Length of Time on Treatment Observed in Ibrutinib Clinical Trials Is Reproducible After Assessment of Real-World Data

Conference Correspondent - EHA 2016

A global named patient program (NPP) was opened in numerous countries worldwide to allow access to ibrutinib for eligible patients with relapsed/refractory chronic lymphocytic leukemia (CLL) prior to approval in those countries. This program provides real-world data on estimated outcomes with ibrutinib across a large, global CLL population.1 Researchers used data from the ibrutinib CLL NPP to learn whether treatment benefits reported in randomized clinical trials are similar to those observed in clinical practice. Specifically, researchers estimated time on treatment in order to provide a conservative approximation of progression-free survival (PFS) using Kaplan-Meier analysis and Cox proportional hazards regression. Patients were censored based on the date of last ibrutinib supply or resupply. (Ibrutinib was resupplied every 1 to 3 months depending on the stage of the NPP.) Patients who transferred to commercial ibrutinib after approval were censored at the time of NPP closure in their country. Overall, 2908 patients with CLL from 30 countries were included in this analysis. Their median age was 69 years; 64% were male. After 12 months, 77% (95% confidence interval [CI], 75%-80%) remained on ibrutinib. This estimate is similar to the 12-month time on treatment (82% [95% CI, 75%-86%]) and PFS (84% [95% CI, 78%-83%]) rates observed in the phase 3 RESONATE study of ibrutinib in relapsed/refractory CLL. (Inclusion criteria were similar for the NPP and RESONATE.) Kaplan-Meier curves for time on treatment for the global NPP population and the RESONATE study were not statistically different (NPP vs RESONATE: hazard ratio, 1.20 [95% CI, 0.86-1.67]). Limited baseline demographic information collected at NPP enrollment allowed exploration of time on treatment via multivariate analysis. Younger patients and those achieving complete or partial response on prior therapy had significantly longer time on ibrutinib. Strong trends showing longer time on treatment were observed for patients who had received fewer prior treatments, as well as males, patients diagnosed with CLL within the past 5 years, and patients with a PFS interval of ≥3 months prior to ibrutinib treatment. Neither refractory disease nor duration of response to prior therapy affected time on ibrutinib treatment. In total, 332 (11%) patients discontinued ibrutinib during the observation period, most commonly for death (4%), disease progression (2%), and adverse events (2%).
  1. Hillmen P, et al. EHA 2016. Abstract P208.