Sepantronium bromide (YM155) induces disruption of the ILF3/p54(nrb) complex, which is required for survivin expression

Survivin and YM155: how faithful is the liaison?

Survivin belongs to the family of apoptosis inhibitors (IAPs), which antagonizes the induction of cell death. Dysregulated expression of IAPs is frequently observed in cancers, and the high levels of survivin in tumors compared to normal adult tissues make it an attractive target for pharmacological interventions. The small imidazolium-based compound YM155 has recently been reported to block the expression of survivin via inhibition of the survivin promoter. Recent data, however, question that this is the sole and main effect of this drug, which is already being tested in ongoing clinical studies. Here, we critically review the current data on YM155 and other new experimental agents supposed to antagonize survivin. We summarize how cells from various tumor entities and with differential expression of the tumor suppressor p53 respond to this agent in vitro and as murine xenografts. Additionally, we recapitulate clinical trials conducted with YM155. Our article further considers the potency of YM155 in combination with other anti-cancer agents and epigenetic modulators. We also assess state-of-the-art data on the sometimes very promiscuous molecular mechanisms affected by YM155 in cancer cells.

Prevention of BMS-777607-induced polyploidy/senescence by mTOR inhibitor AZD8055 sensitizes breast cancer cells to cytotoxic chemotherapeutics

Targeted inhibition of MET/RON signaling by tyrosine kinase inhibitor BMS-777607 for cancer treatment is currently under clinical trials. We have previously shown that BMS-777607 induces chemoresistance in vitro by causing polyploidy, which hampers therapeutic efficacy. Here, we studied polyploidy-associated senescence induced by BMS-777607 in breast cancer cells and its prevention by mTOR inhibitor AZD8055, leading to increased chemosensitivity. In breast cancer T-47D and ZR-75-1 cells, BMS-777607 induced phenotypic changes including enlarged cellular size, flattened morphology, increased DNA content, and activity of senescence-associated β-galactosidase. These changes were accompanied by increased p21/WAF1 expression and decreased Retinoblastoma Ser(780) phosphorylation, indicating that BMS-777607 induces not only polyploidy but also senescence. The appearance of senescence was associated with polyploidy in which β-galactosidase is exclusively expressed in polyploid cells. Survivin expression was increased in polyploid/senescent cells as analyzed by Western blotting. Increased survivin accumulated both in the nucleus and cytoplasm and dissociated with condensed DNA and mitotic spindle at the metaphase. Abnormal accumulation of survivin also rendered polyploid/senescent cells insensitive to cytotoxic activities of YM155, a DNA damaging agent with a suppressive effect on survivin gene transcription. AZD8055, a specific mTOR inhibitor, effectively prevented BMS-777607-induced polyploidy and senescence and restored survivin expression and its nuclear localization to normal levels. Although a synergism was not observed, BMS-777607 plus AZD8055 increased cancer cell sensitivity toward different cytotoxic chemotherapeutics. In conclusion, BMS-777607-induced chemoresistance is associated with cell polyploidy and senescence. Inhibition of mTOR signaling by AZD8055 prevents BMS-777607-induced polyploidy/senescence and increases breast cancer cell chemosensitivity.

YM155 sensitizes ovarian cancer cells to cisplatin inducing apoptosis and tumor regression

OBJECTIVE

The objective of this study is to chemosensitize ovarian cancer (OVCa) cells to cisplatin (CDDP) using an inhibitor of Survivin, YM155. The efficacy of YM155 in combination with CDDP was determined in vitro, ex vivo and in vivo.

METHODS

Human OVCa cell lines A2780p and their cisplatin-resistant derivative A2780cis, were treated with CDDP, YM155, and the combined treatment (YM155+CDDP), and cell viability, mRNA and protein expression levels, cell-cycle distribution, and DNA damage were then evaluated. Furthermore, the efficacy of YM155 combined with CDDP was further examined in established primary cell cultures and xenograft models.

