Pemetrexed monotherapy as salvage treatment in metastatic colorectal cancer patients who failed standard chemotherapy: A phase II single-arm prospective trial.
840 Background: We designed a single-arm, open label phase II study to determine the efficacy and toxicity of pemetrexed monotherapy with vitamin supplement in refractory colorectal (CRC) patients who failed standard treatments, including 5-FU, oxaliplatin, and irinotecan with or without biologic agents. Methods: Patients were treated with pemetrexed 500 mg/m2 on day 1, every 3 weeks, with folic acid and vitamin B12 supplementation. Patients began vitamin supplementation with B12 intramuscular injection (1000 mcg) every 9 weeks starting 1 week before the first pemetrexed dose, and patients received daily oral folic acid (1 mg) starting at least 5 days before the first pemetrexed dose. Treatment was continued until disease progression or intolerable toxicity was observed. Results: Between June 2016 and October 2016, 24 patients were enrolled in this study. One patient withdrew content, leaving a total of 23 patients to be evaluated. The median age of the patients was 54.0 years (range, 23.0 to 67.0), and the median ECOG performance status was 1 (1-2). The median number of previous systemic chemotherapies was 3 (range, 2 to 5). No complete response and no partial response were observed among the patients. Stable disease was observed in 10 patients (43.4%), and 7 patients had a response duration of 2 months or more. The median PFS was 1.6 months (95% CI, 1.1 to 2.0) and the median OS was 9.8 months (95% CI, 5.9 to 13.6). Only one patient experienced treatment-related toxicity of grade 3 or more. Neither hematologic toxicities nor dose reduction due to treatment-related toxicities were observed. There was no treatment-related death. Conclusions: Pemetrexed monotherapy showed moderate disease control and an acceptable toxicity profile as salvage therapy for refractory CRC. Clinical trial information: NCT02588781.