A Study of Imatinib Versus Nilotinib in Adult Patients With Newly Diagnosed Philadelphia Chromosome Positive (Ph+) Chronic Myelogenous Leukemia in Chronic Phase (CML-CP)

Primary objectives of this study:

Compared the efficacy (major molecular response (MMR) rate at 12 months) of nilotinib at 400 mg bid with that of imatinib 400 mg qd in newly diagnosed, previously untreated Ph+ CML-CP patients.
Compared the efficacy (MMR rate at 12 months) of nilotinib at 300 mg bid with that of imatinib 400 mg qd in newly diagnosed, previously untreated Ph+ CML-CP patients.

The Primary objectives of Extension Phase of the study:

- Characterized the safety and tolerability profile of nilotinib 400 mg BID after failure of imatinib or insufficiently responded to nilotinib 300 mg BID therapy and the safety and tolerability profile of imatinib therapy after failure of nilotinib therapy.

The study was designed to determine whether the treatment of newly diagnosed, previously untreated Ph+ CML-CP patients with either nilotinib 300 mg bid or 400 mg bid demonstrated improved efficacy compared to imatinib 400 mg qd. The primary efficacy endpoint was the rate of MMR defined as the proportion of patients who achieved ≥ 3 log reduction in BCR-ABL transcripts compared to either the standardized Baseline established in the IRIS trial (International Randomized Interferon versus STI571) (Cortes et al 2005) or to the BCR-ABL ratio ≤ 0.1% by International Scale, as detected by real-time quantitative polymerase chain reaction (RQ-PCR) at 12 months.

The key secondary endpoint was to compare the rate of durable MMR between nilotinib 300 mg bid with that of imatinib, and of nilotinib 400 mg bid with that of imatinib at 24 months. This report presents the final results of efficacy and safety at the LPLV (21-Aug-2019).

The main data analysis was done at the time when all patients completed 12 cycles of treatment (or discontinued earlier). There were two primary comparisons at this time point: the MMR rate of nilotinib 400 mg versus the MMR rate of imatinib 400 mg, and the MMR rate of the nilotinib 300 mg versus the MMR rate of the imatinib 400 mg. Comparisons were done sequentially, i.e. the MMR rate of nilotinib 400 mg versus the MMR rate of imatinib 400 mg was to be compared first; if it was significant at 5% level, the MMR rate of the nilotinib 300 mg versus the MMR rate of the imatinib 400 mg was to be compared. The study had a 90% power to detect a 15% difference between the nilotinib 400 mg arm versus imatinib 400 mg arm assuming that the MMR rate of imatinib is 40% and the MMR rate of nilotinib is 55%. The study also had a 90% power to detect a 15% difference between the nilotinib 300 mg and the imatinib 400 mg arms, if the comparison between the nilotinib 400 mg and the imatinib 400 mg was significant.

The second main data analysis was done at the time when all patients completed 24 cycles of treatment (or discontinued earlier). There were two key comparisons at this time point: the rate of durable MMR at 24 months of the nilotinib 400 mg versus the imatinib 400 mg, and the rate of durable MMR at 24 months of the nilotinib 300 mg versus the imatinib 400 mg.

In order to control the overall type I error rate at or below 5%, only when the corresponding comparison on the primary efficacy endpoint(s) was (were) significant, the key secondary comparison(s) of the respective nilotinib doses (400 mg bid and/or 300 mg bid) versus imatinib 400 mg qd were tested at two-sided 5% significance level.

Patients participating after demonstrating suboptimal response/treatment failure to their assigned study treatment in the core study were offered the option to continue in the extension study and to receive imatinib 400 mg bid (option available only until protocol amendment 7) or nilotinib therapy at a dose of 400 mg bid.