Gastrointestinal toxicities of 5-fluorouracil increase the proportion of regulatory T cells in intestinal tract: advantages of alternate-day S-1 administration.

BACKGROUND: 5-Fluorouracil (5-FU), a core anticancer agent for malignancies, induces gastrointestinal (GI) toxicities. Despite recent advances in tumor immunology, it still remains unknown how GI toxicities affect antitumor immunity. S-1 is a tegafur-based oral 5-FU prodrug which has been widely introduced in Japan and other countries. The alternate-day S-1 administration has been proposed to minimize its GI and other toxicities without reducing its anticancer efficacy. METHODS: In this study, two S-1 administration regimens were compared in mice to evaluate their impact of GI toxicities on immunity. In the daily group as a standard administration model, S-1 was administered for 14 days on and 14 days off, and in the alternate-day group as a non-GI toxicity model, S-1 was administered every other day for 28 days. As well as physical findings, regulatory T cells, Th1 cells and other cells in murine lymphoid tissues were analyzed with flow cytometry. RESULTS: Only the daily group exhibited body weight loss and GI toxicities. In the daily group, a proportion of regulatory T cells in the intestinal lymphoid tissue were demonstrated to be six-fold higher than in the control without S-1, and the proportion of Th1 cells showed a decreasing trend. However, the alternate-day group exhibited almost no change in T-cell subsets. CONCLUSION: GI toxicities of 5-FU may have a negative influence on antitumor immunity due to increased proportions of regulatory T cells and decreased proportions of Th1 cells. The alternate-day S-1 administration may be a useful regimen with its minimal influence on T-cell subsets.

Usefulness of alternate-day administration of S-1 and leucovorin in a xenograft mouse model of colorectal cancer: a shorter drug-free interval leads to more efficient antitumor effects.

BACKGROUND: A clinical trial of S-1 with leucovorin (S-1/LV) in metastatic colorectal cancer (CRC) patients demonstrated promising efficacy; however, the gastrointestinal toxicities were so severe that it has not been applied in the clinical setting. On the other hand, alternate-day administration of S-1 has been proposed to attenuate the adverse events without reducing its anticancer activity. Our present study was conducted to confirm the feasibility of alternate-day administration of S-1/LV in in vivo xenograft tumor models. METHODS: Mice were treated with S-1/LV in a daily group (2 weeks of administration followed by 2 weeks of withdrawal) or an alternate-day group (administration on alternate days for 4 weeks), then the mice were killed and the xenograft tumors were resected. We compared body weight changes, condition of feces, mucosal injury and myelosuppression and assessed adverse reactions, tumor volume, tumor growth inhibition (TGI) and expression of Ki67, TUNEL, cIAP2 and XIAP to evaluate the antitumor activity and tumor apoptosis. RESULTS: Severe weight loss, diarrhea, mucosal injury and myelosuppression were observed only in the daily group; however, some myelosuppression was also observed in the alternate-day group. The TGI in the alternate-day group was better than in the daily group, possibly resulting from apoptosis due to the suppression of cIAP2 but not XIAP. CONCLUSION: Our findings suggest that alternate-day administration of S-1/LV for CRC treatment can achieve high antitumor activity without severe adverse reactions, and we propose that clinical trials with this regimen should be conducted in CRC patients.

Young-onset peri-anorectal leiomyomatosis: report of a case.

A 23-year-old female was referred with constipation that lasted for 2 years. Preoperative examinations revealed multiple submucosal tumors beside the anorectum, along with subcutaneous tumors in the left buttock. The pathological diagnosis was leiomyoma. Low anterior resection of the rectum with regional lymph node dissection, along with the resection of the subcutaneous tumors in the left buttock through the transdermal approach, was performed, since multiple tumor formation indicated a high malignant potential. The tumors were diagnosed as multiple leiomyomas with no malignancy. Disease categories such as intravenous leiomyomatosis, leiomyomatosis peritonealis disseminata, Alport syndrome, and Currarino syndrome have been reported to be associated with leiomyomatosis; however, the current case of "peri-anorectal leiomyomatosis" was not classified into any of these. The patient was monitored with careful checkups, and the postoperative course was satisfactory for over 5 years without any sign of recurrence or metastasis. Although the clinicopathological features of this case are quite rare and no therapeutic guidelines for such a disease have yet been established, radical resection should be considered, and the elucidation of the histogenesis of this disease will help establish future therapeutic guidelines.

IL-23 directly enhances the proliferative and invasive activities of colorectal carcinoma.

Interleukin-23 (IL-23) plays an essential role in the mucosal immune system. It has been suggested that IL-23 is able to induce carcinogenesis as well as inflammation and a recent study revealed that IL-23R is expressed in colorectal carcinoma cells. However, neither the differences in the IL-23R expression among the patients nor the concrete functions of IL-23 in colorectal carcinoma cells have been revealed. The aim of the present study was to examine the characteristics of IL-23R expression in colorectal carcinoma and the direct effects of IL-23 on colorectal cancer cells. We examined the IL-23R expression in human colorectal cancer tissue samples by immunohistochemistry. Cell proliferation and invasion assays under IL-23 stimulation were performed using cultured cells derived from colorectal cancer. ELISA and real-time PCR were used to evaluate the transforming growth factor (TGF)-ß production due to IL-23 stimulation. All of the TNM stage IV patients were positive for IL-23R. IL-23R expression in the carcinoma tissue was also relatively high at the deepest point of invasion in certain cases. The proliferative and invasive activities and/or TGF-ß production of DLD-1 cells increased by IL-23 stimulation, whereas no change was observed in the activities of MIP101 and KM12c cells. IL-23 directly enhanced the malignancy of the colon carcinoma cells. An autocrine mechanism via TGF-ß production may underlie these effects. IL-23 is therefore a potential target for cancer immunotherapy. However, the homogeneity in IL-23R expression and the effects of IL-23 on colorectal carcinoma cells should be considered.