Drug-induced immune-mediated thrombocytopenia due to bevacizumab-FOLFOX therapy: a case report

Abstract

Drug-induced immune thrombocytopenia (DITP) is a very rare disease, with an estimated annual incidence of 10 cases per million. Oxaliplatin and irinotecan are widely used as chemotherapy for high-risk stage II and III colorectal cancer, and DITP has been reported to occur in patients using those agents. To treat unresectable metastatic colorectal cancer, bevacizumab is used in combination with oxaliplatin or irinotecan, and there have been a few reports of DITP cases in patients receiving that regimen. In this report, we describe a 68-year-old male patient with metastatic colon cancer (KRAS mutant type) to the liver and lung who developed acute immune-mediated thrombocytopenia due to bevacizumab-FOLFOX (5-fluorouracil, leucovorin, and oxaliplatin) therapy. During treatment, he showed purpura in his lower extremities on 21st cycle day 2. Lab work revealed a platelet count of less than 2,000/mL, reflecting a decrease from 135,000/mL at the start of the cycle 1 day prior. He did not have any other types of cytopenia or significant changes in laboratory findings. We diagnosed DITP due to bevacizumab-FOLFOX, and the patient did not show isolated thrombocytopenia after switching to Ziv-aflibercept-FOLFIRI (5-fluorouracil, leucovorin, and irinotecan).