Relevance of poly (ADP-ribose) polymerase inhibitors in prostate cancer

A Risk Model Developed Based on Homologous Recombination Deficiency Predicts Overall Survival in Patients With Lower Grade Glioma

The role of homologous recombination deficiency (HRD) in lower grade glioma (LGG) has not been elucidated, and accurate prognostic prediction is also important for the treatment and management of LGG. The aim of this study was to construct an HRD-based risk model and to explore the immunological and molecular characteristics of this risk model. The HRD score threshold = 10 was determined from 506 LGG samples in The Cancer Genome Atlas cohort using the best cut-off value, and patients with high HRD scores had worse overall survival. A total of 251 HRD-related genes were identified by analyzing differentially expressed genes, 182 of which were associated with survival. A risk score model based on HRD-related genes was constructed using univariate Cox regression, least absolute shrinkage and selection operator regression, and stepwise regression, and patients were divided into high- and low-risk groups using the median risk score. High-risk patients had significantly worse overall survival than low-risk patients. The risk model had excellent predictive performance for overall survival in LGG and was found to be an independent risk factor. The prognostic value of the risk model was validated using an independent cohort. In addition, the risk score was associated with tumor mutation burden and immune cell infiltration in LGG. High-risk patients had higher HRD scores and “hot” tumor immune microenvironment, which could benefit from poly-ADP-ribose polymerase inhibitors and immune checkpoint inhibitors. Overall, this big data study determined the threshold of HRD score in LGG, identified HRD-related genes, developed a risk model based on HRD-related genes, and determined the molecular and immunological characteristics of the risk model. This provides potential new targets for future targeted therapies and facilitates the development of individualized immunotherapy to improve prognosis.

Drug resistance in metastatic castration-resistant prostate cancer: an update on the status quo

Prostate cancer (PCa) is a leading cause of cancer-related morbidity and mortality in men globally. Despite improvements in the diagnosis and treatment of PCa, a significant proportion of patients with high-risk localized disease and all patients with advanced disease at diagnosis will experience progression to metastatic castration-resistant prostate cancer (mCRPC). Multiple drugs are now approved as the standard of care treatments for patients with mCRPC that have been shown to prolong survival. Although the majority of patients will respond initially, primary and secondary resistance to these therapies make mCRPC an incurable disease. Several molecular mechanisms underlie the development of mCRPC, with the androgen receptor (AR) axis being the main driver as well as the key drug target. Understanding resistance mechanisms is crucial for discovering novel therapeutic strategies to delay or reverse the progression of the disease. In this review, we address the diverse mechanisms of drug resistance in mCRPC. In addition, we shed light on emerging targeted therapies currently being tested in clinical trials with promising potential to overcome mCRPC-drug resistance.

Discovering a qualitative transcriptional signature of homologous recombination defectiveness for prostate cancer

The discovery of homologous recombination deficiency (HRD) biomarkers in prostate cancer is important for patients who will benefit from poly ADP-ribose polymerase inhibitor (PARPi). Here, we developed a transcriptional homologous recombination defectiveness (HRDness) signature, comprising 16 gene pairs (16-GPS), for prostate cancer by a relative expression ordering (REO)-based discovery procedure. Subsequently, two newly subtypes classified by 16-GPS showed a higher significance level in various clinicopathological and HRD features than subtypes obtained by other methods, such as HRDetect. HRDness subtype also displayed more aggressive features and higher genomics scores than non-HRDness in three independent datasets. HRDness prostate cancer cells were more sensitive to PARPi than non-HRDness. Moreover, the HRDness samples showed distinct multi-omics characteristics related to homologous recombination repair function loss. Overall, the newly proposed qualitative signature can robustly determine the HRD status for prostate cancer at the personalized level, and especially be an auxiliary tool for PARPi treatment strategy.

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16 gene pairs (16-GPS) could predict HRDness for prostate cancer at individual level

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HRDness samples classified by 16-GPS showed HRD molecular and clinical features

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HRDness cells classified by 16-GPS tend to be sensitive to PARPi

Metastatic castration-resistant prostate cancer: Academic insights and perspectives through bibliometric analysis

BACKGROUND

In recent years, metastatic castration-resistant prostate cancer (MCRPC) and studies related to MCRPC have drawn global attention. The main objective of this bibliometric study was to provide an overview of MCRPC, explore clusters and trends in research and investigate the future direction of MCRPC research.

