Targeting BRCA Deficiency in Breast Cancer: What are the Clinical Evidences and the Next Perspectives?

Aptamer-Based Point-of-Care Devices: Emerging Technologies and Integration of Computational Methods

Recent innovations in point-of-care (POC) diagnostic technologies have paved a critical road for the improved application of biomedicine through the deployment of accurate and affordable programs into resource-scarce settings. The utilization of antibodies as a bio-recognition element in POC devices is currently limited due to obstacles associated with cost and production, impeding its widespread adoption. One promising alternative, on the other hand, is aptamer integration, i.e., short sequences of single-stranded DNA and RNA structures. The advantageous properties of these molecules are as follows: small molecular size, amenability to chemical modification, low- or nonimmunogenic characteristics, and their reproducibility within a short generation time. The utilization of these aforementioned features is critical in developing sensitive and portable POC systems. Furthermore, the deficiencies related to past experimental efforts to improve biosensor schematics, including the design of biorecognition elements, can be tackled with the integration of computational tools. These complementary tools enable the prediction of the reliability and functionality of the molecular structure of aptamers. In this review, we have overviewed the usage of aptamers in the development of novel and portable POC devices, in addition to highlighting the insights that simulations and other computational methods can provide into the use of aptamer modeling for POC integration.

Synergy of ruthenium metallo-intercalator, [Ru(dppz)2(PIP)]2+, with PARP inhibitor Olaparib in non-small cell lung cancer cells

Poly(ADP-ribose) polymerase (PARP) are critical DNA repair enzymes that are activated as part of the DNA damage response (DDR). Although inhibitors of PARP (PARPi) have emerged as small molecule drugs and have shown promising therapeutic effects, PARPi used as single agents are clinically limited to patients with mutations in germline breast cancer susceptibility gene (BRCA). Thus, novel PARPi combination strategies may expand their usage and combat drug resistance. In recent years, ruthenium polypyridyl complexes (RPCs) have emerged as promising anti-cancer candidates due to their attractive DNA binding properties and distinct mechanisms of action. Previously, we reported the rational combination of the RPC DNA replication inhibitor [Ru(dppz)₂(PIP)]²⁺ (dppz = dipyrido[3,2-a:2',3'-c]phenazine, PIP = 2-(phenyl)-imidazo[4,5-f][1,10]phenanthroline), "Ru-PIP", with the PARPi Olaparib in breast cancer cells. Here, we expand upon this work and examine the combination of Ru-PIP with Olaparib for synergy in lung cancer cells, including in 3D lung cancer spheroids, to further elucidate mechanisms of synergy and additionally assess toxicity in a zebrafish embryo model. Compared to single agents alone, Ru-PIP and Olaparib synergy was observed in both A549 and H1975 lung cancer cell lines with mild impact on normal lung fibroblast MRC5 cells. Employing the A549 cell line, synergy was confirmed by loss in clonogenic potential and reduced migration properties. Mechanistic studies indicated that synergy is accompanied by increased double-strand break (DSB) DNA damage and reactive oxygen species (ROS) levels which subsequently lead to cell death via apoptosis. Moreover, the identified combination was successfully able to inhibit the growth of A549 lung cancer spheroids and acute zebrafish embryos toxicity studies revealed that this combination showed reduced toxicity compared to single-agent Ru-PIP.

The Implication of Topoisomerase II Inhibitors in Synthetic Lethality for Cancer Therapy

DNA topoisomerase II (Top2) is essential for all eukaryotic cells in the regulation of DNA topology through the generation of temporary double-strand breaks. Cancer cells acquire enhanced Top2 functions to cope with the stress generated by transcription and DNA replication during rapid cell division since cancer driver genes such as Myc and EZH2 hijack Top2 in order to realize their oncogenic transcriptomes for cell growth and tumor progression. Inhibitors of Top2 are therefore designed to target Top2 to trap it on DNA, subsequently causing protein-linked DNA breaks, a halt to the cell cycle, and ultimately cell death. Despite the effectiveness of these inhibitors, cancer cells can develop resistance to them, thereby limiting their therapeutic utility. To maximize the therapeutic potential of Top2 inhibitors, combination therapies to co-target Top2 with DNA damage repair (DDR) machinery and oncogenic pathways have been proposed to induce synthetic lethality for more thorough tumor suppression. In this review, we will discuss the mode of action of Top2 inhibitors and their potential applications in cancer treatments.

Effectiveness of Secondary Risk-Reducing Strategies in Patients With Unilateral Breast Cancer With Pathogenic Variants of BRCA1 and BRCA2 Subjected to Breast-Conserving Surgery: Evidence-Based Simulation Study

BACKGROUND

Approximately 62% of patients with breast cancer with a pathogenic variant (BRCA1 or BRCA2) undergo primary breast-conserving therapy.

OBJECTIVE

The study aims to develop a personalized risk management decision support tool for carriers of a pathogenic variant (BRCA1 or BRCA2) who underwent breast-conserving therapy for unilateral early-stage breast cancer.

METHODS

We developed a Bayesian network model of a hypothetical cohort of carriers of BRCA1 or BRCA2 diagnosed with stage I/II unilateral breast cancer and treated with breast-conserving treatment who underwent subsequent second primary cancer risk-reducing strategies. Using event dependencies structured according to expert knowledge and conditional probabilities obtained from published evidence, we predicted the 40-year overall survival rate of different risk-reducing strategies for 144 cohorts of women defined by the type of pathogenic variants (BRCA1 or BRCA2), age at primary breast cancer diagnosis, breast cancer subtype, stage of primary breast cancer, and presence or absence of adjuvant chemotherapy.

