov identifier: NCT01316250, https://clinicaltrials.gov/ct2/results?cond=&term=NCT01316250&cntry=&state=&city=&dist=.

Efficacy Predictors of the Third-Line Tyrosine Kinase Inhibitor Therapy in Patients with Chronic Phase of Chronic Myeloid Leukemia: Results of a Multi-Center Study

Background. The introduction of tyrosine kinase inhibitors (TKIs) into real-world clinical practice considerably improved the prognosis for patients with chronic myeloid leukemia (CML). However, during long-term follow-up, almost 1/2 and 2/3 of patients in the chronic phase (CP) discontinue TKI therapy of the first or second line, respectively. According to the Russian and International clinical guidelines, the third-line therapy should include allogeneic hematopoietic stem cell transplantation (allo-HSCT). And yet, some patients on the third-line therapy achieve and sustain optimal response on long-term TKI administration. Up to now, no clear-cut prognostic factors of TKI efficacy in the third-line therapy have been identified. This creates a challenge for treatment decision making after the failures of two lines of TKI therapy. Aim. To assess the efficacy of the third-line TKI therapy in real-world clinical practice and to identify the factors affecting the long-term therapy outcomes in CML-CP. Materials &amp; Methods. The retrospective study enrolled 73 CML-CP patients aged &gt; 18 years, treated with TKIs in the third-line at 5 specialized institutions in Saint Petersburg and Leningrad Region. Among the patients there were 26 men (35 %). The median age of the patients was 51 years (range 25-88 years). Results. With the median (range) third-line TKI therapy duration of 14 (1-120) months, the rate of complete cytogenetic response (CCR) was 30 % (п = 22) in the total cohort. The median time before achieving CCR was 9 (4-25) months. With the median follow-up time from the beginning of third-line TKI therapy till the last visit of 25 (3-136) months, progression to accelerated phase or blast crisis was observed only in 13 (17 %) out of 73 patients. Death was reported in 26 % (n = 19) of cases, among them 5 patients whose death was not CML-associated. At the last visit, 13/73 (18 %) patients were still on third-line TKI therapy. Direct and longterm therapy outcomes, including achievement of CCR and assessment of overall and progression-free survivals, were significantly better in patients with any cytogenetic response (CR) than in those without it or without complete hematologic response. Conclusion. The implementation of TKIs in the third-line CML-CP therapy seems to be suitable for patients with at least some CR, especially if an optimal donor of hematopoietic stem cells is unavailable or if the risk of severe allo-HSCT complications is too high.

A Phase 2 Study of Pemigatinib (FIGHT-203; INCB054828) in Patients with Myeloid/Lymphoid Neoplasms (MLNs) with Fibroblast Growth Factor Receptor 1 (FGFR1) Rearrangement (MLN FGFR1)

A Phase 2 Study of Pemigatinib (FIGHT-203; INCB054828) in Patients with Myeloid/Lymphoid Neoplasms (MLNs) with Fibroblast Growth Factor Receptor 1 (FGFR1) Rearrangement (MLN FGFR1)

Characteristics, Treatment and Outcome of 15 to 18 Years-Old Adolescents with Chronic Myeloid Leukemia (CML): The Experience of the International Registry of Childhood CML (I-CML-Ped Study)

