Mantle cell lymphoma (MCL) is an uncommon but aggressive form of B cell non-Hodgkin lymphoma. It often presents at an advanced stage and with a median survival of 3–5 years and is generally regarded as incurable.1,2 Ibrutinib, an orally activeinhibitor of Bruton’s tyrosine kinase, has demonstrated impressive safety and efficacy in patients with relapsed/refractory MCL within several large clinical trials.3,4 Prior to licensing, the global named patient program (NPP) gave access to ibrutinib for eligible patients with relapsed/refractory MCL in a large number of countries.
Using real-world data from the ibrutinib MCL NPP, the aim of this study was to investigate whether treatment benefits reported in randomised clinical trials were reflected in clinical practice. Data was collected from the NPP on the ordering and reordering of ibrutinib in order to estimate patient time-on-treatment and therefore to provide a conservative approximation of progression-free survival using Kaplan–Meier and Cox proportional hazard regression analysis.
In total, 715 patients from 26 countries were included in this analysis. The median age was 70 years, and 76.1% were male. After 12 months, 52.3% (95% confidence interval: 43.5–60.4%) remained on treatment. This estimate is similar to the 12-month time-on-treatment rate observed in the Phase III RAY study of ibrutinib for relapsed/ refractory MCL.5 Moreover, Kaplan–Meier curves for time on treatment for the global MCL NPP population and the RAY study population were not statistically different. An exploration of time-on-treatment using multivariate analysis revealed that the timing of MCL diagnosis was the only independently significant variable, with time-on- treatment being longer in patients diagnosed with MCL within the last 2 years. In total, 168 patients (23.5%) discontinued treatment during the observation period with the most common reasons being death (10.8%), disease progression (7.3%), and adverse events (1.3%).
Although these data are based on physician declarations and are therefore unmonitored, this analysis provided a conservative proxy for progression-free survival which is similar to that observed in the RAY study. This suggests that the impressive safety and efficacy results observed in clinical trials of ibrutinib for MCL are reproducible in real-world clinical practice.