RESULTS

Absence of adjuvant chemotherapy was the most powerful factor that was linked to a dramatic decline in survival. There was a negligible decline in the mortality in patients with triple-negative breast cancer, who received no chemotherapy and underwent any secondary risk-reducing strategy, compared with surveillance. The potential survival benefit from any risk-reducing strategy was more modest in patients with triple-negative breast cancer who received chemotherapy compared with patients with luminal breast cancer. However, most patients with triple-negative breast cancer in stage I benefited from bilateral risk-reducing mastectomy and risk-reducing salpingo-oophorectomy or just risk-reducing salpingo-oophorectomy. Most patients with luminal stage I/II unilateral breast cancer benefited from bilateral risk-reducing mastectomy and risk-reducing salpingo-oophorectomy. The impact of risk-reducing salpingo-oophorectomy in patients with luminal breast cancer in stage I/II increased with age. Most older patients with the BRCA1 and BRCA2 pathogenic variants in exons 12-24/25 with luminal breast cancer may gain a similar survival benefit from other risk-reducing strategies or surveillance.

CONCLUSIONS

Our study showed that it is mandatory to consider the complex interplay between the types of BRCA1 and BRCA2 pathogenic variants, age at primary breast cancer diagnosis, breast cancer subtype and stage, and received systemic treatment. As no prospective study results are available at the moment, our simulation model, which will integrate a decision support system in the near future, could facilitate the conversation between the health care provider and patient and help to weigh all the options for risk-reducing strategies leading to a more balanced decision.

Clinicopathological characteristics and genetic variations of uterine tumours resembling ovarian sex cord tumours

AIMS

To investigate the clinicopathological and molecular characteristics of uterine tumours resembling ovarian sex cord tumours (UTROSCTs) and the value of molecular diversity in the clinical diagnosis and treatment.

METHODS

Five patients with UTROSCT were enrolled, and their clinical data, pathological morphologies, immunophenotypes and molecular features were analysed. Fluorescence in situ hybridisation for NCOA1, NCOA2, NCOA3, JAZF1 and PHF1 and next-generation sequencing for 27 homologous recombination/repair (HRR) pathway genes were performed on five and three UTROSCT specimens, respectively.

RESULTS

All five patients were treated for abnormal uterine bleeding and grossly presented with intrauterine polyps. Under a microscope, tumour cells grew diffusely and presented a cordlike arrangement and glandular duct-like structures, with nuclei ranging from round to oval, vesicular chromatin and visible nucleoli in some cases. The mitotic count was less than 3/10 high-power fields. Immunohistochemistry showed sex cord, epithelial cell and smooth muscle cell biomarkers and diffuse, strong staining for B cell lymphoma-2 (BCL-2). NCOA1 and NCOA3 rearrangements were identified in 80% (4/5) of the cases. JAZF1 and PHF1 rearrangements were not detected in any of five patients. HRR pathway gene mutations were detected in all three patients, including FANCE, ATR and ARID1A mutations in one case each.

CONCLUSION

UTROSCT is a rare mesenchymal tumour, and biopsy specimens are easily misdiagnosed. UTROSCT diagnosis requires the combined use of biomarkers and molecular detection. BCL-2 has potential diagnostic value as a marker. UTROSCT can have mutations related to the HRR pathway, suggesting that this tumour type may be sensitive to platinum/poly (ADP-ribose) polymerase inhibitors.

Epigenetic Reprogramming and Landscape of Transcriptomic Interactions: Impending Therapeutic Interference of Triple-Negative Breast Cancer in Molecular Medicine

The mechanisms governing the development and progression of cancers are believed to be the consequence of hereditary deformities and epigenetic modifications. Accordingly, epigenetics has become an incredible and progressively explored field of research to discover better prevention and therapy for neoplasia, especially triple-negative breast cancer (TNBC). It represents 15-20% of all invasive breast cancers and will, in general, have bellicose histological highlights and poor clinical outcomes. In the early phases of triple-negative breast carcinogenesis, epigenetic deregulation modifies chromatin structure and influences the plasticity of cells. It up-keeps the oncogenic reprogramming of malignant progenitor cells with the acquisition of unrestrained selfrenewal capacities. Genomic impulsiveness in TNBC prompts mutations, copy number variations, as well as genetic rearrangements, while epigenetic remodeling includes an amendment by DNA methylation, histone modification, and noncoding RNAs of gene expression profiles. It is currently evident that epigenetic mechanisms assume a significant part in the pathogenesis, maintenance, and therapeutic resistance of TNBC. Although TNBC is a heterogeneous malaise that is perplexing to describe and treat, the ongoing explosion of genetic and epigenetic research will help to expand these endeavors. Latest developments in transcriptome analysis have reformed our understanding of human diseases, including TNBC at the molecular medicine level. It is appealing to envision transcriptomic biomarkers to comprehend tumor behavior more readily regarding its cellular microenvironment. Understanding these essential biomarkers and molecular changes will propel our capability to treat TNBC adequately. This review will depict the different aspects of epigenetics and the landscape of transcriptomics in triple-negative breast carcinogenesis and their impending application for diagnosis, prognosis, and treatment decision with the view of molecular medicine.

Role of PARP in TNBC: Mechanism of Inhibition, Clinical Applications, and Resistance

Triple-negative breast cancer is a combative cancer type with a highly inflated histological grade that leads to poor theragnostic value. Gene, protein, and receptor-specific targets have shown effective clinical outcomes in patients with TNBC. Cells are frequently exposed to DNA-damaging agents. DNA damage is repaired by multiple pathways; accumulations of mutations occur due to damage to one or more pathways and lead to alterations in normal cellular mechanisms, which lead to development of tumors. Advances in target-specific cancer therapies have shown significant momentum; most treatment options cause off-target toxicity and side effects on healthy tissues. PARP (poly(ADP-ribose) polymerase) is a major protein and is involved in DNA repair pathways, base excision repair (BER) mechanisms, homologous recombination (HR), and nonhomologous end-joining (NEJ) deficiency-based repair mechanisms. DNA damage repair deficits cause an increased risk of tumor formation. Inhibitors of PARP favorably kill cancer cells in BRCA-mutations. For a few years, PARPi has shown promising activity as a chemotherapeutic agent in BRCA1- or BRCA2-associated breast cancers, and in combination with chemotherapy in triple-negative breast cancer. This review covers the current results of clinical trials testing and future directions for the field of PARP inhibitor development.

