Asciminib (STAMP/BCR-ABL1) pediatric formulation hits 64-67% MMR with adult-equivalent PK in Ph+ CML-CP

Asciminib, an allosteric BCR-ABL1 STAMP inhibitor, was evaluated in the Phase Ib/II ASC4Kids study (NCT04925479). Nineteen children (1–<18 y) with Philadelphia chromosome-positive Chronic Myeloid Leukemia in the Chronic Phase after ≥1 TKI received a pediatric formulation 1.3 mg/kg BID; exposure matched the adult 40 mg BID dose (AUClast 7 091 vs 5 130 hr·ng/mL; Cmax 1 031 vs 939 ng/mL). After 28–40 weeks, 91–100% had BCR::ABL1IS ≤ 1% and64–67% achieved major molecular response, exceeding the ~52% 12-mo MMR reported with second-line dasatinib; Grade ≥3 AEs occurred in 2 out of 19 patients, no DLTs were seen, and early height percentiles were largely maintained, contrasting with the growth deceleration documented for imatinib.