PARP Inhibitors in Breast and Ovarian Cancer

Micro-RNAs in breast cancer progression and metastasis: A chromatin and metabolic perspective

Breast cancer is a highly complex disease with multiple subtypes. While many of the breast cancer cases are sporadic some can be familial or hereditary. Genomic integrity is closely monitored by several mechanisms, such as DNA damage machinery and mitotic checkpoints. Any defect in the key genes involved in the regulation of these mechanisms often results in genomic instability, predisposing the cells to malignancy. This results in altered expression of many coding and noncoding genes. The noncoding RNAs especially the long noncoding RNA (lncRNAs) and microRNA (miRNAs) act as key regulators of cancer gene networks. Some miRNAs repress the expression of the heterochromatin-associated proteins, inducing the formation of open chromatin, and promoting the expression of genes required for oncogenesis. Additionally, specific miRNAs may also favour cancer progression and metastasis by regulating the expression of genes that support the metabolic microenvironment essential for cancer cell growth and proliferation. Understanding how these noncoding RNAs contribute to breast cancer development opens potential avenues for therapeutic intervention, targeting their dysregulated activity.

An Analysis of Genetic Polymorphisms in 76 Genes Related to the Development of Ovarian Tumors of Different Aggressiveness

Borderline ovarian tumors (BOTS) are rare neoplasms of intermediate aggressiveness between cystadenomas and low-grade ovarian cancers (lgOvCa), which they share some molecular resemblances with. In contrast to the most frequent and well-described high-grade ovarian carcinomas (hgOvCa), the molecular background of BOTS and lgOvCa is less thoroughly characterized. Here, we aimed to analyze genetic variants in crucial tumor suppressors and oncogenes in BOTS (with or without the BRAF V600E mutation), lgOvCa, and hgOvCa in two gene panels using next-generation sequencing. Then, we verified the existence of selected polymorphisms by Sanger sequencing. Finally, Western blot analyses were carried out to check the impact of the selected polymorphisms on the expression of the corresponding proteins. Our study contributes to the molecular characterization of ovarian neoplasms, demonstrating divergent polymorphic patterns pointing to distinct signaling pathways engaged in their development. Certain mutations seem to play an important role in BOTS without the BRAF V600E variant (KRAS) and in lgOvCa (KRAS and NRAS), but not in hgOvCa. Additionally, based on multivariable regression analyses, potential biomarkers in BOTS (PARP1) and hgOvCa (FANCI, BRCA2, TSC2, FANCF) were identified. Noteworthy, for some of the analyzed genes, such as FANCI, FANCD2, and FANCI, FANCF, TSC2, the status of BRCA1/2 and TP53, respectively, turned out to be crucial. Our results shed new light on the similarities and differences in the polymorphic patterns between ovarian tumors of diverse aggressiveness. Furthermore, the biomarkers identified herein are of potential use as predictors of the prognosis and/or response to therapy.

Poly(ADP-Ribose) Polymerase (PARP) Inhibitors for Cancer Therapy: Advances, Challenges, and Future Directions

Poly(ADP-ribose) polymerases (PARPs) are crucial nuclear proteins that play important roles in various cellular processes, including DNA repair, gene transcription, and cell death. Among the 17 identified PARP family members, PARP1 is the most abundant enzyme, with approximately 1-2 million molecules per cell, acting primarily as a DNA damage sensor. It has become a promising biological target for anticancer drug studies. Enhanced PARP expression is present in several types of tumors, such as melanomas, lung cancers, and breast tumors, correlating with low survival outcomes and resistance to treatment. PARP inhibitors, especially newly developed third-generation inhibitors currently undergoing Phase II clinical trials, have shown efficacy as anticancer agents both as single drugs and as sensitizers for chemo- and radiotherapy. This review explores the properties, characteristics, and challenges of PARP inhibitors, discussing their development from first-generation to third-generation compounds, more sustainable synthesis methods for discovery of new anti-cancer agents, their mechanisms of therapeutic action, and their potential for targeting additional biological targets beyond the catalytic active site of PARP proteins. Perspectives on green chemistry methods in the synthesis of new anticancer agents are also discussed.

Olaparib plus trastuzumab in HER2-positive advanced breast cancer patients with germline BRCA1/2 mutations: The OPHELIA phase 2 study

PURPOSE

To evaluate the efficacy and safety of the combination of olaparib plus trastuzumab in patients with HER2-positive advanced breast cancer (ABC) and germinal BRCA mutations (gBRCAm).

