Decoding cell death signalling: Impact on the response of breast cancer cells to approved therapies

Breast cancer is a principal cause of cancer-related mortality in female worldwide. While many approved therapies have shown promising outcomes in treating breast cancer, understanding the intricate signalling pathways controlling cell death is crucial for optimizing the treatment outcome. A growing body of evidence has unveiled the aberrations in multiple cell death pathways across diverse cancer types, highlighting these pathways as appealing targets for therapeutic interventions. In this review, we provide a comprehensive overview of the current state of knowledge on the cell death signalling mechanisms with a particular focus on their impact on the response of breast cancer cells to approved therapies. Additionally, we discuss the potentials of combination therapies that exploit the synergy between approved drugs and therapeutic agents targeting modulators of cell death pathways.

Ovarian Cancer: Treatment and Resistance to Pharmacotherapy

Despite advances in surgical techniques and chemotherapy, ovarian cancer is still a leading cause of death among gynecological cancers. In addition to the late detection of the disease, the main reason for poor prognosis is resistance to pharmacotherapy, mostly platinum compounds. About a third of patients do not respond to primary platinum-based chemotherapy treatment, and over time, eventually, 80% of other patients develop chemoresistance, which makes the recurrence of disease incurable. In this review, we describe a difficult clinical hurdle faced in ovarian cancer therapy as a result of platinum resistance, as well as resistance to newer targeted therapy with PARP inhibitors and bevacizumab. We, furthermore, give attention also to the role of the tumor microenvironment as it is less well understood than the tumor cell-intrinsic mechanism. Because a central goal in ovarian cancer research is the development of novel strategies to overcome chemoresistance, treatment for cancer is moving toward personalized therapy.

Diversity of dose-individualization and therapeutic drug monitoring practices of platinum compounds: a review

Introduction: Platinum-derived drugs are commonly used for the treatment of solid tumors. The differences in chemical structures of these molecules lead to different pharmacological properties, in terms of indication, efficacy, and toxicity. Their pharmacokinetics (PK) differ according to their respective renal elimination and have led to many studies investigating their dose optimization. Area covered: This review attempts to summarize and compare PK and pharmacodynamics of cisplatin, carboplatin, and oxaliplatin, with an emphasis on differences of dose calculations and opportunities for therapeutic drug monitoring (TDM) in various patient populations. Expert opinion: Although cisplatin and carboplatin can be considered as analogs since they share the same DNA interacting properties, the slower hydrolysis of the latter results in a better safety profile. Carboplatin is the only drug in oncology to be administrated according to a target area under the curve of concentration versus time, considering that its PK variability is almost fully explained by renal function, not by body size. This enables individual dosing based on predicted carboplatin clearance (along with patients renal characteristics) or on actual clearance with TDM, especially in a high-dose protocol.

[DNA damage repair: An emerging strategy in metastatic prostate cancer]

Genetic instability is one part of the oncogenic process. Gene mutations involved in DNA repair mechanisms can promote this genetic instability and participate in oncogenesis and metastatic progression. In prostate cancer, DNA repair abnormalities mainly correspond to somatic or constitutional mutations of the BRCA2 and ATM genes. Therapeutic management of metastatic castration-resistant prostate cancer (mCRPC) is currently based on new hormonal therapies (abiraterone, enzalutamide) and taxane-type chemotherapy (docetaxel or cabazitaxel). Preliminary data tend to indicate a specific activity of agents causing DNA breaks (platinum salts) and PARP inhibitors in patients with these DNA repair abnormalities. The frequency of DNA repair gene mutations in patients with prostate cancer (around 20%) and the antitumor response of PARP inhibitors make it a possible short-term therapeutic strategy with several registering clinical trials ongoing.

Location of Mutation in BRCA2 Gene and Survival in Patients with Ovarian Cancer

Purpose: BRCA2 plays a central role in homologous recombination by loading RAD51 on DNA breaks. The objective of this study is to determine whether the location of mutations in the RAD51-binding domain (RAD51-BD; exon 11) of BRCA2 gene affects the clinical outcome of ovarian cancer patients.Experimental Design: A study cohort of 353 women with ovarian cancer who underwent genetic germline testing for BRCA1 and BRCA2 genes was identified. Progression-free survival (PFS), platinum-free interval (PFI), and overall survival (OS) were analyzed. The Cancer Genome Atlas (TCGA) cohort of ovarian cancer (n = 316) was used as a validation cohort.Results: In the study cohort, 78 patients were carriers of germline mutations of BRCA2 After adjustment for FIGO stage and macroscopic residual disease, BRCA2 carriers with truncating mutations in the RAD51-BD have significantly prolonged 5-year PFS [58%; adjusted HR, 0.36; 95% confidence interval (CI), 0.20-0.64; P = 0.001] and prolonged PFI (29.7 vs. 15.5 months, P = 0.011), compared with noncarriers. BRCA2 carriers with mutations located in other domains of the gene do not have prolonged 5-year PFS (28%, adjusted HR, 0.67; 95% CI, 0.42-1.07; P = 0.094) or PFI (19 vs. 15.5 months, P = 0.146). In the TCGA cohort, only BRCA2 carriers harboring germline or somatic mutations in the RAD51-BD have prolonged 5-year PFS (46%; adjusted HR, 0.30; 95% CI, 0.13-0.68; P = 0.004) and 5-year OS (78%; adjusted HR, 0.09; 95% CI, 0.02-0.38; P = 0.001).Conclusions: Among ovarian cancer patients, BRCA2 carriers with mutations located in the RAD51-BD (exon 11) have prolonged PFS, PFI, and OS. Clin Cancer Res; 24(2); 326-33. ©2017 AACR.

