Broad spectrum and potent antitumor activities of YM155, a novel small-molecule survivin suppressant, in a wide variety of human cancer cell lines and xenograft models.

Antitumor activities of YM155, a novel small-molecule survivin suppressant, were investigated in a wide variety of human cancer cell lines and xenograft models. YM155 inhibited the growth of 119 human cancer cell lines, with the greatest activity in lines derived from non-Hodgkin's lymphoma, hormone-refractory prostate cancer, ovarian cancer, sarcoma, non-small-cell lung cancer, breast cancer, leukemia and melanoma. The mean log growth inhibition of 50% (GI(50) ) value was 15 nM. The mean GI(50) values of YM155 were 11 nM for p53 mut/null cell lines and 16 nM for p53 WT cell lines, suggesting that YM155 inhibits the growth of human tumor cell lines regardless of their p53 status. In non-small-cell lung cancer (Calu 6, NCI-H358), melanoma (A375), breast cancer (MDA-MB-231) and bladder cancer (UM-UC-3) xenograft models, 3- or 7-day continuous infusions of YM155 (1-10 mg/kg) demonstrated significant antitumor activity without showing significant bodyweight loss. Tumor regressions induced by YM155 were associated with reduced intratumoral survivin expression levels, increased apoptosis and decreased mitotic indices. The broad and potent antitumor activity presented in the present study is indicative of the therapeutic potential of YM155 in the clinical setting.

YM155, a novel small-molecule survivin suppressant, induces regression of established human hormone-refractory prostate tumor xenografts.

Various accumulating evidence suggests that survivin, a member of the inhibitor of apoptosis (IAP) family, plays an important role in drug resistance and cancer cell survival in many types of cancer, including hormone-refractory prostate cancer (HRPC). Here, we characterized YM155, a novel small-molecule survivin suppressant, using a survivin gene promoter activity assay. YM155 suppressed expression of survivin and induced apoptosis in PC-3 and PPC-1 human HRPC cell lines at 10 nmol/L. In contrast, YM155 up to 100 nmol/L showed little effect on expression levels of other IAP- or Bcl-2-related proteins. In a s.c. xenografted PC-3 tumor model in mice, 3-day continuous infusions of YM155 at 3 to 10 mg/kg induced massive tumor regression accompanied by suppression of intratumoral survivin. YM155 also completely inhibited the growth of orthotopically xenografted PC-3 tumors. No significant decreases in body weight were observed in mice treated with YM155 during the experimental period. Pharmacokinetic analyses indicated that YM155 is highly distributed to tumors and at concentrations approximately 20-fold higher than those in plasma. Our findings represent the first attempt to show tumor regression and suppression of survivin in p53-deficient human HRPC cells by a single small molecular compound treatment. Further extensive investigation of YM155 in many types of cancer, including HRPC, seems to be worthwhile to develop this novel therapeutic approach.