PARP Inhibitors and the Evolving Landscape of Ovarian Cancer Management: A Review

Thromboembolic risk in prostate cancer patients treated with PARP inhibitors: A systematic review and meta-analysis

BACKGROUND

Poly (ADP-ribose) polymerase inhibitors (PARPi) have been associated with thrombotic events, although the association with thrombosis risk in different cancers remains poorly defined.

METHODS

This meta-analysis included phase II and phase III clinical trials in which patients with metastatic prostate cancer were treated with PARPi either as monotherapy or in combination. The primary endpoints were the rates of thromboembolic events in prostate cancer patients.

RESULTS

A total of 2210 and 1662 patients with prostate cancer were compared in the PARP inhibitor and control groups, respectively. 96 (4.3 %) and 37 (2.2 %) patients had thrombosis in the PARPi and control groups, respectively. PARPi had a statistically significant increased risk of thrombosis in prostate cancer patients (Odds Ratio (OR)=1.98, 95 % CI: 1.06-3.70, P=0.030).

CONCLUSION

The heightened thrombotic risk associated with PARPi treatment in prostate cancer emphasizes the need for comprehensive management protocols to effectively reduce the risk and ensure safer outcomes.

Improving olaparib exposure to optimize adverse effects management

Background

Olaparib is an inhibitor of the human poly-(ADP-ribose)-polymerase enzymes (PARP1/2) needed to repair single-strand DNA breaks. It is used in breast, ovarian, prostate and pancreatic cancer.

Objectives

This work aimed to describe the pharmacokinetics/pharmacodynamics (PK/PD) relationship between olaparib plasma concentrations and common adverse effects (i.e. anaemia and hypercreatininaemia), in a real-life setting, to propose a target concentration for therapeutic drug monitoring.

Methods

Two PK/PD models describing the evolution of haemoglobinaemia and creatininaemia as a function of time were developed, based on data from, respectively, 38 and 37 patients receiving olaparib. The final model estimates were used to calculate the incidence of anaemia and creatinine increase according to plasma trough concentrations for 1000 virtual subjects to define target exposure.

Results

The final models correctly described the temporal evolution of haemoglobinaemia and creatininaemia for all patients. The haemoglobinaemia PK/PD model is inspired by Friberg's model, and the creatininaemia PK/PD model is an indirect response model. Model parameters were in agreement with physiological values and close to literature values for similar models. The mean (population) plasma haemoglobin concentration at treatment initiation, as estimated by the model, was 11.62 g/dL, while creatinine concentration was 71.91 µmol/L. Using simulations, we have identified a target trough concentration of 3500-4000 ng/mL, above which more than 20% of patients would report grade ≥3 anaemia.

Conclusion

Based on real-world data, we were able to properly describe the time course of haemoglobinaemia and plasma creatininaemia during olaparib treatment.

Paradigm Shift: A Comprehensive Review of Ovarian Cancer Management in an Era of Advancements

Ovarian cancer (OC) is the female genital malignancy with the highest lethality. Patients present a poor prognosis mainly due to the late clinical presentation allied with the common acquisition of chemoresistance and a high rate of tumour recurrence. Effective screening, accurate diagnosis, and personalised multidisciplinary treatments are crucial for improving patients' survival and quality of life. This comprehensive narrative review aims to describe the current knowledge on the aetiology, prevention, diagnosis, and treatment of OC, highlighting the latest significant advancements and future directions. Traditionally, OC treatment involves the combination of cytoreductive surgery and platinum-based chemotherapy. Although more therapeutical approaches have been developed, the lack of established predictive biomarkers to guide disease management has led to only marginal improvements in progression-free survival (PFS) while patients face an increasing level of toxicity. Fortunately, because of a better overall understanding of ovarian tumourigenesis and advancements in the disease's (epi)genetic and molecular profiling, a paradigm shift has emerged with the identification of new disease biomarkers and the proposal of targeted therapeutic approaches to postpone disease recurrence and decrease side effects, while increasing patients' survival. Despite this progress, several challenges in disease management, including disease heterogeneity and drug resistance, still need to be overcome.

Cost-effectiveness of poly-(ADP-ribose) polymerase (PARP)-inhibitors for the maintenance treatment after responding to first- and second-line chemotherapy in advanced ovarian cancer

The introduction of inhibitors of poly-(ADP-ribose) polymerase (PARP) for the treatment of women with epithelial ovarian cancers (EOC) has radically changed the treatment in maintenance setting after responding to first- and second-line chemotherapy. The aim of this paper was to assess the pharmacological costs of PARP inhibitors (olaparib, niraparib, rucaparib and veliparib) in maintenance treatment after responding to first-line chemotherapy in EOC. Incremental cost-effectiveness ratio (ICER) was calculated as the ratio between the difference of the costs in the intervention and in the control groups (pharmacy costs) and the difference between the effect in the intervention and in the control groups (progression-free survival (PFS)). We have considered the pivotal phase III randomized controlled trials (RCTs). Three different populations were considered: the overall population, patients with germline BRCA mutation (gBRCA) and homologous recombination deficiency (HRD) patients non-gBRCA mutation. Three thousand four hundred and twenty patients and 1209 patients were considered in maintenance treatment after responding to first- and second-line chemotherapy in EOC, respectively. At the actual price, the treatment with PARP inhibitors is not cost-effective in maintenance treatment after responding to first-line and second-line chemotherapy in EOC. A reduction in pharmacological costs is mandatory.

