Antitumor efficacy and biodistribution of liposomal sepantronium bromide (YM155), a novel small-molecule survivin suppressant

Advances in nanotechnology-based platforms for survivin-targeted drug discovery

INTRODUCTION

Due to its unique functional impact on multiple cancer cell circuits including proliferation, apoptosis, tumor dissemination, DNA damage repair and immune response, the inhibitor of apoptosis protein (IAP) survivin has gained high interest as a molecular target and a multitude of therapeutics were developed to interfere with survivin expression and functionality. First clinical evaluations of these therapeutics, however, were disappointing highlighting the need to develop advanced delivery systems of survivin-targeting molecules to increase stability, bioavailability as well as the selective guidance to tumor tissue.

AREAS COVERED

: This review focuses on advancements in nanocarriers to molecularly target survivin in human malignancies. A plethora of nanoparticle platforms, including liposomes, polymeric systems, dendrimers, inorganic nanocarriers, RNA/DNA nanotechnology and exosomes are discussed in the background of survivin-tailored RNA interference, small molecule inhibitors, dominant negative mutants or survivin vaccination or combined modality treatment with chemotherapeutic drugs and photo- dynamic/photothermal strategies.

EXPERT OPINION

Novel therapeutic approaches include the use of biocompatible nanoformulations carrying gene silencing or drug molecules to directly or indirectly target proteins, allow for a more precise and controlled delivery of survivin therapeutics. Moreover, surface modification of these nanocarriers may result in a tumor entity specific delivery. Therefore, nanomedicine exploiting survivin-tailored strategies in a multimodal background is considered the way forwaerd to enhance the development of future personalized medicine.

Design, synthesis, and antiproliferative evaluation of novel longifolene-derived tetraline pyrimidine derivatives with fluorescence properties

In the search for novel compounds with both survivin inhibitory activity and fluorescence properties, 18 novel longifolene-derived tetralin pyrimidine compounds were designed using survivin as the target and synthesized from the sustainable natural resource longifolene.

d-a-Tocopheryl Polyethylene Glycol 1000 Succinate and a small-molecule Survivin suppressant synergistically induce apoptosis in SKBR3 breast cancer cells

Breast cancer is the second in mortality rate malignancy among women. Despite the many advances in breast cancer treatment, there is still a need to improve drug efficacy and reduce non-specific effects. D-alpha-tocopheryl polyethylene glycol succinate (TPGS) is frequently used in the development of drug delivery systems to improve the pharmacokinetics of anti-cancer drugs and reduce multi-drug resistance. We have previously shown that TPGS not only acts as a carrier molecule but also exerts anti-cancer effects. As part of this study, we investigated the effect of TPGS with YM155, a small molecule suppressant of Survivin, in various breast cancer cell lines representing different subtypes of the disease. We aimed to evaluate the presumed synergistic effect of the TPGS-YM155 combination and reveal its mechanism of action. Our results show that the TPGS-YM155 combination acts synergistically to reduce specifically the viability of SKBR3 cells. The combination of these agents reduced activation of the AKT pathway, decreased Survivin and Bcl-2 levels, and induced caspase-dependent and independent apoptosis via the mitochondrial pathway. Importantly, the TPGS-YM155 combination did not significantly affect the viability of MCF-10A normal immortalized cells. In conclusion, the combination of YM155 and TPGS could be a promising approach against SKBR3-type breast cancer.

Anti-GD2 Immunoliposomes for Targeted Delivery of the Survivin Inhibitor Sepantronium Bromide (YM155) to Neuroblastoma Tumor Cells

Purpose

Sepantronium bromide (YM155) is a hydrophilic quaternary compound that cannot be administered orally due to its low oral bioavailability; it is furthermore rapidly eliminated via the kidneys. The current study aims at improving the pharmacokinetic profile of YM155 by its formulation in immunoliposomes that can achieve its enhanced delivery into tumor tissue and facilitate uptake in neuroblastoma cancer cells.