Moving beyond PARP Inhibition: Current State and Future Perspectives in Breast Cancer

Breast cancer is the most frequent and lethal tumor in women and finding the best therapeutic strategy for each patient is an important challenge. PARP inhibitors (PARPis) are the first, clinically approved drugs designed to exploit synthetic lethality in tumors harboring BRCA1/2 mutations. Recent evidence indicates that PARPis have the potential to be used both in monotherapy and combination strategies in breast cancer treatment. In this review, we show the mechanism of action of PARPis and discuss the latest clinical applications in different breast cancer treatment settings, including the use as neoadjuvant and adjuvant approaches. Furthermore, as a class, PARPis show many similarities but also certain critical differences which can have essential clinical implications. Finally, we report the current knowledge about the resistance mechanisms to PARPis. A systematic PubMed search, using the entry terms “PARP inhibitors” and “breast cancer”, was performed to identify all published clinical trials (Phase I-II-III) and ongoing trials (ClinicalTrials.gov), that have been reported and discussed in this review.

PARP1: Structural insights and pharmacological targets for inhibition

Poly(ADP-ribose) polymerase 1 (PARP1, also known as ADPRT1) is a multifunctional human ADP-ribosyltransferase. It plays a role in multiple DNA repair pathways, including the base excision repair (BER), non-homologous end joining (NHEJ), homologous recombination (HR), and Okazaki-fragment processing pathways. In response to DNA strand breaks, PARP1 covalently attaches ADP-ribose moieties to arginine, glutamate, aspartate, cysteine, lysine, and serine acceptor sites on both itself and other proteins. This signal recruits DNA repair proteins to the site of DNA damage. PARP1 binding to these sites enhances ADP-ribosylation via allosteric communication between the distant DNA binding and catalytic domains. In this review, we provide a general overview of PARP1 and emphasize novel potential approaches for pharmacological inhibition. Clinical PARP1 inhibitors bind the catalytic pocket, where they directly interfere with ADP-ribosylation. Some inhibitors may further enhance potency by "trapping" PARP1 on DNA via an allosteric mechanism, though this proposed mode of action remains controversial. PARP1 inhibitors are used clinically to treat some cancers, but resistance is common, so novel pharmacological approaches are urgently needed. One approach may be to design novel small molecules that bind at inter-domain interfaces that are essential for PARP1 allostery. To illustrate these points, this review also includes instructive videos showing PARP1 structures and mechanisms.

Pharmacogenomics in the era of next generation sequencing - from byte to bedside

Pharmacogenetic research has resulted in the identification of a multitude of genetic variants that impact drug response or toxicity. These polymorphisms are mostly common and have been included as actionable information in the labels of numerous drugs. In addition to common variants, recent advances in Next Generation Sequencing (NGS) technologies have resulted in the identification of a plethora of rare and population-specific pharmacogenetic variations with unclear functional consequences that are not accessible by conventional forward genetics strategies. In this review, we discuss how comprehensive sequencing information can be translated into personalized pharmacogenomic advice in the age of NGS. Specifically, we provide an update of the functional impacts of rare pharmacogenetic variability and how this information can be leveraged to improve pharmacogenetic guidance. Furthermore, we critically discuss the current status of implementation of pharmacogenetic testing across drug development and layers of care. We identify major gaps and provide perspectives on how these can be minimized to optimize the utilization of NGS data for personalized clinical decision-support.

Landscape of somatic mutations in breast cancer: new opportunities for targeted therapies in Saudi Arabian patients

Breast cancer (BCa) ranks first in incidence rate among cancers in Arab females. The association between genetic polymorphisms in tumor suppressor genes and the risk of BCa has been studied in many ethnic populations with conflicting conclusions while Arab females and Saudi Arabian studies are still lacking. We screened a cohort of Saudi BCa patients by NGS using a bespoke gene panel to clarify the genetic landscape of this population, correlating and assessing genetic findings with clinical outcomes. We identified a total of 263 mutations spanning 51 genes, including several frequently mutated. Among the genes analyzed, the highest mutation rates were found in PIK3CA (12.9%), BRCA2 (11.7%), BRCA1 (10.2%), TP53 (6.0%), MSH2 (3.8%), PMS2 (3.8%), BARD1 (3.8%), MLH1 (3.4%), CDH1 (3.0%), RAD50 (3.0%), MSH6 (3.0%), NF1 (2.6%), in addition to others. We identified multiple common recurrent variants and previously reported mutations. We also identified 46 novel variants in 22 genes that were predicted to have a pathogenic effect. Survival analysis according to the four most common mutations (BRCA1, BRCA2, TP53, and PIK3CA) showed reduced survival in BRCA1 and BRCA2-mutant patients compared to total patients. Moreover, BRCA2 was demonstrated as an independent predictor of reduced survival using independent Cox proportional hazard models.

We reveal the landscape of the mutations associated with BCa in Saudi women, highlighting the importance of routine genetic sequencing in implementation of precision therapies in KSA.

Phase II Trial of Neoadjuvant Carboplatin and Nab-Paclitaxel in Patients with Triple-Negative Breast Cancer

BACKGROUND

In this phase II clinical trial, we evaluated the efficacy of the nonanthracycline combination of carboplatin and nab-paclitaxel in early stage triple-negative breast cancer (TNBC).

