Drug-induced immune-mediated thrombocytopenia secondary to sunitinib in a patient with metastatic renal cell carcinoma: a case report

INTRODUCTION Sunitinib is an oral multi-targeted tyrosine kinase inhibitor approved for first line treatment for metastatic renal cell carcinoma and imatinib-resistant metastatic gastrointestinal stromal tumors. Sunitinib administration can cause myelosuppression resulting in neutropenia and thrombocytopenia. Here we present the case of a patient with metastatic renal cell carcinoma who developed sunitinib-induced immune-mediated thrombocytopenia and who was treated with withdrawal of sunitinib and administration of intravenous immunoglobulin and steroids. CASE PRESENTATION This case report describes a 70-year-old Aboriginal Australian with a diagnosis of metastatic renal cell carcinoma. Three weeks after the initiation of sunitinib he developed epistaxis and was admitted with thrombocytopenia (platelets 7 × 109/L) which was found to be refractory to platelet transfusion. Sunitinib was stopped and he was treated with intravenous immunoglobulin and steroids. His platelet count rapidly improved and returned to baseline in three weeks. Only two cases of sunitinib-induced immune-mediated thrombocytopenia have been described in the literature. CONCLUSION Clinicians should have a high index of suspicion for the potential of immune-mediated thrombocytopenia after the initiation of multi-targeted tyrosine kinase inhibitors such as sunitinib. This is a diagnosis of exclusion and can be safely treated by drug withdrawal.