Fenebrutinib at highest dose generally well tolerated

In 13 completed randomised controlled and open-label extension trials, the oral Bruton’s tyrosine kinase inhibitor (BTKi) fenebrutinib was generally well tolerated at the highest dose. There were no increases in infection rates. The observed safety profile of fenebrutinib supports testing in phase 3 clinical trials in multiple sclerosis (MS).

Of currently investigated BTKis in MS, fenebrutinib has the largest clinical safety database, allowing for assessment of its potential in MS management. A total of 13 completed phase 2 trials and extensions in rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and chronic spontaneous urticaria (CSU) were analysed [1]. Safety assessments included adverse events (AEs), laboratory results, ECGs, and vital signs. This analysis only included patients who received fenebrutinib at the highest dose of 200 mg twice daily (n=792) or placebo.

In the fenebrutinib and placebo groups, 299 and 278 patients experienced one or more AEs, respectively; these were mostly not serious. AEs reported in >5% of fenebrutinib-treated patients were nasopharyngitis (6%), nausea (5.7%), and headache (5.4%). Serious infections were reported in 6 patients (2%) receiving fenebrutinib and 5 patients (1.8%) receiving placebo. Asymptomatic, reversible grade 2 and 3 alanine aminotransferase elevations were seen in 11 (3.7%) and 3 (1.1%) patients, respectively. Bleeding or bruising was reported in 23 (7.7%) and 9 (3.2%) patients, with no major haemorrhage. AEs generally became less frequent with prolonged exposure during open-label extension trials.

1. Oh J, et al. The Safety of Fenebrutinib in a Large Population of Patients With Diverse Autoimmune Indications Supports Investigation in Multiple Sclerosis (MS). S25.005, AAN 2021 Virtual Congress, 17-22 April.

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