Deep learning magnetic resonance imaging predicts platinum sensitivity in patients with epithelial ovarian cancer

Objective

The aim of the study is to develop and validate a deep learning model to predict the platinum sensitivity of patients with epithelial ovarian cancer (EOC) based on contrast-enhanced magnetic resonance imaging (MRI).

Methods

In this retrospective study, 93 patients with EOC who received platinum-based chemotherapy (≥4 cycles) and debulking surgery at the Sun Yat-sen Memorial Hospital from January 2011 to January 2020 were enrolled and randomly assigned to the training and validation cohorts (2:1). Two different models were built based on either the primary tumor or whole volume of the abdomen as the volume of interest (VOI) within the same cohorts, and then a pre-trained convolutional neural network Med3D (Resnet 10 version) was transferred to automatically extract 1,024 features from two MRI sequences (CE-T1WI and T2WI) of each patient to predict platinum sensitivity. The performance of the two models was compared.

Results

A total of 93 women (mean age, 50.5 years ± 10.5 [standard deviation]) were evaluated (62 in the training cohort and 31 in the validation cohort). The AUCs of the whole abdomen model were 0.97 and 0.98 for the training and validation cohorts, respectively, which was better than the primary tumor model (AUCs of 0.88 and 0.81 in the training and validation cohorts, respectively). In k-fold cross-validation and stratified analysis, the whole abdomen model maintained a stable performance, and the decision function value generated by the model was a prognostic indicator that successfully discriminates high- and low-risk recurrence patients.

Conclusion

The non-manually segmented whole-abdomen deep learning model based on MRI exhibited satisfactory predictive performance for platinum sensitivity and may assist gynecologists in making optimal treatment decisions.

CT imaging phenotypes linked to CA125 and HE4 biomarkers are highly predictive in discriminating between hereditary and sporadic ovarian cancer patients

BACKGROUND: Hereditary ovarian cancers (HOC) represent about 23% of ovarian cancer (OC) cases: they are most frequently related to germline mutations in the BRCA genes. OBJECTIVE: We aimed to compare CA125/HE4 serum levels and Computed Tomography (CT) features at time of ovarian cancer (OC) diagnosis in two populations: BRCA mutant and BRCA wild-type (WT) OC, and to investigate the relationship between this laboratory and radiological biomarker and BRCA mutation status. METHODS: This retrospective study included 60 newly diagnosed OC patients with FIGO stage IIIC-IV disease, tested for BRCA1/2 germline mutation status of which preoperative CT scan and serum tumor marker assay were available. RESULTS: The median level of CA125 (708 U/mL) was significantly higher (p < 0.002) in BRCA1/2 mutated patients than in WT patients (176 U/mL), whereas the median level of HE4 (492 pmol/L) was significantly higher (p < 0.002) in WT than in BRCA-mutated patients (252 pmol/L). BRCA mutation carriers showed a higher incidence of bilateral ovarian masses (p = 0.0303) characterized by solid structures (p < 0.00001), higher peritoneal tumor load, macronodular implants >2 cm (p = 0.000099), increased frequency of lymphadenopathies (p = 0.019), and metastasis (p = 0.052) compared to patients with BRCA WT. CONCLUSIONS: Tumor markers and CT patterns may help in identifying BRCA mutation status in OC directing patients towards a personalized treatment.

An effective AKT inhibitor-PARP inhibitor combination therapy for recurrent ovarian cancer

BACKGROUND

Although the use of PARP inhibitor has received considerable amount of attention in ovarian cancer, PARP inhibitor resistance still emerges with disease progression. PI3K/AKT pathway inhibitors have been proposed to synergize with PARP inhibition to slow tumor growth, but the exact molecular mechanisms are still elusive.

METHODS

Utilizing tumor samples from recurrent EOC patients with platinum resistance and prior PARP inhibitor use, Mini PDX and PDX models were established to study the anti-tumor effect of AKT inhibitor (LAE003) and LAE003/PARP inhibitor (Olaparib) in combination. Five ovarian cancer cell lines were treated with Olaparib or LAE003 or in combination in vitro. Cell viability and apoptosis rate were measured after the treatments. Combination index by the Chou-Talalay was used to evaluate in vitro combination effect of Olaparib and LAE003. The protein expression level of PARP1 and PAR was measured by Western blot in cell lines and by immunohistochemistry in PDX tumor tissues.

RESULTS

Tumor cells from two out of five platinum-resistant ovarian cancer patients previously treated with PARP inhibitor were sensitive to AKT inhibition in Mini-PDX study. Inhibition of AKT further increased the response of tumor cells to Olaparib in a PDX model derived from a recurrent platinum-resistant ovarian cancer patient. Additive anti-proliferation effect of LAE003 and Olaparib was also observed in three ovarian cancer cell lines with high PARP1 protein level. Interestingly, mechanism study revealed that AKT inhibition decreased PARP enzyme activity as measured by PAR level and/or reduced PARP1 protein level in the tumor cell lines and PDX tumor tissues, which may explain the observed combined anti-tumor effect of LAE003 and Olaparib.

CONCLUSION

Collectively, our results suggest that the combination of AKT inhibitor and PARP inhibitor could be a viable approach for clinical testing in recurrent ovarian cancer patients.

