Supplementary Material for: Successful treatment of refractory immune-mediated colitis and duodenitis with tofacitinib

Introduction: Immune-mediated colitis (IMC) is a common and potentially severe immune-related adverse event of immune checkpoint inhibitors (ICIs). Although corticosteroids and biologics are standard treatments, some cases remain refractory. Tofacitinib, a Janus kinase inhibitor, has shown promise in refractory IMC; however, evidence regarding its treatment effects remains limited. Case presentation: Here, we present a case of pembrolizumab-induced IMC and duodenitis refractory to corticosteroids, infliximab, and vedolizumab. The patient was successfully treated after receiving a 30-day course of tofacitinib, which resulted in rapid symptom resolution and mucosal healing. No recurrence of colitis was observed 3 months after treatment cessation. Conclusion: As ICIs are increasingly used, the incidence of refractory IMC and other immune-related toxicities is expected to rise. This case highlights the need for further studies to establish the optimal use of tofacitinib in refractory IMC and duodenitis.