Phase II Study of Combination of the Hypercvad Regimen with Dasatinib in the Front Line Therapy of Patients with Philadelphia Chromosome (Ph) Positive Acute Lymphoblastic Leukemia (ALL).

Abstract Abstract 837 Background: Combination therapy with cytotoxic chemotherapy and tyrosine kinase inhibitors has improved the outcome for patients with Ph+ ALL with durable remissions in some patients even without an allogeneic stem cell transplant. The dual Src and Abl inhibitor dasatinib has ∼325 times more potent in vitro kinase inhibition than imatinib against BCR-ABL with significant clinical activity in patients with imatinib-resistant lymphoid blast phase CML (CML-LB) and Ph+ ALL. Aim: To determine the efficacy and safety of combining chemotherapy with dasatinib for treating patients with Ph+ ALL. Methods: In this phase II trial, patients with newly diagnosed Ph+ ALL receive dasatinib 50 mg po bid (or 100 mg daily) for the first 14 days of each of 8 cycles of alternating hyperCVAD and high dose cytarabine and methotrexate. Patients in CR continue to receive maintenance dasatinib 50 mg po bid (or 100 mg daily) and vincristine and prednisone monthly for 2 years followed by dasatinib indefinitely. Results: We have enrolled in the study 34 patients with untreated Ph+ ALL and 7 patients with 1 prior cycle of chemotherapy (before Ph+/BCR-ABL+ status was known). Patients younger than 50 years old have received a median of 6 cycles (range 2-8) and patients 50 years and older have received a median of 6 cycles (range 1-8). 20 patients are receiving maintenance in CR and two have completed the entire treatment regimen. Median age is 51 years (range 21 – 79); 22 patients were older than 50 years, Median WBC at diagnosis was 13.6 × 109/L (range, 1-276 × 109/L). 12 patients had CNS involvement at presentation. All patients are evaluable for assessment of response to induction; 39 (95%) achieved CR after first cycle or were CR at start. Two patients died before response assessment from infections. Thirty-one of 39 (79%) evaluable patients achieved cytogenetic (CG) CR after 1 cycle; 4 had a major CG response (3 had 5% and one had 15% Ph+), 2 had insufficient metaphases, and 2 are unknown (no CG exam on day 21 marrow). To date, 22 patients (56%) have achieved complete molecular remission (CMR) and another 8 (21%) have achieved a major (but not complete) molecular response (MMR) at a median of 14 weeks from initiation of treatment (range 2 – 59 weeks). Minimal residual disease assessment by flow cytometry is negative in 35 (90%) patients at a median of 3 weeks (range, 2-18 weeks). The median time to neutrophil and platelet recovery for cycle 1 is 18 and 23 days and for subsequent cycles is 15 and 20 days. Grade 3 and 4 adverse events have included bleeding (GI, GU, soft tissue and subdural hematomas)(18), pleural effusions (9), pericardial effusion (1), reversible rise in creatinine (10), deep vein thromboses (6), pulmonary emboli (3), as well as diarrhea, infections, hypophosphatemia, hypokalemia, hypocalcemia, hyperglycemia, and elevated transaminases. With a median follow up of 13 months (range 1-33), 29 patients (71%) are alive and 27 (66%) are in CR; 4 patients died in CR; 1 from an unrelated cardiac event and 3 from infections. Three patients have undergone an allogeneic stem cell transplant. The median disease free survival is 48+ weeks (range,1 to 140+) and the median overall survival is 52+ weeks (range, 3 to 143+). Eight patients have relapsed with a median response duration of 51 weeks (range 23-73) and 6 of them have died. In 5 patients morphological relapse was preceded by flow and molecular relapse. Five relapsed patients had ABL mutations (3 T315I, 1 F359V, and 1 V299L). Conclusion: Combination of chemotherapy with dasatinib is effective in achieving long term remissions in patients with newly diagnosed Ph+ ALL. Disclosures: Ravandi: Bristol Myers Squibb: Honoraria, Research Funding. Kantarjian: Bristol Myers Squibb: Research Funding. Wierda: Genzyme: Research Funding; Genentech: Consultancy, Honoraria. Cortes: Bristol Myers Squibb: Research Funding. O'Brien: Bristol Myers Squibb: Research Funding.