METHODS

OPHELIA (NCT03931551) was a single-arm, open-label, phase 2 clinical trial. Patients aged ≥18 years diagnosed with HER2-positive ABC with germinal deleterious mutations in BRCA1 or BRCA2 who had received at least one prior systemic regimen for advanced disease were enrolled. Patients received olaparib plus trastuzumab until disease progression, unacceptable toxicity, or consent withdrawal. The primary endpoint was investigator-assessed clinical benefit rate for at least 24 weeks as per RECIST v.1.1. Key secondary endpoints included overall response rate (ORR) and safety profile.

RESULTS

A total of 68 pre-treated HER2-positive ABC patients were screened. Due to slow accrual the trial was stopped after enrolling 5 patients instead of the planned sample size of 20. Four patients achieved clinical benefit (80.0 %, 95 % CI; 28.4-99.5, p < 0.001) and the primary endpoint was met. The ORR was 60.0 % (95 % CI; 14.7-94.7), including one complete response. Four (80.0 %) patients experienced at least one treatment-related treatment-emergent adverse event (TEAE). Most TEAEs were grade 1 or 2. There were no treatment-related deaths and no new safety signals were identified.

CONCLUSIONS

This study suggests that the combination of olaparib plus trastuzumab may be effective and safe in pre-treated patients with HER2-positive gBRCAm ABC. This ABC patient population should be further studied and not be pre-emptively excluded from clinical trials of targeted therapy for BRCA1/2-driven cancers.

PARP inhibitors in ovarian cancer: Mechanisms, resistance, and the promise of combination therapy

Current approaches to treating ovarian cancer focus mainly on surgical cytoreduction and chemotherapy using platinum-based drugs, while newer methods such as immunotherapy are being investigated to enhance treatment outcomes. Treating ovarian cancer is complicated by challenges such as late-stage detection, tumor diversity, and limited treatment choices. Therefore, innovative strategies such as precision medicine and targeted therapies like PARPi (Poly ADP-Ribose Polymerase inhibitors) are increasingly necessary. The article highlights the significance of an innovative therapeutic approach focusing on PARPi in revolutionizing ovarian cancer treatment and improving patient outcomes. It covers the basic knowledge of PARP, its structure, and its function in DNA repair. It further emphasizes how inhibiting PARP can help in treating ovarian cancer. It elaborates on the mechanism of action of PARPi. It covers the clinical trials governing PARPi and the combination of drugs used with PARPi. It mentions how the resistance is developed to PARPi and the strategies to overcome the resistance developed.

BRCA genetic testing and counseling in breast cancer: how do we meet our patients' needs?

BRCA1 and BRCA2 are tumor suppressor genes that have been linked to inherited susceptibility of breast cancer. Germline BRCA1/2 pathogenic or likely pathogenic variants (gBRCAm) are clinically relevant for treatment selection in breast cancer because they confer sensitivity to poly(ADP-ribose) polymerase (PARP) inhibitors. BRCA1/2 mutation status may also impact decisions on other systemic therapies, risk-reducing measures, and choice of surgery. Consequently, demand for gBRCAm testing has increased. Several barriers to genetic testing exist, including limited access to testing facilities, trained counselors, and psychosocial support, as well as the financial burden of testing. Here, we describe current implications of gBRCAm testing for patients with breast cancer, summarize current approaches to gBRCAm testing, provide potential solutions to support wider adoption of mainstreaming testing practices, and consider future directions of testing.

New target therapies in prostate cancer: from radioligand therapy, to PARP-inhibitors and immunotherapy

Prostate cancer (PCa) remains a significant global health challenge, particularly in its advanced stages. Despite progress in early detection and treatment, PCa is the second most common cancer diagnosis among men. This review aims to provide an overview of current therapeutic approaches and innovations in PCa management, focusing on the latest advancements and ongoing challenges. We conducted a narrative review of clinical trials and research studies, focusing on PARP inhibitors (PARPis), phosphoinositide 3 kinase-protein kinase B inhibitors, immunotherapy, and radioligand therapies (RLTs). Data was sourced from major clinical trial databases and peer-reviewed journals. Androgen deprivation therapy and androgen-receptor pathway inhibitors remain foundational in managing castration-sensitive and early-stage castration-resistant PCa (CRPC). PARPi's, such as olaparib and rucaparib, have emerged as vital treatments for metastatic CRPC with homologous recombination repair gene mutations, highlighting the importance of personalized medicine. Immune checkpoint inhibitors (ICIs) have shown clinical benefit limited to specific subgroups of PCa, demonstrating significant improvement in efficacy in patients with microsatellite instability/mismatch repair or cyclin-dependent kinase 12 alteration, highlighting the importance of focusing ongoing research on identifying and characterizing these subgroups to maximize the clinical benefits of ICIs. RLTs have shown effectiveness in treating mCRPC. Different alpha emitters (like [225Ac]PSMA) and beta emitters compounds (like [177Lu]PSMA) impact treatment differently due to their energy transfer characteristics. Clinical trials like VISION and TheraP have demonstrated positive outcomes with RLT, particularly [177Lu]PSMA-617, leading to FDA approval. Ongoing trials and future perspectives explore the potential of [225Ac]PSMA, aiming to improve outcomes for patients with mCRPC. The landscape of PCa treatment is evolving, with significant advancements in both established and novel therapies. The combination of hormonal therapies, chemotherapy, PARPis, immunotherapy, and RLTs, guided by genetic and molecular insights, opens new possibilities for personalized treatment.