In vitro and ex vivo vanadium antitumor activity in (TGF-β)-induced EMT. Synergistic activity with carboplatin and correlation with tumor metastasis in cancer patients

Epithelial to mesenchymal transition (EMT) plays a key role in tumor progression and metastasis as a crucial event for cancer cells to trigger the metastatic niche. Transforming growth factor-β (TGF-β) has been shown to play an important role as an EMT inducer in various stages of carcinogenesis. Previous reports had shown that antitumor vanadium inhibits the metastatic potential of tumor cells by reducing MMP-2 expression and inducing ROS-dependent apoptosis. However, the role of vanadium in (TGF-β)-induced EMT remains unclear. In the present study, we report for the first time on the inhibitory effects of vanadium on (TGF-β)-mediated EMT followed by down-regulation of ex vivo cancer stem cell markers. The results demonstrate blockage of (TGF-β)-mediated EMT by vanadium and reduction in the mitochondrial potential of tumor cells linked to EMT and cancer metabolism. Furthermore, combination of vanadium and carboplatin (a) resulted in synergistic antitumor activity in ex vivo cell cultures, and (b) prompted G0/G1 cell cycle arrest and sensitization of tumor cells to carboplatin-induced apoptosis. Overall, the findings highlight the multifaceted antitumor action of vanadium and its synergistic antitumor efficacy with current chemotherapy drugs, knowledge that could be valuable for targeting cancer cell metabolism and cancer stem cell-mediated metastasis in aggressive chemoresistant tumors.

Platinum compounds sensitize ovarian carcinoma cells to ABT-737 by modulation of the Mcl-1/Noxa axis

Ovarian cancer is the leading cause of death from gynecological cancer. The anti-apoptotic protein Bcl-x(L) is frequently overexpressed in ovarian carcinoma which correlates with chemotherapy resistance. It has been demonstrated that Bcl-x(L) cooperates with another anti-apoptotic protein, Mcl-1, to protect ovarian cancer cells against apoptosis, and that their concomitant inhibition induces massive cell death. Here, we examined the interest of ABT-737, a potent BH3-mimetic molecule targeting Bcl-x(L), both alone and in combination with Mcl-1 modulators, in ovarian cancer cell lines. As a single agent, ABT-737 was ineffective at promoting cell death in the four cell lines we tested in vitro. However, the specific inhibition of Mcl-1 by siRNA dramatically increased the sensitivity of chemoresistant cells to ABT-737. Platinum compounds also sensitize to ABT-737 by dose-dependently decreasing Mcl-1 expression or by increasing the expression of pro-apoptotic BH3-only proteins Noxa and, to a lower extent, Bim. Furthermore, we demonstrated that Noxa accumulation was involved in apoptosis occurring in response to the combination of ABT-737 and platinum compounds, since cells were protected from apoptosis by its silencing. Moreover, the combination was also highly cytotoxic ex vivo in sliced SKOV3 tumor nodes. However we observed in these slices a strong basal expression of Noxa and apoptotic cell death in response to ABT-737 alone. Therefore, we have revealed that the modulation of the Mcl-1/Noxa axis by platinum compounds results in a strong sensitization of chemoresistant ovarian carcinoma cells to ABT-737, which could constitute a promising therapeutic in these cancers.

Nyamori V, Omondi B, Masimirembwa C, Simoyi RH. Kinetics and mechanistic investigation into the possible activation of imidazolium trans-[tetrachloridodimethylsulfoxideimidazoleruthenate(iii)], NAMI-A, by 2-mercaptoethane sulfonate

NAMI-A is a promising antimetastatic prodrug with high specificity for metastatic cancer cells.

Taxanes in combination with biologic agents for ovarian and breast cancers

Taxane-based cytotoxic therapy is commonly prescribed for breast and ovarian cancers. Although these cancers are often sensitive to such therapy, clinical benefit and overall survival are limited owing to the development of chemoresistance and recurrence. Biologic agents that specifically target proteins of growth factor signaling pathways, which are hyperactivated in cancers, offer attractive targets for cancer therapeutics and may work synergistically with standard taxane-based chemotherapy to improve patient outcomes. We review clinical trials of biologic agents--angiogenic, tyrosine kinase, and antibody inhibitors--in combination with taxane-based therapy for ovarian and breast cancers. Many clinical trials have shown promising results. However, some biologic agents still need larger trials to assess safety and efficacy. As research into the heterogeneity and complexity of ovarian and breast cancers improves our understanding of the molecular pathways involved, there is no question that targeted therapies with biologic agents will expand the future array of available cancer therapeutics.