Importance: Patients with chronic myeloid leukemia (CML) or Philadelphia chromosome–positive acute lymphoblastic leukemia (ALL) resistant or intolerant to BCR-ABL1 tyrosine kinase inhibitors (TKIs) have limited treatment options. Olverembatinib, which is approved in China, has only been tested in Chinese patients.Objective: To assess the pharmacokinetics, safety, efficacy, and recommended dose of olverembatinib in patients with CML or Philadelphia chromosome–positive ALL resistant or intolerant to at least 2 TKIs.Design, Setting, and Participants: This multicenter phase 1b randomized clinical trial was conducted from January 28, 2020, to January 2, 2024, with a median (range) follow-up of 48 (0-166) weeks. Patients with CML or Philadelphia chromosome–positive ALL were enrolled. This bridging study was performed in part to confirm that there are no racial differences in the pharmacokinetic profile of olverembatinib.Interventions: Patients were randomly assigned to 30, 40, or 50 mg of olverembatinib orally every other day in 28-day cycles.Main Outcomes and Measures: Pharmacokinetic profile of olverembatinib.Results: Of 80 included patients, 46 (58%) were male, and the median (range) age was 54.0 (21-80) years. The pharmacokinetic profile of olverembatinib was compatible with alternate-day dosing and similar to that in Chinese patients. Based on investigators’ assessments, 60 patients (75%) experienced at least 1 treatment-related adverse event; 32 (40%) experienced grade 3 or higher treatment-related adverse events; and 12 (15%) experienced treatment-related serious adverse events, none of which were fatal. Frequently reported (10% or more) treatment-emergent adverse events included elevated blood creatine phosphokinase (all grades, 31 [39%]; grade 3 or higher, 10 [13%]) and thrombocytopenia (all grades, 23 [29%]; grade 3 or higher, 14 [18%]). Among evaluable patients with chronic-phase CML, complete cytogenetic response (CCyR) occurred in 31 of 51 patients (61%; 95% CI, 46.1-74.2), and major molecular response (MMR) occurred in 25 of 59 patients (42%; 95% CI, 29.6-55.9). Cytogenetic and molecular responses were similar in patients with or without T315I variants. A total of 15 of 26 patients with prior ponatinib treatment (58%; 95% CI, 36.9-76.6) achieved CCyR, and 11 of 30 (37%; 95% CI, 19.9-56.1) achieved MMR. A total of 4 of 8 patients with asciminib resistance (50%; 95% CI, 15.7-84.3) had CCyR, and 4 of 12 (33%; 95% CI, 9.9-65.1) had MMR. The recommended phase 3 dose of olverembatinib is 30 mg every other day in patients without T315I variants.Conclusions and Relevance: In this trial, olverembatinib had a favorable pharmacokinetic profile, was generally well tolerated, and showed strong antileukemic activity in patients with heavily pretreated chronic-phase CML with or without T315I variants, including prior ponatinib and/or asciminib failure. Olverembatinib may provide a viable new treatment option for patients after failure of 2 or more TKIs.Trial Registration: ClinicalTrials.gov Identifier: NCT04260022

Myeloblast expansion is a hallmark of disease progression and comprises CD34+ hematopoietic stem and progenitor cells (HSPC). How this compartment evolves during disease progression in chronic myeloid neoplasms is unknown. Using single-cell RNA sequencing and high-parameter flow cytometry, we show that chronic myelomonocytic leukemia (CMML) CD34+ HSPC can be classified into three differentiation trajectories: monocytic, megakaryocyte-erythroid progenitor (MEP), and normal-like. Hallmarks of monocytic-biased trajectory were enrichment of CD120b+ inflammatory granulocyte–macrophage progenitor (GMP)-like cells, activated cytokine receptor signaling, phenotypic hematopoietic stem cell (HSC) depletion, and adverse outcomes. Cytokine receptor diversity was generally an adverse feature and elevated in CD120b+ GMPs. Hypomethylating agents decreased monocytic-biased cells in CMML patients. Given the enrichment of RAS pathway mutations in monocytic-biased cells, NRAS-competitive transplants and LPS-treated xenograft models recapitulated monocytic-biased CMML, suggesting that hematopoietic stress precipitates the monocytic-biased state. Deconvolution of HSPC compartments in other myeloid neoplasms and identifying therapeutic strategies to mitigate the monocytic-biased differentiation trajectory should be explored. Significance: Our findings establish that multiple differentiation states underlie CMML disease progression. These states are negatively augmented by inflammation and positively affected by hypomethylating agents. Furthermore, we identify HSC depletion and expansion of GMP-like cells with increased cytokine receptor diversity as a feature of myeloblast expansion in inflammatory chronic myeloid neoplasms. This article is highlighted in the In This Issue feature, p. 476

Drug development for chronic myelomonocytic leukemia (CMML) has failed to parallel the recent success observed in related myeloid neoplasms. To address these shortcomings, the US Food and Drug Administration (FDA) held a “Mini-symposium on CMML: Current State of the Art and Trial Design” in September 2023. This symposium brought together a panel of key FDA regulators and academic experts in CMML drug development to discuss challenges and provide perspectives on future drug development for this disease. The panel explored unique challenges that underlie the lack of therapeutic advances in CMML to date and discussed relevant topics such as clinical trial design, study end points, and key regulatory considerations. This article summarizes the key points of discussion from this symposium to facilitate advancements in the field.

PURPOSE: Chronic myelomonocytic leukemia (CMML) is a rare myeloid neoplasm characterized by clinical heterogeneity and is associated with poor outcomes. To date, limited molecular information has been incorporated into disease classification and risk stratification. We aimed to integrate genomic features into the clinical decision-making process for CMML. PATIENTS AND METHODS: We analyzed a retrospective cohort of 3013 patients with CMML (training set) and a prospective population of 516 patients (validation set). Using an innovative framework for multimodal data analysis, we developed molecular-based disease taxonomy and prognostication. RESULTS: Unsupervised clustering identified nine entities with distinct genomic features and outcomes ( P < .001), including splicing machinery, transcription factors, signal transduction and tyrosine kinase pathways aberrations, and high-risk molecular signatures. Notably, 15% of patients showed molecular/clinical overlap with other myeloid neoplasms. We integrated molecular and clinical information to build the international CMML Prognostic Scoring System (iCPSS), incorporating mutations in nine genes together with hematologic parameters and cytogenetic abnormalities. The iCPSS identified five groups with distinct probability of overall and leukemia-free survival in both training and validation cohorts ( P < .001), outperforming existing prognostic models. Importantly, 55% of patients were reassigned to higher or lower risk groups by the iCPSS. Decision analysis demonstrated that iCPSS could refine the optimal timing of allogeneic transplantation at the individual level; compared with conventional prognostic tools, iCPSS-based decision modeling changed transplantation strategy in 31% of cases, resulting in a significant gain-in-life expectancy for eligible patient population ( P < .001). A federated learning platform was implemented to enable continuous, privacy-preserving model update across multiple centers. CONCLUSION: Molecular information improves CMML classification and prognostication, supports more effective clinical decision making, and potentially refines the design of clinical trials.