Immune checkpoint inhibitor refractory colitis leading to total colectomy in a melanoma patient.

Immunotherapy is becoming more and more relevant in the treatment of advanced melanoma. Proper management of its side effects can prevent severe complications. We describe the case of a 73-year-old patient with severe refractory colitis secondary to immunotherapy. The patient has been treated for 6 months with Nivolumab, an anti-PD-1, as adjuvant therapy for locally advanced melanoma. He was admitted to the hospital with a deteriorating general condition associated with severe diarrhea and rectal bleeding for 3 weeks. Despite three lines of treatment (high dose corticosteroids, infliximab, mycophenolate mofetil), the patient still presented clinical and endoscopic colitis, with additional infectious complications. The patient required surgical management for total colectomy. In this article we present one of the rare cases of autoimmune colitis that did not respond to various immunosuppressive treatments and required surgery.

Auto-immune gastritis induced by pembrolizumab, an anti-PD-1, in a melanoma patient.

We report a case of a 67-years-old woman presenting a severe acute lymphocytic gastritis induced by pembrolizumab, an immune check point inhibitor (ICI). This gastritis was her third auto-immune adverse event after 5 years of treatment with pembrolizumab, it was metabolically active at the PET Scan and confirmed by analysis of the gastric biopsies. Pembrolizumab treatment cessation and high doses of corticosteroids completely normalized the stomach clinically, endoscopically and histologically. This patient was in complete remission of her metastatic melanoma. Therefore, pembrolizumab therapy was not restarted and the patient is still in remission 6 months later. This strategy is supported by recent publications describing a relapse rate inferior to 10% in patients in complete remission after 2 years of immunotherapy. Particularities of this case are: rareness of this adverse event, late onset after introduction of pembrolizumab, evocative PET scan image, specific endoscopic aspect and histology. In addition, the favorable oncologic evolution of the patient after treatment cessation confirms the prolonged remission after immunotherapy.