Background: Pemetrexed and oxaliplatin have clinical activity as single agents in colorectal cancer (response rates, 10%-17%). In this study, these drugs were used in combination as first-line therapy in a group of patients with metastatic colorectal cancer.
Patients and methods: Fifty-four evaluable patients were to receive pemetrexed (500 mg/m2) with folic acid and vitamin B12 supplementation and oxaliplatin (120 mg/m2) every 21 days for 6 cycles or until disease progression occurred. Patients with stable or responding disease could continue therapy beyond 6 cycles at the discretion of the investigator. Eligibility criteria included a diagnosis of untreated metastatic adenocarcinoma of the colon or rectum, measurable disease, Zubrod performance status <or=2, no adjuvant chemotherapy within 6 months, and >or=12 weeks life expectancy.
Results: The confirmed clinical response rate (primary endpoint) was 29.6% (95% confidence interval [CI], 18%-48.6%), with 1 complete response and 15 partial responses. Median time to progression was 5.3 months (95% CI, 3.9-6.3 months), and median survival was 12.3 months (95% CI, 8.6-17 months). Grade 3/4 nadir neutropenia occurred in 33.3% of patients, and 3 patients experienced grade 3 febrile neutropenia or infection associated with grade 3/4 neutropenia. Grade 3/4 nadir thrombocytopenia was seen in 11.1% of patients. Only 4% of the patients developed grade 3/4 neurotoxicity.
Conclusion: This regimen of pemetrexed and oxaliplatin has activity in advanced colorectal cancer, and the toxicity profile suggests that escalation of the dose of pemetrexed in this combination may be possible.