S-1 (Japan)

[Rich66]

1: Breast Cancer. 2006;13(2):220-4. Links

S-1 (TS-1) maintained complete response for approximately 10 years in a case of metastatic breast cancer.

Taira N, Aogi K, Ohsumi S, Takashima S, Nishimura R, Doihara H, Saeki T.
Department of Surgery, National Hospital Organization, National Shikoku Cancer Center, Matsuyama-city, Ehime, Japan. ntaira@shikoku-cc.go.jp
We present a patient with pulmonary metastasis from breast cancer who received S-1 (TS-1) and maintained complete response for approximately 10 years after recurrence. A 51-year-old woman underwent modified radical mastectomy for left breast cancer in November 1991. Her cancer was postoperatively classified as pT2 pN0 M0 Stage IIA. As postoperative adjunctive treatment, tamoxifen and hexylcarbamoyl 1-5-FU (HCFU) were given. During the administration period (30 months after surgery), a solitary pulmonary metastasis occurred. Three months after the start of S-1 (100 mg/body/day), the tumor disappeared on images. Thereafter she took S-1 orally for approximately 10 years, and the pulmonary metastatic focus maintained complete response. In addition, no recurrent focus was observed. The adverse events observed during S-1 treatment were nausea, low-grade neutropenia and pigmentation of fingers. All were mild, and S-1 could be continued. Our case illustrates two important characteristics of S-1. First, S-1 was effective even though this patient had a lung metastasis during adjuvant treatment with HCFU. S-1 is a combined formulation containing 5-chloro-2, 4-dihydroxypyrimidine (CDHP; gimestat), which inhibits an enzyme that metabolites 5-FU, dihydropyrimidine dehydrogenase (DPD). Therefore, high 5-FU concentrations are maintained with S-1, and S-1 may be effective in the patients who do not respond to other fluoropyrimidine agents. Second, since S-1 toxicity was mild, long-term treatment for approximately 10 years was possible. Since S-1 contains potassium oxonate (OXO; otastat), gastrointestinal toxicities, the main adverse events of 5-FU agents, could be reduced. The purpose of treatments for metastatic breast cancer is to maintain favorable quality of life (QOL), as well as to improve survival. S-1 could be a valuable agent for breast cancer treatments, since it showed clinical efficacy and mild toxicity, and can be given orally.

Efficacy of S-1 in heavily pretreated patients with metastatic breast cancer: cross-resistance to capecitabine.

Ito Y, Osaki Y, Tokudome N, Sugihara T, Takahashi S, Iwase T, Hatake K.
Department of Medical Oncology, The Cancer Institute of Japanese Foundation for Cancer Research, 3-10-6, Ariake, Koto-ku, Tokyo, 135-8550, Japan, yito@jfcr.or.jp.
BACKGROUND: It is not clear what the optimal treatment of chemotherapy is for patients with heavily treated metastatic breast cancer (MBC). We have retrospectively examined the efficacy and safety of S-1 in patients with MBC who had been previously treated with anthracycline, taxane, and capecitabine. METHODS: Patients with MBC who had been administered S-1, an oral modulated compound containing a fluoropyrimidine derivative, between November 2001 and June 2003 at the Cancer Institute Hospital were retrospectively reviewed. S-1 at a standard dose of 50 mg/body was administered twice daily for four weeks, followed by a two-week rest period. This was repeated every six weeks until disease progression or unacceptable toxicity. RESULTS: Thirty-five patients were assessed. The patients were heavily pretreated with anthracycline (100%), taxane (paclitaxel or docetaxel) (100%), capecitabine (100%), vinorelbine (71%), and mitomycin (69%). Median follow-up time of patients was 9.6 months (range, 1.2-26.6). ORR was 3% (95% confidence interval: 0-9%), and CBR was 20% (95% confidence interval: 6-33%). Time to treatment failure was 2.8 months. Overall survival was 21.4 months. Grade 1 or 2 adverse events were observed in 17% and 13%, respectively. Grade 3 events occurred as anorexia (9%), nausea (9%), vomiting (9%), diarrhea (14%), fatigue (3%), and elevation of AST/ALT (3%). No grade 3 was seen as hand-foot syndrome. Neither grade 3 nor 4 was observed in bone marrow suppression. CONCLUSIONS: S-1 was fairly well tolerated, but demonstrated very limited activity in capecitabine-pretreated patients who had already been exposed to anthracycline and taxane. It was suggested that S-1 clinically exhibited cross-resistance to capecitabine.


A phase II study of S-1 in patients with metastatic breast cancer--a Japanese trial by the S-1 Cooperative Study Group, Breast Cancer Working Group.

Saek T, Takashima S, Sano M, Horikoshi N, Miura S, Shimizu S, Morimoto K, Kimura M, Aoyama H, Ota J, Noguchi S, Taguchi T.
Department of Clinical Research and Surgery, National Shikoku Cancer Center Hospital, Horinouchi 13, Matsuyama 790-0007, Japan. tsaeki@shikoku-cc.go.jp
BACKGROUND: S-1 is a newly developed novel oral dihydrouracil dehydrogenase inhibiting fluoropyrimidine drug consisting of 1 M tegafur (FT), 0.4 M 5-chloro-2, 4-dihydroxypyrimidine (gimeracil), and 1 M potassium oxonate (oteracil), with efficient antitumor activity and low gastrointestinal toxicity which is widely used in Japan against advanced gastric, head and neck cancers. We investigated its clinical efficacy against metastatic breast cancer. METHODS: A non-blind phase II study was carried out to evaluate the efficacy and toxicity in metastatic breast cancer patients. Patients with measurable metastasis foci (n=111) were enrolled, and 108 patients were regarded as eligible. S-1 was administered orally at a standard dose of 80 mg/m2/day b.i.d. One course consisted of 28 consecutive days of administration followed by a 14-day rest, and courses were repeated up to six times. RESULTS: Among the eligible patients, 10 had a complete response and 35 had a partial response, with an overall response rate (CR+PR) of 41.7% (95% confidence interval: CI, 32.3-51.5%). The incidences of toxicity (> or =grade 3) were neutropenia 9.1%, anemia 0.9%, anorexia 3.6%, stomatitis 1.8%, nausea/vomiting 1.8%, diarrhea 0.9%, and fatigue 2.7%, however no treatment-related deaths were observed. The median survival time was 872 days (95% CI, 572-1,110 days). There was no difference in response rate or toxicity between the under 65-year-old group and the older group. CONCLUSION: S-1 was demonstrated to have high efficacy with low gastrointestinal toxicity even in older patients and will be a promising new chemotherapy drug for metastatic breast cancer.