Immune-mediated thrombocytopenia resulting from sensitivity to oxaliplatin

Thrombocytopenia developing in the course of chemotherapy for malignant disease is usually attributed to drug-induced marrow suppression and/or marrow replacement by tumor. We describe two patients who developed severe thrombocytopenia and hemorrhagic symptoms while being treated with oxaliplatin, 5-fluorouracil, and leukovorin for metastatic colon cancer in whom platelet destruction appears to have been caused by oxaliplatin-dependent antibodies specific for the platelet glycoprotein IIb/IIIa complex (alpha(IIb)/beta(3) integrin). Drug-induced immune thrombocytopenia (DITP) should be considered in patients who experience a sudden, isolated drop in platelet levels while being treated with chemotherapeutic agents, especially when adequate numbers of megakaryocytes are present in the bone marrow.