Unusually prolonged pemetrexed cytotoxicity in a patient with a lung adenocarcinoma: a case report

BACKGROUND We describe a case of pemetrexed toxicities related to reabsorption by an ileal neobladder, which caused prolonged hematotoxicity and nephrotoxicity. CASE PRESENTATION A 59-year-old white man was diagnosed with metastatic wild-type adenocarcinoma of the upper lobe of his right lung. After a first cycle of cisplatin and pemetrexed, he had unusually prolonged aplasia and acute kidney injury. The prolonged aplasia was caused by pemetrexed reabsorption by the ileal mucosa of the neobladder as pemetrexed was eliminated renally in an active form and is partly lipophilic. CONCLUSIONS Pemetrexed may be reabsorbed by the ileal mucosa of the neobladder because of its hydrophobic structure and renal excretion in its active form. Acute urinary retention may maintain this phenomenon. Published data excluded a potential role for cisplatin in this toxicity; furthermore, we could not assess pemetrexed concentrations in the blood or urine as these assay techniques are not validated. Thus, care is needed when giving chemotherapy to patients with a neobladder.