Thrombotic thrombocytopenic purpura as a complication of pembrolizumab: a case report and literature review

The success of immune checkpoint inhibitors (ICIs) has revolutionized oncology, with an increasing number of patients receiving treatment every year. However, this progress has been accompanied by a rise in immune-related adverse events (irAEs). One such irAE is thrombotic thrombocytopenic purpura (TTP), a rare and potentially life-threatening complication. This report presents a unique case of TTP following a single dose of pembrolizumab. A 76-year-old man with suspected advanced renal cell carcinoma received pembrolizumab as initial treatment. Eleven days later, the patient developed severe thrombocytopenia, bleeding problems, and hemolytic anemia. The following day, the ADAMTS13 activity levels was 3.8% (ref. 40-130%), confirming the diagnosis of TTP. Given the patient's poor overall condition and limited life expectancy, plasma exchange was not initiated. The patient passed away 15 days after receiving pembrolizumab. In conclusion, physicians should be aware that even a single dose of the ICI pembrolizumab can trigger TTP. A review of current case reports on pembrolizumab-induced TTP is also provided.