PATIENTS AND METHODS

Patients with newly diagnosed stage II-III TNBC (n = 69) were treated with neoadjuvant carboplatin (area under the curve 6) every 28 days for four cycles plus nab-paclitaxel (100 mg/m2 ) weekly for 16 weeks. Pathological complete response (pCR) and residual cancer burden (RCB) were analyzed with germline mutation status, tumor-infiltrating lymphocytes (TILs), TNBC molecular subtype, and GeparSixto immune signature (GSIS).

RESULTS

Sixty-seven patients were evaluable for safety and response. Fifty-three (79%) patients experienced grade 3/4 adverse events, including grade 3 anemia (43%), neutropenia (39%), leukopenia (15%), thrombocytopenia (12%), fatigue (7%), peripheral neuropathy (7%), neutropenia (16%), and leukopenia (1%). Twenty-four patients (35%) had at least one dose delay, and 50 patients (72%) required dose reduction. Sixty-three (94%) patients completed scheduled treatment. The responses were as follows: 32 of 67 patients (48%) had pCR (RCB 0), 10 of 67 (15%) had RCB I, 19 of 67 (28%) had RCB II, 5 of 67 (7%) had RCB III, and 1 of 67 (2%) progressed and had no surgery. Univariate analysis showed that immune-hot GSIS and DNA repair defect (DRD) were associated with higher pCR with odds ratios of 4.62 (p = .005) and 4.76 (p = .03), respectively, and with RCB 0/I versus RCB II/III with odds ratio 4.80 (p = .01). Immune-hot GSIS was highly correlated with DRD status (p = .03), TIL level (p < .001), and TNBC molecular subtype (p < .001). After adjusting for age, race, stage, and grade, GSIS remained associated with higher pCR and RCB class 0/I versus II/III with odds ratios 7.19 (95% confidence interval [CI], 2.01-25.68; p = .002) and 8.95 (95% CI, 2.09-38.23; p = .003), respectively.

CONCLUSION

The combination of carboplatin and nab-paclitaxel for early stage high-risk TNBC showed manageable toxicity and encouraging antitumor activity. Immune-hot GSIS is associated with higher pCR rate and RCB class 0/1. This study provides an additional rationale for using nonanthracycline platinum-based therapy for future neoadjuvant trials in early stage TNBCs. Clinical trial identification number: NCT01525966 IMPLICATIONS FOR PRACTICE: Platinum is an important neoadjuvant chemotherapy agent for treatment of early stage triple-negative breast cancer (TNBC). In this study, carboplatin and nab-paclitaxel were well tolerated and highly effective in TNBC, resulting in pathological complete response of 48%. In univariate and multivariate analyses adjusting for age, race, tumor stage and grade, "immune-hot" GeparSixto immune signature (GSIS) and DNA repair defect (DRD) were associated with higher pathological complete response (pCR) and residual cancer burden class 0/1. The association of immune-hot GSIS with higher pCR holds promise for de-escalating neoadjuvant chemotherapy for patients with early stage TNBC. Although GSIS is not routinely used in clinic, further development of this immune signature into a clinically applicable assay is indicated.

New insights in the expression of stromal caveolin 1 in breast cancer spread to axillary lymph nodes

Recent evidence suggests that a loss of expression of caveolin in the stromal compartment (sCav-1) of human invasive breast carcinoma (IBC) may be a predictor of disease recurrence, metastasis and poor outcome. At present, there is little knowledge regarding the expression of sCav-1 at the metastatic sites. We therefore studied sCav-1 expression in IBCs and in their axillary lymph nodes to seek a correlation with cancer metastasis. 189 consecutive invasive IBCs (53 with axillary lymph node metastases and 136 without) were studied by immunohistochemistry, using a rabbit polyclonal anti-Cav-1 antibody. In IBCs sCav-1 was evaluated in fibroblasts scattered in the tumor stroma whereas in lymph nodes sCav-1 was assessed in fibroblast-like stromal cells. For the first time, we observed a statistically significant progressive loss of sCav-1 from normal/reactive axillary lymph nodes of tumors limited to the breast to metastatic axillary lymph nodes, through normal/reactive axillary lymph nodes of tumors with axillary metastatic spread. These data indicate that Cav-1 expressed by the stromal compartment of lymph nodes, somehow, may possibly contribute to metastatic spread in IBC.

Germline BRCA1/2 mutations and severe haematological toxicities in patients with breast cancer treated with neoadjuvant chemotherapy

BACKGROUND

BRCA1 and BRCA2 play a central role in DNA repair. Therefore, patients harbouring germline (g) BRCA1/2 mutations (m) treated with chemotherapy might be at higher risk of haematological toxicities.

METHODS

Patients from German Breast Group (GBG) and Arbeitsgemeinschaft Gynäkologische Onkologie-breast group studies with early triple-negative breast cancer (TNBC) and known gBRCA1/2m status treated with anthracycline-taxane-based neoadjuvant chemotherapy were analysed. Primary objective was the rate of neutropenia grade (G)III-IV in cycle 1 (C1). Secondary objectives included effects on overall and other haematological toxicities GIII-IV in C1, cumulative haematological toxicity across all cycles, relative total dose intensity, and granulocyte-colony stimulating factor prophylaxis. Haematological toxicities under taxanes, carboplatin, and cyclophosphamide were explored.

RESULTS

Two hundred nine of 1171 (17.8%) evaluated patients had gBRCA1/2m. In C1, 37.4% gBRCA1/2m versus 35.7% wild-type patients had neutropenia GIII-IV (P = 0.683). For C1, gBRCA1/2m predicted neither for neutropenia GIII-IV (odds ratio [OR]: 1.26, 95% confidence intervals [CI]: 0.87-1.82, P = 0.226) nor for other haematological toxicities GIII-IV (OR: 0.91, 95% CI: 0.64-1.31, P = 0.625) in multivariable regression models. Analyses of cumulative toxicities across all cycles yielded similar results except thrombocytopaenia GIII-IV, which was increased in gBRCA1m patients. In patients treated with taxanes, the rate of haematological toxicities GIII-IV was higher in gBRCA1/2m compared with wild-type (59.5% versus 43.1%; p < 0.001). No difference was seen under cyclophosphamide or platinum-containing chemotherapies.

