Plain language summary

What is this summary about?This is a summary of the ARROYO study, originally published in the British Journal of Dermatology.Chronic spontaneous urticaria (CSU) is a skin condition that lasts for at least 6 weeks, appears suddenly with no known cause, and develops temporary, raised red itchy skin (also known as hives or wheals). CSU is an autoimmune disease; a condition where the body’s own immune system – the body’s natural defense system – mistakenly attacks healthy cells and tissues and causes inflammation. Different parts of the immune system, including a type of blood cell linked to inflammation called eosinophils, are involved in CSU.Antihistamines are a type of medicine that reduce urticaria symptoms, such as inflammation and itching. However, some patients with CSU receiving antihistamine treatment still have symptoms. Omalizumab is the only biologic medicine approved for treating CSU at the time of writing. Some patients still have symptoms of CSU after being treated with omalizumab, so new treatments are needed.Recent clinical study results have shown that benralizumab treatment might help people with CSU. Benralizumab is an injected biologic medicine. Benralizumab quickly lowers the number of eosinophils in different parts of the body, including the blood, reducing inflammation. ARROYO looked at how well the medicine benralizumab worked and how many side effects it had in patients with CSU whose symptoms did not get better after taking antihistamines.What were the main results of the ARROYO study?Adult patients with CSU took either benralizumab or placebo for 24 weeks. Patients taking benralizumab had lower amounts of eosinophils in the blood at Weeks 12 and 24 compared to those taking placebo. This was the same as results from other studies that looked at how benralizumab works. At Week 12, there was no meaningful difference between the amount of itching or wheals in patients taking benralizumab compared with those taking placebo. Patients taking benralizumab or placebo had similar side effects, which was the same as results from other studies.What do the results of the ARROYO study mean?The ARROYO study showed that lowering eosinophil levels is not enough to reduce CSU symptoms. Further research is needed to understand CSU and find better treatments for it.[Box: see text].