Combination Platinum-based and DNA Damage Response-targeting Cancer Therapy: Evolution and Future Directions

Toxoflavin analog D43 exerts antiproliferative effects on breast cancer by inducing ROS-mediated apoptosis and DNA damage

Triple-negative breast cancer (TNBC) is regarded as the deadliest subtype of breast cancer because of its high heterogeneity, aggressiveness, and limited treatment options. Toxoflavin has been reported to possess antitumor activity. In this study, a series of toxoflavin analogs were synthesized, among which D43 displayed a significant dose-dependent inhibitory effect on the proliferation of TNBC cells (MDA-MB-231 and HCC1806). Additionally, D43 inhibited DNA synthesis in TNBC cells, leading to cell cycle arrest at the G2/M phase. Furthermore, D43 consistently promoted intracellular ROS generation, induced DNA damage, and resulted in apoptosis in TNBC cells. These effects could be reversed by N-acetylcysteine. Moreover, D43 significantly inhibited the growth of breast cancer patient-derived organoids and xenografts with a favorable biosafety profile. In conclusion, D43 is a potent anticancer agent that elicits significant antiproliferation, oxidative stress, apoptosis, and DNA damage effects in TNBC cells, and D43 holds promise as a potential candidate for the treatment of TNBC.

Measuring the composition of the tumor microenvironment with transcriptome analysis: past, present and future

Interactions between tumor cells and immune cells in the tumor microenvironment (TME) play a vital role the mechanisms of immune evasion, by which cancer cells escape immune elimination. Thus, the characterization and quantification of different components in the TME is a hot topic in molecular biology and drug discovery. Since the development of transcriptome sequencing in bulk tissue, single cells and spatial dimensions, there are increasing methods emerging to deconvolute and subtype the TME. This review discusses and compares such computational strategies and downstream subtyping analyses. Integrative analyses of the transcriptome with other data, such as epigenetics and T-cell receptor sequencing, are needed to obtain comprehensive knowledge of the dynamic TME.

Different Impacts of DNA-PK and mTOR Kinase Inhibitors in Combination with Ionizing Radiation on HNSCC and Normal Tissue Cells

Despite substantial advancements in understanding the pathomechanisms of head and neck squamous cell carcinoma (HNSCC), effective therapy remains challenging. The application of kinase inhibitors (KIs) in HNSCC, specifically mTOR and DNA-PK inhibitors, can increase radiosensitivity and therefore presents a promising strategy when used simultaneously with ionizing radiation (IR) in cancer treatment. Our study focused on the selective DNA-PK-inhibitor AZD7648; the selective mTOR-inhibitor Sapanisertib; and CC-115, a dual inhibitor targeting both mTOR and DNA-PK. The impact of these KIs on HNSCC and normal tissue cells was assessed using various analytical methods including cell death studies, cell cycle analysis, real-time microscopy, colony-forming assays and immunohistochemical staining for γH2AX and downstream mTOR protein p-S6. We detected a strong inhibition of IR-induced DNA double-strand break (DSB) repair, particularly in AZD7648-treated HNSCC, whereas normal tissue cells repaired DNA DSB more efficiently. Additionally, AZD7648 + IR treatment showed a synergistic decline in cell proliferation and clonogenicity, along with an elevated G2/M arrest and cell death in the majority of HNSCC cell lines. CC-115 + IR treatment led to an elevation in G2/M arrest, increased cell death, and a synergistic reduction in cell proliferation, though the effect was notably lower compared to the AZD7648 + IR- treated group. Sapanisertib led to a high cellular toxicity in both HNSCC and normal tissue cells, even in non-irradiated cells. Regarding cell proliferation and the induction of apoptosis and necrosis, Sapanisertib + IR was beneficial only in HPV+ HNSCC. Overall, this study highlights the potential of AZD7648 as a radiosensitizing agent in advanced-stage HPV-positive and negative HNSCC, offering a promising therapeutic strategy. However, the dual mTOR/DNA-PK-I CC-115 did not provide a distinct advantage over the use of selective KIs in our investigations, suggesting limited benefits for its application in KI + IR therapy. Notably, the selective mTOR-inhibitor Sapanisertib was only beneficial in HPV+ HNSCC and should not be applied in HPV- cases.

Genomic Features of Homologous Recombination Deficiency in Breast Cancer: Impact on Testing and Immunotherapy

Genomic instability is one of the well-established hallmarks of cancer. The homologous recombination repair (HRR) pathway plays a critical role in correcting the double-stranded breaks (DSB) due to DNA damage in human cells. Traditionally, the BRCA1/2 genes in the HRR pathway have been tested for their association with breast cancer. However, defects in the HRR pathway (HRD, also termed 'BRCAness'), which has up to 50 genes, have been shown to be involved in tumorigenesis and treatment susceptibility to poly-ADP ribose polymerase inhibitors (PARPis), platinum-based chemotherapy, and immune checkpoint inhibitors (ICIs). A reliable consensus on HRD scores is yet to be established. Emerging evidence suggests that only a subset of breast cancer patients benefit from ICI-based immunotherapy. Currently, albeit with limitations, the expression of programmed death-ligand 1 (PDL1) and tumor mutational burden (TMB) are utilized as biomarkers to predict the favorable outcomes of ICI therapy in breast cancer patients. Preclinical studies demonstrate an interplay between the HRR pathway and PDL1 expression. In this review, we outline the current understanding of the role of HRD in genomic instability leading to breast tumorigenesis and delineate outcomes from various clinical trials. Furthermore, we discuss potential strategies for combining HRD-targeted therapy with immunotherapy to achieve the best healthcare outcomes in breast cancer patients.

Advances in DNA damage response inhibitors in colorectal cancer therapy

One potential cause of cancer is genomic instability that arises in normal cells due to years of DNA damage in the body. The clinical application of radiotherapy and cytotoxic drugs to treat cancer is based on the principle of damaging the DNA of cancer cells. However, the benefits of these treatments also have negative effects on normal tissue. While there have been notable advancements in molecular-driven therapy and immunotherapy for colorectal cancer (CRC), a considerable portion of patients with advanced CRC do not experience any benefits from these treatments, leading to a poor prognosis. In recent years, targeted therapy aimed at suppressing the DNA damage response (DDR) in cancer cells has emerged as a potential treatment option for CRC patients, offering them more choices for treatment. Currently, the integration of DDR and clinical intervention remains in the exploratory phase. This review primarily elucidates the fundamental principles of DDR inhibitors, provides an overview of their current clinical application status in CRC, and discusses the advancements as well as limitations observed in relevant studies.

Platinum-based chemotherapy in metastatic prostate cancer: what possibilities?

Metastatic prostate cancer is a major health burden worldwide, necessitating the continuous development of effective treatment strategies. Androgen deprivation therapy remains the cornerstone of prostate cancer treatment, but novel approaches are needed for metastatic castration-resistant prostate cancer (mCRPC). Recent studies have highlighted the prevalence of mutations in DNA repair genes, including BRCA1 and BRCA2, in mCRPC patients, rendering them more susceptible to platinum-based chemotherapy and Poly (ADP-ribose) polymerase (PARP) inhibitors. Platinum-based chemotherapy, particularly in combination with taxanes, has demonstrated encouraging activity in mCRPC, as well as homologous recombination gene alterations have shown increased sensitivity to platinum compounds in these patients. The combination of platinum-based chemotherapy with PARP inhibitors represents a novel and potentially effective therapeutic strategy for this subgroup of patients. However, the optimal sequence of administering these agents and the potential for cross-resistance and cross-toxicities remain areas requiring further investigation. Prospective randomized studies are essential to elucidate the most effective treatment approach for this challenging patient population. This review aims to explore the potential of platinum-based chemotherapy in the context of prostate cancer, and more in detail in homologous recombination repair (HRR) mutated patients. We discuss the synergistic effects of combining platinum compounds with PARP inhibitors and the potential benefits of adopting specific therapeutic sequences.

Beyond matrix stiffness: targeting force-induced cancer drug resistance

During tumor progression, mechanical abnormalities in the tumor microenvironment (TME) trigger signaling pathways in cells that activate cellular programs, resulting in tumor growth and drug resistance. In this review, we describe mechanisms of action for anti-cancer therapies and mechanotransduction programs that regulate cellular processes, including cell proliferation, apoptosis, survival and phenotype switching. We discuss how the therapeutic response is impacted by the three main mechanical TME abnormalities: high extracellular matrix (ECM) composition and stiffness; interstitial fluid pressure (IFP); and elevated mechanical forces. We also review drugs that normalize these abnormalities or block mechanosensors and mechanotransduction pathways. Finally, we discuss current challenges and perspectives for the development of new strategies targeting mechanically induced drug resistance in the clinic.