CONCLUSIONS

gBRCA1/2m was not associated with higher risk of overall severe haematological toxicities in the first cycle or cumulatively across all cycles under standard chemotherapy for TNBC. Under taxane, patients with gBRCA1/2m might have a higher risk of haematological toxicities GIII-IV, requiring further research.

Heritability of Low ER Staining/HER2-Breast Tumors: Are We Missing an Opportunity for Germline Testing?

In 2010, the genetic testing criteria was changed to allow women diagnosed ≤ 60 years old with triple negative breast cancer (TNBC) to undergo germline testing. In the same year, estrogen receptor (ER) positivity was defined as having ≥1% ER staining cells. While tumors with 1–10% ER staining cells and HER2 negative (HER2-) status share characteristics with TNBC, the utility of germline testing in women with ER low positive/HER2- (ERLP/HER2-) tumors is not well-understood. To this end, all patients with hormone receptor positive staining cells ≤ 10% and negative HER2 status were identified. Clinical genetic test results were extracted for patients who underwent testing. Panel testing was performed for those women who had genomic DNA available for research purposes. ERLP/HER2-tumors constituted 2.7% of all tumors in the database. Patients did not differ significantly from those with TNBC by age at diagnosis, ethnicity, family history or tumor size, stage or grade (p > 0.05). Mutation frequency did not differ significantly (p = 0.757) between groups (ERLP/HER2- 16.1%; TNBC 16.7%). Hereditary forms of breast cancer were similar in both ERLP/HER2- and TNBC, thus current guidelines may result in the under testing of women with low ER tumors, resulting in missed opportunities to improve patient management.

Combining PARP Inhibition with Platinum, Ruthenium or Gold Complexes for Cancer Therapy

Platinum drugs are heavily used first-line chemotherapeutic agents for many solid tumours and have stimulated substantial interest in the biological activity of DNA-binding metal complexes. These complexes generate DNA lesions which trigger the activation of DNA damage response (DDR) pathways that are essential to maintain genomic integrity. Cancer cells exploit this intrinsic DNA repair network to counteract many types of chemotherapies. Now, advances in the molecular biology of cancer has paved the way for the combination of DDR inhibitors such as poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi) and agents that induce high levels of DNA replication stress or single-strand break damage for synergistic cancer cell killing. In this review, we summarise early-stage, preclinical and clinical findings exploring platinum and emerging ruthenium anti-cancer complexes alongside PARPi in combination therapy for cancer and also describe emerging work on the ability of ruthenium and gold complexes to directly inhibit PARP activity.

A review of current progress in triple-negative breast cancer therapy

Triple-negative breast cancer (TNBC) is a particularly aggressive subtype known for its extremely high drug resistance, progression, poor prognosis, and lack of clear therapeutic targets. Researchers are aiming to advance TNBC treatment worldwide. In the past 2–3 years, more positive results have emerged in the clinical research on TNBC treatment. Based on the results, several impressive drugs have been approved to benefit patients with TNBC, including the PARP inhibitors olaparib and talazoparib for germline BRCA mutation-associated breast cancer (gBRCAm-BC) and immunotherapy using the checkpoint inhibitor atezolizumab in combination with nab-paclitaxel for programmed cell death-ligand 1-positive (PD-L1+) advanced TNBC. Although neoadjuvant therapy has focused on combinations of systemic agents to optimize pathologically complete response, metastatic TNBC still has a poor prognosis. Innovative multidrug combination systemic therapies based on neoadjuvants and adjuvants have led to significant improvements in outcomes, particularly over the past decade.

BRCA1 and BRCA2 associated breast cancer and the roles of current modelling systems in drug discovery

For a drug candidate to be fully developed takes years and investment of hundreds of millions of dollars. There is no doubt that drug development is difficult and risky, but vital to protecting against devastating disease. This difficulty is clearly evident in BRCA1 and BRCA2 related breast cancer, with current treatment options largely confined to invasive surgical procedures, as well as chemotherapy and radiotherapy regimes which damage healthy tissue and can leave remnant disease. Consequently, patient survival and relapse rates are far from ideal, and new candidate treatments are needed. The preclinical stages of drug discovery are crucial to get right for translation to hospital beds. Disease models must take advantage of current technologies and be accurate for rapid and translatable treatments. Careful selection of cell lines must be coupled with high throughput techniques, with promising results trialled further in highly accurate humanised patient derived xenograft models. Traditional adherent drug screening should transition to 3D culture systems amenable to high throughput techniques if the gap between in vitro and in vivo studies is to be partially bridged. The possibility of organoid, induced pluripotent stem cell, and conditionally reprogrammed in vitro models is tantalising, however protocols are yet to be fully established. This review of BRCA1 and BRCA2 cancer biology and current modelling systems will hopefully guide the design of future drug discovery endeavours and highlight areas requiring improvement.

Accuracy of Digital Image Analysis (DIA) of Borderline Human Epidermal Growth Factor Receptor (HER2) Immunohistochemistry in Invasive Ductal Carcinoma

Background: Digital image analysis (DIA), used to extract information from pathology slides, provides better precision and no limitation regarding different interpretations by observers. Objectives: The present study aimed at evaluating the accuracy of DIA in the interpretation of borderline (2+) human epidermal growth factor receptor 2 (HER2) immunohistochemistry (IHC) slides of invasive ductal carcinoma of the breast. Methods: Sixty pathology samples with invasive ductal carcinoma of the breast were extracted based on HER2 (2+) and their fluorescence in situ hybridization (FISH), and chromogenic in situ hybridization (CISH) responses (as reference standard). The slides were digitized and, then, two pathologists examined the slides and documented diagnosis. DIA was performed by a free web application. Results: Totally, 307 digital images with 298 megabytes volume were extracted. The accuracy, sensitivity, and specificity values of DIA were 86 %, 46.1 %, and 97.8 %, respectively, with 8 false-negative cases. There was moderate agreement between the pathologist 1 (kappa = 0.42) and pathologist 2 (kappa = 0.41) with DIA. Conclusions: DIA had good accuracy and could be used for the interpretation of borderline HER2 IHC method in invasive ductal carcinoma.