Introduction: CML is a rare disease in children and adolescents, accounting for 2-3% of leukemia cases in this population. Pediatric CML is more frequent in the 2 nd decade of life but data on adolescents are limited. Only response to treatment has been analyzed in few studies and seems to be poorer in this age cohort. The International Registry of Childhood Chronic Myeloid Leukemia gave us the opportunity to analyze the characteristics and outcome in a large cohort of adolescents.Aims and objectives: To report on clinical features and response to treatment in adolescents (15-18 years of age at diagnosis) with CML in chronic phase (CML-CP).Material and methods: The International Registry of Childhood CML (I-CML-Ped Study, registered at www.clinicaltrials.gov NCT01281735) enrolled patients less than 18 years of age at diagnosis of CML in all phases according to the criteria of the European Leukemia Net (ELN). Data from this registry collected from Jan 2011 - Mar 2021 into the I-CML-Ped Study (Poitiers, France) were retrospectively analyzed.Results: Out of 614 patients (pts) registered in the I-CML-Ped Study, we identified 144 (23.4%) adolescents (15-18 years of age at diagnosis) with sufficient available data. Among them, according to the ELN criteria, 132 (92%), 7 (5%), and 5 (3%) pts presented with CML-CP, accelerated phase (AP), and blastic phase (BP), respectively. The median age of the cohort comprising 132 adolescents with CML-CP was 16.2 years [range, 15-18]. Ratio male/female was 1.75. Splenomegaly was reported in 66% of the pts with a median spleen size of 11.5 cm below the costal margin [range, 1-32]. Hepatomegaly was reported in 31% of the pts with a median liver size of 2.5 cm below the costal margin [range, 1-19]. Pain, asthenia and weight loss were the most frequent symptoms at diagnosis in 35%, 33%, and 20% of pts, respectively. The performance status according to the OMS and Karnofsky scores were 0 and 100% in 81% and 57% of the pts, respectively. At diagnosis, median leukocyte count was 181 G/L [range, 7-820]; median platelet count was 516 G/L [range, 102-2619], and median hemoglobin level was 10.45 g/dL [range, 4-17]. BCR-ABL1 transcript type b3a2 was present in 53% of the assessable pts. Additional chromosomal abnormalities and variants were found in 5% of the pts. 9% and 40% of pts were considered at high-risk according to the ELTS score and to the Sokal score (for pts less than 45 years), respectively. The majority of pts (97%) were treated with imatinib as first line treatment. After 12 months of treatment, in pts with data available, rate of complete cytogenetic response (CCyR) was 74/109 (68%) pts with imatinib first line. Overall, rate of CCyR was 101/109 (93%) pts with imatinib first line [88/109 (81%) pts receiving imatinib only, 13/109 (12%) pts after switching to another TKI, 8/109 (7%) pts did not achieve CCyR]. Median time to achieve CCyR was 8.2 months [range, 2.7-106.7]. The cumulative rate of MMR at month 12 was 40/111 (36%) pts. Overall rate of MMR was 91/111 (82%) pts [72/111 (65%) pts with first line imatinib only; 19/111 (17%) pts with another TKI]. Median time to achieve first MMR was 14.5 months [range, 0.9-63.1]. Out of all patients on first line imatinib, 11/123 (9%) pts progressed: 3/11 pts progressed to AP and 8/11 pts to BP. Further progress to BP was observed in 2 of the 3 pts with AP. BP phenotype was myeloid in 5/10 pts, lymphoid in 3/10 pts and bilineage in 1/10 pts (no data for 1/10 pts). With imatinib first line, deaths occurred in 5/123 (4%) pts, among them 4/5 due to complications associated with hematopoietic stem cell transplantation. With a median follow up of 37 months [range, 0.9-231], the overall survival rate was 89.2% [83.6%; 94.7%] for pts treated with imatinib first line (N = 123).Conclusion: Our results are in line with publications describing adolescents and young adults (AYAs) as a risk population for a poorer treatment outcome: when comparing AYAs (15-29 yrs) to adults (>30 yrs), CCyR and MMR were inferior in AYAs (cumulative CCyR 84% vs 93%, cumulative MMR 75% vs 86%, respectively) [Pemmaraju N et al., Haematologica 2012] and rates of progression to AP and BP were 8.7% in AYAs (16-29 yrs) but only 5.3% and 6.1% in adults (45-59 yrs and >60 yrs, respectively) [Kalmanti L et al. , Ann Hematol. 2013]. Additional research is required in adolescents with CML to shed light on the cause(s) for the observed differences and to further improve the outcome. DisclosuresNo relevant conflicts of interest to declare.

The Comparison of Dasatinib 70 Mg/Day to 100 Mg/Day in Newly Diagnosed Patients with Chronic Myeloid Leukemia in Chronic Phase (CML-CP): A Multicenter, Prospective, Randomized Controlled Study

Background:The purpose of this study is to compare efficacy and safety of patients with newly diagnosed chronic myeloid leukemia in chronic phase (CML-CP) treated with frontline dasatinib 70 mg/day with those who received standard-dose dasatinib 100 mg/day.Method:From July 2019 to July 2021, 81 patients with newly diagnosed CML-CP were enrolled across 11 centers. All of the patients were randomly treated with dasatinib 70 mg/day (N=43) or standard-dose dasatinib 100 mg/day (N=38).Results:Among 81 enrolled patients, 16 patients were off study at different times for different reasons.All patients achieved hematological remission after 3 months of treatment, and the best response rates were 84.00% (21/25) and 88.89% (24/27) for 70mg/d and 100mg/d groups (P>0.05).At 6 months, the best response, complete cytogenetic response (CCyR) and major molecular response (MMR) rate were 94.44% vs 92.86% (P > 0.05), 94.44% vs 92.86% (P > 0.05) and 55.56% vs 71.43% (P > 0.05), respectively.At 9 months, the rates of CCyR and MMR were 90.91% vs 88.89% (P > 0.05) and 66.67% vs 72.73% (P > 0.05);CCyR and MMR by 12 months, respectively, were 90.91% vs 100.00% (P > 0.05), 81.82% vs 80.00% (P > 0.05).The adverse events (AEs) of the two groups were mild, and there was no significant difference (P > 0.05).The most common grade ≥3 hematological AEs in 70 mg/d group were leukopenia (1/43), neutropenia (1/43) and anemia (2/43), and In 100mg/d group were leukopenia (4/38), neutropenia (6/38), anemia (3/38) and thrombocytopenia (3/38).Conclusions:Our study suggests that patients with newly diagnosed CML-CP treated with dasatinib 70 mg/day or 100 mg/day, there is no significant difference in efficacy and safety. Decreasing the dose of dasatinib can ensure the efficacy of patients, while reducing the economic burden of patients and increasing patient compliance. DisclosuresNo relevant conflicts of interest to declare.