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ritlecitinib
Modality
small molecule (kinase inhibitor)
Mechanism
12.1 Mechanism of Action LITFULO is a kinase inhibitor. 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.
Targets
BMX, BTK, ITK, JAK3, TEC, TXK
Storage
—
Approved
alopecia areata — FDA
In trial
alopecia areata, vitiligo, hidradenitis suppurativa, chronic urticaria
Black-box warnings
serious infections; mortality (all-cause, RA pts ≥50 with CV risk); malignancy; MACE (non-fatal MI / stroke); thrombosis (DVT, PE, arterial)
Last verified
2026-06-14
lib/moa-data.ts for the shape; add an entry keyed by ritlecitinib.Monitoring & workup
Baseline workup
- •TB IGRA (or PPD)
- •HBV sAg + core Ab; HCV Ab
- •CBC with differential
- •CMP (creatinine, LFTs)
- •Fasting lipid panel
- •HCG if female of childbearing potential
- •Update age-appropriate vaccines (no live vaccines once started)
Ongoing monitoring
- •CBC + LFT at 4 weeks, then every 3 months
- •Lipid panel at week 12 then annually
- •Watch for herpes zoster, VTE, serious infection, MACE (class BBW)