Rare Delayed Immune Thrombocytopenic Purpura Associated With Neoadjuvant Immunotherapy

BACKGROUND: Immunotherapy targeting the PD-L1/PD-1 checkpoint pathway with monoclonal antibodies has demonstrated significant and durable efficacy across various malignancies. However, these immunotherapies can induce adverse reactions, collectively referred to as immune-related adverse events (irAEs). Most irAEs occur during immunotherapy. To date, there have been no reported cases of immune thrombocytopenia occurring after the cessation of immunotherapy and subsequent surgery. This article aims to detail such an immune-related adverse event. METHODS: The authors describe a 67-year-old male patient with oral squamous cell carcinoma who underwent 4 cycles of neoadjuvant immunochemotherapy without complications during treatment. On the seventh day post-surgery, the patient developed immune thrombocytopenia. Upon the onset of thrombocytopenia, platelet transfusions and thrombopoietic agents were administered, but without significant improvement. Intravenous immunoglobulin (IVIG) therapy was then initiated. RESULTS: The patient received IVIG at a dose of 400 mg/kg for 5 consecutive days. both platelet count and hemoglobin levels stabilized. CONCLUSION: Immune thrombocytopenia typically occurs within 10 weeks of initiating immunotherapy. In this case, the patient experienced no hematologic complications during a treatment period extending over 3 months. However, after cessation of immunotherapy and subsequent surgery, delayed onset immune thrombocytopenia occurred. Clinicians must recognize the importance and complexity of diagnosing immune thrombocytopenia (ITP).