Phase I and pharmacokinetic study of the multitargeted antifolate pemetrexed in combination with oxaliplatin in patients with advanced solid tumors

Background: This phase I and pharmacokinetic study of pemetrexed in combination with oxaliplatin was performed to determine the maximum tolerated dose (MTD), and to evaluate safety and pharmacokinetics in patients with metastatic solid tumors. Patients and methods: Pemetrexed was administered as a 10- min i.v. infusion followed 30 min later by oxaliplatin as a 2-h infusion, once every 21 days. Up to two previous chemotherapy regimens were allowed. Vitamin B₁₂ supplementation and folic acid were not included in this study. Results: Thirty-six patients were treated in six escalating dose levels. Dose-limiting toxicities at dose level 6 (pemetrexed 500 mg/m² plus oxaliplatin 130 mg/m²) were febrile neutropenia, grade 3-4 diarrhea and grade 3 paresthesia. The MTD was not reached. The most common toxicity was neutropenia, with grade 3-4 occurring in 61% of patients. The pharmacokinetics of this pemetrexed-oxaliplatin combination are consistent with those following single-agent administration. Five responses (all partial) were observed over a broad range of solid tumors. Conclusions: This pemetrexed-oxaliplatin combination (without vitamin supplementation) every 21 days can be administered using full therapeutic doses of each agent with acceptable tolerability and no overlapping toxicity. The recommended regimen for phase II studies is pemetrexed 500 mg/m² plus oxaliplatin 120mg/m².