Novartis has announced that the UK Medicines and Healthcare products Regulatory Agency (MHRA) has granted marketing authorisation for Rhapsido (remibrutinib) for the treatment of adults with Chronic Spontaneous Urticaria (CSU) whose symptoms are not adequately controlled with H1 antihistamines alone.

The approval makes remibrutinib the first oral Bruton’s Tyrosine Kinase (BTK) inhibitor licensed for CSU in the UK, providing an additional treatment option for patients who continue to experience symptoms despite standard antihistamine therapy.

CSU is a chronic form of urticaria characterised by recurrent itchy hives and, in some patients, deeper swelling known as angioedema. Symptoms persist for at least six weeks and can significantly affect sleep, emotional wellbeing, daily activities and work productivity. Although H1 antihistamines are widely used as first-line therapy, more than half of patients continue to experience inadequately controlled disease.

The MHRA authorisation is supported by results from the Phase 3 REMIX-1 and REMIX-2 trials, which evaluated remibrutinib in a total of 925 patients with CSU who remained symptomatic despite treatment with second-generation H1 antihistamines.

The trials met their primary endpoints, with remibrutinib demonstrating statistically significant improvements in the Urticaria Activity Score over seven days (UAS7) compared with placebo at Week 12.

In REMIX-1, the change from baseline in UAS7 was -20.0 with remibrutinib compared with -13.8 with placebo, while REMIX-2 recorded changes of -19.4 and -11.7, respectively. Both trials demonstrated statistically significant treatment differences, with p<0.001.

All secondary endpoints assessing reductions in itching, measured through the Itch Severity Score over seven days (ISS7), and hives, assessed through the Hive Severity Score over seven days (HSS7), were also achieved.

The safety profile of remibrutinib was described as acceptable and remained consistent through 52 weeks of treatment. The most frequently reported adverse reaction was upper respiratory tract infection, reported in 14.7 percent of patients, including nasopharyngitis in 6.6 percent and influenza in 2.5 percent.

Rob Hastings, Chief Medical Officer, Novartis UK, said, “Today’s announcement highlights our proud heritage in immunology stemming from over a decade of innovation in this field. He added that the MHRA authorisation could represent a step forward for eligible UK patients who remain symptomatic despite antihistamine treatment.

Remibrutinib is a highly selective oral BTK inhibitor that targets the BTK signalling pathway involved in the activation and release of histamine and other inflammatory mediators associated with CSU symptoms, including itchy hives and swelling.

The REMIX-1 (NCT05030311) and REMIX-2 (NCT05032157) studies were identically designed, global, multicentre, randomised, double-blind, placebo-controlled Phase 3 trials. The primary endpoint in both studies was the change from baseline in UAS7 at Week 12, while secondary measures included changes in ISS7 and HSS7 and safety.

CSU affects an estimated 40 million people worldwide. The condition can occur across age groups but is most commonly diagnosed between 20 and 40 years, with women affected nearly twice as often as men. Beyond physical symptoms, CSU can contribute to sleep disruption, emotional distress, anxiety, depression and reduced productivity.

The UK authorisation expands treatment options for patients living with inadequately controlled CSU and adds to Novartis’ growing portfolio in immunology. The company said its medicines currently reach more than 300 million people globally as it continues to develop treatments aimed at addressing serious diseases.