RESULTS

The combination of YM155 with CDDP induced G2/M cell cycle arrest and apoptosis, increased DNA damage, and decreased Survivin levels, especially in A2780cis CDDP-resistant cells. Additionally, YM155 in combination with CDDP sensitized primary cell cultures to CDDP. Studies in vivo showed how this combination significantly decreased the tumor size of OVCa xenografts.

CONCLUSIONS

Our results demonstrate that in OVCa cells the expression of Survivin did not affect their sensitivity to YM155, suggesting that Survivin was not the only target of YM155. The combination of YM155 with CDDP could be a good option for therapy of CDDP-resistant OVCa, independently of p53 status.

Response of Merkel cell polyomavirus-positive merkel cell carcinoma xenografts to a survivin inhibitor

Merkel cell carcinoma (MCC) is a neuroendocrine skin cancer associated with high mortality. Merkel cell polyomavirus (MCV), discovered in 2008, is associated with ~80% of MCC. The MCV large tumor (LT) oncoprotein upregulates the cellular oncoprotein survivin through its conserved retinoblastoma protein-binding motif. We confirm here that YM155, a survivin suppressor, is cytotoxic to MCV-positive MCC cells in vitro at nanomolar levels. Mouse survival was significantly improved for NOD-Scid-Gamma mice treated with YM155 in a dose and duration dependent manner for 3 of 4 MCV-positive MCC xenografts. One MCV-positive MCC xenograft (MS-1) failed to significantly respond to YM155, which corresponds with in vitro dose-response activity. Combination treatment of YM155 with other chemotherapeutics resulted in additive but not synergistic cell killing of MCC cell lines in vitro. These results suggest that survivin targeting is a promising therapeutic approach for most but not all MCV-positive MCCs.

A phase I/II study of sepantronium bromide (YM155, survivin suppressor) with paclitaxel and carboplatin in patients with advanced non-small-cell lung cancer

BACKGROUND

This phase I/II study examined the safety and efficacy of Sepantronium Bromide (S), a small-molecule selective survivin suppressant, administered in combination with carboplatin (C) and paclitaxel (P).

PATIENTS AND METHODS

Forty-one patients were treated on study. Twenty-two patients received escalating doses of S (3.6-12 mg/m(2)) and 19 with untreated stage IV non-small-cell lung cancer (NSCLC) were treated with the maximum tolerated dose of 10 mg/m(2) in combination with standard doses of C (AUC6) and P (200 mg/m(2)) for six cycles. S was administered as a continuous intravenous infusion (CIVI) over 72 h in 21-day treatment cycles. Study end points included safety and toxic effect, response rate, progression-free and overall survival (PFS and OS), as well as exploratory pharmacodynamic correlates.

RESULTS

Treatment with S was well tolerated, and toxic effects were mostly hematological in the phase II study. Two (11%) partial responses were observed with a median PFS of 5.7 months and median OS 16.1 months. Pharmacodynamic analysis did not demonstrate an association with response.

CONCLUSION

The combination of S (10 mg/m(2)/day 72-h CIVI) administered with C and P every 3 weeks exhibited a favorable safety profile but failed to demonstrate an improvement in response rate in advanced NSCLC.

CLINICAL TRIAL NUMBER

NCT01100931.

Discovery of survivin inhibitors and beyond: FL118 as a proof of concept

Survivin, a novel antiapoptotic protein molecule, plays a central role in cancer cell survival/proliferation networks and has therefore become a therapeutic target for cancer drug discovery efforts. There are two strategies for discovering survivin inhibitors. One is based on survivin interactions within the cell and the other strategy is based on blocking survivin expression. Survivin inhibitors developed by the first strategy would disrupt a particular survivin function. These survivin inhibitors could also be useful tools for delineating the mechanism of action of survivin. The second strategy may use a reporter system of the survivin gene to screen drug libraries. To date, two molecules, YM155 and FL118, have been identified using this strategy. These two examples provide a proof of concept that screens for inhibitors of survivin expression using survivin gene reporter assays as surrogate markers will uncover versatile small molecules that not only inhibit survivin but also inhibit other essential cancer survival/proliferation-associated targets and/or signaling pathways. This review provides an overview of current information in the area relevant to survivin inhibitors that may facilitate future studies.