Long-term follow-up of a phase 2 study of chemotherapy plus dasatinib for the initial treatment of patients with Philadelphia chromosome-positive acute lymphoblastic leukemia.

BACKGROUND: The long-term efficacy of a combination of chemotherapy and dasatinib in patients with Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL) is not well established.

METHODS: Patients received dasatinib with 8 cycles of alternating hyperfractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone and high-dose cytarabine and methotrexate. Patients in complete remission (CR) continued maintenance dasatinib, vincristine, and prednisone for 2 years, which was followed by dasatinib indefinitely. Patients eligible for allogeneic stem cell transplantation (SCT) received it during their first CR.

RESULTS: Seventy-two patients with a median age of 55 years (range, 21-80 years) were treated; 69 (96%) achieved CR. Among them, 57 (83%) achieved cytogenetic CR after 1 cycle, and 64 (93%) achieved a major molecular response at a median of 4 weeks (range, 2-38 weeks). Sixty-five patients (94%) were negative for minimal residual disease assessed by flow cytometry at a median of 3 weeks (range, 2-37 weeks). Dasatinib-related grade 3 and 4 adverse events included bleeding, pleural/pericardial effusions, and elevated transaminases. With a median follow-up of 67 months (range, 33-97 months), 33 patients (46%) were alive, and 30 (43%) were in CR; 12 underwent allogeneic SCT. Thirty-nine patients died (3 at induction, 19 after relapse, 7 after SCT performed during first CR, and 10 during CR). The median disease-free survival and overall survival were 31 (range, 0.3-97 months) and 47 months (range, 0.2-97 months), respectively. Seven relapsed patients had BCR-ABL kinase domain mutations, including 4 with T315I.

CONCLUSIONS: A combination of chemotherapy with dasatinib is effective in achieving long-term remission for patients with newly diagnosed Ph + ALL.