The US Food and Drug Administration (FDA) has approved Novartis’ Rhapsido (remibrutinib) as an oral treatment for adult patients with chronic spontaneous urticaria (CSU) who continue to experience symptoms despite H1 antihistamine therapy.

Taken twice daily, Rhapsido is the first FDA-approved Bruton’s tyrosine kinase inhibitor (BTKi) for CSU. Unlike some existing therapies, it requires no injections or routine lab monitoring. By targeting BTK, the drug helps inhibit the release of histamine and other proinflammatory mediators, offering a unique approach to CSU treatment.  

CSU is a mast cell–driven disorder believed to result from immune system dysregulation. Immune activation through allergic (IgE) or autoimmune (IgG) pathways causes mast cells and basophils to activate the BTK protein. This activation leads to the release of histamine and other inflammatory mediators that may cause the characteristic red, itchy, and swollen hives commonly seen in CSU. While antihistamines are the first-line therapy, more than half of patients continue to experience symptoms even at higher doses. Injectable treatments are available for those who don't respond to antihistamines, yet fewer than 20 percent of eligible patients receive them.

The FDA approval is supported by data from the Phase III REMIX-1 and REMIX-2 trials, which enrolled patients who remained symptomatic on second-generation H1 antihistamines. In these studies, Rhapsido significantly improved itch (ISS7), hives (HSS7), and weekly urticaria activity (UAS7) scores compared with placebo at Week 12. More patients receiving Rhapsido achieved well-controlled disease as early as Week 2 and by Week 12, and about one-third of patients achieved complete absence of itch and hives at Week 12. Rhapsido has a demonstrated safety profile that requires no lab monitoring. 

“This approval of Rhapsido as the first and only BTK inhibitor in CSU is an important milestone in our journey to reshape care for overlooked immune-related conditions and offer more patients the potential to find fast relief,” said Victor Bultó, President, US, Novartis.

“Building on our legacy in advancing the treatment of allergic, dermatologic, and rheumatologic conditions, we are deeply committed to further investing in innovative, patient-focused therapies across immunology,” he added.

Discovered and developed by Novartis to target the BTK pathway as a driver of inflammation, remibrutinib is also being investigated in ongoing clinical trials across a variety of immune-related conditions, including chronic inducible urticaria (CIndU), hidradenitis suppurativa (HS), and food allergy.

The company has completed regulatory submissions for Rhapsido for the treatment of CSU across many countries, including in the European Union, Japan, and China, with priority review granted in China.