A novel marker integrating multiple genetic alterations better predicts platinum sensitivity in ovarian cancer than HRD score

Introduction: Platinum-based chemotherapy is the first-line treatment strategy for ovarian cancer patients. The dismal prognosis of ovarian cancer was shown to be stringently associated with the heterogeneity of tumor cells in response to this therapy, therefore understanding platinum sensitivity in ovarian cancer would be helpful for improving patients' quality of life and clinical outcomes. HRDetect, utilized to characterize patients' homologous recombination repair deficiency, was used to predict patients' response to platinum-based chemotherapy. However, whether each of the single features contributing to HRD score is associated with platinum sensitivity remains elusive. Methods: We analyzed the whole-exome sequencing data of 196 patients who received platinum-based chemotherapy from the TCGA database. Genetic features were determined individually to see if they could indicate patients' response to platinum-based chemotherapy and prognosis, then integrated into a Pt-score employing LASSO regression model to assess its predictive performance. Results and discussion: Multiple genetic features, including bi-allelic inactivation of BRCA1/2 genes and genes involved in HR pathway, multiple somatic mutations in genes involved in DNA damage repair (DDR), and previously reported HRD-related features, were found to be stringently associated with platinum sensitivity and improved prognosis. Higher contributions of mutational signature SBS39 or ID6 predicted improved overall survival. Besides, arm-level loss of heterozygosity (LOH) of either chr4p or chr5q predicted significantly better disease-free survival. Notably, some of these features were found independent of HRD. And SBS3, an HRD-related feature, was found irrelevant to platinum sensitivity. Integrated all candidate markers using the LASSO model to yield a Pt-score, which showed better predictive ability compared to HRDetect in determining platinum sensitivity and predicting patients' prognosis, and this performance was validated in an independent cohort. The outcomes of our study will be instrumental in devising effective strategies for treating ovarian cancer with platinum-based chemotherapy.

Transcriptomic analyses of ovarian clear-cell carcinoma with concurrent endometriosis

Introduction

Endometriosis, a benign inflammatory disease whereby endometrial-like tissue grows outside the uterus, is a risk factor for endometriosis-associated ovarian cancers. In particular, ovarian endometriomas, cystic lesions of deeply invasive endometriosis, are considered the precursor lesion for ovarian clear-cell carcinoma (OCCC).

Methods

To explore this transcriptomic landscape, OCCC from women with pathology-proven concurrent endometriosis (n = 4) were compared to benign endometriomas (n = 4) by bulk RNA and small-RNA sequencing.

Results

Analysis of protein-coding genes identified 2449 upregulated and 3131 downregulated protein-coding genes (DESeq2, P< 0.05, log2 fold-change > |1|) in OCCC with concurrent endometriosis compared to endometriomas. Gene set enrichment analysis showed upregulation of pathways involved in cell cycle regulation and DNA replication and downregulation of pathways involved in cytokine receptor signaling and matrisome. Comparison of pathway activation scores between the clinical samples and publicly-available datasets for OCCC cell lines revealed significant molecular similarities between OCCC with concurrent endometriosis and OVTOKO, OVISE, RMG1, OVMANA, TOV21G, IGROV1, and JHOC5 cell lines. Analysis of miRNAs revealed 64 upregulated and 61 downregulated mature miRNA molecules (DESeq2, P< 0.05, log2 fold-change > |1|). MiR-10a-5p represented over 21% of the miRNA molecules in OCCC with endometriosis and was significantly upregulated (NGS: log2fold change = 4.37, P = 2.43e-18; QPCR: 8.1-fold change, P< 0.05). Correlation between miR-10a expression level in OCCC cell lines and IC50 (50% inhibitory concentration) of carboplatin in vitro revealed a positive correlation (R2 = 0.93). MiR-10a overexpression in vitro resulted in a significant decrease in proliferation (n = 6; P< 0.05) compared to transfection with a non-targeting control miRNA. Similarly, the cell-cycle analysis revealed a significant shift in cells from S and G2 to G1 (n = 6; P< 0.0001). Bioinformatic analysis predicted that miR-10a-5p target genes that were downregulated in OCCC with endometriosis were involved in receptor signaling pathways, proliferation, and cell cycle progression. MiR-10a overexpression in vitro was correlated with decreased expression of predicted miR-10a target genes critical for proliferation, cell-cycle regulation, and cell survival including [SERPINE1 (3-fold downregulated; P< 0.05), CDK6 (2.4-fold downregulated; P< 0.05), and RAP2A (2-3-fold downregulated; P< 0.05)].

Discussion

These studies in OCCC suggest that miR-10a-5p is an impactful, potentially oncogenic molecule, which warrants further studies.

Phase II Window Study of Olaparib Alone or with Cisplatin or Durvalumab in Operable Head and Neck Cancer

Purpose

We conducted a phase II randomized noncomparative window of opportunity (WOO) trial to evaluate the inhibition of cellular proliferation and the modulation of immune microenvironment after treatment with olaparib alone or in combination with cisplatin or durvalumab in patients with operable head and neck squamous cell carcinoma (HNSCC).

Experimental Design

Forty-one patients with HNSCC were randomized to cisplatin plus olaparib (arm A), olaparib alone (arm B), no treatment (arm C) or durvalumab plus olaparib (arm D). The primary endpoint was to evaluate the percentage of patients in each arm that achieved a reduction of at least 25% in Ki67. Secondary endpoints included objective response rate (ORR), safety, and pathologic complete response (pCR) rate. Paired baseline and resection tumor biopsies and blood samples were evaluated for prespecified biomarkers.

Results

A decrease in Ki67 of at least 25% was observed in 44.8% of treated patients, as measured by quantitative immunofluorescence. The ORR among treated patients was 12.1%. pCR was observed in 2 patients. Two serious adverse events occurred in 2 patients.Programmed death ligand 1 (PD-L1) levels [combined positive score (CPS)] were significantly higher after treatment in arms A and D. Expression of CD163 and colony-stimulating factor 1 receptor (CSF1R) genes, markers of M2 macrophages, increased significantly posttreatment whereas the expression of CD80, a marker of M1 macrophages, decreased.

Conclusion

Preoperative olaparib with cisplatin or alone or with durvalumab was safe in the preoperative setting and led to decrease in Ki67 of at least 25% in 44.8% of treated patients. Olaparib-based treatment modulates the tumor microenvironment leading to upregulation of PD-L1 and induction of protumor features of macrophages.

Significance

HNSCC is characterized by defective DNA repair pathways and immunosuppressive tumor microenvironment. PARP inhibitors, which promote DNA damage and "reset" the inflammatory tumor microenvironment, can establish an effective antitumor response. This phase II WOO trial in HNSCC demonstrated the immunomodulatory effects of PARP inhibitor-induced DNA damage. In this chemo-naïve population, PARP inhibitor-based treatment, reduced tumor cell proliferation and modulated tumor microenvironment. After olaparib upregulation of PD-L1 and macrophages, suggests that combinatorial treatment might be beneficial.

Synopsis

Our WOO study demonstrates that preoperative olaparib results in a reduction in Ki67, upregulation of PD-L1 CPS, and induction of protumor features of macrophages in HNSCC.

Factors for the development of anemia in patients with newly introduced olaparib: A retrospective case-control study

Anemia is the most common dose-limiting toxicity of olaparib. However, few studies have analyzed the clinical features of olaparib-induced anemia. This study investigated the clinical features of olaparib-induced anemia. Additionally, the role of folate or vitamin B12 in olaparib-induced anemia was examined. This retrospective case-control study included patients who received olaparib at Mie University Hospital between January 2018 and December 2020. Data were collected between initiation of olaparib and discontinuation of olaparib or till December 2021. We investigated the development of grade ≥ 3 anemia during olaparib administration for at least 1 year. We examined patients with grade ≥ 3 anemia considering the mean corpuscular volume (MCV), its association with gastrointestinal events and cumulative dose of carboplatin. For the sub-study analysis, data on patients treated with olaparib for ovarian or endometrial cancer were collected to evaluate the Common Terminology Criteria for Adverse Events (CTCAE) or monthly changes in folate or vitamin B12 levels from baseline to 3 months after olaparib initiation. These data were collected between initiation of olaparib and discontinuation of olaparib or till November 2022. Patients with no data on folic acid or vitamin B12 levels were excluded from the sub-study. In the main study, 40 patients were included. Eighteen patients (45%) developed grade ≥ 3 anemia, and all patients discontinued treatment (94%) or reduced olaparib dose (67%) after developing anemia. Among the patients with grade ≥ 3 anemia, 9 (50%) exhibited macrocytic anemia and 15 (83%) had previously received carboplatin. The incidence of grade ≥ 2 dysgeusia was significantly higher in patients with grade ≥ 3 anemia (P = .034). Moreover, the cumulative dose of previously administered carboplatin was higher in patients who had 3 episodes of anemia (P = .102). In sub-study, 12 had data on folic acid and vitamin B12 levels. Sub-study analysis showed that none fulfilled the criteria for deficiency of folate or vitamin B12, while 3 developed grade 3 anemia. This study revealed that olaparib-induced anemia frequently occurs as macrocytic and normocytic erythroblastic anemia without folate or vitamin B12 deficiencies. A high cumulative dose of previously administered carboplatin and dysgeusia may be associated with olaparib-induced anemia.

