IntroductionImmune checkpoint inhibitors (ICIs), including PD-1 inhibitors, have significantly improved survival outcomes in patients with melanoma; however, serious adverse events may occur as a consequence of immune dysregulation. Autoimmune hemolytic anemia (AIHA) is a rare but potentially life-threatening condition.
While corticosteroids remain the cornerstone of AIHA management, some patients with severe anemia require additional immunosuppressive agents beyond steroids alone.Case reportA 52-year-old woman with anal canal malignant melanoma presented with severe generalized fatigue, lower back pain, and gross hematuria. She had received one cycle of pembrolizumab two weeks prior to presentation.
She had severe anemia with reticulocytosis, elevated lactate dehydrogenase and bilirubin levels, and a positive direct Coombs test, and was diagnosed with severe AIHA secondary to pembrolizumab therapy. Despite initial treatment with corticosteroids and intravenous immunoglobulin (IVIG), hemolysis progressed.
The condition was ultimately controlled with cyclophosphamide (CTX) and fluorouracil (5-FU) in addition to corticosteroids. Three months later, pembrolizumab was again administered and the resulting AIHA was managed with corticosteroids alone.
It notes AIHA as a potential but rare adverse event linked to immune checkpoint inhibitors (ICIs), specifically PD-1 blockade, and highlights that corticosteroids are standard first-line therapy while some cases require additional immunosuppression.