Last reviewed 2026-04-20 · How we verify

Alimta (pemetrexed)

Alimta works by inhibiting the enzyme dihydrofolate reductase, which is necessary for DNA synthesis and cell division.

Alimta (pemetrexed) is a small molecule folate analog metabolic inhibitor developed by Lilly and currently owned by Actavis. It targets the folate receptor alpha and is used to treat malignant mesothelioma of the pleura and non-small cell lung cancer. Alimta was FDA-approved in 2004 and remains a branded product due to its off-patent status. Key safety considerations include its potential to cause myelosuppression, renal toxicity, and gastrointestinal side effects. As a folate analog, Alimta works by inhibiting the enzyme dihydrofolate reductase, which is essential for DNA synthesis and cell division.

At a glance

Mechanism of action

Pemetrexed Injection is folate analog metabolic inhibitor that disrupts folate-dependent metabolic processes essential for cell replication. In vitro studies show that pemetrexed inhibits thymidylate synthase (TS), dihydrofolate reductase, and glycinamide ribonucleotide formyltransferase (GARFT), which are folate-dependent enzymes involved in the de novo biosynthesis of thymidine and purine nucleotides. Pemetrexed is taken into cells by membrane carriers such as the reduced folate carrier and membrane folate binding protein transport systems. Once in the cell, pemetrexed is converted to polyglutamate forms by the enzyme folylpolyglutamate synthetase. The polyglutamate forms are retained in cells and are inhibitors of TS and GARFT.

Approved indications

• Malignant mesothelioma of pleura
• Non-small cell lung cancer

Common side effects

• Fatigue
• Nausea
• Vomiting
• Anorexia
• Constipation
• Stomatitis/pharyngitis
• Neutropenia
• Anemia
• Thrombocytopenia
• Elevated creatinine
• Diarrhea
• Dyspepsia/heartburn

Key clinical trials

• A Study of Induction and Maintenance Treatment of Advanced Non-squamous Non-Small Cell Lung Cancer (PHASE3)
• Pemetrexed and Best Supportive Care Versus Placebo and Best Supportive Care in Non-Small Cell Lung Cancer (NSCLC) (PHASE3)
• A Randomized Phase 3 Trial of Pemetrexed and Cisplatin Versus Gemcitabine and Cisplatin in Patients With Locally Advanced or Metastatic Non Small Cell Lung Cancer (PHASE3)
• Cisplatin With or Without Pemetrexed Disodium in Treating Patients With Malignant Mesothelioma of the Pleura That Cannot be Removed by Surgery (PHASE3)
• Vaccine Therapy in Treating Patients With Advanced Cancer (PHASE1)
• Reduced-dose Carboplatin-doublet-chemotherapy + Cemiplimab vs Cemiplimab Monotherapy in Treatment Naive Older and Frail Patients With Metastatic NSCLC With PD-L1 <50% (PHASE2)
• A Study to Compare Sacituzumab Tirumotecan (MK-2870) Monotherapy Versus Treatment of Physician's Choice as Second-line Treatment for Participants With Recurrent or Metastatic Cervical Cancer (MK-2870-020/TroFuse-020/Gog-3101/ENGOT-cx20) (PHASE3)
• Sacituzumab Tirumotecan (MK-2870) Versus Pemetrexed and Carboplatin Combination Therapy in Participants With Epidermal Growth Factor (EGFR)-Mutated, Advanced Nonsquamous Non-small Cell Lung Cancer (NSCLC) Who Have Progressed on Prior EGFR Tyrosine Kinase Inhibitors (MK-2870-009) (PHASE3)

Patents

Primary sources

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Competitive intelligence

For the full competitive landscape — auto-detected comparators, recent regulatory actions across the set, upcoming PDUFA, patent timeline, sponsor landscape:

• Alimta CI brief — competitive landscape report
• Alimta updates RSS · CI watch RSS
• Actavis portfolio CI