Prospective Exploratory Phase II Studies of A Rotating Regime of Nilotinib and Imatinib for Frontline Treatment of Philadelphia POSITIVE (Ph+) Chronic Myeloid Leukemia (CML) and Acute Lymphoblastic Leukemia (ALL).

Abstract 4972

The introduction of Imatinib (IM) and subsequently of Dasatinib and Nilotinib (NI) has made a substantial contribution to the therapy of all Ph+ leukemias. With IM alone, a complete cytogenetic response (CCgR) is achieved in about 75% of CML patients who are treated frontline, but about 15% of them loose the response in the first 3 years. A complete hematologic response (CHR) is achieved in almost all ALL patients, but about 50% of them relapse with BCR-ABL mutated clones within one year. With NI alone, a complete cytogenetic response is obtained in about 40% of Ph+ leukemia patients who are resistant to IM, and in more than 90% of early chronic phase, previously untreated, CML patients. NI is a derivative of IM, but has different pharmacokinetic and pharmacodynamic properties, and inhibits most of BCR-ABL mutants which are resistant to IM. Moreover, the toxicity profile of the two drugs is different. The administration of two tyrosine kinase inhibitors (TKIs) may increase the strength of initial therapy, so increasing the rate and the solidity of the response, and reducing the rate of failures. To test the feasibility and the validity of this hypothesis the GIMEMA CML WP designed a rotating regime of NI and IM to be tested front-line in patients with Ph+ CML, and in the patients with Ph+ ALL who are more than 60 years old. The first course is with NI 400 mg twice daily. The second course is with IM 400 mg once daily. A course lasts 3 months in CML, and 6 weeks in ALL. Treatment duration (study core) is 2 years in CML (8 courses), and 36 weeks in ALL (6 courses). The primary endpoint is event-free survival at 24 months in CML, and disease-free survival at 6 months in ALL. CML patients enrollment (n = 120) has been completed between February and August 2009. The results of the first interim analysis at 3 and 6 months will be presented. The enrollment of ALL patients will begin September 2009.