Severe Rapid-onset Drug-induced Thrombocytopenia during Oxaliplatin Re-administration after a Prolonged Drug-free Interval: A Case Report

Oxaliplatin (L-OHP), a third-generation platinum agent widely used for gastrointestinal cancers, is associated with a rare type of poorly characterized drug-induced thrombocytopenia (DITP). We report a patient with gastroesophageal junction cancer with severe rapid-onset DITP with life-threatening tumor bleeding following L-OHP re-administration after a prolonged drug-free interval. A woman in her 60s with unresectable gastroesophageal junction cancer had previously received mFOLFOX6 and multiple subsequent therapies. After disease progression and an approximately 1-year interval without L-OHP, mFOLFOX6 was reintroduced. During the eighth cycle of re-administration, the patient developed hematemesis within 10 h. Laboratory findings revealed a precipitous decline in platelet counts (from 10.7 × 104/μL to 0.2 × 104/μL) and hemoglobin levels without neutropenia, and endoscopy confirmed tumor bleeding. Thrombocytopenia was refractory to platelet transfusions. Suspecting DITP, corticosteroid therapy (prednisolone 1 mg/kg) was initiated, and a subsequent elevation in platelet-associated IgG suggested an immune-mediated mechanism. Platelet counts gradually recovered within 7 days following the discontinuation of treatment and steroid administration, with resolution of bleeding. Based on the clinical course, exclusion of alternative etiologies, and Naranjo scale assessment, L-OHP was considered the most likely causative agent. This report highlights the potential for extremely rapid and severe DITP upon re-exposure to L-OHP, even after a long drug-free interval. Early recognition, prompt discontinuation of the causative agent, and timely corticosteroid therapy are essential for optimal disease management.