[A phase I study of postoperative combination therapy with TS-1 and low dose cisplatin against stage IV gastric carcinoma].

A dose-escalation study was conducted for postoperative patients with stage IV gastric cancer to determine the recommended dose of daily intravenous cisplatin combined with a fixed dose of TS-1. TS-1 was administered orally twice daily for 2 weeks followed by a 1-week rest. The dose of TS-1 was based on the body surface area (BSA) as follows: 80 mg/day for BSA less than 1.25, 100 mg/day for BSA 1.25 to less than 1.50, and 120 mg/day for BSA 1.5 or more. Three dose levels of cisplatin (2, 4, 6 mg/m(2)) were studied, and two courses were performed. Cisplatin was infused on day 1-5 and 8-12 for 30 minutes. The National Cancer Institute common toxicity criteria (NCI-CTC Version 3) were used to evaluate the grade of toxicity. Three patients enrolled in each level. Dose escalation was performed when dose-limiting toxicities (DLT) were seen in 0/3, and 3 more cases of the same level were added when DLTs were seen 1-2/3. Maximum-tolerated dose (MTD) were determined when DLTs were seen in 3 cases. DLTs were not recorded during the administration of CDDP up to 4 mg/m(2). However, DLTs were seen 3/3 at level 3. From these results, cisplatin of 4 mg/m(2)was determined to be the recommended dose (RD) in this protocol for postoperative stage IV gastric carcinoma.

Immediate early response gene X-1, a stress-inducible antiapoptotic gene, encodes cytotoxic T-lymphocyte (CTL) epitopes capable of inducing human leukocyte antigen-A33-restricted and tumor-reactive CTLs in gastric cancer patients.

Peptide-based vaccine therapy, which is designed to elicit T-cell immunity against tumors, is an attractive approach for the treatment of cancer patients. To provide a scientific basis for peptide therapy, an increasing number of CTL-directed peptides have been identified, and some of them have been tried as antigen-specific immunotherapy in the past decade. Only a few studies, however, have been performed on such peptides restricted with alleles other than HLA-A2 and -A24. In the present study, we show that immediate early response gene X-1 (IEX-1), a stress-inducible protein associated with the regulation of cell proliferation and apoptosis, produces antigenic epitopes recognized by 850B-CTLs, HLA-A33-restricted CTLs newly established from T cells infiltrating into gastric adenocarcinoma. The IEX-1 gene was highly expressed in most cell lines and tissues from various types of cancer at both the mRNA and protein levels. However, it was not expressed at the protein level in any normal epithelium or connective tissues tested. Three IEX-1-derived peptides at positions 47-56, 61-69, and 65-73, which were recognized by the 850B-CTLs, could induce CD8(+) peptide-specific CTL reaction to tumor cells from HLA-A33(+) gastric cancer patients and other epithelial cancer patients, but not from healthy donors, in an HLA class I-restricted manner. Because increased expression of IEX-1 is suggested to be involved in the resistance to apoptosis and in the proliferation of cancer cells, these antigenic peptides could be potent candidates for peptide-based specific immunotherapy against HLA-A33(+) gastric cancer and other epithelial cancers.