Exploiting DNA repair defects in triple negative breast cancer to improve cell killing

Background:

The lack of molecular targets for triple negative breast cancer (TNBC) has limited treatment options and reduced survivorship. Identifying new molecular targets may help improve patient survival and decrease recurrence and metastasis. As DNA repair defects are prevalent in breast cancer, we evaluated the expression and repair capacities of DNA repair proteins in preclinical models.

Methods:

DNA repair capacity was analyzed in four TNBC cell lines, MDA-MB-157 (MDA-157), MDA-MB-231 (MDA-231), MDA-MB-468 (MDA-468), and HCC1806, using fluorescence multiplex host cell reactivation (FM-HCR) assays. Expression of DNA repair genes was analyzed with RNA-seq, and protein expression was evaluated with immunoblot. Responses to the combination of DNA damage response inhibitors and primary chemotherapy drugs doxorubicin or carboplatin were evaluated in the cell lines.

Results:

Defects in base excision and nucleotide excision repair were observed in preclinical TNBC models. Gene expression analysis showed a limited correlation between these defects. Loss in protein expression was a better indicator of these DNA repair defects. Over-expression of PARP1, XRCC1, RPA, DDB1, and ERCC1 was observed in TNBC preclinical models, and likely contributed to altered sensitivity to chemotherapy and DNA damage response (DDR) inhibitors. Improved cell killing was achieved when primary therapy was combined with DDR inhibitors for ATM, ATR, or CHK1.

Conclusion:

Base excision and nucleotide excision repair pathways may offer new molecular targets for TNBC. The functional status of DNA repair pathways should be considered when evaluating new therapies and may improve the targeting for primary and combination therapies with DDR inhibitors.

Therapeutic Potential of Chemically Modified miR-489 in Triple-Negative Breast Cancers

Triple-negative breast cancers (TNBCs) lack ER, PR and her2 receptors that are targets of common breast cancer therapies with poor prognosis due to their high rates of metastasis and chemoresistance. Based on our previous studies that epigenetic silencing of a potential metastasis suppressor, arrestin domain-containing 3 (ARRDC3), is linked to the aggressive nature of TNBCs, we identified a sub-group of tumor suppressing miRNAs whose expressions were significantly up-regulated by ARRDC3 over-expression in TNBC cells. Among these tumor suppressing miRs, we found that miR-489 is most anti-proliferative in TNBC cells. miR-489 also blocked DNA damaging responses (DDRs) in TNBC cells. To define the mechanism by which miR-489 inhibits TNBC cell functions, we screened the potential target genes of miR-489 and identified MDC-1 and SUZ-12 as novel target genes of miR-489 in TNBC cells. To further exploit the therapeutic potentials of miR-489 in TNBC models, we chemically modified the guide strand of miR-489 (CMM489) by replacing Uracil with 5-fluorouracil (5-FU) so that tumor suppressor (miR-489) and DNA damaging (5-FU) components are combined into a single agent as a novel drug candidate for TNBCs. Our studies demonstrated that CMM489 shows superior effects over miR-489 or 5-FU in inhibition of TNBC cell proliferation and tumor progression, suggesting its therapeutic efficacy in TNBC models.

PARP Inhibitors in the Treatment of Early Breast Cancer: The Step Beyond?

Exquisitely exploiting defects in homologous recombination process, poly(ADP-ribose) polymerase (PARP) inhibitors have recently emerged as a promising class of therapeutics in human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer with germline breast cancer 1 (BRCA1) or breast cancer 2 (BRCA2) mutations (gBRCA1/2m). In this setting, PARP inhibitors, either as single agent or in combination with platinum-based chemotherapy, significantly increased progression-free survival, as compared to conventional chemotherapy. Accordingly, further therapeutic advances are expected at an earlier stage of the disease. In the neoadjuvant setting, veliparib failed to increase the pathological complete response rate when added to a carboplatin-based regimen, in unselected triple-negative breast cancer patients. Similarly, when administered before anthracycline-cyclophosphamide, the neoadjuvant olaparib-paclitaxel combination was not superior to carboplatin–paclitaxel, in patients with HER2-negative breast cancer and BRCA1/2 mutation, or homologous recombination defect. Yet, neoadjuvant talazoparib, administered as a single-agent in patients with HER2-negative breast cancer and germline BRCA1/2 mutation, achieved an impressive pathological complete response rate of nearly 50%. In the adjuvant setting, the results from the OlympiA phase III study, evaluating adjuvant olaparib in HER2-negative early breast cancer and germline BRCA1/2 mutations, are eagerly awaited. Ongoing trials should clarify whether PARP inhibitors might improve outcome when administered in the adjuvant or neoadjuvant setting in early breast cancer patients with BRCA1/2 mutation or homologous recombination defect.

Immuno-Oncology Biomarkers for Personalized Immunotherapy in Breast Cancer

The immune checkpoint blockade therapy has drastically advanced treatment of different types of cancer over the past few years. Female breast cancer is the second leading cause of death in the overall burden of cancers worldwide that is encouraging healthcare professionals to improve cancer care management. The checkpoint blockade therapies combined with novel agents become the recent focus of various clinical trials in breast cancer. However, identification of the patients who are responsive to these therapeutic strategies remained as a major issue for enhancing the efficacy of these treatments. This highlights the unmet need in discovery and development of novel biomarkers to add predictive values for prosperous personalized medicine. In this review we summarize the advances done in the era of biomarker studies and highlight their link in supporting breast cancer immunotherapy.

