FDA Approves Chronic Spontaneous Urticaria Drug, Rhapsido

The FDA has approved Rhapsido (remibrutinib), an oral treatment for adult patients with chronic spontaneous urticaria (CSU), according to a news release from drug manufacturer, Novartis.

Rhapsido is the first and only Bruton’s tyrosine kinase (BTK) inhibitor approved for CSU. It works by inhibiting the BTK protein, which is thought to be the cause of CSU flares. Flares can last for hours and are characterized by red, swollen and itchy hives.

During a CSU flare, the immune system becomes overactive, activated by an allergic reaction or autoimmune response. Specifically, immune cells called mast cells and basophils activate the BTK protein.

CSU affects approximately 1.7 million people in the United States, and more than half remain symptomatic despite increasing doses of antihistamines. Symptoms are often unpredictable and can reoccur for 6 weeks at a time, disrupting the sleep, work and the mental health of patients. CSU flares often have no identifiable cause and for this reason, diagnosis can take up to 2 years.

Antihistamines are often the first line of treatment for CSU but are effective in less than half of patients. Injectable treatments also exist, but less than 20% of patients have access to them due to discrepancies between recommendations for managing CSU in international guidelines.

“The approval of remibrutinib is an important development in CSU care. It quickly reduces symptoms, offering patients control of the hives and itching that they experience on a daily basis,” Giselle Mosnaim, M.D., MS, an allergist and immunologist from Endeavor Health, clinical associate professor at the University of Chicago Pritzker School of Medicine and REMIX trial investigator, said in the news release. “This is significant because it expands beyond existing injectable treatments and gives patients an oral option that can easily be incorporated into their daily lives.”

This approval was made using the results from phase 3 REMIX-1 (NCT05030311) and REMIX-2 (NCT05032157) clinical trials, which enrolled a total of 925 patients with CSU. Participants received either Rhapsido or placebo.

Efficacy was measured with weekly urticaria activity score (UAS7), in which patients rated their symptoms from 0 to 42, with 0 indicating no symptom activity.

In REMIX-1, by week 12, approximately 31% of patients treated with Rhapsido had a UAS7 score of 0, compared with 10% of patients given placebo.

In REMIX-2, approximately 28% of patients treated with Rhapsido reported a UAS7 score of 0 by week 12, compared with 7% of patients given placebo.

The most common adverse reactions were nasal congestion (11%), bleeding (9%) and headache (7%).

The recommended dosage of Rhapsido is a 25 mg tablet taken twice daily, taken with or without food, according to the prescribing information.

“Many CSU patients feel misunderstood and settle for treatments that don’t fully meet their needs,” Lynda Mitchell, CEO of Allergy & Asthma Network, said in the news release. “We support new treatment options that empower patients to choose what works best for them. This convenient new oral therapy offers a promising new way to manage CSU and potentially improve daily life for those living with this challenging condition.”

Remibrutinib is also being studied for patients with other immune-related conditions such as chronic inducible urticaria, food allergies and hidradenitis suppurativa.