Pemetrexed Cisplatin First Line
Executive Summary
Pemetrexed (Alimta) combined with cisplatin is the FDA-approved first-line chemotherapy regimen for unresectable malignant pleural mesothelioma.[1] The regimen was established as standard of care after the EMPHACIS trial reported a median overall survival of 12.1 months for the combination versus 9.3 months for cisplatin alone, with a 41.3% response rate. The 2020 CheckMate 743 trial demonstrated that nivolumab plus ipilimumab provides longer overall survival in first-line treatment of unresectable pleural mesothelioma, but pemetrexed + cisplatin remains a recognized first-line option for patients who are not candidates for dual checkpoint inhibition.[2]
At-a-Glance
- FDA approved 2004 for unresectable malignant pleural mesothelioma in combination with cisplatin
- Pivotal evidence: EMPHACIS phase III trial (Vogelzang et al., 2003), pemetrexed + cisplatin vs cisplatin alone
- Median overall survival: 12.1 months (Pem+Cis) vs 9.3 months (Cis alone)
- Objective response rate: 41.3% in Pem+Cis arm
- Vitamin supplementation required — folic acid 350–1000 µg/day and vitamin B12 1000 µg every 9 weeks reduce hematologic toxicity
- Current standing: First-line alongside nivolumab + ipilimumab (CheckMate 743 backbone); pemetrexed + platinum remains widely used where dual checkpoint inhibition is not feasible
- Trial-design caveat: EMPHACIS predates immunotherapy era — modern selection criteria for first-line decisions weigh patient performance status, histology, and access to checkpoint inhibitors
Mechanism and Regimen
Pemetrexed is a multitargeted antifolate that inhibits thymidylate synthase, dihydrofolate reductase, and glycinamide ribonucleotide formyltransferase. The combination with cisplatin disrupts both DNA synthesis (pemetrexed via folate-dependent enzymes) and DNA cross-linking (cisplatin via platinum–DNA adducts), producing additive cytotoxicity in mesothelioma cell lines and patient tumors. Standard dosing is pemetrexed 500 mg/m² plus cisplatin 75 mg/m², both administered intravenously on day 1 of a 21-day cycle, typically for six cycles. Folate and vitamin B12 supplementation is mandatory and significantly reduces grade 3–4 hematologic toxicity.
Where This Regimen Fits in 2026
The 2020 FDA approval of nivolumab + ipilimumab (CheckMate 743) added an immunotherapy option to first-line treatment of unresectable pleural mesothelioma, with longer median overall survival than the historical Pem+Cis benchmark, particularly for non-epithelioid histology. The 2024 FDA approval of pembrolizumab + pemetrexed + platinum (KEYNOTE-483) further expanded the immunotherapy-based first-line landscape. Pemetrexed + cisplatin without immunotherapy remains a recognized regimen for patients with contraindications to checkpoint inhibition, performance status that precludes combination immunotherapy, or limited access to newer agents.
References
- ↑ Vogelzang NJ, Rusthoven JJ, Symanowski J, Denham C, Kaukel E, et al. Phase III study of pemetrexed in combination with cisplatin versus cisplatin alone in patients with malignant pleural mesothelioma. J Clin Oncol. 2003;21(14):2636-2644. PMID: 12860938.
- ↑ Baas P, Scherpereel A, Nowak AK, Fujimoto N, Peters S, et al. First-line nivolumab plus ipilimumab in unresectable malignant pleural mesothelioma (CheckMate 743): a multicentre, randomised, open-label, phase 3 trial. Lancet. 2021;397(10272):375-386. PMID: 33485464.