An immune-centric exploration of BRCA1 and BRCA2 germline mutation related breast and ovarian cancers

Background

BRCA1/2 germline mutation related cancers are candidates for new immune therapeutic interventions. This study was a hypothesis generating exploration of genomic data collected at diagnosis for 19 patients. The prominent tumor mutation burden (TMB) in hereditary breast and ovarian cancers in this cohort was not correlated with high global immune activity in their microenvironments. More information is needed about the relationship between genomic instability, phenotypes and immune microenvironments of these hereditary tumors in order to find appropriate markers of immune activity and the most effective anticancer immune strategies.

Methods

Mining and statistical analyses of the original DNA and RNA sequencing data and The Cancer Genome Atlas data were performed. To interpret the data, we have used published literature and web available resources such as Gene Ontology, The Cancer immunome Atlas and the Cancer Research Institute iAtlas.

Results

We found that BRCA1/2 germline related breast and ovarian cancers do not represent a unique phenotypic identity, but they express a range of phenotypes similar to sporadic cancers. All breast and ovarian BRCA1/2 related tumors are characterized by high homologous recombination deficiency (HRD) and low aneuploidy. Interestingly, all sporadic high grade serous ovarian cancers (HGSOC) and most of the subtypes of triple negative breast cancers (TNBC) also express a high degree of HRD.

Conclusions

TMB is not associated with the magnitude of the immune response in hereditary BRCA1/2 related breast and ovarian cancers or in sporadic TNBC and sporadic HGSOC. Hereditary tumors express phenotypes as heterogenous as sporadic tumors with various degree of “BRCAness” and various characteristics of the immune microenvironments. The subtyping criteria developed for sporadic tumors can be applied for the classification of hereditary tumors and possibly also characterization of their immune microenvironment. A high HRD score may be a good candidate biomarker for response to platinum, and potentially PARP-inhibition.

Trial registration

Phase I Study of the Oral PI3kinase Inhibitor BKM120 or BYL719 and the Oral PARP Inhibitor Olaparib in Patients With Recurrent TNBC or HGSOC (NCT01623349), first posted on June 20, 2012. The design and the outcome of the clinical trial is not in the scope of this study.

DNA damage repair functions and targeted treatment in breast cancer

Cell DNA is continuously attacked by endogenous and exogenous agents, which causes DNA damage. During long-term evolution, complex defense systems for DNA damage repair are formed by cells to maintain genome stability. Defects in the DNA damage repair process may lead to various diseases, including tumors. Therefore, DNA damage repair systems have become a new anti-tumor drug target. To date, a number of inhibitors related to DNA damage repair systems have been developed, particularly for tumors with BRCA1 and BRCA2 mutations. Poly (ADP-ribose) polymerase inhibitors developed by synthetic lethality are widely used in individualized tumor therapy. In this review, we briefly introduce the mechanisms underlying DNA damage repair, particularly in breast cancer, and mainly focus on new treatments targeting the DNA damage repair pathway in breast cancer.

MRE11-RAD50-NBS1 complex alterations and DNA damage response: implications for cancer treatment

Genome instability is a hallmark of cancer cells and can be accelerated by defects in cellular responses to DNA damage. This feature of malignant cells opens new avenues for tumor targeted therapy. MRE11-RAD50-NBS1 complex plays a crucial role in sensing and repair of DNA damage. Through interacting with other important players of DNA damage response, MRE11-RAD50-NBS1 complex is engaged in various DNA damage repair pathways. Mutations in any member of this complex may lead to hypersensitivity to genotoxic agents and predisposition to malignancy. It is assumed that the defects in the complex may contribute to tumorigenesis and that treatments targeting the defect may be beneficial to cancer patients. Here, we summarized the recent research findings of the role of MRE11-RAD50-NBS1 complex in tumorigenesis, cancer treatment and discussed the potential approaches of targeting this complex to treat cancer.

Targeting of prostate-specific membrane antigen for radio-ligand therapy of triple-negative breast cancer

Background

Triple-negative breast cancer has extremely high risk of relapse due to the lack of targeted therapies, intra- and inter-tumoral heterogeneity, and the inherent and acquired resistance to therapies. In this study, we evaluate the potential of prostate-specific membrane antigen (PSMA) as target for radio-ligand therapy (RLT).

Methods

Tube formation was investigated after incubation of endothelial HUVEC cells in tumor-conditioned media and monitored after staining using microscopy. A binding study with ⁶⁸Ga-labeled PSMA-addressing ligand was used to indicate targeting potential of PSMA on tumor-conditioned HUVEC cells. For mimicking of the therapeutic application, tube formation potential and vitality of tumor-conditioned HUVEC cells were assessed following an incubation with radiolabeled PSMA-addressing ligand [¹⁷⁷Lu]-PSMA-617. For in vivo experiments, NUDE mice were xenografted with triple-negative breast cancer cells MDA-MB231 or estrogen receptor expressing breast cancer cells MCF-7. Biodistribution and binding behavior of [⁶⁸Ga]-PSMA-11 was investigated in both tumor models at 30 min post injection using μPET. PSMA- and CD31-specific staining was conducted to visualize PSMA expression and neovascularization in tumor tissue ex vivo.

Results

The triple-negative breast cancer cells MDA-MB231 showed a high pro-angiogenetic potential on tube formation of endothelial HUVEC cells. The induced endothelial expression of PSMA was efficiently addressed by radiolabeled PSMA-specific ligands. ¹⁷⁷Lu-labeled PSMA-617 strongly impaired the vitality and angiogenic potential of HUVEC cells. In vivo, as visualized by μPET, radiolabeled PSMA-ligand accumulated specifically in the triple-negative breast cancer xenograft MDA-MB231 (T/B ratio of 43.3 ± 0.9), while no [⁶⁸Ga]-PSMA-11 was detected in the estrogen-sensitive MCF-7 xenograft (T/B ratio of 1.1 ± 0.1). An ex vivo immunofluorescence analysis confirmed the localization of PSMA on MDA-MB231 xenograft-associated endothelial cells and also on TNBC cells.

