Durable Platelet Response Observed With Rilzabrutinib in Adults With ITP

Positive results were announced from a phase 3 study evaluating the efficacy and safety of rilzabrutinib in adults with persistent or chronic immune thrombocytopenia (ITP).

The randomized, double-blind LUNA 3 study (ClinicalTrials.gov Identifier: NCT04562766) evaluated the safety and efficacy of rilzabrutinib, an oral, reversible, covalent Bruton tyrosine kinase inhibitor, in adult and adolescent patients with persistent or chronic ITP. At baseline, the median platelet count was 15,000/μL. Study participants had received a median of 4 prior ITP therapies.

Patients were randomly assigned to receive either rilzabrutinib 400mg orally twice a day or placebo through a 12- to 24-week double-blind period, followed by a 28-week open-label treatment period, and then a 4-week safety follow-up or long-term extension period. 

Findings showed a statistically significantly higher proportion of adult patients who received rilzabrutinib achieved platelet counts at or above 50,000/μL for at least 8 out of the last 12 weeks of the 24-week blinded treatment period in the absence of rescue therapy (primary endpoint). Improvements in key secondary endpoints (ie, number of weeks with and time to platelet responses, rescue therapy use, physical fatigue, bleeding score) were also observed.

The Food and Drug Administration (FDA) previously granted Fast Track designation to rilzabrutinib for this indication. Detailed study results will be presented at a medical congress later this year. The adolescent portion of the study is ongoing.