Ritlecitinib irreversibly inhibits Janus kinase 3 (JAK3) and the tyrosine kinase expressed in hepatocellular carcinoma (TEC) kinase family by blocking the adenosine triphosphate (ATP) binding site. In cellular settings, ritlecitinib inhibits cytokine induced STAT phosphorylation mediated by JAK3-dependent receptors. Additionally, ritlecitinib inhibits signaling of immune receptors dependent on TEC kinase family members. The relevance of inhibition of specific JAK or TEC family enzymes to therapeutic effectiveness is not currently known.

LITFULO is a kinase inhibitor indicated for the treatment of severe alopecia areata in adults and adolescents 12 years and older.

The recommended dosage of LITFULO is 50 mg orally once daily with or without food.

Most common adverse reactions (incidence ≥1%) are headache, diarrhea, acne, rash, urticaria, folliculitis, pyrexia, atopic dermatitis, dizziness, blood creatine phosphokinase increased, herpes zoster, red blood cell count decreased, and stomatitis.

LITFULO is contraindicated in patients with known hypersensitivity to ritlecitinib or any of its excipients.

• Hypersensitivity: Discontinue LITFULO if a clinically significant hypersensitivity reaction occurs.
• Laboratory Abnormalities: Perform ALC and platelet counts prior to LITFULO initiation. Treatment interruption or discontinuation are recommended based on ALC and platelet count abnormalities.
• Vaccinations: Avoid use of live vaccines during or shortly prior to LITFULO treatment.