Pharmacokinetics and Pharmacodynamics of PARP Inhibitors in Oncology

Olaparib, niraparib, rucaparib, and talazoparib are poly (ADP-ribose) polymerase (PARP) inhibitors approved for the treatment of ovarian, breast, pancreatic, and/or prostate cancer. Poly (ADP-ribose) polymerase inhibitors are potent inhibitors of the PARP enzymes with comparable half-maximal inhibitory concentrations in the nanomolar range. Olaparib and rucaparib are orally dosed twice a day, extensively metabolized by cytochrome P450 enzymes, and inhibitors of several enzymes and drug transporters with a high risk for drug-drug interactions. Niraparib and talazoparib are orally dosed once a day with a lower risk for niraparib and a minimal risk for talazoparib to cause drug-drug interactions. All four PARP inhibitors show moderate-to-high interindividual variability in plasma exposure. Higher exposure is associated with an increase in toxicity, mostly hematological toxicity. For talazoparib, exposure-efficacy relationships have been described, but for olaparib, niraparib, and rucaparib this relationship remains inconclusive. Further studies are required to investigate exposure-response relationships to improve dosing of PARP inhibitors, in which therapeutic drug monitoring could play an important role. In this review, we give an overview of the pharmacokinetic properties of the four PARP inhibitors, including considerations for patients with renal dysfunction or hepatic impairment, the effect of food, and drug-drug interactions. Furthermore, we focus on the pharmacodynamics and summarize the available exposure-efficacy and exposure-toxicity relationships.

Hepatic Hilar Lymph Node Resection in Cytoreductive Surgery for Advanced Ovarian Cancer: A Necessity or Not?

Objective

This review aims to clarify the necessity of hepatic hilar lymph node resection on advanced ovarian cancer patients.

Background

PARP inhibitors and surgery have significantly improved the survival of patients with ovarian cancer. However, for patients with advanced ovarian cancer, there are often extensive epigastric disseminated metastatic lesions, especially the lymph nodes in the hepatic hilar area. Because of the complicated anatomical relationship and lack of experience in this area, this is easily ignored by gynecological oncologists.

Methods

Through the retrieval and analysis of the current database, namely PubMed, Medline, Web of Science, EMBASE, Cochrane Library, and Wangfang, etc., the literature regarding this topic published before March 2021 were thoroughly investigated.

Conclusion

For the hepatic hilar regional lymph node surgery, through careful preoperative evaluation, surgical-indication clarification, appropriate case selection, standardized surgical operations and multidisciplinary cooperation with general surgeons, the prognosis of patients is significantly improved. Postoperative complications are also safe and controllable and convincing. To conclude, the application of hilar region lymph node cytoreductive surgery for patients with advanced ovarian cancer is a feasible and preferred choice.

Real-world treatment patterns and outcomes in platinum-sensitive recurrent high-grade serous ovarian cancer patients

Aim: To describe the overall cancer-related healthcare utilization patterns, treatment patterns and outcomes in women diagnosed with platinum-sensitive recurrent high-grade serous ovarian cancer. Patients & methods: Subanalysis of the Spanish sample of a retrospective, noninterventional, multinational, observational study. Results: BRCA-mutated patients had better outcomes in terms of progression-free survival and overall survival than patients who were BRCA wild-type. It was observed that patients' treatment outcomes after the first recurrence progressively worsened as the patient underwent subsequent chemotherapy lines. Healthcare resource utilization when accounting for the follow-up time did not substantially differ between BRCA1/2-mutated and BRCA wild-type patients. Conclusion: BRCA1/2 mutation carriers have better treatment outcomes, including longer survival, without a negative impact on the use of healthcare resources.

Olaparib: A Review as First-Line Maintenance Therapy in Advanced Ovarian Cancer

Olaparib (Lynparza^®) is a poly (adenosine diphosphate-ribose) polymerase (PARP) inhibitor approved for first-line maintenance treatment in adults with advanced ovarian cancer who are in complete or partial response to first-line, platinum-based chemotherapy. Originally approved as monotherapy, olaparib is also approved to be administered in combination with bevacizumab in patients whose cancer is associated with homologous recombination deficiency (HRD), defined by either a BRCA1/2 mutation and/or genomic instability. In phase III trials, olaparib monotherapy significantly improved progression-free survival (PFS) relative to placebo (SOLO-1), as did olaparib plus bevacizumab relative to placebo plus bevacizumab (PAOLA-1), in patients with advanced ovarian cancer who had responded to platinum-based chemotherapy. In PAOLA-1, improvements in PFS with olaparib plus bevacizumab were not seen in patients with HRD-negative tumours relative to placebo plus bevacizumab. Both olaparib monotherapy and olaparib in combination with bevacizumab had generally manageable tolerability profiles. Olaparib, alone or in combination with bevacizumab, is a useful option for the first-line maintenance treatment of adults with HRD-positive, advanced epithelial ovarian, fallopian tube or primary peritoneal cancer who are in complete or partial response to first-line, platinum-based chemotherapy.

