Asciminib plus dasatinib and prednisone for Philadelphia chromosome-positive acute leukemia

• Dasatinib, asciminib, and prednisone can be safely combined for dual targeting of BCR::ABL1 in Philadelphia-positive (Ph+) acute leukemia.

• Dasatinib and asciminib combination treatment has promising efficacy for upfront treatment of Ph+ acute lymphoblastic leukemia.

Dasatinib is effective treatment for Philadelphia chromosome-positive (Ph+) acute leukemia but some patients develop resistance. Combination treatment with dasatinib and asciminib, an allosteric inhibitor of BCR::ABL1, may deepen responses and prevent the emergence of dasatinib-resistant clones. In this phase 1 study (NCT03595017), 24 adults with Ph+ acute lymphoblastic leukemia (ALL, n=22; p190, n=16; p210, n=6) and chronic myeloid leukemia in lymphoid blast crisis (CML-LBC, n=2) were treated with escalating daily doses of asciminib in combination with dasatinib 140 mg daily plus prednisone 60 mg/m2 daily to determine the maximum tolerated dose (MTD). After a 28-day induction, dasatinib and asciminib continued indefinitely or until hematopoietic stem cell transplant. The median age was 64.5 years (range, 33-85; 50% ³65). The recommended phase 2 dose of asciminib was 80 mg daily in combination with dasatinib and prednisone. The dose limiting toxicity at 160 mg daily was asymptomatic grade 3 pancreatic enzyme elevation without symptomatic pancreatitis. There were no vaso-occlusive events. Among patients with de novo ALL, the complete hematologic remission rate at day 28 and 84 was 84% and 100%, respectively. At day 84, 100% of patients achieved complete cytogenetic remission, 89% achieved measurable residual disease negativity (<0.01%) by multicolor flow cytometry, and 74% and 26% achieved BCR::ABL1 RT-PCR <0.1% and <0.01%. Dual BCR::ABL1 inhibition with dasatinib and asciminib is safe with encouraging activity in patients with de novo Ph+ ALL. ClinicalTrials.gov NCT02081378