Novel anticancer drugs in Japan.

This review summarizes the results reported in preclinical and clinical trials of three novel anticancer drugs developed and tested in Japan. In phase II trials, Irinotecan, a semisynthetic analog of camptothecin, has yielded response rates exceeding 20% in non-small-cell lung cancer, small-cell lung cancer, breast cancer, gastric cancer, colorectal cancer, ovarian cancer, uterine cervical cancer, and non-Hodgkini's lymphoma. It was modestly active on pancreatic cancer and was not active on acute leukemias. Dose-limiting toxicities were leukopenia and diarrhea, and other major toxicities were nausea, vomiting, and alopecia. Amrubicin, a totally synthetic anthracycline, exhibited both higher efficacy on human tumor xenografts and cardiotoxicity milder than that of doxorubicin in preclinical studies. The dose-limiting toxicity in phase I trials was leukopenia. In phase II trials, amrubicin has shown activity equivalent to that of doxorubicin on non-Hodgkin's lymphoma, response rates exceeding 20% on non-small-cell lung cancer, and a response rate of 78.8% on untreated extensive-stage small-cell lung cancer. S-1 is an oral formulation consisting of ftorafur (an analog of 5-fluorouracil), 5-chloro-2, 4-dehydropyrimidine, which inhibits degradation of 5-fluorouracil, and potassium oxonate, which reduces gastrointestinal toxicity, at a molar ratio of 1:0.4:1. In phase I trials, dose-limiting toxicities (myelosuppression and gastrointestinal toxicities) were judged to be milder than those induced by UFT (ftorafur plus uracil). The response rates obtained in phase II trials were 40-49% on advanced gastric cancer, 35.5% on colorectal cancer, 37.5% on head and neck cancer, and 40.7% on breast cancer.