Molecular pathogenesis of hereditary lung cancer: a literature review

Among all cancer types, pulmonary cancer has the highest mortality rate. Tobacco consumption remains the major risk factor for the development of lung cancer. However, many studies revealed a correlation between inherited genetic variants and predisposition to lung cancer, especially in nonsmokers. To date, genetic testing for the detection of germline mutations is not yet recommended in patients with lung cancer and testing is focused on somatic alterations given their implication in the treatment choice. Understanding the impact of genetic predisposition on the occurrence of lung cancer is essential to enable the introduction of accurate guidelines and recommendations that might reduce mortality. In this review paper, we describe familial lung cancer, and expose germline mutations that are linked to this type of cancer. We also report pathogenic genetic variants linked to syndromes associated with lung cancer.

Cytocidal Antitumor Effects against Human Ovarian Cancer Cells Induced by B-Lactam Steroid Alkylators with Targeted Activity against Poly (ADP-Ribose) Polymerase (PARP) Enzymes in a Cell-Free Assay

We evaluated three newly synthesized B-lactam hybrid homo-aza-steroidal alkylators (ASA-A, ASA-B and ASA-C) for their PARP1/2 inhibition activity and their DNA damaging effect against human ovarian carcinoma cells. These agents are conjugated with an alkylating component (POPA), which also served as a reference molecule (positive control), and were tested against four human ovarian cell lines in vitro (UWB1.289 + BRCA1, UWB1.289, SKOV-3 and OVCAR-3). The studied compounds were thereafter compared to 3-AB, a known PARP inhibitor, as well as to Olaparib, a standard third-generation PARP inhibitor, on a PARP assay investigating their inhibitory potential. Finally, a PARP1 and PARP2 mRNA expression analysis by qRT-PCR was produced in order to measure the absolute and the relative gene expression (in mRNA transcripts) between treated and untreated cells. All the investigated hybrid steroid alkylators and POPA decreased in vitro cell growth differentially, according to the sensitivity and different gene characteristics of each cell line, while ASA-A and ASA-B presented the most significant anticancer activity. Both these compounds induced PARP1/2 enzyme inhibition, DNA damage (alkylation) and upregulation of PARP mRNA expression, for all tested cell lines. However, ASA-C underperformed on average in the above tasks, while the compound ASA-B induced synthetic lethality effects on the ovarian cancer cells. Nevertheless, the overall outcome, leading to a drug-like potential, provides strong evidence toward further evaluation.

The developmental origin of cancers defines basic principles of cisplatin resistance

Cisplatin-based chemotherapy has been used for more than four decades as a standard therapeutic option in several tumor entities. However, being a multifaceted and heterogeneous phenomenon, inherent or acquired resistance to cisplatin remains a major obstacle during the treatment of several solid malignancies and inevitably results in disease progression. Hence, we felt there was an urgent need to evaluate common mechanisms between multifarious cancer entities to identify patient-specific therapeutic strategies. We found joint molecular and (epi)genetic resistance mechanisms and specific cisplatin-induced mutational signatures that depended on the developmental origin (endo-, meso-, ectoderm) of the tumor tissue. Based on the findings of thirteen tumor entities, we identified three resistance groups, where Group 1 (endodermal origin) prominently indicates NRF2-pathway activation, Group 2 (mesodermal origin, primordial germ cells) shares elevated DNA repair mechanisms and decreased apoptosis induction, and Group 3 (ectodermal and paraxial mesodermal origin) commonly presents deregulated apoptosis induction and alternating pathways as the main cisplatin-induced resistance mechanisms. This review further proposes potential and novel therapeutic strategies to improve the outcome of cisplatin-based chemotherapy.

Deregulation of Exo70 Facilitates Innate and Acquired Cisplatin Resistance in Epithelial Ovarian Cancer by Promoting Cisplatin Efflux

Simple Summary

Innate and acquired platinum resistance are the leading causes of epithelial ovarian cancer (EOC) mortality. However, the mechanisms remain elusive. Here we found that Exo70, a key subunit of the exocyst, is upregulated in EOC and promotes cisplatin efflux to facilitate innate resistance. More interestingly, cisplatin could downregulate Exo70 to sustain cell sensitivity. However, this function was hampered during prolonged cisplatin treatment, which in turn stabilized Exo70 to facilitate the acquired cisplatin resistance of EOC cells. Our study potentiates Exo70 as a promising target to overcome cisplatin resistance in EOC.

Abstract

Whilst researches elucidating a diversity of intracellular mechanisms, platinum-resistant epithelial ovarian cancer (EOC) remains a major challenge in the treatment of ovarian cancer. Here we report that Exo70, a key subunit of the exocyst complex, contributes to both innate and acquired cisplatin resistance of EOC. Upregulation of Exo70 is observed in EOC tissues and is related to platinum resistance and progression-free survival of EOC patients. Exo70 suppressed the cisplatin sensitivity of EOC cells through promoting exocytosis-mediated efflux of cisplatin. Moreover, cisplatin-induced autophagy-lysosomal degradation of Exo70 protein by modulating phosphorylation of AMPK and mTOR, thereby reducing the cellular resistance. However, the function was hampered during prolonged cisplatin treatment, which in turn stabilized Exo70 to facilitate the acquired cisplatin resistance of EOC cells. Knockdown of Exo70, or inhibiting exocytosis by Exo70 inhibitor Endosidin2, reversed the cisplatin resistance of EOC cells both in vitro and in vivo. Our results suggest that Exo70 overexpression and excessive stability contribute to innate and acquired cisplatin resistance through the increase in cisplatin efflux, and targeting Exo70 might be an approach to overcome cisplatin resistance in EOC treatment.

