Last month, at the American Academy of Dermatology (AAD) Virtual Annual Meeting, Dr. Dedee F. Murrell, MD, explained the efficacy of rilzabrutinib for treating pemphigus. According to MDedge, many prior pemphigus treatments required the use of systemic corticosteroids. However, rilzabrutinib reduced this need and improved patient outcomes.
Pemphigus is a chronic autoimmune disorder which usually affects people who are middle-aged or older. With autoimmune diseases, the immune system mistakenly views the body as a foreign invader. As a result, it attacks and damages healthy tissue. In this case, pemphigus causes the immune system to damage the skin and mucus membranes.
People with pemphigus usually develop blisters and/or sores on the skin and mucus membranes. Where the blisters develop depend on the type: vulgaris or foliaceus. In the former, blisters form in the mouth and may spread to the genitals. While the blisters are painful, and can cause issues with eating or drinking, they are not itchy. In the latter, itchy blisters form on the back, chest, and shoulders.
If the blisters burst, people are at risk of infection, which can spread to the bloodstream. Malnutrition is an additional complication. Learn more about pemphigus here.
Normally, first-line treatments for pemphigus include corticosteroids or topical steroids. However, says Dr. Murrell, these sometimes come with adverse reactions such as high blood pressure, confusion, and fluid retention. In pediatric or elderly patients, these treatments can also be dangerous.
On the other hand, the Phase 2b BELIEVE-PV trial showcased the potential benefits of rilzabrutinib in treating this condition. Developed by Principia Biopharma, rilzabrutinib is a novel, orally-administered Bruton’s tyrosine kinase (BTK) inhibitor. BTK plays a role in B-cell growth and development. In some cases, B cells contribute to cell malignancy. So, through this inhibitor, researchers hope to prevent the development of new lesions and sores.
The BELIEVE-PV clinical trial followed 15 patients with pemphigus over a period of 24 weeks (5.5 months). Of the patients, nine (60%) had relapsing pemphigus and six (40%) were newly diagnosed. During the trial, nine patients reached the primary endpoint (no new sores / healing of old sores) within 1 month. 13 patients reached this endpoint within 3 months. Throughout the trial, patients also experienced a reduced need for other treatments. Six patients (40%) experienced complete remission by the end of the trial.
Additionally, rilzabrutinib was found to be fairly safe and well-tolerated. While 8 patients (53%) experienced some side effects, they were fairly mild: nausea, dizziness, and abdominal swelling and bloating.
Now, Dr. Murrell is running a Phase 3 PEGASUS trial to see whether these results can be replicated in a larger sample size (120 patients with pemphigus). During the PEGASUS trial, patients will receive either a placebo or 400mg rilzabrutinib 2x per day.