Methods

PEGylated YM155 loaded liposomes composed of DPPC, cholesterol and DSPE-PEG₂₀₀₀ were prepared via passive film-hydration and extrusion method. Targeted (i.e. immuno-)liposomes were prepared by surface functionalization with SATA modified monoclonal anti-disialoganglioside (GD2) antibodies. Liposomes were characterized based on their size, charge, antibody coupling and YM155 encapsulation efficiency, and stability. Flow cytometry analysis and confocal microscopy were performed on IMR32 and KCNR neuroblastoma cell lines. The efficacy of developed formulations were assessed by in-vitro toxicity assays. A pilot pharmacokinetic analysis was performed to assess plasma circulation and tumor accumulation profiles of the developed liposomal formulations.

Results

YM155 loaded immunoliposomes had a size of 170 nm and zeta potential of −10 mV, with an antibody coupling efficiency of 60% andYM155 encapsulation efficiency of14%. Targeted and control liposomal formulations were found to have similar YM155 release rates in a release medium containing 50% serum. An in-vitro toxicity study on KCNR cells showed less toxicity for immunoliposomes as compared to free YM155. In-vivo pharmacokinetic evaluation of YM155 liposomes showed prolonged blood circulation and significantly increased half-lives of liposomal YM155 in tumor tissue, as compared to a bolus injection of free YM155.

Conclusions

YM155 loaded immunoliposomes were successfully formulated and characterized, and initial in-vivo results show their potential for improving the circulation time and tumor accumulation of YM155.

Electronic supplementary material

The online version of this article (10.1007/s11095-018-2373-x) contains supplementary material, which is available to authorized users.

Targeting Survivin Enhances Chemosensitivity in Retinoblastoma Cells and Orthotopic Tumors

Treatments for retinoblastoma (Rb) vary depending on the size and location of the intraocular lesions and include chemotherapy and radiation therapy. We examined whether agents used to treat Rb induce a pro-survival phenotype associated with increased expression of survivin, a member of the inhibitor of apoptosis family of proteins. We document that exposure to carboplatin, topotecan or radiation resulted in elevated expression of survivin in two human Rb cell lines but not in normal retinal pigmented epithelial (RPE) cells. Cellular levels of survivin were attenuated in Rb cells exposed to an imidazolium-based survivin suppressant, Sepantronium bromide (YM155). Protein expression patterns of survivin in RPE cells were not altered following treatment protocols involving exposure to YM155. Including YM155 with chemotherapy or radiation increased levels of apoptosis in Rb cells but not in RPE cells. Intraocular luciferase expressing Rb tumors were generated from the Rb cell lines and used to evaluate the effects of carboplatin and YM155 on in-vivo survivin expression and tumor growth. Carboplatin induced expression of survivin while carboplatin combined with YM155 reduced survivin expression in tumor bearing eyes. The combination protocol was also most effective in reducing the rate of tumor regrowth. These results indicate that targeted inhibition of the anti-apoptotic protein survivin provides a therapeutic advantage for Rb cells and tumors treated with chemotherapy.

YM155 exerts a growth inhibitory effect on human osteosarcoma in vitro and in vivo

YM155, a novel small-molecule inhibitor of survivin, is known to exert antitumor effects on various cancers, including breast, prostate and lung cancer. However, there are few studies describing the inhibitory effect of YM155 on human osteosarcoma (OS) which highly expresses survivin. Here, we tested the effects of YM155 on OS cells by several in vitro experiments. It was found that YM155 inhibited cell proliferation, colony formation, migration and invasion, induced cell apoptosis, as well as increased caspase-3, -8 and -9 activity in the OS cell lines in a dose-dependent manner. We also found that YM155 suppressed Mcl-1 and survivin expression without affecting the expression of anti-apoptotic proteins X-linked inhibitor of apoptosis (XIAP) and Bcl-2. In addition, YM155 decreased phosphoinositide 3-kinase (PI3K) and AKT expression without effecting total PI3K and AKT in the OS cell lines, which contributed to suppression of OS tumor growth at least in part. In addition, YM155 also suppressed tumor growth in vivo, reducing the size of OS MG63 cell xenografts. Taken together, the findings revealed that YM155 suppresses the tumor growth of OS in vitro and in vivo, suggesting that YM155 has potential as a therapeutic agent for the treatment of OS.