Immune-induced thrombocytopenia by pembrolizumab: case report and review of literature.

Immune-checkpoint blockades (ICBs) are now used in early-stage diseases like triple-negative breast cancer (TNBC). While effective, they can cause severe toxicities. We report the first case of life-threatening immune thrombocytopenia (ITP) induced by pembrolizumab during neoadjuvant chemo-immunotherapy for early TNBC. A 42-year-old woman with early-stage TNBC developed grade 4 thrombocytopenia, diagnosed as ITP, after 107 days of pembrolizumab treatment. She required intensive care unit (ICU) admission and high-dose steroids, and intravenous immunoglobulin therapy, leading to a rapid recovery. ITP is a rare but potentially fatal complication of immunotherapy, with an incidence of less than 1% and a mortality rate of up to 20% in affected patients. Immediate recognition and steroid therapy are critical, as platelet transfusion is usually ineffective. Diagnosis is often delayed due to its similarity to chemotherapy-induced marrow toxicity. Immunotherapy-induced ITP generally contraindicates further use of the treatment. ITP, although uncommon, is a serious complication of immunotherapy requiring immediate intervention. The growing use of immunotherapy necessitates increased awareness of its potential toxicities among healthcare providers.