PARP Power: A Structural Perspective on PARP1, PARP2, and PARP3 in DNA Damage Repair and Nucleosome Remodelling

Poly (ADP-ribose) polymerases (PARP) 1-3 are well-known multi-domain enzymes, catalysing the covalent modification of proteins, DNA, and themselves. They attach mono- or poly-ADP-ribose to targets using NAD⁺ as a substrate. Poly-ADP-ribosylation (PARylation) is central to the important functions of PARP enzymes in the DNA damage response and nucleosome remodelling. Activation of PARP happens through DNA binding via zinc fingers and/or the WGR domain. Modulation of their activity using PARP inhibitors occupying the NAD⁺ binding site has proven successful in cancer therapies. For decades, studies set out to elucidate their full-length molecular structure and activation mechanism. In the last five years, significant advances have progressed the structural and functional understanding of PARP1-3, such as understanding allosteric activation via inter-domain contacts, how PARP senses damaged DNA in the crowded nucleus, and the complementary role of histone PARylation factor 1 in modulating the active site of PARP. Here, we review these advances together with the versatility of PARP domains involved in DNA binding, the targets and shape of PARylation and the role of PARPs in nucleosome remodelling.

Role of hsa‑miR‑105 during the pathogenesis of paclitaxel resistance and its clinical implication in ovarian cancer

More than 70% of patients with epithelial ovarian cancer (EOC), one of the leading cause of gynecological cancer-related deaths worldwide, are diagnosed at an advanced stage of the disease. Currently, the mainstay for treatment of advanced EOC is tumor debulking surgery followed by combined platinum- and paclitaxel (PTX)-based chemotherapy. However, most patients eventually develop chemoresistance, which remains a major obstacle to successful treatment. Herein, by using clinical specimens and experimentally induced cell models, we found that the expression levels of hsa-miR-105 were significantly decreased in PTX-resistant EOC tissues and cell lines. Follow-up functional experiments demonstrated that repression of hsa-miR-105 conferred resistance to paclitaxel in EOC cells, whereas restoration of hsa-miR-105 expression in situ via intratumoral injection of hsa-miR-105 micrON™ agomir potentiated in vivo sensitivity to PTX and thereafter significantly inhibited tumor growth in a PTX-challenged xenograft model. Mechanistically, hsa-miR-105 exerted its tumor suppressor function by directly inhibiting the zinc and ring finger 2 (ZNRF2) signaling pathway. Importantly, aberrant expression of hsa-miR-105 in both tumor and circulating samples predicted a poor post-chemotherapy prognosis in EOC patients. These findings collectively suggest that hsa-miR-105 may act as a potent tumor suppressor miRNA during the progression of EOC, likely affecting cell proliferation, invasiveness and chemosensitivity to PTX, and functioning at least in part via inhibition of ZNRF2 signaling. The stability and availability and ease in measurement of circulating hsa-miR-105 make it a valuable diagnostic/prognostic biomarker candidate for chemotherapy of EOC.

Long-Term Follow-Up of a Female Patient Treated with Olaparib-Hope for a Long Life without Relapse?

Ovarian cancer is one of the most common cancers of the reproductive organs. As there are no symptoms in the early stages, it is mainly detected in the advanced stages. Even then, the symptoms are non-specific and include, for example, abdominal pain, early satiety, or changes in bowel habits. Both biochemical marker levels and imaging studies are used in the initial diagnosis. However, it should be emphasized that they are not characterized by high specificity. Treatment is multistage, and usually first-line debulking surgery is used followed by platinum-based chemotherapy. Here we present a clinical case of a 56-year-old female, a carrier of a mutation in the BRCA1 gene, with a history of breast cancer and with recurrent epithelial ovarian cancer. The patient was qualified for treatment with a PARP inhibitor and is currently undergoing treatment with olaparib. In the patient’s follow up of 50 months to date, there has been no recurrence of cancer. Few side effects have been observed, and the most serious one that can be effectively treated is anemia. On the basis of the described case, the authors concluded that olaparib treatment is effective, relatively safe, and does not significantly affect daily functioning.

Revisiting chemoresistance in ovarian cancer: Mechanism, biomarkers, and precision medicine

Among the gynecological cancers, ovarian cancer is the most lethal. Its therapeutic options include a combination of chemotherapy with platinum-based compounds and cytoreductive surgery. Most ovarian cancer patients exhibit an initial response to platinum-based therapy, however, platinum resistance has led to up to 80% of this responsive cohort becoming refractory. Ovarian cancer recurrence and drug resistance to current chemotherapeutic options is a global challenge. Chemo-resistance is a complex phenomenon that involves multiple genes and signal transduction pathways. Therefore, it is important to elucidate on the underlying molecular mechanisms involved in chemo-resistance. This inform decisions regarding therapeutic management and help in the identification of novel and effective drug targets. Studies have documented the individual biomarkers of platinum-resistance in ovarian cancer that are potential therapeutic targets. This review summarizes the molecular mechanisms of platinum resistance in ovarian cancer, novel drug targets, and clinical outcomes.

The efficacy and toxicity of angiogenesis inhibitors for ovarian cancer: a meta-analysis of randomized controlled trials

PURPOSE

To evaluate the efficacy and toxicity of angiogenesis inhibitors for the treatment of ovarian cancer patients, we conducted a meta-analysis of the published literature on this subject.