Biomarkers in Breast Cancer: An Old Story with a New End

Breast cancer is the second most frequent cancer in the world. It is a heterogeneous disease and the leading cause of cancer mortality in women. Advances in molecular technologies allowed for the identification of new and more specifics biomarkers for breast cancer diagnosis, prognosis, and risk prediction, enabling personalized treatments, improving therapy, and preventing overtreatment, undertreatment, and incorrect treatment. Several breast cancer biomarkers have been identified and, along with traditional biomarkers, they can assist physicians throughout treatment plan and increase therapy success. Despite the need of more data to improve specificity and determine the real clinical utility of some biomarkers, others are already established and can be used as a guide to make treatment decisions. In this review, we summarize the available traditional, novel, and potential biomarkers while also including gene expression profiles, breast cancer single-cell and polyploid giant cancer cells. We hope to help physicians understand tumor specific characteristics and support decision-making in patient-personalized clinical management, consequently improving treatment outcome.

The role of the genomic mutation signature and tumor mutation burden on relapse risk prediction in head and neck squamous cell carcinoma after concurrent chemoradiotherapy

Personalized genetic profiling has focused on improving treatment efficacy and predicting risk stratification by identifying mutated genes and selecting targeted agents according to genetic testing. Therefore, we evaluated the role of genetic profiling and tumor mutation burden (TMB) using next-generation sequencing in patients with head and neck squamous cell carcinoma (HNSC). The relapse mutation signature (RMS) and chromatin remodeling mutation signature (CRMS) were explored to predict the risk of relapse in patients with HNSC treated with concurrent chemoradiotherapy (CCRT) with platinum-based chemotherapy. Patients in the high RMS and CRMS groups showed significantly shorter relapse-free survival than those in the low RMS and CRMS groups, respectively (p < 0.001 and p = 0.006). Multivariate Cox regression analysis showed that extranodal extension, CCRT response, and three somatic mutation profiles (TMB, RMS, and CRMS) were independent risk predictors for HNSC relapse. The predictive nomogram showed satisfactory performance in predicting relapse-free survival in patients with HNSC treated with CCRT.

Autophagy and Breast Cancer: Connected in Growth, Progression, and Therapy

Despite an increase in the incidence of breast cancer worldwide, overall prognosis has been consistently improving owing to the development of multiple targeted therapies and novel combination regimens including endocrine therapies, aromatase inhibitors, Her2-targeted therapies, and cdk4/6 inhibitors. Immunotherapy is also being actively examined for some breast cancer subtypes. This overall positive outlook is marred by the development of resistance or reduced efficacy of the drug combinations, but the underlying mechanisms are somewhat unclear. It is interesting to note that cancer cells quickly adapt and evade most therapies by activating autophagy, a catabolic process designed to recycle damaged cellular components and provide energy. In this review, we discuss the role of autophagy and autophagy-associated proteins in breast cancer growth, drug sensitivity, tumor dormancy, stemness, and recurrence. We further explore how autophagy intersects and reduces the efficacy of endocrine therapies, targeted therapies, radiotherapy, chemotherapies as well as immunotherapy via modulating various intermediate proteins, miRs, and lncRNAs. Lastly, the potential application of autophagy inhibitors and bioactive molecules to improve the anticancer effects of drugs by circumventing the cytoprotective autophagy is discussed.

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.

Nuclear translocation of Gasdermin D sensitizes colorectal cancer to chemotherapy in a pyroptosis-independent manner

Gasdermin D (GSDMD) has recently been identified as a cytoplasmic effector protein that plays a central role in pyroptosis of immune cells. However, GSDMD is a universally expressed protein, and its function beyond pyroptosis, especially in cancer cells, has not been well characterized. Here, we report that predominant localization of GSDMD in the nucleoplasm in vivo indicates favorable clinical outcomes in colorectal cancer, while a lack of nuclear localization of GSDMD is associated with poor outcomes. Nuclear GSDMD, rather than cytoplasmic GSDMD, inhibits cell growth and promotes apoptosis in colorectal cancer. Hypoxia in the tumor microenvironment accounts for mild or moderate nuclear translocation of GSDMD in vivo. Under the stimulation of chemotherapy drugs, nuclear GSDMD promotes apoptosis via regulation of its subcellular distribution rather than pyroptosis-related cleavage. After nuclear translocation, GSDMD interacts with PARP-1 to dramatically inhibit its DNA damage repair-related function by functioning like the PARP inhibitor olaparib, thus forming a "hypoxia/chemotherapy-GSDMD nuclear translocation-PARP-1 blockade-DNA damage and apoptosis" axis. This study redefines the pyroptosis-independent function of GSDMD and suggests that the subcellular localization of GSDMD may serve as a molecular indicator of clinical outcomes and a promising therapeutic target in colorectal cancer.

Homologous Recombination Deficiency Scar: Mutations and Beyond-Implications for Precision Oncology

Homologous recombination deficiency (HRD) is a prevalent in approximately 17% of tumors and is associated with enhanced sensitivity to anticancer therapies inducing double-strand DNA breaks. Accurate detection of HRD would therefore allow improved patient selection and outcome of conventional and targeted anticancer therapies. However, current clinical assessment of HRD mainly relies on determining germline BRCA1/2 mutational status and is insufficient for adequate patient stratification as mechanisms of HRD occurrence extend beyond functional BRCA1/2 loss. HRD, regardless of BRCA1/2 status, is associated with specific forms of genomic and mutational signatures termed HRD scar. Detection of this HRD scar might therefore be a more reliable biomarker for HRD. This review discusses and compares different methods of assessing HRD and HRD scar, their advances into the clinic, and their potential implications for precision oncology.

Cancer chemotherapy: insights into cellular and tumor microenvironmental mechanisms of action

Chemotherapy has historically been the mainstay of cancer treatment, but our understanding of what drives a successful therapeutic response remains limited. The diverse response of cancer patients to chemotherapy has been attributed principally to differences in the proliferation rate of the tumor cells, but there is actually very little experimental data supporting this hypothesis. Instead, other mechanisms at the cellular level and the composition of the tumor microenvironment appear to drive chemotherapy sensitivity. In particular, the immune system is a critical determinant of chemotherapy response with the depletion or knock-out of key immune cell populations or immunological mediators completely abrogating the benefits of chemotherapy in pre-clinical models. In this perspective, we review the literature regarding the known mechanisms of action of cytotoxic chemotherapy agents and the determinants of response to chemotherapy from the level of individual cells to the composition of the tumor microenvironment. We then summarize current work toward the development of dynamic biomarkers for response and propose a model for a chemotherapy sensitive tumor microenvironment.

The Role of Curcumin in Prostate Cancer Cells and Derived Spheroids

A major challenge in the clinical management of prostate cancer (PC) is to inhibit tumor growth and prevent metastatic spreading. In recent years, considerable efforts have been made to discover new compounds useful for PC therapy, and promising advances in this field were reached. Drugs currently used in PC therapy frequently induce resistance and PC progresses toward metastatic castration-resistant forms (mCRPC), making it virtually incurable. Curcumin, a commercially available nutritional supplement, represents an attractive therapeutic agent for mCRPC patients. In the present study, we compared the effects of chemotherapeutic drugs such as docetaxel, paclitaxel, and cisplatin, to curcumin, on two PC cell lines displaying a different metastatic potential: DU145 (moderate metastatic potential) and PC-3 (high metastatic potential). Our results revealed a dose-dependent reduction of DU145 and PC-3 cell viability upon treatment with curcumin similar to chemotherapeutic agents (paclitaxel, cisplatin, and docetaxel). Furthermore, we explored the EGFR-mediated signaling effects on ERK activation in DU145 and PC-3 cells. Our results showed that DU145 and PC-3 cells overexpress EGFR, and the treatment with chemotherapeutic agents or curcumin reduced EGFR expression levels and ERK activation. Finally, chemotherapeutic agents and curcumin reduced the size of DU145 and PC-3 spheroids and have the potential to induce apoptosis and also in Matrigel. In conclusion, despite different studies being carried out to identify the potential synergistic curcumin combinations with chemopreventive/therapeutic efficacy for inhibiting PC growth, the results show the ability of curcumin used alone, or in combinatorial approaches, to impair the size and the viability of PC-derived spheroids.

