Pemetrexed is an antifolate metabolite that inhibits several enzymes involved in the folate pathway. It has activity against various solid tumours, and has been approved for treatment of malignant pleural mesothelioma on the basis of findings from a randomised phase III trial.1 The main toxic effects noted for pemetrexed have been rash, myelosuppression, diarrhoea, mucositis, and reversible elevation of liver enzymes—effects that are preventable partly by vitamin supplementation.
