Used primarily in oncology, this compound functions as a chemotherapeutic agent targeting rapidly dividing cancer cells. It inhibits key enzymes involved in folate metabolism, disrupting DNA and RNA synthesis, which leads to cancer cell death. Commonly used in the treatment of non-small cell lung cancer and malignant pleural mesothelioma, it is often administered in combination with platinum-based drugs. Its trisodium salt form improves solubility, enhancing intravenous delivery and bioavailability. Due to its mechanism, patients typically require supplementation with folic acid and vitamin B12 to reduce toxicity while maintaining efficacy.