Phase II Study of Pemetrexed as Second or Third Line Combined Chemotherapy in Patients with Colorectal Cancer

Purpose: To investigate the safety and efficacy of pemetrexed combined with chemotherapy as second or third line in patients with stage IV colorectal cancer (CRC). Patients and Methods: This trial was conducted to evaluate the effectiveness and safety of pemetrexed given to patients with recurrent or metastatic colorectal carcinoma who previously received 5-FU-based chemotherapy. All patients were required to have a histological diagnosis of colorectal adenocarcinoma with measurable metastatic disease and prior chemotherapy. Patients received pemetrexed at a dose of 500 $mg/m^2$ by 10 minute infusion on day 1, repeated every 21 days. Doses were modified depending on nadir counts. Combined chemotherapy included Oxaliplatin, Irinotecan and cis-platinum. Results: Thirty patients were enrolled and twenty-nine were evaluable for response. One patient did not have repeat radiological testing to determine response because he went off study after only one cycle of treatment for economic reasons. For 29 evaluable patients, 1 partial response, 6 stable disease and 22 progressive disease were recorded. Response rate was 3.45% (1/29). All responses occurred in patients receiving a starting dose of pemetrexed 500 $mg/m^2$. Median time to progression for all eligible patients was 2.5 months. The most common toxicities experienced were mild to moderate fever, hepatic damage, myelosuppression, nausea, vomiting, constipation, abdominal pain, diarrhea, and skin rash. Conclusion: Pemetrexed at 500 $mg/m^2$ given every three weeks combined with chemotherapy is associated with moderate response and good tolerability in patients with stage IV CRC.