Abstract
BACKGROUND: The combination of the immune checkpoint inhibitors (ICIs) ipilimumab and nivolumab is a mainstay of treatment for selected patients with metastatic melanoma. This combination also results in more frequent immune-related adverse events (irAEs) than either ICI alone. These irAEs can be severe and their pathogenesis is poorly understood. CASE PRESENTATION: We report a case of a woman with metastatic melanoma, treated with combined ipilimumab and nivolumab, who developed severe anaemia. While initial workup revealed autoimmune haemolytic anaemia, the anaemia persisted despite corticosteroids and paradoxical reticulocytopenia was observed. Bone marrow biopsy demonstrated a CD8(+) T cell-mediated destruction of the red cell precursors implying concurrent pure red cell aplasia. Both processes resolved after the addition of cyclosporine A. CONCLUSIONS: This report describes a rare case of two concurrent mechanisms of haematological irAE in a patient treated with combined ICI therapy. Successful treatment resulted only after the second underlying mechanism of toxicity was uncovered. Prompt recognition of these unusual presentations of rare irAEs is now key to effective irAE management.