Deuruxolitinib is a Janus kinase (JAK) inhibitor. JAKs mediate the signaling of a number of cytokines and growth factors that are important for hematopoiesis and immune function. JAK signaling involves recruitment of STATs (signal transducers and activators of transcription) to cytokine receptors, activation and subsequent localization of STATs to the nucleus leading to modulation of gene expression.

In an in vitro kinase activity assay, deuruxolitinib had greater inhibitory potency for JAK1, JAK2 and TYK2 relative to JAK3. The relevance of inhibition of JAK enzymes to therapeutic effectiveness is not currently known.

LEQSELVI is a Janus kinase (JAK) inhibitor indicated for the treatment of adults with severe alopecia areata.

Limitations of Use:

LEQSELVI is not recommended for use in combination with other JAK inhibitors, biologic immunomodulators, cyclosporine or other potent immunosuppressants.

Recommended dosage is 8 mg twice daily. 

Most common adverse reactions (≥1%) are: headache, acne, nasopharyngitis, blood creatine phosphokinase increased, hyperlipidemia, fatigue, weight increased, lymphopenia, thrombocytosis, anemia, skin and soft tissue infections, neutropenia, and herpes.

LEQSELVI is contraindicated in patients:

• Who are CYP2C9 poor metabolizers.
• Using moderate or strong CYP2C9 inhibitors.

• Increased Risk of LEQSELVI-Associated Serious Adverse Reactions in CYP2C9 Poor Metabolizers or with Concomitant Use of Moderate or Strong CYP2C9 Inhibitors: LEQSELVI is contraindicated in patients who are CYP2C9 poor metabolizers or patients taking a moderate or strong CYP2C9 inhibitor.
• Gastrointestinal Perforations: Monitor patients who may be at increased risk for gastrointestinal perforation. Evaluate promptly patients presenting with new onset abdominal symptoms.
• Lipid Elevations, Anemia, Neutropenia, and Lymphopenia: Monitor for changes in lipids, hemoglobin, neutrophils, and lymphocytes. 
• Immunizations: Avoid use of live vaccines during or immediately prior to LEQSELVI treatment.