BUB1 is overexpressed in most human solid cancers including breast cancer. Higher BUB1 levels are associated with poor prognosis especially in patients with triple-negative breast cancer (TNBC). Women with TNBC often develop resistance to chemotherapy and radiotherapy, which are still the mainstay of treatment for TNBC. Our previous studies demonstrated that BUB1 kinase inhibitor (BAY1816032) reduced tumor cell proliferation and significantly enhanced radiotherapy efficacy in TNBC. In this study, we evaluated the effectiveness of BAY1816032 with a PARP inhibitor (olaparib), platinum agent (cisplatin), and microtubule poison (paclitaxel) alone or in combination with radiotherapy using cytotoxicity and clonogenic survival assays. BUB1 inhibitor sensitized BRCA1/2 wild-type SUM159 and MDA-MB-231 cells to olaparib, cisplatin and paclitaxel synergistically (combination index; CI

BOLD-100, a ruthenium-based complex, sodium trans-[tetrachloridobis(1H-indazole)ruthenate(III)] (also known as IT-139, NKP1339 or KP1339), is a novel small molecule drug that demonstrated a manageable safety profile at the maximum tolerated dose and modest antitumor activity in a phase I clinical trial. BOLD-100 has been reported to inhibit the upregulation of the endoplasmic reticulum stress sensing protein GRP78. However, response to BOLD-100 varies in different cancer models and the precise mechanism of action in high-response versus low-response cancer cells remains unclear. In vitro studies have indicated that BOLD-100 induces cytostatic rather than cytotoxic effects as a monotherapy. To understand BOLD-100 mediated signaling mechanism in breast cancer cells, we used estrogen receptor positive (ER+) MCF7 breast cancer cells to obtain gene-metabolite integrated models. Particularly, BOLD-100 significantly reduced expression of genes involved in the DNA repair pathway. BOLD-100 also induced reactive oxygen species (ROS) and phosphorylation of histone H2AX, gH2AX (Ser139), suggesting disruption of proper DNA surveillance. In estrogen receptor negative (ER-) breast cancer cells, combination of BOLD-100 with a PARP inhibitor, olaparib, induced significant inhibition of cell growth and xenografts and increased gH2AX. Thus, BOLD-100 is a novel DNA repair pathway targeting agent and can be used with other chemotherapies in ER- breast cancer.

The purpose of this study is to develop and evaluate a self-microemulsifying drug delivery system (SMEDDS) to improve the oral absorption of poorly water-soluble Olaparib. Through the solubility test of Olaparib in various oils, surfactants and co-surfactants, pharmaceutical excipients for use in SMEDDS manufacturing were selected. Self-emulsifying regions were identified by mixing the selected materials at various ratios, and a pseudoternary phase diagram was constructed by synthesizing these results. Various physicochemical properties of microemulsion incorporating Olaparib were confirmed by investigating the particle morphology, particle size, zeta potential, drug content and stability. In addition, the improved dissolution and oral absorption of Olaparib were also confirmed through a dissolution test and a pharmacokinetic study. An optimal microemulsion was generated in the formulation of Capmul MCM EP/NF 10%, Labrasol 80% and PEG 400 10%. Fabricated nano-sized microemulsions were well-dispersed in aqueous solutions, and it was also confirmed that it was maintained well without any problems of either physical or chemical stability. The 5 min initial dissolution of Olaparib in fabricated formulations was improved by 10.6 times (pH1.2), 14.8 times (pH6.8) and 14.8 times (distilled water) compared to the values of Olaparib powder. The dissolution at 120min was 45.4±4.0%(pH1.2), 53.5±1.1% (pH6.8) and 58.1±1.00% (distilled water) in Olaparib powder but has been significantly improved by 1.7 times (74.8±1.9%), 1.6 times (84.2±0.3%) and 1.5 times (81.2±0.7%) in SMEDDS. Associated with the high dissolutions of Olaparib in fabricated microemulsions, the pharmacokinetic parameters were also greatly improved. The Cmax and AUCinf of Olaparib in the prepared microemulsion were increased 4.2- and 3.2-fold, respectively, compared to powder. Taken together with the results mentioned above, the microemulsion system could be an effective tool as an oral delivery formulation for Olaparib. Additionally, our results demonstrate that the SMEDDS systems comprising Capmul MCM, Labrasol and PEG 400 could be a useful option for improvement of several other poorly water-soluble drugs with physico-chemical properties similar to Olaparib.