Exploration of poly (ADP-ribose) polymerase inhibitor resistance in the treatment of BRCA1/2-mutated cancer

Breast cancer susceptibility 1/2 (BRCA1/2) genes play a crucial role in DNA damage repair, yet mutations in these genes increase the susceptibility to tumorigenesis. Exploiting the synthetic lethality mechanism between BRCA1/2 mutations and poly(ADP-ribose) polymerase (PARP) inhibition has led to the development and clinical approval of PARP inhibitor (PARPi), representing a milestone in targeted therapy for BRCA1/2 mutant tumors. This approach has paved the way for leveraging synthetic lethality in tumor treatment strategies. Despite the initial success of PARPis, resistance to these agents diminishes their efficacy in BRCA1/2-mutant tumors. Investigations into PARPi resistance have identified replication fork stability and homologous recombination repair as key factors sensitive to PARPis. Additionally, studies suggest that replication gaps may also confer sensitivity to PARPis. Moreover, emerging evidence indicates a correlation between PARPi resistance and cisplatin resistance, suggesting a potential overlap in the mechanisms underlying resistance to both agents. Given these findings, it is imperative to explore the interplay between replication gaps and PARPi resistance, particularly in the context of platinum resistance. Understanding the impact of replication gaps on PARPi resistance may offer insights into novel therapeutic strategies to overcome resistance mechanisms and enhance the efficacy of targeted therapies in BRCA1/2-mutant tumors.

FSP1 inhibition enhances olaparib sensitivity in BRCA-proficient ovarian cancer patients via a nonferroptosis mechanism

Poly ADP-ribose polymerase inhibitors (PARPis) exhibit promising efficacy in patients with BRCA mutations or homologous repair deficiency (HRD) in ovarian cancer (OC). However, less than 40% of patients have HRD, it is vital to expand the indications for PARPis in BRCA-proficient patients. Ferroptosis suppressor protein 1 (FSP1) is a key protein in a newly identified ferroptosis-protective mechanism that occurs in parallel with the GPX4-mediated pathway and is associated with chemoresistance in several cancers. Herein, FSP1 is reported to be negatively correlated with the prognosis in OC patients. Combination therapy comprising olaparib and iFSP1 (a FSP1 inhibitor) strongly inhibited tumour proliferation in BRCA-proficient OC cell lines, patient-derived organoids (PDOs) and xenograft mouse models. Surprisingly, the synergistic killing effect could not be reversed by ferroptosis inhibitors, indicating that mechanisms other than ferroptosis were responsible for the synergistic lethality. In addition, cotreatment was shown to induce increased γH2A.X foci and to impair nonhomologous end joining (NHEJ) activity to a greater extent than did any single drug. Mass spectrometry and immunoprecipitation analyses revealed that FSP1 interacted with Ku70, a classical component recruited to and occupying the end of double-strand breaks (DSBs) in the NHEJ process. FSP1 inhibition decreased Ku70 PARylation, impaired subsequent DNA-PKcs recruitment to the Ku complex at DSB sites and was rescued by restoring PARylation. These findings unprecedentedly reveal a novel role of FSP1 in DNA damage repair and provide new insights into how to sensitize OC patients to PARPi treatment.

