Asciminib in Pediatric Philadelphia-Positive Chronic Myeloid Leukemia in Chronic Phase With or Without T315I Mutation: Phase II Safety and Efficacy Study

The primary objective is to estimate the efficacy of asciminib in pediatric participants with chronic myeloid leukemia in chronic phase, including newly diagnosed disease without known T315I mutation, disease resistant or intolerant to previous TKI therapy without known T315I mutation, and disease with known T315I mutation irrespective of prior TKI treatment. This is clinically relevant because it evaluates antileukemic activity across key pediatric subgroups with distinct treatment histories and mutation status. The secondary objectives are to estimate additional efficacy parameters, characterize safety and tolerability, assess growth and sexual maturation, and characterize the pharmacokinetic profile of asciminib in pediatric participants.

The trial population included 34 participants with Philadelphia-positive chronic myeloid leukemia in chronic phase. Male and female pediatric participants aged 1 to less than 18 years were selected. The population comprised newly diagnosed cases within 3 months of screening and participants with disease resistant or intolerant to previous tyrosine kinase inhibitor therapy, with or without the T315I mutation. Participants were required to have cytogenetic confirmation of Philadelphia-positive disease, evidence of a typical BCR::ABL1 transcript amenable to standardized quantification, and adequate performance status. The source did not provide information on general health status beyond these disease-related criteria or on lifestyle factors such as diet, physical activity, or habits.

This is a phase II, multicenter, open-label, single-arm study designed to evaluate the safety and efficacy of asciminib in pediatric participants with newly diagnosed or previously treated chronic myeloid leukemia in chronic phase with or without the T315I mutation. The trial is planned from 2026-08-01 to 2033-02-23. Study participation begins with a screening visit to confirm eligibility, including informed consent, age, diagnosis, cytogenetic confirmation of Philadelphia chromosome positivity, transcript suitability for standardized quantification, and performance status. Eligible participants then enter treatment and are followed at scheduled study visits for assessment of efficacy, safety, growth and development measures, and pharmacokinetic parameters. The end-of-study visit is performed at study completion to collect final efficacy and safety data. The expected duration of participant involvement is not explicitly stated. Early termination may occur if eligibility criteria are no longer met, if disease progression or treatment failure is observed, if unacceptable toxicity or other treatment-emergent adverse events occur, or for other reasons determined by the study protocol.

The investigational treatment was asciminib, administered as film-coated granules for oral use. The stated dose was 520 mg for Asciminib and 510 mg for ASCIMINIB HYDROCHLORIDE, with administration by the oral route and no frequency specified in the source data. Both entries were identified as test products containing asciminib hydrochloride.

No non-experimental treatment, placebo, or comparator therapy was specified in the source data. The study was described as a single-arm trial, and no additional information on dosing schedule, dose modification, or participant compliance monitoring was provided.

Efficacy will be assessed by Major Molecular Response (MMR) at Week 48 as the primary endpoint. Secondary efficacy assessments will include MMR at Week 96 and MMR at scheduled timepoints. Additional efficacy measures will include hematologic, cytogenetic, and other molecular responses at scheduled timepoints. Time to response, duration of response limited to binary response endpoints, time to treatment failure, time to disease progression, event-free survival, and overall survival will also be evaluated.