Early CP CML, Nilotinib 400 mg Twice Daily Frontline: Beyond 3 Years, Results Remain Excellent and Stable (A GIMEMA CML Working Party Trial)

Nilotinib is a potent and selective BCR-ABL inhibitor. The phase 3 ENESTnd trial demonstrated superior efficacy nilotinib vs. imatinib, with higher and faster molecular responses. After 24 months, the rates of progression to accelerated-blastic phase (ABP) were 0.7% and 1.1% with nilotinib 300mg and 400mg BID, respectively, significantly lower compared to imatinib (4.2%). Nilotinib has been approved for the frontline treatment of Ph+ CML. With imatinib 400mg (IRIS trial), the rate of any event and of progression to ABP were higher during the first 3–4 years. Consequently, a confirmation of the durability of responses to nilotinib beyond 3 years is extremely relevant.

To evaluate the long term outcome of patients treated with nilotinib 400mg BID as frontline therapy.

A multicentre phase 2 trial was conducted by the GIMEMA CML WP (ClinicalTrials.gov.NCT00481052). Median 48-month follow-up data for all patients will be presented. Definitions: MR^3.0 (Major Molecular Response) as a BCR-ABL/ABL ratio <0,1%IS; MR^4.0, undetectable transcript levels with ≥10,000 ABL transcripts; failures: according to the revised ELN recommendations; events: failures and treatment discontinuation for any reason. All the analysis has been made according to the intention-to-treat principle.

73 patients enrolled: median age 51 years; 45% low, 41% intermediate and 14% high Sokal risk. The cumulative incidence of CCgR at 12 months was 100%. CCgR at each milestone: 78%, 96%, 96%, 95%, 92% at 3, 6, 12, 18 and 24 months, respectively. The overall estimated probability of MR^3.0 was 99%, while the rates of MR^3.0 at 3, 6, 12, 18 and 24 months were 52%, 66%, 85%, 81% and 82%, respectively. Two out of 73 patients never achieved a MR^3.0, 1 who progressed to AP/BP (see below) and 1 in stable and confirmed CCgR at 36 months. Three pts had a confirmed loss of MR^3.0 due to low adherence (all 3 still on nilotinib). The overall estimated probability of MR^4.0 was 79%, while the rates of MR^4.0 at 12, 24 and 36 months were 12%, 27% and 25%, respectively. One third (21/73 pts) showed a stable MR^4.0 (defined based on 3 consecutive MR^4.0 samples 4 months apart). Only one patient progressed at 6 months to ABP and subsequently died (high Sokal risk, T315I mutation). Adverse events were mostly grade 1 or 2 and manageable with appropriate dose adaptations. During the first 12 months, the mean daily dose was 600–800mg in 74% of patients. The nilotinib last daily dose was as follows: 800mg in 46 (63%) patients, 600mg in 3 (4%) patients and 400mg in 18 (25%), 6 permanent discontinuations. Detail of discontinuation: 1 patient progressed to ABP; 3 patients had recurrent episodes of amylase and/or lipase increase (no pancreatitis); 1 patient had atrial fibrillation (unrelated to study drug) and 1 patient died after 32 months of mental deterioration and starvation (unrelated to study drug). Two patients are currently on imatinib second-line and 2 on dasatinib third-line. With a median follow-up of 39 months, the estimated probability of overall survival, progression-free survival and failure-free survival was 97%, the estimated probability of event-free survival was 91%.

The rate of failures was very low during the first 3 years. Responses remain stable. The high rates of responses achieved during the first 12–18 months are being translated into optimal outcome for most of patients.

European LeukemiaNet, COFIN, Bologna University, BolognAIL

Gugliotta:Novartis: Honoraria; Bristol-Myers-Squibb: Honoraria. Castagnetti:Novartis: Honoraria; Bristol Myers Squibb: Honoraria. Cuneo:Roche: Consultancy, Speakers Bureau. Soverini:Novartis: Consultancy; ARIAD: Consultancy; Bristol-Myers Squibb: Consultancy. Saglio:Novartis Pharmaceutical: Consultancy, Speakers Bureau; Bristol-Myers Squibb: Consultancy, Speakers Bureau; Pfizer: Consultancy. Rosti:Novartis: Consultancy; Bristol Myers Squibb: Consultancy; Novartis: Research Funding; Novartis: Honoraria; Bristol Myers Squibb: Honoraria.