Discovery of novel 7,8-dihydropteridine-6(5H)-one-based DNA-PK inhibitors as potential anticancer agents via scaffold hopping strategy

DNA-dependent protein kinase (DNA-PK) is an essential element in the DNA damage response (DDR) pathway and has been regarded as a druggable target for antineoplastic agents. Starting from AZD-7648, a potent DNA-PK inhibitor being investigated in phase II clinical trials for advanced cancer treatment, two series of DNA-PK inhibitors were rationally designed via scaffold hopping strategy, synthesized, and assessed for their biological activity. Most compounds exhibited potent biochemical activity on DNA-PK enzymatic assay with IC₅₀ values below 300 nM. Among these compounds, DK1 showed the best DNA-PK-inhibitory potency (IC₅₀ = 0.8 nM), slightly better than that of AZD-7648 (IC₅₀ = 1.58 nM). Mode of action studies revealed that compound DK1 decreased the expression levels of γH2A.X and demonstrated synergistic antiproliferative activity against a series of cancer cell lines when used in combination with doxorubicin. Moreover, DK1 showed reasonable in vitro drug-like properties and favorable in vivo pharmacokinetics as an oral drug candidate. Importantly, the combination therapy of DK1 with DNA double-strand break (DSB)-inducing agent doxorubicin showed synergistic anticancer efficacy in the HL-60 xenograft model with a tumor growth inhibition (TGI) of 52.4% and 62.4% for tumor weight and tumor volume, respectively. In conclusion, DK1 is a novel DNA-PK inhibitor with great promise for further study.

PARP inhibitors rising as an epoch-making strategy in first-line maintenance therapy of ovarian cancer: A systematic review and meta-analysis

Background To illustrate the accurate location of PARP inhibitor (PARPi) as the first-line maintenance therapy in advanced ovarian cancer (AOC).Methods Search for eligible studies and calculate clinical outcomes.Results PARPi as a first-line maintenance treatment significantly prolonged the BRCAmut population and the HRD positive population.Conclusion PARPi as first-line maintenance therapy significantly improves the PFS in AOC, especially in the BRCAmut and HRD positive populations. PARPi has been becoming the standard first-line maintenance therapy for AOC.

Therapeutic implications of germline vulnerabilities in DNA repair for precision oncology

DNA repair vulnerabilities are present in a significant proportion of cancers. Specifically, germline alterations in DNA repair not only increase cancer risk but are associated with treatment response and clinical outcomes. The therapeutic landscape of cancer has rapidly evolved with the FDA approval of therapies that specifically target DNA repair vulnerabilities. The clinical success of synthetic lethality between BRCA deficiency and poly(ADP-ribose) polymerase (PARP) inhibition has been truly revolutionary. Defective mismatch repair has been validated as a predictor of response to immune checkpoint blockade associated with durable responses and long-term benefit in many cancer patients. Advances in next generation sequencing technologies and their decreasing cost have supported increased genetic profiling of tumors coupled with germline testing of cancer risk genes in patients. The clinical adoption of panel testing for germline assessment in high-risk individuals has generated a plethora of genetic data, particularly on DNA repair genes. Here, we highlight the therapeutic relevance of germline aberrations in DNA repair to identify patients eligible for precision treatments such as PARP inhibitors (PARPis), immune checkpoint blockade, chemotherapy, radiation therapy and combined treatment. We also discuss emerging mechanisms that regulate DNA repair.

Perspectives on the role of breast cancer susceptibility gene in breast cancer

PURPOSE

Breast cancer susceptibility gene 1/2 can repair damaged DNA through homologous recombination. Besides, the local immune microenvironment of breast cancer is closely linked to the prognosis of patients. But the relationship of breast cancer susceptibility gene 1/2 expression and local immunosuppressive microenvironment in breast cancer is not clear. The aim of this study was to discuss the correlation between them.

METHODS

The fresh primary breast tumors and paired normal tissues of 156 cases of breast cancer patients as well as peripheral blood of 156 cases among them in Tianjin Medical University Cancer Institute and Hospital from January 2014 to October 2018 were collected. The association between breast cancer susceptibility gene 1/2 germline mutation and immune status of microenvironment in situ was analyzed.

RESULTS

The results indicated that the germline mutation of breast cancer susceptibility gene 1/2 was inconsistent with the breast cancer susceptibility gene 1/2 protein expression, and the proportion of immune cells in patients with negative expression of breast cancer susceptibility gene 1/2 protein was higher than patients with positive expression of breast cancer susceptibility gene 1/2 protein (p < 0.05). And the expression of programmed cell death protein 1, cytotoxic T-Lymphocyte Antigen 4, programmed death ligand-1 of CD3⁺ T cells in patients with negative expression of breast cancer susceptibility gene 1/2 protein was higher than patients with positive expression of breast cancer susceptibility gene 1/2 protein (p < 0.05). The breast cancer susceptibility gene 1 protein expression was significantly correlated with family history of breast cancer patients (p = 0.006), local lymph node metastases (p = 0.001), and TNM staging (p ≤ 0.001). The breast cancer susceptibility gene 2 protein expression was significantly related to local lymph node metastases (p ≤ 0.001), III stage rate(p = 0.003) and molecular subtyping (p ≤ 0.001). Besides, the 5 years disease free survival was worse for G1 group and pathological III stage patients than other groups and other TNM stage patients.

CONCLUSION

In short, the immune therapy may be a potential therapy method for breast cancer patients with negative expression of breast cancer susceptibility gene 1/2 protein.

Overexpression of 15-Hydroxyprostaglandin Dehydrogenase Inhibits A549 Lung Adenocarcinoma Cell Growth via Inducing Cell Cycle Arrest and Inhibiting Epithelial-Mesenchymal Transition

Purpose

Lung cancer is one of the most commonly diagnosed cancer as well as the leading cause of cancer-related mortality worldwide, among which lung adenocarcinoma (LUAD) is the most frequent form of lung cancer. Previous studies have shown that 15-hydroxyprostaglandin dehydrogenase (15-PGDH) catalyzes the oxidation of prostaglandins to reduce their biological activities and behaves as a tumor suppressor in various cancers. Thus, we aimed to systematically examine the effects of 15-PGDH overexpression on cellular processes in lung adenocarcinoma cells.

Methods

The stable 15-PGDH-overexpressing A549 cell line was constructed using lentivirus particles. CCK-8 assay was used to determine the cell proliferation rate and sensitivity to cisplatin. Tandem mass tag (TMT)-based quantitative proteomic analysis was used to identify differentially expressed proteins between control and 15-PGDH-overexpression cells. The cell cycle was determined by a flow cytometer. The expression levels of mesenchymal and epithelial markers were measured using Western blotting. Wound healing and transwell assays were used to detect the cell migration and cell invasion ability, respectively.

Results

Analysis of datasets in The Cancer Genome Atlas revealed that the PGDH gene expression level in the lung adenocarcinoma tissues was significantly lower than that in the pericarcinous tissues. 15-PGDH overexpression in A549 cells reduced cell proliferation rate. Quantitative proteomics revealed that 15-PGDH overexpression inhibited PI3K/AKT/mTOR signaling pathway, which is a signaling pathway driving tumor cell growth and epithelial-mesenchymal transition (EMT) process. In addition, both cell cycle and DNA repair-related proteins were down-regulated in 15-PGDH overexpressed cells. 15-PGDH overexpression induced G1/S cell cycle arrest and increased susceptibility to DNA damaging reagent cisplatin. Importantly, overexpression of 15-PGDH inhibited EMT process with the downregulation of β-catenin and Snail-1 as well as upregulation of E-cadherin and ZO-1.

Conclusion

15-PGDH is a tumor suppressor in lung cancer and may serve as a potential therapeutic target to prevent lung adenocarcinoma.