Complexity of the Genetic Background of Oncogenesis in Ovarian Cancer-Genetic Instability and Clinical Implications

Ovarian cancer is a leading cause of death among women with gynecological cancers, and is often diagnosed at advanced stages, leading to poor outcomes. This review explores genetic aspects of high-grade serous, endometrioid, and clear-cell ovarian carcinomas, emphasizing personalized treatment approaches. Specific mutations such as TP53 in high-grade serous and BRAF/KRAS in low-grade serous carcinomas highlight the need for tailored therapies. Varying mutation prevalence across subtypes, including BRCA1/2, PTEN, PIK3CA, CTNNB1, and c-myc amplification, offers potential therapeutic targets. This review underscores TP53's pivotal role and advocates p53 immunohistochemical staining for mutational analysis. BRCA1/2 mutations' significance as genetic risk factors and their relevance in PARP inhibitor therapy are discussed, emphasizing the importance of genetic testing. This review also addresses the paradoxical better prognosis linked to KRAS and BRAF mutations in ovarian cancer. ARID1A, PIK3CA, and PTEN alterations in platinum resistance contribute to the genetic landscape. Therapeutic strategies, like restoring WT p53 function and exploring PI3K/AKT/mTOR inhibitors, are considered. The evolving understanding of genetic factors in ovarian carcinomas supports tailored therapeutic approaches based on individual tumor genetic profiles. Ongoing research shows promise for advancing personalized treatments and refining genetic testing in neoplastic diseases, including ovarian cancer. Clinical genetic screening tests can identify women at increased risk, guiding predictive cancer risk-reducing surgery.

Discovery of Tetrahydropyrazolopyrazine Derivatives as Potent and Selective MYT1 Inhibitors for the Treatment of Cancer

Breast and gynecological cancers are among the leading causes of death in women worldwide, illustrating the urgent need for innovative treatment options. We identified MYT1 as a promising new therapeutic target for breast and gynecological cancer using PandaOmics, an AI-driven target discovery platform. The synthetic lethal relationship of MYT1 in tumor cell lines with CCNE1 amplification enhanced this rationale. Through structure-based drug design, we developed a series of novel, potent, and highly selective inhibitors specifically targeting MYT1. Importantly, our lead compound, featuring a tetrahydropyrazolopyrazine ring, exhibits remarkable selectivity over WEE1, a related kinase associated with bone marrow suppression upon inhibition. Optimization of potency and physical properties resulted in the discovery of compound 21, a novel MYT1 inhibitor, exhibiting optimal pharmacokinetic properties and promising in vivo antitumor efficacy.

Novel PARP7 Inhibitors for Treating Cancer

Provided herein are novel PARP7 inhibitors, pharmaceutical compositions, use of such compounds in treating cancer, and processes for preparing such compounds.

Specialty Care and Counselling about Hereditary Cancer Risk Improves Adherence to Cancer Screening and Prevention in Newfoundland and Labrador Patients with BRCA1/2 Pathogenic Variants: A Population-Based Retrospective Cohort Study

Pathogenic variants (PVs) in BRCA1 and BRCA2 increase the lifetime risks of breast and ovarian cancer. Guidelines recommend breast screening (magnetic resonance imaging (MRI) and mammogram) or risk-reducing mastectomy (RRM) and salpingo-oophorectomy (RRSO). We sought to (1) characterize the population of BRCA1/2 PV carriers in Newfoundland and Labrador (NL), (2) evaluate risk-reducing interventions, and (3) identify factors influencing screening and prevention adherence. We conducted a retrospective study from a population-based provincial cohort of BRCA1/2 PV carriers. The eligibility criteria for risk-reducing interventions were defined for each case and patients were categorized based on their level of adherence with recommendations. Chi-squared and regression analyses were used to determine which factors influenced uptake and level of adherence. A total of 276 BRCA1/2 PV carriers were identified; 156 living NL biological females composed the study population. Unaffected females were younger at testing than those with a cancer diagnosis (44.4 years versus 51.7 years; p = 0.002). Categorized by eligibility, 61.0%, 61.6%, 39.0%, and 75.7% of patients underwent MRI, mammogram, RRM, and RRSO, respectively. Individuals with breast cancer were more likely to have RRM (64.7% versus 35.3%; p < 0.001), and those who attended a specialty hereditary cancer clinic were more likely to be adherent to recommendations (73.2% versus 13.4%; p < 0.001) and to undergo RRSO (84.1% versus 15.9%; p < 0.001). Nearly 40% of the female BRCA1/2 PV carriers were not receiving breast surveillance according to evidence-based recommendations. Cancer risk reduction and uptake of breast imaging and prophylactic surgeries are significantly higher in patients who receive dedicated specialty care. Organized hereditary cancer prevention programs will be a valuable component of Canadian healthcare systems and have the potential to reduce the burden of disease countrywide.

