Phase II Study of S-1 Monotherapy as a First-line, Combination Therapy of S-1 plus Cisplatin as a Second-line, and Weekly Paclitaxel Monotherapy as a Third-line Therapy in Patients with Advanced Gastric Carcinoma: Phase II Study of S-1, S-1 plus Cisplatin, and Weekly Paclitaxel in Patients with Advanced Gastric Carcinoma

Regulatory T-cell density and cytotoxic T lymphocyte density are associated with complete response to neoadjuvant paclitaxel and carboplatin chemoradiotherapy in gastric cancer

Regulatory T-cell density and cytotoxic T lymphocyte density are crucial in regulating antitumor immune responses. Tumor infiltration has marked therapeutic effects in gastric carcinoma, and there is evidence that chemoradiotherapy (CRT) exhibits an immune-mediated component. In the present study, the density of CD4⁺ and CD8⁺ cells were evaluated in post-CRT surgical samples from 68 patients with gastric cancer using immunohistochemistry. The associations between T-cell density, cytotoxic T lymphocyte density and clinical survival rate were also analyzed. Cytotoxic T lymphocyte density was associated with gastric carcinoma regression grade and regulatory T-cell density was also associated with gastric carcinoma regression grade. Of the patients who had a pathologic complete response, 84 and 76% were found to have a high CD3⁺ and CD4⁺ cell density, which was significantly different to patients who had a low CD3⁺ and CD4⁺ cell density. High cytotoxic T lymphocyte density was also associated with improved survival rates of patients with gastric cancer. In conclusion, these outcomes indicated that regulatory T-cell density and cytotoxic T lymphocyte density in the tumor microenvironment were associated with the response to neoadjuvant CRT and may represent a therapeutic target for gastric cancer.

A Phase II Study of S-1 Monotherapy as a First-line Combination Therapy of S-1 Plus Cisplatin as a Second-line Therapy, and Weekly Paclitaxel Monotherapy as a Third-line Therapy in Patients with Advanced Gastric Carcinoma: A Second Report

BACKGROUND

We have previousy reported on a Phase II study of S-1 monotherapy as a first line, combination therapy of S-1 plus cisplatin as a second line, and weekly paclitaxel monotherapy as a third line therapy in patients with advanced gastric carcinomas. The median survival time (MST) of patients over the whole course of treatment was not previously calculated because 12 out of 19 patients had not yet succumbed. Since then, we have calculated the MST for this study and herein report our findings.

PATIENTS AND METHODS

Between 2002 and 2005, 19 patients were enrolled in this study. Chemotherapy consisted of either 60 mg/m(2) of S-1 for 4 weeks at 6-week intervals, a combination of 60 mg/m(2) S-1 for 3 weeks and 60 mg/m(2) cisplatin on day 8 at 5-week intervals, or 60 mg/m(2) paclitaxel at days 1, 8, and 15, at 4-week intervals. The regimens were repeated until the occurrence of unacceptable toxicities, disease progression, or patient noncompliance. The primary end point was the overall survival.

RESULTS

The median survival time was 774 days. The response rates were 33.3% (3/9), 12.5% (1/8), and 0% (0/4) after the first, second, and third line chemotherapies, respectively. The major adverse hematological toxicity was leukopenia, which reached grades 3-4 in all lines of chemotherapy investigated. In addition, the major adverse non-hematological toxicity was anorexia, which reached grade 3-4 in second line chemotherapy, and no deaths were attributable to the adverse effects of the drugs.

CONCLUSION

This sequential therapy was an effective treatment for advanced gastric cancer with acceptable toxic side-effects. We considered this therapy to be effective because of the smooth transition to the next regimen.