Olaparib with or without bevacizumab or bevacizumab and 5-fluorouracil in advanced colorectal cancer: Phase III LYNK-003

Oxaliplatin-based chemotherapy with a regimen such as FOLFOX with or without targeted therapy is a standard of care option for advanced colorectal cancer; however, long-term exposure to oxaliplatin is associated with cumulative toxicity. Growing evidence suggests maintenance therapy with a less intensive regimen after platinum-based induction therapy can provide continuing benefit with reduced toxicity. We describe the rationale and design of the Phase III LYNK-003 trial, which will evaluate the efficacy and safety of olaparib with or without bevacizumab compared with 5-fluoruracil plus bevacizumab in patients with unresectable or metastatic colorectal cancer that has not progressed on an induction course of FOLFOX plus bevacizumab. The primary end point is progression-free survival by independent central review; secondary end points include overall survival, objective response, duration of response and safety. Clinical trial registration: NCT04456699.

Cisplatin Reduces the Frequencies of Radiotherapy-Induced Micronuclei in Peripheral Blood Lymphocytes of Patients with Gynaecological Cancer: Possible Implications for the Risk of Second Malignant Neoplasms

Gynaecologic cancers are common among women and treatment includes surgery, radiotherapy or chemotherapy, where the last two methods induce DNA damage in non-targeted cells like peripheral blood lymphocytes (PBL). Damaged normal cells can transform leading to second malignant neoplasms (SMN) but the level of risk and impact of risk modifiers is not well defined. We investigated how radiotherapy alone or in combination with chemotherapy induce DNA damage in PBL of cervix and endometrial cancer patients during therapy. Blood samples were collected from nine endometrial cancer patients (treatment with radiotherapy + chemotherapy-RC) and nine cervical cancer patients (treatment with radiotherapy alone-R) before radiotherapy, 3 weeks after onset of radiotherapy and at the end of radiotherapy. Half of each blood sample was irradiated ex vivo with 2 Gy of gamma radiation in order to check how therapy influenced the sensitivity of PBL to radiation. Analysed endpoints were micronucleus (MN) frequencies, apoptosis frequencies and cell proliferation index. The results were characterised by strong individual variation, especially the MN frequencies and proliferation index. On average, despite higher total dose and larger fields, therapy alone induced the same level of MN in PBL of RC patients as compared to R. This result was accompanied by a higher level of apoptosis and stronger inhibition of cell proliferation in RC patients. The ex vivo dose induced fewer MN, more apoptosis and more strongly inhibited proliferation of PBL of RC as compared to R patients. These results are interpreted as evidence for a sensitizing effect of chemotherapy on radiation cytotoxicity. The possible implications for the risk of second malignant neoplasms are discussed.

FGF13 enhances resistance to platinum drugs by regulating hCTR1 and ATP7A via a microtubule-stabilizing effect

Platinum‐based regimens are the most widely used chemotherapy regimens, but cancer cells often develop resistance, which impedes therapy outcome for patients. Previous studies have shown that fibroblast growth factor 13 (FGF13) is associated with resistance to platinum drugs in HeLa cells. However, the mechanism and universality of this effect have not been clarified. Here, we found that FGF13 was associated with poor platinum‐based chemotherapy outcomes in a variety of cancers, such as lung, endometrial, and cervical cancers, through bioinformatics analysis. We then found that FGF13 simultaneously regulates the expression and distribution of hCTR1 and ATP7A in cancer cells, causes reduced platinum influx, and promotes platinum sequestration and efflux upon cisplatin exposure. We subsequently observed that FGF13‐mediated platinum resistance requires the microtubule‐stabilizing effect of FGF13. Only overexpression of FGF13 with the ‐SMIYRQQQ‐ tubulin‐binding domain could induce the platinum resistance effect. This phenomenon was also observed in SK‐MES‐1 cells, KLE cells, and 5637 cells. Our research reveals the mechanism of FGF13‐induced platinum drug resistance and suggests that FGF13 can be a sensibilization target and prognostic biomarker for chemotherapy.

A highly potent ruthenium(II)-sonosensitizer and sonocatalyst for in vivo sonotherapy

As a basic structure of most polypyridinal metal complexes, [Ru(bpy)₃]²⁺, has the advantages of simple structure, facile synthesis and high yield, which has great potential for scientific research and application. However, sonodynamic therapy (SDT) performance of [Ru(bpy)₃]²⁺ has not been investigated so far. SDT can overcome the tissue-penetration and phototoxicity problems compared to photodynamic therapy. Here, we report that [Ru(bpy)₃]²⁺ is a highly potent sonosensitizer and sonocatalyst for sonotherapy in vitro and in vivo. [Ru(bpy)₃]²⁺ can produce singlet oxygen (¹O₂) and sono-oxidize endogenous 1,4-dihydronicotinamide adenine dinucleotide (NADH) under ultrasound (US) stimulation in cancer cells. Furthermore, [Ru(bpy)₃]²⁺ enables effective destruction of mice tumors, and the therapeutic effect can reach deep tissues over 10 cm under US irradiation. This work paves a way for polypyridinal metal complexes to be applied to the noninvasive precise sonotherapy of cancer.

Sonodynamic therapy has therapeutic promise due to its safety and good tissue penetration, but is currently bottlenecked due to a lack of efficient and safe sonosensitizers. Here the authors show that [Ru(bpy)₃]²⁺ can produce singlet oxygen and sonooxidize NADH in deep tissue, and destroy mouse tumors effectively.

MiR-200c-3p Modulates Cisplatin Resistance in Biliary Tract Cancer by ZEB1-Independent Mechanisms

Simple Summary

Biliary tract cancer is a rare malignancy with poor overall survival. The majority of patients are faced with advanced disease stage. Cisplatin-based treatment schedules represent the mainstay of first-line therapeutic strategy, yet only a small portion of patients develop a treatment response. One of the main reasons is acquired drug resistance. Previous studies correlated certain microRNAs (miRNAs), including miR-200c-3p, with drug resistance in various cancer types. However, limited knowledge exists about miR-200c-3p expression and cisplatin resistance in biliary tract cancer. Thus, the main aim of this study was to investigate the influence of miR-200c-3p on the cisplatin resistance in this cancer entity. We demonstrated that miR-200c-3p contributes to cisplatin resistance independently of its known influence on ZEB1 expression.

Abstract

Biliary tract cancer is a major global health issue in cancer-related mortality. Therapeutic options are limited, and cisplatin-based treatment schedules represent the mainstay of first-line therapeutic strategies. Although the gain of survival by the addition of cisplatin to gemcitabine is moderate, acquired cisplatin resistance frequently leads to treatment failures with mechanisms that are still poorly understood. Epithelial–mesenchymal transition (EMT) is a dynamic process that changes the shape, function, and gene expression pattern of biliary tract cancer cells. In this study, we explored the influence of the EMT-regulating miR-200c-3p on cisplatin sensitivity in biliary tract cancer cells. Using gain of function experiments, we demonstrated that miR-200c-3p regulates epithelial cell markers through the downregulation of the transcription factor ZEB1. MiR-200c-3p upregulation led to a decreased sensitivity against cisplatin, as observed in transient overexpression models as well as in cell lines stably overexpressing miR-200c-3p. The underlying mechanism seems to be independent of miR-200c-3p’s influence on ZEB1 expression, as ZEB1 knockdown resulted in the opposite effect on cisplatin resistance, which was abolished when ZEB1 knockdown and miR-200c-3p overexpression occurred in parallel. Using a gene panel of 40 genes that were previously associated with cisplatin resistance, two (Dual Specificity Phosphatase 16 (DUSP16) and Stratifin (SFN)) were identified as significantly (>2 fold, p-value < 0.05) up-regulated in miR-200c-3p overexpressing cells. In conclusion, miR-200c-3p might be an important contributor to cisplatin resistance in biliary tract cancer, independently of its interaction with ZEB1.

Metal- and metalloid-based compounds to target and reverse cancer multidrug resistance

Drug resistance remains the major cause of cancer treatment failure especially at the late stage of the disease. However, based on their versatile chemistry, metal and metalloid compounds offer the possibility to design fine-tuned drugs to circumvent and even specifically target drug-resistant cancer cells. Based on the paramount importance of platinum drugs in the clinics, two main areas of drug resistance reversal strategies exist: overcoming resistance to platinum drugs as well as multidrug resistance based on ABC efflux pumps. The current review provides an overview of both aspects of drug design and discusses the open questions in the field. The areas of drug resistance covered in this article involve: 1) Altered expression of proteins involved in metal uptake, efflux or intracellular distribution, 2) Enhanced drug efflux via ABC transporters, 3) Altered metabolism in drug-resistant cancer cells, 4) Altered thiol or redox homeostasis, 5) Altered DNA damage recognition and enhanced DNA damage repair, 6) Impaired induction of apoptosis and 7) Altered interaction with the immune system. This review represents the first collection of metal (including platinum, ruthenium, iridium, gold, and copper) and metalloid drugs (e.g. arsenic and selenium) which demonstrated drug resistance reversal activity. A special focus is on compounds characterized by collateral sensitivity of ABC transporter-overexpressing cancer cells. Through this approach, we wish to draw the attention to open research questions in the field. Future investigations are warranted to obtain more insights into the mechanisms of action of the most potent compounds which target specific modalities of drug resistance.