Conclusions

Here we demonstrate PSMA as promising target for two-compartment endogenous radio-ligand therapy of triple-negative breast cancer.

Precision Oncology-The Quest for Evidence

The molecular characterization of patient tumors provides a rational and highly promising approach for guiding oncologists in treatment decision-making. Notwithstanding, genomic medicine still remains in its infancy, with innovators and early adopters continuing to carry a significant portion of the clinical and financial risk. Numerous innovative precision oncology trials have emerged globally to address the associated need for evidence of clinical utility. These studies seek to capitalize on the power of predictive biomarkers and/or treatment decision support analytics, to expeditiously and cost-effectively demonstrate the positive impact of these technologies on drug resistance/response, patient survival, and/or quality of life. Here, we discuss the molecular foundations of these approaches and highlight the diversity of innovative trial strategies that are capitalizing on this emergent knowledge. We conclude that, as increasing volumes of clinico-molecular outcomes data become available, in future, we will begin to transition away from expert systems for treatment decision support (TDS), towards the power of AI-assisted TDS-an evolution that may truly revolutionize the nature and success of cancer patient care.

Next-Generation Sequencing May Discriminate Extreme Long-term versus Short-term Survival in Patients with Metastatic Small Cell Lung Cancer (SCLC)

BACKGROUND: Molecular underpinnings that may prognosticate survival could increase understanding of small cell lung cancer (SCLC) tumor behavior. Here, we report the clinicopathological characteristics and biomarker profiles of short-term (ST) versus long-term (LT) survival in patients with metastatic SCLC. METHODS: Of the 876 consecutive metastatic SCLC patients receiving standard of care therapy, 44 met the definition of LT and 91 for ST, respectively. Available FFPE tumor tissue blocks were analyzed by next-generation sequencing (NGS). Analysis included gene mutations, copy number variations, mRNA expression, and protein expression by immunohistochemistry, followed by correlation with clinicopathological characteristics. RESULTS: There were no statistically significant and clinically relevant differences in cases with or without FFPE according to major clinicopathological variables in ST and LT. However, according to NGS, five mutually exclusive gene mutations were identified (E1A binding protein P300 [EP300] p.N217S; p.E152K; human epidermal growth factor receptor 4 [ERBB4] p.E317K; BRCA1, DNA repair associated [BRCA1] p.E1661N, and epidermal growth factor receptor [EGFR] p.V742A). Comparing LT vs. ST survivals, a twofold increase was found in the average predicted number of drugs per patient off compendium. We found high SSTR2 mRNA expressions in all LT patients (vs. two [20%] ST patients), which may reflect more benign neuroendocrine tumor characteristics. CONCLUSIONS: Consolidation radiation therapy and higher predicted drug sensitivity for off compendium were associated with LT compared to ST patients in SCLC. NGS profiling of extreme survivals may improve classification of SCLC and possibly identify clinically relevant new targets.

PD-1/PD-L1 Targeting in Breast Cancer: The First Clinical Evidences Are Emerging. A Literature Review

Recently, the development of immunotherapy through the immune checkpoint blockade led to long-lasting responses in several types of cancers that are refractory to conventional treatments, such as melanoma or non-small cell lung cancer. Immunotherapy has also demonstrated significant improvements in various other types of cancers. However, breast cancer remains one of the tumors that have not experienced the explosion of immunotherapy yet. Indeed, breast cancer was traditionally considered as being weakly immunogenic with a lower mutational load compared to other tumor types. In the last few years, anti-PD1/PD-L1 (Programmed death-ligand 1) agents have been evaluated in breast cancer, particularly in the triple negative subtype, with promising results observed when delivered as monotherapy or in combination with conventional treatments. In this review, we will report the results of the most recent studies evaluating immune checkpoint inhibitors in breast cancer. In addition, we will discuss the concomitant development of possible biomarkers, which is required for improving the selection of patients with the highest probability of benefiting from these agents.

PARPs and PAR as novel pharmacological targets for the treatment of stress granule-associated disorders

Among the post-translational modifications, ADP-ribosylation has been for long time the least integrated in the scheme of the structural protein modifications affecting physiological functions. In spite of the original findings on bacterial-dependent ADP-ribosylation catalysed by toxins such as cholera and pertussis toxin, only with the discovery of the poly-ADP-ribosyl polymerase (PARP) family the field has finally expanded and the role of ADP-ribosylation has been recognised in both physiological and pathological processes, including cancer, infectious and neurodegenerative diseases. This is now a rapidly expanding field of investigation, centred on the role of the different PARPs and their substrates in various diseases, and on the potential of PARP inhibitors as novel pharmacological tools to be employed in relevant pathological context. In this review we analyse the role that members of the PARP family and poly-ADP-ribose (PAR; the product of PARP1 and PARP5a activity) play in the processes following the exposure of cells to different stresses. The cell response that arises following conditions such as heat, osmotic, oxidative stresses or viral infection relies on the formation of stress granules, which are transient cytoplasmic membrane-less structures, that include untranslated mRNA, specific proteins and PAR, this last one serving as the "collector" of all components (that bind to it in a non-covalent manner). The resulting phenotypes are cells in which translation, intracellular transport or pro-apoptotic pathways are reversibly inhibited, for the time the given stress holds. Interestingly, the formation of defective stress granules has been detected in diverse pathological conditions including neurological disorders and cancer. Analysing the molecular details of stress granule formation under these conditions offers a novel view on the pathogenesis of these diseases and, as a consequence, the possibility of identifying novel drug targets for their treatment.