Autoimmune diseases

More positive results for BTK inhibitor in pemphigus vulgaris

Patients with pemphigus vulgaris may benefit from treatment with a BTK inhibitor rilzabrutinib, according to new results from an Australian-led phase 2 study.

Following promising findings in 27 patients enrolled in the BELIEVE proof-of-concept study, investigators led by Professor Dedee Murell of the University of NSW have now shown that rilzabrutinib may be effective when used in broader dose ranges and for longer periods in patients with newly diagnosed or relapsing pemphigus vulgaris.

They conducted a follow on study in 15 patients with either mild-to-moderate (PDAI score 8 to <15) or moderate to severe (PDAI >15) who received rilzabrutinib doses of up to a maximum 600 mg twice daily, with treatment given for 24 weeks.

Patients were also allowed treatment with corticosteroids (prednisone-equivalent ≤0.5 mg/kg/day) .

Published in the Journal of the European Academy of Dermatology and Venereology, their results showed that 60% of patients achieved the primary endpoint of Control of Disease Activity (CDA) by four weeks, with the median time to CDA of 29 days.

At week 28, 40% of patients achieved complete healing of all lesions with the absence of new lesions on less than 10 mg/day of corticosteroids on at least one visit (i.e. complete response).

Among patients who achieved CDA the median time to first relapse in was 198 days.

According to the study investigators, the improvements in clinical outcomes were supported by reductions in PDAI scores and reductions in corticosteroid doses. There were also reductions in levels of anti-desmoglein-3 autoantibody associated with pemphigus over time, while scores for Autoimmune Bullous Disease Quality of Life (ABQoL) were maintained or increased, along with nutrition scores, suggesting there was no appetite suppression.

Treatment-related adverse events such as nausea and abdominal distension were all grade 1/2 and transient.

“Although results were limited by a small number of patients, rilzabrutinib (with or without corticosteroid) demonstrated a consistently favourable benefit-risk profile with broader rilzabrutinib doses and longer treatment in newly diagnosed/relapsing pemphigus patients,” the authors concluded.

The study was sponsored by Principia Biopharma Inc, a Sanofi Company.

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