Nilotinib Demonstrates Superior Efficacy Compared with Imatinib in Patients with Newly Diagnosed Chronic Myeloid Leukemia in Chronic Phase: Results From the International Randomized Phase III ENESTnd Trial

Nilotinib is a highly potent and the most selective inhibitor of BCR-ABL, the only proven molecular target for CML therapy. ENESTnd (Evaluating Nilotinib Efficacy and Safety in Clinical Trials-Newly Diagnosed Patients) is a phase 3, randomized, open-label, multicenter study comparing the efficacy and safety of 300 or 400 mg bid nilotinib with 400 mg qd imatinib in patients (pts) with newly diagnosed Ph+ CML in chronic phase (CML-CP).

846 pts with newly diagnosed Ph+ CML-CP, diagnosed within 6 mos, and stratified by Sokal risk score, were randomized 1:1:1 to nilotinib 300 mg bid (n=282), nilotinib 400 mg bid (n=281), and imatinib 400 mg qd (n=283) arms. The primary endpoint was rate of major molecular response (MMR) at 12 months (mos). All pts had a minimum of 12 mos of treatment or discontinued early; median follow-up was 14 mos. MMR was defined as a value of ≤ 0.1% of BCR-ABL/ABL ratio on the International Scale. Molecular response was assessed by RQ-PCR at baseline, monthly for 3 mos and every 3 mos thereafter. Samples were analyzed at a central PCR laboratory. The major secondary endpoint was rate of complete cytogenetic response (CCyR) by 12 mos based on bone marrow cytogenetics.

Baseline demographics, disease characteristics, and Sokal scores were well balanced among the 3 arms; pts with high-risk Sokal scores were 28% in all arms. Median dose intensities of nilotinib delivered were 592 mg/day for 300 mg bid and 779 mg/day for 400 mg bid; imatinib dose intensity was 400 mg/day. Overall, 84%, 82%, and 79% of pts remained on the study for 300 mg bid nilotinib, 400 mg bid nilotinib, and 400 mg qd imatinib, respectively. Rates of MMR at 12 mos (Table) were superior for nilotinib 300 mg bid compared with imatinib 400 mg qd (44% vs. 22%,P < .0001) and also for nilotinib 400 mg bid compared with imatinib 400 mg qd (43% vs. 22%,P < .0001). Median time to MMR among pts who achieved MMR was faster for nilotinib 300 mg bid (5.7 mos) and nilotinib 400 mg bid (5.8 mos) compared with imatinib 400 mg qd (8.3 mos). Rates of CCyR by 12 mos were significantly higher for both nilotinib at either 300 mg bid compared with imatinib 400 mg qd (80% vs. 65%,P < .0001) and for nilotinib 400 mg bid compared with imatinib 400 mg qd (78% vs. 65%,P = .0005). Overall, progression to advanced disease was lower for nilotinib 300 mg bid (2 pts) and nilotinib 400 mg bid (1 pt) compared with imatinib 400 mg qd (11 pts). Overall, both drugs were well-tolerated. Rates of discontinuation due to adverse events or laboratory abnormalities were 7% for nilotinib 300 mg bid, 11% for nilotinib 400 mg bid, and 9% for imatinib 400 mg qd. Pts were monitored for QT prolongation and LVEF. No patients in any treatment arm showed a QTcF interval > 500 msec. There was no decrease from baseline in mean LVEF anytime during treatment in any arm. The study is ongoing.

Nilotinib at both 300 mg bid and 400 mg bid induced significantly higher and faster rates of MMR and CCyR compared with imatinib 400 mg qd, the current standard of care in pts with newly diagnosed CML. Nilotinib was effective across all Sokal scores. After only one year of treatment, both nilotinib arms resulted in a meaningful clinical benefit compared to imatinib, with reduction of transformation to AP/BC. Nilotinib exhibited a favorable safety and tolerability profile. The superior efficacy and favorable tolerability profile of nilotinib compared with imatinib suggests that nilotinib may become the standard of care in newly diagnosed CML.

Saglio:Novartis: Consultancy, Speakers Bureau; BMS: Consultancy, Speakers Bureau. Off Label Use: Nilotinib is not currently approved for first-line treatment of CML. The presentation will report the results from a randomized study of imatinib versus nilotinib in patients with newly diagnosed Ph+ CML-CP. Kim:Novartis: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; BMS: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Wyeth: Research Funding. le Coutre:Novartis: Honoraria, Research Funding; BMS: Honoraria. Reiffers:Novartis: Research Funding. Pasquini:Novartis: Consultancy, Membership on an entity’s Board of Directors or advisory committees; BMS: Membership on an entity’s Board of Directors or advisory committees; Schering: Membership on an entity’s Board of Directors or advisory committees. Clark:Novartis: Honoraria, Research Funding, Speakers Bureau. Hughes:Novartis: Honoraria, Research Funding; BMS: Honoraria, Research Funding. Hochhaus:Novartis: Research Funding. Gallagher:Novartis: Employment, Equity Ownership. Hoenekopp:Novartis: Employment. Dong:Novartis: Employment, Equity Ownership. Haque:Novartis: Employment. Larson:Novartis: