Ritlecitinib (PF-06651600) is a highly selective inhibitor of Janus kinase 3 (JAK3) and the tyrosine kinase expressed in hepatocellular carcinoma (TEC) kinase family. In June 2023, it was approved by the FDA for the treatment of severe alopecia areata in adults and adolescents 12 years and older. It was further approved by the EMA in September 2023. Ritlecitinib is administered orally and is the first member of its class.
Ritlecitinib binds covalently to Cys-909 of JAK3, a site where other JAK isoforms have a serine residue. This makes ritlecitinib a highly selective and irreversible JAK3 inhibitor. Other kinases have a cysteine at a position equivalent to Cys-909 in JAK3, and several of them belong to the TEC kinase family. It has been suggested that the dual activity of ritlecitinib toward JAK3 and the TEC kinase family block cytokine signaling as well as the cytolytic activity of T cells, both implicated in the pathogenesis of alopecia areata.
Ritlecitinib is indicated for the treatment of severe alopecia areata in adults and adolescents 12 years and older. It is not recommended for use in combination with other JAK inhibitors, biologic immunomodulators, cyclosporine or other potent immunosuppressants.
New Haven Clinical Research Unit, New Haven, Connecticut, United States
Peking University Third Hospital, Beijing, Beijing, China
North District of Peking University Third Hospital, Beijing, China
Stony Brook Dermatology, Stony Brook, New York, United States
Lynderm Research Inc., Markham, Ontario, Canada
Marvel Clinical Research 002, LLC, Huntington Beach, California, United States
Independent Medical Diagnostic Laboratory Mediscan EOOD, Plovdiv, Bulgaria
MHAT Plovdiv AD, Plovdiv, Bulgaria
DCC Sveti Georgi EOOD, Plovdiv, Bulgaria
Research Centers of America ( Hollywood ), Hollywood, Florida, United States
Prism Research LLC dba Nucleus Network, Saint Paul, Minnesota, United States
New Haven Clinical Research Unit, New Haven, Connecticut, United States
Brussels Clinical Research Unit, Brussels, Bruxelles-capitale, Région DE, Belgium
Brussels Clinical Research Unit, Brussels, Bruxelles-capitale, Région DE, Belgium
Investigational Drug Services (IDS) University of Miami Hospitals and Clinics, Miami, Florida, United States
University of Miami Division of Clinical Pharmacology, Miami, Florida, United States
Prism Clinical Research, LLC, Saint Paul, Minnesota, United States
Quotient Sciences Screening Office, Coral Gables, Florida, United States
Quotient Sciences, Miami, Miami, Florida, United States
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