Widespread use of pemetrexed in oncology: has it turned it into a new drug?

To the editor, Pemetrexed is a multitargeted antifolate approved for nonsmall cell lung cancer, non-squamous type, either as initial treatment in combination with cisplatin or as monotherapy for maintenance or second-line, and for non-resectable malignant pleural mesothelioma in combination with cisplatin (1,2). Pemetrexed is usually a well-tolerated drug, however, it has got certain side-effects. The most common adverse reactions (occurring in ≥20%) when used as single-agent are fatigue, nausea and anorexia, but it may have additional complications such as diarrhea, rash or myelosuppression (3), which is generally the dose-limiting toxicity. As expected, when combined with cisplatin some of these side-effects may be more noticeable, especially myelosuppression and stomatitis. Despite using steroids as prophylaxis, to reduce potential cutaneous toxicities (CT) or their severity, these adverse reactions have been described in up to 14% of the patients treated with pemetrexed alone, and in 22% when combined with cisplatin, being grade 3 or 4 in approximately 0.8-1.3% of cases (4,5).