A phase II study of nilotinib administered to imatinib resistant and intolerant patients with chronic myelogenous leukemia (CML) in chronic phase (CP)

Abstract

7007 Background: Nilotinib is a highly selective Bcr-Abl tyrosine kinase inhibitor that is 30-fold more potent than imatinib. The objective of this phase II open-label study was to evaluate the safety and efficacy of nilotinib in imatinib-resistant or -intolerant CML-CP pts Methods: Imatinib-resistance was defined using standard criteria and had failed imatinib >/= 600mg/day. Imatinib intolerance was defined as intolerant symptoms and lack of MCyR. Primary endpoint was MCyR determined by conventional ITT analysis. Planned nilotinib dose was 400mg BID with escalation to 600mg BID for inadequate responses Results: 316 pts were enrolled and included for safety analysis; efficacy results are from 279 pts with at least 6 mos of follow up. 221 (70%) pts were imatinib-resistant and 95 (30%) were imatinib- intolerant. Median duration of CML was 58 mos; median prior imatinib use was 33 mos. 227 (73%) pts had prior imatinib dose >/= 600mg/day. Treatment with nilotinib is ongoing for 221 (70%) pts. 95 (30%) pts have discontinued treatment (41 for AEs, 32 for disease progression). Median duration of nilotinib exposure was 247 days; overall median average dose intensity was 797mg/day. Median cumulative duration of dose interruptions was 19 days. MCyR was achieved in 145 (52%), 96 (34%) were complete and 49 (18%) partial. Median time to MCyR was 2.8 mos. CHR was achieved in 137/185 (74%) pts without baseline CHR. Median time to CHR was 1.0 mos. Response rates were similar in imatinib- resistant and -intolerant pts. After 10 mos of follow up, the median duration of CHR and MCyR has not been reached. The most frequent Grade 3/4 laboratory abnormalities included thrombocytopenia in (29%), neutropenia in (28%), and asymptomatic lipase elevation in (15%) pts. Rare (<1%) pleural effusion, pericardial effusion, or pulmonary edema were observed. Requirements for growth factors and platelet transfusions were minimal. Conclusions: Nilotinib resulted in significant response rates in pts with imatinib-resistant or -intolerant CML-CP and excellent tolerability as indicated by high dose intensity, favorable rates of myelosuppression, and no serious episodes of fluid retention. No significant financial relationships to disclose.