Phase II Study of Combination of the HyperCVAD Regimen with Dasatinib in Patients with Philadelphia Chromosome (Ph) or BCR-ABL Positive Acute Lymphoblastic Leukemia (ALL) and Lymphoid Blast Phase Chronic Myeloid Leukemia (CML-LB).

Combination of cytotoxic chemotherapy with imatinib has improved the outcome for patients with Ph+ ALL and resulted in eradication of minimal residual disease and durable remissions without allogeneic stem cell transplant in some patients (Thomas D, Blood, 2004; Yanada M, JCO, 2006; Wassmann B, Blood, 2006; de Labarthe A, Blood, 2007). The dual Src and Abl inhibitor dasatinib has a significantly higher in vitro kinase inhibition against BCR-ABL and has demonstrated potent clinical activity in patients with imatinib-resistant lymphoid blast phase CML (CML-LB) and Ph+ ALL with over 50% complete cytogenetic responses (CG CR) in phase I and II trials but with median progression free survival of only 3 to 4 months. We are conducting a phase II trial in which patients with newly diagnosed or relapsed Ph+ ALL or CML-LB receive dasatinib 50 mg po bid for the first 14 days of each of 8 cycles of alternating hyperCVAD and high dose cytarabine and methotrexate. Patients in complete remission (CR) continue to receive maintenance dasatinib 50 mg po bid daily and vincristine and prednisone monthly for 2 years followed by dasatinib indefinitely. To date 15 newly diagnosed patients with Ph+ ALL (cohort I) and 4 patients with relapsed Ph+ ALL or CML-LB (cohort II) have received a median of 4 cycles (range 1 – 8); 4 patients are receiving maintenance in CR. Median age for cohort I is 55 years (range 23 – 79) and for cohort II, 43 years (range 26 – 69); 13 and 3 patients were older than 50 years, respectively. Median WBC at diagnosis for cohort I was 4.3 × 10⁹/L (range, 0.8 – 203.4 x 10⁹/L). Three patients had CNS involvement. Fourteen and 3 patients in the 2 cohorts are evaluable for response to induction; 2 are too early. Thirteen patients (93%) in cohort I and all evaluable patients in cohort II have achieved CR after the first cycle; 1 patient in cohort I died on day 20 from infections before response assessment; her bone marrow exam on day 14 showed no detectable disease. Ten of 11 (91%) patients in cohort I have achieved CG CR after 1 cycle; 3 are too early. Three of 4 patients in cohort II have achieved CG CR after 1 cycle; 1 had a new CG abnormality and 1 is too early. Six patients have achieved complete molecular remission after the first cycle with the lowest BCR-ABL/ABL in the other patients ranging from 0.01 to 1.91. Median time to neutrophil and platelet recovery for cohort I is 18 and 25 days and for cohort II 18.5 and 30.5 days. Grade 3 and 4 toxicity has included 7 episodes of GI bleeding as well as infections, diarrhea, hypophosphatemia, hypocalcemia, elevated transaminases, and acute renal failure unrelated to treatment. With a median follow up of 4 months (range, 0 – 10), 15 patients are alive and in CR; 1 died at induction, 1 died in CR from an unrelated cardiac event, and 2 are too early. No patient has relapsed and no patient has received an allogeneic transplant. We conclude that the combination of the hyperCVAD regimen with dasatinib is feasible and can achieve early molecular remissions in patients with Ph+ ALL and CML-LB.