METHODS

In this meta-analysis, we searched PubMed, EMBASE, Web of Science, and Cochrane Library databases for randomized controlled trials (RCTs). The literature search was performed up to August 12, 2019. The risk of bias of the included studies was evaluated using The Cochrane Collaboration's tool, and the statistical analyses were performed using RevMan 5.3 software. The sensitivity analysis was performed with Stata 12.0 software.

RESULTS

22 RCTs with 11,254 patients were included. Our meta-analysis demonstrates that angiogenesis inhibitors therapy can significantly improve progression-free survival (PFS) (hazard ratio [HR] 0.71, 95% CI 0.63-0.79, I² = 80%, P < 0.00001) and overall survival (OS) (HR 0.95, 95% CI 0.90-0.99, I² = 0%, P = 0.03) in ovarian cancer patients. The subgroups results suggest differences in the benefit in OS in first-line treatment (HR 1.00, 95% CI 0.93-1.08, I² = 0%, P = 0.90) compared with treatment at relapse (HR 0.87, 95% CI 0.81-0.95, I² = 0%, P = 0.0008). The PFS improved both in first-line treatment (HR 0.87, 95% CI 0.79-0.95, I² = 60%, P = 0.003) and recurrent treatment (HR 0.60, 95% CI 0.53-0.67, I² = 57% P < 0.0001) patients. The PFS and OS in recurrent group were prolonged both in the platinum-resistant group(PFS: HR 0.50, 95% CI 0.42-0.60, I² = 0%, P < 0.00001; OS: HR 0.76, 95% CI 0.62-0.93, I² = 0%, P = 0.007) and the platinum-sensitive group (PFS: HR 0.58, 95% CI 0.49-0.69, I² = 64%, P < 0.00001; OS: HR 0.88, 95% CI 0.79-0.99, I² = 0%, P = 0.03). However, this therapy is associated with a higher risk of common adverse events of grade ≥ 3 (risk ratio [RR]: 1.12; 95% CI 1.07-1.17; I² = 0%, P = 0.68) such as arterial thromboembolic disease, ascites, diarrhea, gastrointestinal perforations, headache, hemorrhagic, hypertension, hypokalemia, leucopenia, pain, proteinuria, thrombocytopenia, and thrombosis or embolism.

CONCLUSION

This meta-analysis suggests angiogenesis inhibitors may significantly improve PFS and OS of ovarian cancer patients and increase the incidence of common adverse events.

Surgical and Systemic Treatment of Hereditary Breast Cancer: A Mini-Review With a Focus on BRCA1 and BRCA2 Mutations

Hereditary breast cancer accounts for 5%-10% of breast cancer cases. The majority of familial cases have been linked to germline mutations in BRCA1 and BRCA2 genes, though other high penetrance susceptibility genes have also been identified through genomic testing advances. Optimal surgical treatment for these patients, who are of a younger age, has several challenges as it usually involves aggressive therapeutic and risk reducing interventions. At the same time, the therapeutic armamentarium for BRCA1/2 mutation carriers apart from platinum salts, has been enriched with the addition of poly-ADP ribose polymerase (PARP) inhibitors with promising outcomes. In this review we provide a succinct and comprehensive overview of the surgical and systemic treatment options for patients with BRCA1/2 mutation related breast cancer and an update on the most recent systemic treatment advances.

Ovarian cancer predisposition beyond BRCA1 and BRCA2 genes

Several genes associated with hereditary ovarian cancer have been discovered as a result of the work done with next generation sequencing. It is estimated that approximately 23% of ovarian carcinomas have a hereditary predisposition. The most common hereditary condition is represented by germline mutations in BRCA1 or BRCA2 genes that account for 20-25% of high grade serous ovarian cancer. A number of other hereditary ovarian cancers are associated with different genes, with a crucial role in the DNA damage response pathway, such as the mismatch repair genes in Lynch syndrome, TP53 in Li-Fraumeni syndrome, STK11 in Peutz-Jeghers syndrome, CHEK2, RAD51, BRIP1, and PALB2. The goal of this manuscript is to summarize the published data regarding the molecular pathways involved in the pathogenesis of non-BRCA related hereditary ovarian cancer and to provide a tool that might be useful in discussing risk assessment, genetic testing, prevention strategies, as well as clinical and therapeutic implications for patients with ovarian cancer.

Role of the pathologist in assessing response to treatment of ovarian and endometrial cancers

Standardisation of pathological evaluation of tissue responses to therapy permits robust stratification of patient outcomes for management decisions and allows comparison of results across clinical trials. In gynaecological pathology there are two major areas where pathological assessment of treatment response is currently used to determine ongoing therapy. High-grade serous carcinoma (HGSC) of tubo-ovarian origin frequently presents as high-stage disease and may be managed by neoadjuvant chemotherapy with debulking surgery. The chemotherapy response score (CRS) is a reproducible, validated three-tiered morphological scoring system to assess the response of HGSC to treatment. Interobserver agreement is shown to be substantial following online training, and women with CRS3 have significantly improved progression-free and overall survival. Low-grade endometrioid endometrial cancer and atypical hyperplasia/endometrioid intraepithelial neoplasia may be managed by progestogenic therapy in women who wish to preserve fertility or for whom medical co-morbidities preclude surgical management. The response to treatment is assessed histologically in successive endometrial biopsies. The histological parameters are well described, but the pathological classification of treatment response is still under development. Pathological assessment of the response to treatment is incorporated into clinical guidelines.

