[Pilot study of TS-1 combined with lentinan in patients with unresectable or recurrent advanced gastric cancer].

TS-1, an anticancer, antimetabolis agent, has shown clinically superior antitumor activity against unresectable advanced or recurrent gastric cancer (UARG). A biological response modifier, lentinan (LNT) prolonged the survival period of patients with UARG when combined with tegafur (FT). To assess the efficacy, the safety and prognostic factors of chemo-immunotherapy using TS-1, a FT derivative, and LNT, we conducted a multi-institutional pilot study in patients with UARG. Patients were treated with TS-1 at 80 mg/m2/day (bid) for 4-weeks, and LNT was given at 2 mg/body (i.v.) in a week, followed by a 2-week rest for 4 cycles. Twenty-two patients were entered from 4 institutes and 19 patients were eligible. The median survival time in eligible patients was 400 days. The incidence of hematological toxicity (grade 2 leukopenia), and non-hematological toxicity (grade 3 nausea or fatigue) was 5.3% (1/19) and no grade 4 toxicity was observed. The response ratio was 37.5% in 8 patients who had been administered the planned dose of TS-1. In subset analyses, the survival period of the patients with normal (< 500 micrograms/ml) serum immunosuppressive acidic protein level was significantly (p < 0.0001) better than that of the higher one. The survival period for those patients whose granulocytes/lymphocytes ratio was not more than 2 tended to be better. From the prolonged survival periods, chemo-immunotherapy using TS-1 combined with LNT would seem to have a benefit against UARG, and reduced toxicity. Future clinical trials are warranted to confirm its potency.