Used primarily in chemotherapy, this compound is effective in treating non-small cell lung cancer and malignant pleural mesothelioma. It works by inhibiting multiple enzymes involved in folate metabolism, which are essential for DNA synthesis and cell division. As a result, rapidly dividing cancer cells are targeted and their growth is suppressed. It is typically administered intravenously in combination with other chemotherapeutic agents like cisplatin. Due to its mechanism, patients are often supplemented with folic acid and vitamin B12 to reduce toxicity and improve tolerability. Its role in combination therapy has made it a key option in first-line and maintenance treatment regimens for specific cancers.