A Proof of Concept for Biomarker-Guided Targeted Therapy against Ovarian Cancer Based on Patient-Derived Tumor Xenografts

Advanced ovarian cancers are a leading cause of cancer-related death in women and are currently treated with surgery and chemotherapy. This standard of care is often temporarily successful but exhibits a high rate of relapse, after which, treatment options are few. Here we investigate whether biomarker-guided use of multiple targeted therapies, including small molecules and antibody-drug conjugates, is a viable alternative. A panel of patient-derived ovarian cancer xenografts (PDX), similar in genetics and chemotherapy responsiveness to human tumors, was exposed to 21 monotherapies and combination therapies. Three monotherapies and one combination were found to be active in different subsets of PDX. Analysis of gene expression data identified biomarkers associated with responsiveness to each of the three targeted therapies, none of which directly inhibits an oncogenic driver. While no single treatment had as high a response rate as chemotherapy, nearly 90% of PDXs were eligible for and responded to at least one biomarker-guided treatment, including tumors resistant to standard chemotherapy. The distribution of biomarker positivity in The Cancer Genome Atlas data suggests the potential for a similar precision approach in human patients. SIGNIFICANCE: This study exploits a panel of patient-derived xenografts to demonstrate that most ovarian tumors can be matched to effective biomarker-guided treatments.

Identification of ovarian high-grade serous carcinoma cell lines that show estrogen-sensitive growth as xenografts in immunocompromised mice

Ovarian cancer remains a significant challenge in women worldwide. Tumors of the high-grade serous carcinoma (HGSC) type represent the most common form of the disease. Development of new therapies for HGSC has been hampered by a paucity of preclinical models in which new drugs could be tested for target engagement and anti-tumor efficacy. Here, we systematically assessed in vivo growth of ovarian cancer cells, including six validated HGSC cell lines, in highly immunocompromised NSG mice by varying the injection site. We found that, with the exception of OVCAR3, HGSC cell lines COV318, COV362, KURAMOCHI, OVCAR4, and OVSAHO, generally demonstrate poor growth as either subcutaneous or intraperitoneal xenografts. Intrabursal injections performed with KURAMOCHI and COV362 cells did not improve tumor growth in vivo. Additional analysis revealed that OVSAHO and COV362 express moderate levels of estrogen receptor (ERα), which translated into improved growth of xenografts in the presence of 17β-Estradiol. Surprisingly, we also found that the growth of the widely used non-HGSC ovarian cell line SKOV3 could be significantly improved by estrogen supplementation. By describing successful establishment of estrogen-sensitive HGSC xenograft models, OVSAHO and COV362, this work will enable testing of novel therapies for this aggressive form of ovarian cancer.

Comprehensive Molecular Characterization Identifies Distinct Genomic and Immune Hallmarks of Renal Medullary Carcinoma

Renal medullary carcinoma (RMC) is a highly lethal malignancy that mainly afflicts young individuals of African descent and is resistant to all targeted agents used to treat other renal cell carcinomas. Comprehensive genomic and transcriptomic profiling of untreated primary RMC tissues was performed to elucidate the molecular landscape of these tumors. We found that RMC was characterized by high replication stress and an abundance of focal copy-number alterations associated with activation of the stimulator of the cyclic GMP-AMP synthase interferon genes (cGAS-STING) innate immune pathway. Replication stress conferred a therapeutic vulnerability to drugs targeting DNA-damage repair pathways. Elucidation of these previously unknown RMC hallmarks paves the way to new clinical trials for this rare but highly lethal malignancy.

Non-BRCA DNA Damage Repair Gene Alterations and Response to the PARP Inhibitor Rucaparib in Metastatic Castration-Resistant Prostate Cancer: Analysis From the Phase II TRITON2 Study

PURPOSE

Genomic alterations in DNA damage repair (DDR) genes other than BRCA may confer synthetic lethality with PARP inhibition in metastatic castration-resistant prostate cancer (mCRPC). To test this hypothesis, the phase II TRITON2 study of rucaparib included patients with mCRPC and deleterious non-BRCA DDR gene alterations.

PATIENTS AND METHODS

TRITON2 enrolled patients who had progressed on one or two lines of next-generation androgen receptor-directed therapy and one taxane-based chemotherapy for mCRPC. Key endpoints were investigator-assessed radiographic response per modified RECIST/PCWG3 and PSA response (≥50% decrease from baseline).

RESULTS

TRITON2 enrolled 78 patients with a non-BRCA DDR gene alteration [ATM (n = 49), CDK12 (n = 15), CHEK2 (n = 12), and other DDR genes (n = 14)]. Among patients evaluable for each endpoint, radiographic and PSA responses were observed in a limited number of patients with an alteration in ATM [2/19 (10.5%) and 2/49 (4.1%), respectively], CDK12 [0/10 (0%) and 1/15 (6.7%), respectively], or CHEK2 [1/9 (11.1%) and 2/12 (16.7%), respectively], including no radiographic or PSA responses in 11 patients with confirmed biallelic ATM loss or 11 patients with ATM germline mutations. Responses were observed in patients with alterations in the DDR genes PALB2, FANCA, BRIP1, and RAD51B.

