Summary: The purpose of the study is to learn about the safety and effects of the study medicine (called ritlecitinib) for the treatment of chronic spontaneous urticaria (CSU) that is not effectively treated by antihistamines which are used to stop the body's allergy alarm system from overreacting. Chronic spontaneous urticaria is a disease that causes itchy hives and swellings in the deep layers of skin a...

Summary: The purpose of this study is to learn about the safety and effects of the study medicine (called ritlecitinib) for the possible treatment of severe alopecia areata. Alopecia areata is a condition that causes hair loss. This study is seeking participants who have: * at least 50% scalp hair loss due to alopecia areata. * received varicella vaccination (2 doses) or have been infected by varicella zos...

Summary: Alopecia areata (AA) is a chronic relapsing autoimmune disease characterized by nonscarring hair loss affecting children, adolescents, and adults across all ages, races, and genders. AA primarily affects the scalp; however, it also can affect nails, eyelashes, eyebrows, and other hair follicles on the patient's body. The 3 main types of AA are: * Patchy alopecia (PA), as seen in 90% of clinical di...