First long-term efficacy data of a BTK inhibitor

In the open-label extension of a phase 2 trial, the improvement in annualised relapse rate (ARR) with the Bruton’s tyrosine kinase (BTK) inhibitor evobrutinib 75 mg twice daily (BID) at week 48 was maintained at week 108. These long-term efficacy data in patients with relapsing multiple sclerosis (MS) are the first to be reported for the class of agents that inhibits BTK.

Evobrutinib targets both B cells and myeloid cells, which are known to play a key role in the pathogenesis of autoimmune diseases, such as MS. A previous phase 2, randomised controlled trial showed clinical efficacy of evobrutinib in relapsing MS, with a significant reduction of T1 Gd-enhancing lesions compared with placebo at week 24 and a continued efficacy through week 48 [1]. Of 213 patients randomised in the double-blind phase of the trial, 164 patients (77%) entered the open-label extension phase. Of them, 148 patients (90%) completed ≥108 weeks of treatment overall. At the ECF 28^th Annual Meeting, results of long-term efficacy of evobrutinib in the ongoing open-label extension were presented by Prof. Xavier Montalban (Hospital University Vall d’Hebron, Spain) [2].

Efficacy was assessed by ARR as well as cumulative probability of and time to first qualified relapse in patients completing ≥60 weeks of open-label extension treatment. Compared with those initiated in other double-blind period arms, patients initiated on evobrutinib 75 mg BID had lower ARR (0.11 at week 48, and 0.12 at week 108) and lower cumulative probability of first qualified relapse (0.08 at week 48, and 0.20 at week 96). The estimated time by which 20% of patients had a qualified relapse was almost 3 times longer for those initiated on 75 mg BID versus placebo.

Both outcome measures of probability and time to first qualified relapse highlighted that patients initiated on 75 mg BID achieved greater treatment efficacy than those initiated on evobrutinib 25 mg once daily, 75 mg once daily, or placebo.

1. Montalban X, et al. N Engl J Med. 2019;380:2406-2417.
2. Montalban X, et al. Evobrutinib efficacy is maintained over two years in patients with relapsing MS Clinical relapse rates in relapsing multiple sclerosis patients treated with the BTK inhibitor evobrutinib: results of an open-label extension to a Phase II study. ECF 28^th Annual Meeting. Abstract 31.

Posted on 16 December, 202016 December, 2020