Oxaliplatin Antibody-Related Thrombocytopenia: A Case Report.

Oxaliplatin is used in combination with fluorouracil and leucovorin as part of the FOLFOX (fluorouracil, leucovorin, and oxaliplatin) regimen for colorectal cancer (CRC). Oxaliplatin has been shown to cause thrombocytopenia in a majority of CRC patients receiving this drug. Although this thrombocytopenia mainly occurs through myelosuppression, in rare cases, it can be immune-mediated. However, unlike other chemotherapy-induced myelosuppression, oxaliplatin-induced thrombocytopenia presents with a sudden drop within hours to days of oxaliplatin administration. The majority of cases who present with oxaliplatin-induced thrombocytopenia typically present after actively being treated with oxaliplatin. Here, we present the case of a 59-year-old female with biopsy-proven CRC on FOLFOX therapy found to have oxaliplatin antibody-mediated thrombocytopenia. She was originally treated with FOLFOX; however, due to response and clinical symptoms, her regimen was changed to include FOLFIRI (leucovorin calcium, fluorouracil, and irinotecan hydrochloride) and bevacizumab before reinitiating FOLFOX due to disease progression. During this case, she presented with rectal bleeding and was found to have severe thrombocytopenia. She was treated with platelet transfusion, intravenous immunoglobulin, and steroids for concerns of immune thrombocytopenia; however, through the use of flow cytometry, oxaliplatin and leucovorin antibodies were discovered. Ultimately, oxaliplatin was permanently discontinued due to concerns about further events of thrombocytopenia.