The phase 2 RILECSU clinical trial has brought encouraging news for patients suffering from chronic spontaneous urticaria (CSU) that doesn’t respond well to standard antihistamines. Rilzabrutinib, an investigational oral Bruton tyrosine kinase inhibitor (BTKI), significantly reduced key CSU symptoms—including itch, hives, and angioedema—within just one week of starting treatment.
At a daily dose of 1200 mg, rilzabrutinib met its primary and most secondary endpoints, providing rapid and meaningful symptom relief by week 12. These effects were observed across subgroups, including those considered harder to treat, such as patients with type IIb CSU, which is often resistant.
What sets rilzabrutinib apart is its dual action: it helps reduce disease-causing autoantibodies and calms overactive immune cells like basophils and mast cells, all without depleting B cells. The drug also lowered biomarkers linked to more severe CSU, such as IL-31 and sMRGPRX2, which are associated with intense itching and inflammation.
Equally important, rilzabrutinib demonstrated a favorable safety profile. Serious adverse events were rare and not linked to the drug, and no issues commonly seen with other BTKIs, like bleeding or a-fib, were reported. This may be due to rilzabrutinib’s unique design as a reversible and covalent BTKI, which aims to deliver effectiveness with fewer side effects.
While these early findings are promising, the study's limitations include a small sample size and a short treatment period. Ongoing and future phase 3 trials aim to provide longer-term data and include a more diverse patient population.
For a link to the original article in JAMA Dermatology, click here
Elevate-Derm Alliance Editorial Board