A Meta-Analysis of Randomized Clinical Trials Assessing the Efficacy of PARP Inhibitors in Metastatic Castration-Resistant Prostate Cancer

Prostate cancer ranks as the second most common malignancy in males. Prostate cancer progressing on androgen deprivation therapy (ADT) is castration-resistant prostate cancer (CRPC). Poly-ADP ribose polymerase (PARP) inhibitors (PARPis) have been at the forefront of the treatment of CRPC. We aim to better characterize the progression-free survival (PFS) and overall survival (OS) in metastatic CRPC patients treated with PARPis. A systemic review search was conducted using National Clinical Trial (NCT), PubMed, Embase, Scopus, and Central Cochrane Registry. The improvement in overall survival was statistically significant, favoring PARPis (hazard ratio (HR) 0.855; 95% confidence interval (CI) 0.752-0.974; p = 0.018). The improvement in progression-free survival was also statistically significant, with results favoring PARPis (HR 0.626; 95%CI 0.566-0.692; p = 0.000). In a subgroup analysis, similar results were observed where the efficacy of PARPis was evaluated in a subgroup of patients without homologous recombination repair (HRR) gene mutation, which showed improvement in PFS favoring PARPis (HR 0.747; 95%CI 0.0.637-0.877; p = 0.000). Our meta-analysis of seven RCTs showed that PARPis significantly increased PFS and OS when used with or without antihormonal agents like abiraterone or enzalutamide.

The Complex Network of ADP-Ribosylation and DNA Repair: Emerging Insights and Implications for Cancer Therapy

ADP-ribosylation is a post-translational modification of proteins that plays a key role in various cellular processes, including DNA repair. Recently, significant progress has been made in understanding the mechanism and function of ADP-ribosylation in DNA repair. ADP-ribosylation can regulate the recruitment and activity of DNA repair proteins by facilitating protein-protein interactions and regulating protein conformations. Moreover, ADP-ribosylation can influence additional post-translational modifications (PTMs) of proteins involved in DNA repair, such as ubiquitination, methylation, acetylation, phosphorylation, and SUMOylation. The interaction between ADP-ribosylation and these additional PTMs can fine-tune the activity of DNA repair proteins and ensure the proper execution of the DNA repair process. In addition, PARP inhibitors have been developed as a promising cancer therapeutic strategy by exploiting the dependence of certain cancer types on the PARP-mediated DNA repair pathway. In this paper, we review the progress of ADP-ribosylation in DNA repair, discuss the crosstalk of ADP-ribosylation with additional PTMs in DNA repair, and summarize the progress of PARP inhibitors in cancer therapy.

The role of inflammatory factors and T-cell subsets in the diagnosis of recurrence in epithelial ovarian cancer patients and the effect of olaparin treatment on them

BACKGROUND

The aim of the study is to investigate the role of serum inflammatory factors and T-cell subsets in the diagnosis of recurrence in epithelial ovarian cancer patients and the effect of olaparib on inflammatory factor and T-lymphocyte subsets in patients with recurrent epithelial ovarian cancer.

METHODS

In this study, 100 patients diagnosed as recurrent epithelial ovarian cancer in our hospital and 100 patients without recurrent epithelial ovarian cancer in the same period were selected. According to the treatment plan, the recurrent patients were divided into conventional therapy group (Paclitaxel and Carboplatin) and combined therapy group (Paclitaxel, Carboplatin, and olaparib). The levels of serum inflammatory factors were evaluated by enzyme-linked immunosorbent assay. The peripheral blood T-lymphocyte subsets in each group were detected by flow cytometry.

RESULTS

Compared with nonrecurrent patients, recurrent patients have higher serum interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) levels (p < .05), and lower interferon-γ (IFN-γ) level and the CD4+/CD8+ ratio. After adjusting for confounding factors, the results showed that the serum IL-6, IFN-γ, and TNF-α levels were influencing factors of recurrence in epithelial ovarian cancer patients. The area under the receiver operating curve and the sensitivity of serum TNF-α in predicting ovarian cancer recurrence were higher than those of IL-6 and IFN-γ. After secondary chemotherapy and/or olaparib maintenance treatment, the IL-6 (p < .001) and TNF-α (p < .001) levels in combined therapy group were lower than those in the conventional therapy, whereas the IFN-γ level (p < .001), the CD4+ T-cell proportion (p = .0069) and the CD4+/CD8+ ratio (p = .0201) were higher than those in the conventional therapy.

CONCLUSION

The serum IL-6, TNF-α, and IFN-γ levels were closely related to the recurrence of ovarian cancer. Olaparib maintenance treatment can significantly decrease the IL-6 and TNF-α level, and increase IFN-γ level and the CD4+/CD8+ ratio in patients with recurrent ovarian cancer.