METHODS

A total of 4089 publications published between 1979 and 2018 were retrieved from the Web of Science (WoS) Core Collection database. Different aspects of MCRPC research, including the countries/territories, institutions, journals, authors, research areas, funding agencies and author keywords, were analyzed.

RESULTS

The number of annual MCRPC publications increased rapidly after 2010. American researchers played a vital role in this increase, as they published the most publications. The most productive institution was Memorial Sloan Kettering Cancer Center. De Bono, JS (the United Kingdom [UK]) and Scher, HI (the United States of America [USA]) were the two most productive authors. The National Institutes of Health (NIH) funded the largest number of published papers. Analyses of keywords suggested that therapies (abiraterone, enzalutamide, etc.) would attract global attention after US Food and Drug Administration (FDA) approval.

CONCLUSIONS

Developed countries, especially the USA, were the leading nations for MCRPC research because of their abundant funding and frequent international collaborations. Therapy was one of the most vital aspects of MCRPC research. Therapies targeting DNA repair or the androgen receptor (AR) signing pathway and new therapies especially prostate-specific membrane antigen (PSMA)-based radioligand therapy (RLT) would be the next focus of MCRPC research.

Identification of Novel Biomarkers of Homologous Recombination Defect in DNA Repair to Predict Sensitivity of Prostate Cancer Cells to PARP-Inhibitors

One of the most common malignancies in men is prostate cancer, for which androgen deprivation is the standard therapy. However, prostate cancer cells become insensitive to anti-androgen treatment and proceed to a castration-resistant state with limited therapeutic options. Therefore, besides the androgen deprivation approach, novel biomarkers are urgently required for specific targeting in this deadly disease. Recently, germline or somatic mutations in the homologous recombination (HR) DNA repair genes have been identified in at least 20–25% of metastatic castration-resistant prostate cancers (mCRPC). Defects in genes involved in HR DNA repair can sensitize cancer cells to poly(ADP-ribose) polymerase (PARP) inhibitors, a class of drugs already approved by the Food and Drug Administration (FDA) for breast and ovarian cancer carrying germline mutations in BRCA1/2 genes. For advanced prostate cancer carrying Breast cancer1/2 (BRCA1/2) or ataxia telengiectasia mutated (ATM) mutations, preclinical studies and clinical trials support the use of PARP-inhibitors, which received breakthrough therapy designation by the FDA. Based on these assumptions, several trials including DNA damage response and repair (DDR) targeting have been launched and are ongoing for prostate cancer. Here, we review the state-of-the-art potential biomarkers that could be predictive of cancer cell synthetic lethality with PARP inhibitors. The identification of key molecules that are affected in prostate cancer could be assayed in future clinical studies to better stratify prostate cancer patients who might benefit from target therapy.

Assessment of the in vitro cytochrome P450 (CYP) inhibition potential of ZYTP1, a novel poly (ADP-ribose) polymerase inhibitor

ZYTP1 is a novel Poly (ADP-ribose) polymerase protein inhibitor being developed for cancer indications. The focus of the work was to determine if ZYTP1 had a perpetrator role in the in vitro inhibition of cytochrome P450 (CYP) enzymes to aid dosing decisions during the clinical development of ZYTP1. ZYTP1 IC₅₀ for CYP1A2, 2B6, 2C8, 2C9, 2C19, 2D6 and 3A4/5 was determined using human liver microsomes and LC-MS/MS detection. CYP3A4/5 IC₅₀ of depropylated metabolite of ZYTP1 was also determined. Time dependent inhibition of CYP3A4/5 by ZYTP1 was also assessed using substrates, testosterone and midazolam. The mean IC₅₀ values of ZYTP1 were >100 µM for CYP1A2, 2B6 and 2D6, while 56.1, 24.5, 39.5 and 23.3-58.7 µM for CYP2C8, 2C9, 2C19 and 3A4/5, respectively. The CYP3A4/5 IC₅₀ of depropylated metabolite was 11.95-24.51 µM. Time dependent CYP3A4/5 inhibition was noted for testosterone and midazolam with IC₅₀ shift of 10.9- and 39.9-fold, respectively. With midazolam, the kinact and KI values of ZYTP1 were 0.075 min^-1 and 4.47 µM for the CYP3A4/5 time dependent inhibition, respectively. Because of potent inhibition of CYP3A4/5, drugs that undergo metabolism via CYP3A4/5 pathway should be avoided during ZYTP1 therapy.