Triple Negative Breast Cancer: A Mountain Yet to Be Scaled Despite the Triumphs

Metastatic progression and tumor recurrence pertaining to TNBC are certainly the leading cause of breast cancer-related mortality; however, the mechanisms underlying TNBC chemoresistance, metastasis, and tumor relapse remain somewhat ambiguous. TNBCs show 77% of the overall 4-year survival rate compared to other breast cancer subtypes (82.7 to 92.5%). TNBC is the most aggressive subtype of breast cancer, with chemotherapy being the major approved treatment strategy. Activation of ABC transporters and DNA damage response genes alongside an enrichment of cancer stem cells and metabolic reprogramming upon chemotherapy contribute to the selection of chemoresistant cells, majorly responsible for the failure of anti-chemotherapeutic regime. These selected chemoresistant cells further lead to distant metastasis and tumor relapse. The present review discusses the approved standard of care and targetable molecular mechanisms in chemoresistance and provides a comprehensive update regarding the recent advances in TNBC management.

Analysis of Adaptive Olaparib Resistance Effects on Cisplatin Sensitivity in Triple Negative Breast Cancer Cells

Poly-(ADP)-ribose polymerase inhibitors (PARPi) and platinum-based drugs are promising therapies for triple negative breast cancers (TNBC) with BRCA1 or BRCA2 loss. PARPi(s) show better efficacies when combined with platinum-based therapy, however, acquisition of PARPi resistance has been linked with co-resistance to platinum-based drugs. Here, we show that TNBCs with constitutively hyperactivated PARP-1 display greater tolerances for the PARPi olaparib and cisplatin, and respond synergistically to olaparib/cisplatin combinations with increased cytotoxicity. Regardless of BRCA1 and PARP-1 activity status, upon gaining olaparib resistance (OlaR), OlaR MDA-MB-468 (BRCA1 wild-type) and SUM1315 (BRCA1 mutant) TNBC cells retain cisplatin sensitivities of their isogenic parental counterparts. OlaR TNBC cells express decreased levels of PARP-1 and Pol η, a translesion-synthesis polymerase important in platinum-induced interstrand crosslink repair. Although native RAD51 recombinase levels are unaffected, anti-RAD51 immunoreactive low molecular weight sbands are exclusively detected in OlaR cells. Despite normal BRCA1, RAD51 foci formation/recruitment to double-strand breaks are impaired in OlaR MDA-MB-468 cells, suggesting homologous-recombination impairment. RNA-seq and pathway analysis of cisplatin-affected genes revealed enrichment of G2/M cell cycle regulation and DNA repair pathways in parental and OlaR MDA-MB-468 cells whereas parental and OlaR SUM1315 cells showed enrichment of inflammatory stress response pathways associated with TNFR1/2, TWEAK and IL-17 signaling. These data show that TNBC models with wild type versus mutant BRCA1 exhibit differences in CDDP-induced cellular response pathways, however, the CDDP-induced signaling responses remain stable across the isogenic models of OlaR from the same lineage. These data also show that adaptive OlaR does not automatically promote cisplatin resistance, implicating the potential benefit of platinum-based therapy for OlaR TNBCs.

The germline/somatic DNA damage repair gene mutations modulate the therapeutic response in Chinese patients with advanced pancreatic ductal adenocarcinoma

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is a fatal disease with molecular heterogeneity, inducing differences in biological behavior, and therapeutic strategy. NGS profiles of pathogenic alterations in the Chinese PDAC population are limited. We conducted a retrospective study to investigate the predictive role of DNA damage repair (DDR) mutations in precision medicine.

METHODS

The NGS profiles were performed on resected tissues from 195 Chinese PDAC patients. Baseline clinical or genetic characteristics and survival status were collected. The Kaplan-Meier survival analyses were performed by the R version 3.6.1.

RESULTS

The main driver genes were KRAS, TP53, CDKN2A, and SMAD4. Advanced patients with KRAS mutation showed a worse OS than KRAS wild-type (p = 0.048). DDR pathogenic deficiency was identified in 30 (15.38%) of overall patients, mainly involving BRCA2 (n = 9, 4.62%), ATM (n = 8, 4.10%) and RAD50 genes (n = 3, 1.54%). No significance of OS between patients with or without DDR mutations (p = 0.88). But DDR mutation was an independent prognostic factor for survival analysis of advanced PDAC patients (p = 0.032). For DDR mutant patients, treatment with platinum-based chemotherapy (p = 0.0096) or olaparib (p = 0.018) respectively improved the overall survival. No statistical difference between tumor mutation burden (TMB) and DDR mutations was identified. Treatment of PD-1 blockades did not bring significantly improved OS to DDR-mutated patients than the naive DDR group (p = 0.14).

CONCLUSIONS

In this retrospective study, we showed the role of germline and somatic DDR mutation in predicting the efficacy of olaparib and platinum-based chemotherapy in Chinese patients. However, the value of DDR mutation in the prediction of hypermutation status and the sensitivity to the PD-1 blockade needed further investigation.

BRCA Mutational Status is a Promising Predictive Biomarker for Platinum- based Chemotherapy in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) can be distinguished from other breast malignancies by the lack of expression of estrogen receptors (ER), progesterone receptors (PR) as well as human epidermal growth factor receptor 2 (HER2). TNBC is associated with adverse clinical outcomes and high risk of metastasis. Currently, several clinical and translational reports are focusing on developing targeted therapies for this aggressive cancer. In addition to approved targeted drugs such as poly(ADP-ribose) polymerase inhibitors (PARPi) and immune-checkpoint inhibitors, platinum-based chemotherapy is still a cornerstone therapeutic option in TNBC. However, despite the observed improved outcomes with platinum- based chemotherapy in TNBC, there is still a large proportion of patients who do not respond to this treatment, hence, the need for predictive biomarkers to stratify TNBC patients and therefore, avoiding unwanted toxicities of these agents. With the emergence of genetic testing, several recent studies suggested mutations in breast cancer susceptibility gene (BRCA) in TNBC patients as important predictors of outcomes. These mutations alter the homologous recombination repair (HRR) mechanisms leading to genomic instability. Consequently, sensitivity to platinum-based treatments in this subpopulation of TNBC patients may be explained by cell death enhanced by deoxyribonucleic acid (DNA) damage induced by these potent anticancer drugs. Through this paper, we review several recent studies on this topic to better understand the mechanisms and discuss the potential of BRCA mutational status as a predictive biomarker of platinum-based chemotherapy in TNBC.

Water-Soluble Iridic-Porphyrin Complex for Non-invasive Sonodynamic and Sono-oxidation Therapy of Deep Tumors

Due to conventional photodynamic therapy encountering serious problems of phototoxicity and low tissue-penetrating depth of light, other dynamic therapy-based therapeutic methods such as sonodynamic therapy (SDT) are expected to be developed. To improve the therapeutic response to SDT, more effective sonosensitizers are imperative. In this study, a novel water-soluble iridium(III)-porphyrin sonosensitizer (IrTMPPS) was synthesized and used for SDT. IrTMPPS generated ample singlet oxygen (¹O₂) under US irradiation and especially showed distinguished US-activatable abilities at more than 10 cm deep-tissue depths. Interestingly, under US irradiation, IrTMPPS sonocatalytically oxidized intracellular NADH, which would enhance SDT efficiency by breaking the redox balance in the tumor. Moreover, IrTMPPS displayed great sonocytotoxicity toward various cancer cells, and in vivo experiments demonstrated efficient tumor inhibition and anti-metastasis to the lungs in the presence of IrTMPPS and US irradiation. This report gives a novel idea of metal-based sonosensitizers for sonotherapy by fully taking advantage of non-invasiveness, water solubility, and deep tumor therapy.