CONCLUSIONS

In this prospective, genomics-driven study of rucaparib in mCRPC, we found limited radiographic/PSA responses to PARP inhibition in men with alterations in ATM, CDK12, or CHEK2. However, patients with alterations in other DDR-associated genes (e.g., PALB2) may benefit from PARP inhibition.See related commentary by Sokolova et al., p. 2439.

Opportunities and Challenges of the Human Microbiome in Ovarian Cancer

Ovarian cancer is the most lethal malignancy among gynecological cancers worldwide. Most ovarian cancer patients are diagnosed at an advanced stage because of non-specific clinical symptoms. The human microbiome plays a crucial role in maintaining the normal physiological and pathological state of the body. With the development of technologies such as DNA and 16S rRNA sequencing, an increasing number of findings on the role of microbiome in cancers are being reported. Microbiome abnormalities are increasingly associated with diseases, including cancer development, and response to therapies. Some studies have shown the relationship between microbiome changes and ovarian cancer. However, the mechanisms underlying this relationship are not yet fully understood. Here, we summarize the key findings in this regard by focusing on estrogen metabolism and host recognition receptors in microorganisms and changes in the gut or pelvic microbiome in patients with ovarian cancer. We further discuss the potential of using the microbiome as a novel biomarker for cancers. We also highlight the possibility to use microorganisms as a treatment modality to enhance the immune system, activate anti-tumor response, mediate chemotherapy resistance, and ameliorate the adverse effects of the treatment.

MiR-21 modulates the polarization of macrophages and increases the effects of M2 macrophages on promoting the chemoresistance of ovarian cancer

AIMS

Chemoresistance is a major underlying cause of relapse or death in ovarian cancer patients. Emerging evidence has shown that macrophages could play an essential role in mediating the chemoresistance of cancer cells. MiR-21 has been reported to be an oncogene, which promotes chemoresistance in cancer. Here, we aim to investigate the role that miR-21 plays in polarization of macrophages and ovarian cancer progression.

MAIN METHODS

The CIBERSORT algorithm was used to investigate immune cell infiltration in ovarian cancer tissues. To explore the role that miR-21 played in macrophages, M2 macrophages transfected with a miR-21 mimic or a miR-21 inhibitor were co-cultured with ovarian cancer cells. Western blotting was used to detect protein expression levels. CCK8 was used to detect the IC50 of ovarian cancer cells. Flow cytometry was used to detect apoptosis and the cell cycle of ovarian cancer cells.

KEY FINDINGS

In this study, we found that higher expression of M1 macrophages and lower expression of M2 macrophages correlated with a better prognosis of ovarian cancer patients. M2 macrophages promoted the chemoresistance of ovarian cancer cells. The results showed that miR-21 could partially regulate the polarization of macrophages. Furthermore, M2 macrophages transfected with the miR-21 mimic significantly promoted chemoresistance and inhibited apoptosis of ovarian cancer cells, while the M2 macrophages transfected with the miR-21 inhibitor showed the opposite effects.

SIGNIFICANCE

miR-21 plays an important role in regulating macrophage polarization, therefore increasing the M2 macrophage-mediated chemoresistance in ovarian cancer cells.

Addressing the Challenges of High-Throughput Cancer Tissue Proteomics for Clinical Application: ProCan

The cancer tissue proteome has enormous potential as a source of novel predictive biomarkers in oncology. Progress in the development of mass spectrometry (MS)-based tissue proteomics now presents an opportunity to exploit this by applying the strategies of comprehensive molecular profiling and big-data analytics that are refined in other fields of 'omics research. ProCan (ProCan is a registered trademark) is a program aiming to generate high-quality tissue proteomic data across a broad spectrum of cancer types. It is based on data-independent acquisition-MS proteomic analysis of annotated tissue samples sourced through collaboration with expert clinical and cancer research groups. The practical requirements of a high-throughput translational research program have shaped the approach that ProCan is taking to address challenges in study design, sample preparation, raw data acquisition, and data analysis. The ultimate goal is to establish a large proteomics knowledge-base that, in combination with other cancer 'omics data, will accelerate cancer research.

SLFN11 is a general target for enhancing the sensitivity of cancer to chemotherapy (DNA-damaging agents)

In patients with cancer, drug tolerance often occurs during the use of chemotherapy drugs, seriously affecting patient prognosis and survival. Therefore, scientists began to study the factors that affect chemotherapy drug sensitivity, and the high correlation between Schlafen-11 (SLFN11) and sensitivity to chemical drugs (mainly DNA-damaging agents, DDAs) has received increasing attention since it was discovered through bioinformatics analyses. Regarding the mechanism, SLFN11 may sensitise cells to chemotherapy drugs by preventing DNA damage repair. In recent years, SLFN11 has gradually become a hot research topic, and the results are enriching our understanding of this molecule. Indeed, the biological functions of SLFN11 under normal physiological conditions and in cancer, changes in its expression levels and mechanisms promoting apoptosis within the context of chemotherapeutic interventions have gradually been uncovered. Studies to date provide knowledge and the experimental and theoretical bases underlying SLFN11 and its effects on sensitivity to chemotherapy drugs. This review summarises the existing research on SLFN11 with the aim of achieving a more comprehensive understanding and furthering the development of strategies to target SLFN11 in the treatment of cancer.