Ritlecitinib (PF 06651600) is an investigational drug (referred to as "study drug" from here on) and is being developed as possible study treatment for participants with non segmental vitiligo (both active and stable vitiligo). The study drug will be compared with a placebo to find out if the study drug is better than the placebo for the study treatment of vitiligo. After a screening period of up to 30 days, approximately 1000 eligible participants (Part Ia) will be randomized in a 3:1:1 ratio to ritlecitinib 100 mg QD (600 participants), ritlecitinib 50mg QD (200 participants), and placebo (200 participants) in the 52-week placebo-controlled treatment period. At Week 52, based how patients respond to the study drug will enter the 52 week extension period.

M1095-HS-304 is a Phase 3, open-label, single-arm design that assesses the safety and tolerability of sonelokimab in adolescent patients with HS. The study population will comprise adolescent participants (aged ≥12 to ≤17 years) with moderate to severe HS.

This study aims to evaluate the effectiveness of ruxolitinib cream compared to a placebo (vehicle) cream in treating vitiligo in children aged 2 to 12 years. The vehicle cream looks identical to the ruxolitinib cream but contains no active medication. By comparing these two treatments, researchers hope to determine whether ruxolitinib is more effective than the placebo in improving facial and body vitiligo symptoms. This study could provide important insights into new treatment options for young children affected by this condition.