Kinase Inhibitors of DNA-PK, ATM and ATR in Combination with Ionizing Radiation Can Increase Tumor Cell Death in HNSCC Cells While Sparing Normal Tissue Cells

(1) Kinase inhibitors (KI) targeting components of the DNA damage repair pathway are a promising new type of drug. Combining them with ionizing radiation therapy (IR), which is commonly used for treatment of head and neck tumors, could improve tumor control, but could also increase negative side effects on surrounding normal tissue. (2) The effect of KI of the DDR (ATMi: AZD0156; ATRi: VE-822, dual DNA-PKi/mTORi: CC-115) in combination with IR on HPV-positive and HPV-negative HNSCC and healthy skin cells was analyzed. Cell death and cell cycle arrest were determined using flow cytometry. Additionally, clonogenic survival and migration were analyzed. (3) Studied HNSCC cell lines reacted differently to DDRi. An increase in cell death for all of the malignant cells could be observed when combining IR and KI. Healthy fibroblasts were not affected by simultaneous treatment. Migration was partially impaired. Influence on the cell cycle varied between the cell lines and inhibitors; (4) In conclusion, a combination of DDRi with IR could be feasible for patients with HNSCC. Side effects on healthy cells are expected to be limited to normal radiation-induced response. Formation of metastases could be decreased because cell migration is impaired partially. The treatment outcome for HPV-negative tumors tends to be improved by combined treatment.

DNA repair pathways and their roles in drug resistance for lung adenocarcinoma

Lung cancer is the leading cancer type of death rate. The lung adenocarcinoma subtype is responsible for almost half of the total lung cancer deaths. Despite the improvements in cancer treatment in recent years, lung adenocarcinoma patients' overall survival rate remains poor. Immunetherapy and chemotherapy are two of the most widely used options for the treatment of cancer. Although many cancer types initially respond to these treatments, the development of resistance is inevitable. The rapid development of drug resistance mainly characterizes lung adenocarcinoma. Despite being the subject of many studies in recent years, the resistance initiation and progression mechanism is still unclear. In this review, we have examined the role of the primary DNA repair pathways (non-homologous end joining (NHEJ) pathway, homologous-recombinant repair (HR) pathway, base excision repair (BER) pathway, and nucleotide excision repair (NER) pathway and transactivation mechanisms of tumor protein 53 (TP53) in drug resistance development. This review suggests that mentioned pathways have essential roles in developing the resistance against chemotherapy and immunotherapy in lung adenocarcinoma patients.

FEN1 Blockade for Platinum Chemo-Sensitization and Synthetic Lethality in Epithelial Ovarian Cancers

Simple Summary

Overall survival outcomes, despite platinum-based chemotherapy, for patients with advanced ovarian cancer remains poor. Increased DNA repair capacity is a key route to platinum resistance in ovarian cancer. In the current study, we show that FEN1, a key player in DNA repair, is overexpressed in ovarian cancer and associated with poor survival. Pre-clinically FEN1 blockade not only increased platinum sensitivity but was also synthetically lethal in BRCA2 and POLβ deficient ovarian cancer cells. Together the data provides evidence that FEN1 is a promising anti-cancer target in ovarian cancer.

Abstract

FEN1 plays critical roles in long patch base excision repair (LP-BER), Okazaki fragment maturation, and rescue of stalled replication forks. In a clinical cohort, FEN1 overexpression is associated with aggressive phenotype and poor progression-free survival after platinum chemotherapy. Pre-clinically, FEN1 is induced upon cisplatin treatment, and nuclear translocation of FEN1 is dependent on physical interaction with importin β. FEN1 depletion, gene inactivation, or inhibition re-sensitizes platinum-resistant ovarian cancer cells to cisplatin. BRCA2 deficient cells exhibited synthetic lethality upon treatment with a FEN1 inhibitor. FEN1 inhibitor-resistant PEO1R cells were generated, and these reactivated BRCA2 and overexpressed the key repair proteins, POLβ and XRCC1. FEN1i treatment was selectively toxic to POLβ deficient but not XRCC1 deficient ovarian cancer cells. High throughput screening of 391,275 compounds identified several FEN1 inhibitor hits that are suitable for further drug development. We conclude that FEN1 is a valid target for ovarian cancer therapy.

Bone tumor-targeted delivery of theranostic 195mPt-bisphosphonate complexes promotes killing of metastatic tumor cells

Platinum-based drugs such as cisplatin are very potent chemotherapeutics, whereas radioactive platinum (195mPt) is a rich source of low-energy Auger electrons, which kills tumor cells by damaging DNA. Auger electrons damage cells over a very short range. Consequently, 195mPt-based radiopharmaceuticals should be targeted toward ​tumors to maximize radiotherapeutic efficacy and minimize Pt-based systemic toxicity. Herein, we show that systemically administered radioactive bisphosphonate-functionalized platinum (195mPt-BP) complexes specifically accumulate in intratibial bone metastatic lesions in mice. The 195mPt-BP complexes accumulate 7.3-fold more effectively in bone 7 days after systemic delivery compared to 195mPt-cisplatin lacking bone-targeting bisphosphonate ligands. Therapeutically, 195mPt-BP treatment causes 4.5-fold more γ-H2AX formation, a biomarker for DNA damage in metastatic tumor cells compared to 195mPt-cisplatin. We show that systemically administered 195mPt-BP is radiotherapeutically active, as evidenced by an 11-fold increased DNA damage in metastatic tumor cells compared to non-radioactive Pt-BP controls. Moreover, apoptosis in metastatic tumor cells is enhanced more than 3.4-fold upon systemic administration of 195mPt-BP vs. radioactive 195mPt-cisplatin or non-radioactive Pt-BP controls. These results provide the first preclinical evidence for specific accumulation and strong radiotherapeutic activity of 195mPt-BP in bone metastatic lesions, which offers new avenues of research on radiotherapeutic killing of tumor cells in bone metastases by Auger electrons.

RAD50 deficiency is a predictor of platinum sensitivity in sporadic epithelial ovarian cancers

Intrinsic or acquired resistance seriously limits the use of platinating agents in advanced epithelial ovarian cancers. Increased DNA repair capacity is a key route to platinum resistance. RAD50 is a critical component of the MRN complex, a ‘first responder’ to DNA damage and essential for the repair of DSBs and stalled replication forks. We hypothesised a role for RAD50 in ovarian cancer pathogenesis and therapeutics. Clinicopathological significance of RAD50 expression was evaluated in clinical cohorts of ovarian cancer at the protein level (n = 331) and at the transcriptomic level (n = 1259). Sub-cellular localization of RAD50 at baseline and following cisplatin therapy was tested in platinum resistant (A2780cis, PEO4) and sensitive (A2780, PEO1) ovarian cancer cells. RAD50 was depleted and cisplatin sensitivity was investigated in A2780cis and PEO4 cells. RAD50 deficiency was associated with better progression free survival (PFS) at the protein (p = 0.006) and transcriptomic level (p < 0.001). Basal level of RAD50 was higher in platinum resistant cells. Following cisplatin treatment, increased nuclear localization of RAD50 was evident in A2780cis and PEO4 compared to A2780 and PEO1 cells. RAD50 depletion using siRNAs in A2780cis and PEO4 cells increased cisplatin cytotoxicity, which was associated with accumulation of DSBs, S-phase cell cycle arrest and increased apoptosis. We provide evidence that RAD50 deficiency is a predictor of platinum sensitivity. RAD50 expression-based stratification and personalization could be viable clinical strategy in ovarian cancers.

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.

Platinum-Based Neoadjuvant Chemotherapy for Breast Cancer With BRCA Mutations: A Meta-Analysis

Background

Triple-negative breast cancer (TNBC) is one of the most aggressive subtypes of breast cancer and the major phenotype of BRCA related hereditary breast cancer. Platinum is a promising chemotherapeutic agent for TNBC. However, its efficacy for breast cancer with BRCA germline mutation remains inconclusive. Here we present a meta-analysis to evaluate the effect of platinum agents for breast cancer patients with BRCA mutation in neoadjuvant setting.

Materials and Methods

Pubmed, Embase, and Cochrane Central Register of Controlled Trials databases were searched for relevant studies on neoadjuvant platinum treatment and BRCA related breast cancer. Fixed- and random-effect models were adopted for meta-analyses. Heterogeneity investigation was conducted by sensitivity and subgroup analyses. Publication bias was evaluated by funnel plot and Begg’s test.

Results

In all, five studies with 363 patients were included for meta-analysis. The pooled pathological complete response (pCR) rates were 43.4% (59/136) and 33.9% (77/227) for platinum and control groups, respectively. Adding platinum to neoadjuvant regimen did not significantly improved pCR rate (odds ratio [OR]: 1.340, 95% confidence interval [CI] = 0.677–2.653, p = 0.400). Sensitivity analyses also revealed platinum did not significantly increase pCR rate in either TNBC or HER2- patients (TNBC subgroup: OR: 1.028, 95% CI = 0.779–1.356, p = 0.846; HER2- subgroup: OR: 0.935, 95% CI = 0.716–1.221, p = 0.622).

