Phase II study of pemetrexed disodium (Alimta®) administered with oral folic acid in patients with advanced gastric cancer

Background: The aim of this study was to assess the activity of pemetrexed in patients with advanced gastric cancer. Patients and methods: Thirty-eight eligible patients (median age 60 years) received pemetrexed 500 mg/m(2) every 3 weeks. Since toxicity was considerable in the first six patients, the protocol was amended to supplement subsequent patients with oral folic acid (5 mg/day on days -2 to +2 of every cycle). Results: Among 36 stage IV patients evaluable for efficacy (six non-supplemented\30 supplemented), there were two complete and six partial responses. The response rate was 21% (95% confidence interval 8% to 32%) according to intention-to-treat analysis. All responding patients were in the supplemented group. The median duration of response was 4.6 months and the median survival was 7.8 months. Five of six non-supplemented patients (83%) developed grade 3/4 neutropenia; two (33%) unsupplemented patients discontinued: two (33%) patients died due to toxicity. In the supplemented group, 12 of 32 patients (37%) had grade 3/4 neutropenia. None of the supplemented patients discontinued treatment due to hematological toxicity. Severe non-hematoloical toxicities were infrequent. Conclusions: The activity of pemetrexed is promising in light of the tumor burden in these patients (all patients were stage IV and 39% had three or more organs involved). Toxicities were remarkably decreased with folic acid supplementation. Combination studies are warranted.