Conclusions

Our meta-analysis suggested that the addition of platinum to neoadjuvant chemotherapy did not significantly improve pCR rate for patients with BRCA mutations. Further large-scale randomized control trial with survival data may provide more robust evidence on therapeutic value of platinum for breast cancer neoadjuvant treatment.

Analyzing the key gene expression and prognostics values for acute myeloid leukemia

BACKGROUND

Acute myeloid leukemia (AML) is one of the first tumor types sequenced at the whole genome level. However, numbers of the mutated genes expression levels, functions, and prognostics values still unclear.

METHODS

To most ordinary mutated genes were analyzed via cancer virtual cohort discovery analysis platform (CVCDAP), and further investigated the mutational conversions, variant allele frequencies (VAF), driver genes, and potential druggable mutated genes in AML. The top mutated gene mRNA expression levels and the relationship between gene expression levels and prognosis for AML patients were performed by Gene Expression Profiling Interactive Analysis (GEPIA). Moreover, we used the UALCAN dataset to confirm the association between gene expression levels and prognosis for AML patients. Enrichment functions of the top mutated genes of AML were analyzed through Metascape. Finally, the role of these defined genes in cancer pathways and potential drug targets were analyzed by gene set cancer analysis (GSCALite).

RESULTS

The top 20 mutated genes for AML included FLT3, HPS3, ABCA6, PCLO, SLIT2, and other ones. Compared to normal control samples, NPM1 and GABRB3 were significantly downregulated in AML samples, but TP53, DNMT3A, HPS3, FLT3, SENP6, and RUNX1 were significantly overexpressed (all these genes P value <0.01). Overexpression of FLT3 and PCLO indicated a poor prognosis, but the overexpression of SLIT3 functioned as a protector for AML via GEPIA. HSP3 indicates the favorable factor for AML, but overexpression of ABCA6 (P=0.066) may act as the adverse factor by UALCAN analysis. Enrichment function analysis shows the functions of defining genes, including negative regulation of cell differentiation, small GTPase mediated signal transduction, and immune system process. Finally, these genes participate in apoptosis, cell cycle, PI3K/AKT, and RAS/MAPK signaling pathway, and FLT3 is sensitive to 5-Fluorouracil, Methotrexate, ATRA. DNMT3A and IDH2 are resistant to Trametinib. RUNX1 and TP53 were sensitive to I-BET-762 and Tubastatin A.

CONCLUSIONS

Present study showed overexpression of FLT3, ABCA6, and PCLO indicated the poor prognosis of AML, but overexpression of SLIT3 and HSP3 functioned as an AML protector. There are several drugs and small molecules that target the top 20 mutated genes in AML.

The anti-malarial drug atovaquone potentiates platinum-mediated cancer cell death by increasing oxidative stress

Platinum chemotherapies are highly effective cytotoxic agents but often induce resistance when used as monotherapies. Combinatorial strategies limit this risk and provide effective treatment options for many cancers. Here, we repurpose atovaquone (ATQ), a well-tolerated & FDA-approved anti-malarial agent by demonstrating that it potentiates cancer cell death of a subset of platinums. We show that ATQ in combination with carboplatin or cisplatin induces striking and repeatable concentration- and time-dependent cell death sensitization in vitro across a variety of cancer cell lines. ATQ induces mitochondrial reactive oxygen species (mROS), depleting intracellular glutathione (GSH) pools in a concentration-dependent manner. The superoxide dismutase mimetic MnTBAP rescues ATQ-induced mROS production and pre-loading cells with the GSH prodrug N-acetyl cysteine (NAC) abrogates the sensitization. Together, these findings implicate ATQ-induced oxidative stress as key mediator of the sensitizing effect. At physiologically achievable concentrations, ATQ and carboplatin furthermore synergistically delay the growth of three-dimensional avascular spheroids. Clinically, ATQ is a safe and specific inhibitor of the electron transport chain (ETC) and is concurrently being repurposed as a candidate tumor hypoxia modifier. Together, these findings suggest that ATQ is deserving of further study as a candidate platinum sensitizing agent.

Zebrafish Xenografts Unveil Sensitivity to Olaparib beyond BRCA Status

Poly (ADP-ribose) polymerase (PARP) inhibition in BRCA-mutated cells results in an incapacity to repair DNA damage, leading to cell death caused by synthetic lethality. Within the treatment options for advanced triple negative breast cancer, the PARP inhibitor olaparib is only given to patients with BRCA1/2 mutations. However, these patients may show resistance to this drug and BRCA1/2 wild-type tumors can show a striking sensitivity, making BRCA status a poor biomarker for treatment choice. Aiming to investigate if the zebrafish model can discriminate sensitivities to olaparib, we developed zebrafish xenografts with different BRCA status and measured tumor response to treatment, as well as its impact on angiogenesis and metastasis. When challenged with olaparib, xenografts revealed sensitivity phenotypes independent of BRCA. Moreover, its combination with ionizing radiation increased the cytotoxic effects, showing potential as a combinatorial regimen. In conclusion, we show that the zebrafish xenograft model may be used as a sensitivity profiling platform for olaparib in monotherapy or in combinatorial regimens. Hence, this model presents as a promising option for the future establishment of patient-derived xenografts for personalized medicine approaches beyond BRCA status.

Synthesis, chemical characterization, PARP inhibition, DNA binding and cellular uptake of novel ruthenium(II)-arene complexes bearing benzamide derivatives in human breast cancer cells

Inhibitors of poly(ADP-ribose) polymerase-1 (PARP-1) showed remarkable clinical efficacy in BRCA-mutated tumors. Based on the rational drug design, derivatives of PARP inhibitor 3-aminobenzamide (3-AB), 2-amino-4-methylbenzamide (L1) and 3-amino-N-methylbenzamide (L2), were coordinated to the ruthenium(II) ion, to form potential drugs affecting DNA and inhibiting PARP enzyme. The four conjugated complexes of formula: C1 [(ƞ⁶-toluene)Ru(L1)Cl]PF₆, C2 [(ƞ⁶-p-cymene)Ru(L1)Cl]PF₆, C3 [(ƞ⁶-toluene)Ru(L2)Cl₂] and C4 [(ƞ⁶-p-cymene)Ru(L2)Cl₂], have been synthesized and characterized. Colorimetric 3-(4.5-dimethylthiazol-2-yl)-2.5-diphenyltetrazolium bromide (MTT) assay showed the highest antiproliferative activity of C1 in HCC1937, MDA-MB-231, and MCF-7 breast cancer cells. Efficiency of inhibition of PARP-1 enzymatic activity in vitro decreased in order: C2 > C4 > 3-AB>C1 > C3. ICP-MS study of intracellular accumulation and distribution in BRCA1-mutated HCC1937 revealed that C1-C4 entered cells within 24 h. The complex C1 showed the highest intracellular accumulation, nuclear-targeting properties, and exhibited the highest DNA binding (39.2 ± 0.6 pg of Ru per μg of DNA) that resulted in the cell cycle arrest in the S phase.

Design, synthesis and antitumour evaluation of pyrrolo[1,2-f]-phenanthridine and dibenzo[f,h]pyrrolo[1,2-b]isoquinoline derivatives

A series of 1,2-bis(hydroxymethyl)pyrrolo[1,2-f]phenanthridine derivatives and their alkyl (ethyl and isopropyl) carbamates and 12,13-bis(hydroxymethyl)-9,14-dihydro-dibenzo[f,h]pyrrolo[1,2-b]isoquinoline derivatives were synthesized for antiproliferative evaluation. The preliminary antitumour studies revealed that these two types of bis(hydroxymethyl) derivatives showed significant antitumour activities and were able to inhibit the growth of various human tumour cell lines in vitro. Several of the derivatives were demonstrated to cause DNA interstrand cross-links by an alkaline agarose gel shifting assay. These conjugates were cytotoxic to a variety of cancer cell lines by inducing DNA damage, delaying cell cycle progression in the G2/M phase and triggering apoptosis. Compound 21a, dissolved in a vehicle suitable for intravenous administration, was selected for antitumour studies in animal models. We demonstrated that at a dose that did not cause body weight loss in mice, compound 21a could significantly suppress the growth of tumour xenografts of human lung cancer H460 and colorectal cancer HCT-116 cells in nude mice. Our present results confirm the antitumour activities of these conjugates.