The 5-WS of targeting DNA-damage repair (DDR) pathways in prostate cancer

DNA-damage repair (DDR) pathways alterations, a growing area of interest in oncology, are detected in about 20% of patient with prostate cancer and are associated with improved sensitivity to poly(ADP ribose) polymerases (PARP) inhibitors. In May 2020, the Food and Drug Administration (FDA) approved two PARP inhibitors (olaparib and rucaparib) for prostate cancer treatment. Moreover, germline aberrations in DDR pathways genes have also been related to familial or hereditary prostate cancer, requiring tailored health-care programs. These emerging scenarios are rapidly changing diagnostic, prognostic and therapeutic approaches in prostate cancer management. The aim of this review is to highlight the five W-points of DDR pathways in prostate cancer: why targeting DDR pathways in prostate cancer; what we should test for genomic profiling in prostate cancer; "where" testing genetic assessment in prostate cancer (germline or somatic, solid or liquid biopsy); when genetic testing is appropriate in prostate cancer; who could get benefit from PARP inhibitors; how improve patients outcome with combinations strategies.

Niraparib plus abiraterone acetate with prednisone in patients with metastatic castration-resistant prostate cancer and homologous recombination repair gene alterations: second interim analysis of the randomized phase III MAGNITUDE trial

BACKGROUND

Patients with metastatic castration-resistant prostate cancer (mCRPC) and BRCA alterations have poor outcomes. MAGNITUDE found patients with homologous recombination repair gene alterations (HRR+), particularly BRCA1/2, benefit from first-line therapy with niraparib plus abiraterone acetate and prednisone (AAP). Here we report longer follow-up from the second prespecified interim analysis (IA2).

PATIENTS AND METHODS

Patients with mCRPC were prospectively identified as HRR+ with/without BRCA1/2 alterations and randomized 1 : 1 to niraparib (200 mg orally) plus AAP (1000 mg/10 mg orally) or placebo plus AAP. At IA2, secondary endpoints [time to symptomatic progression, time to initiation of cytotoxic chemotherapy, overall survival (OS)] were assessed.

RESULTS

Overall, 212 HRR+ patients received niraparib plus AAP (BRCA1/2 subgroup, n = 113). At IA2 with 24.8 months of median follow-up in the BRCA1/2 subgroup, niraparib plus AAP significantly prolonged radiographic progression-free survival {rPFS; blinded independent central review; median rPFS 19.5 versus 10.9 months; hazard ratio (HR) = 0.55 [95% confidence interval (CI) 0.39-0.78]; nominal P = 0.0007} consistent with the first prespecified interim analysis. rPFS was also prolonged in the total HRR+ population [HR = 0.76 (95% CI 0.60-0.97); nominal P = 0.0280; median follow-up 26.8 months]. Improvements in time to symptomatic progression and time to initiation of cytotoxic chemotherapy were observed with niraparib plus AAP. In the BRCA1/2 subgroup, the analysis of OS with niraparib plus AAP demonstrated an HR of 0.88 (95% CI 0.58-1.34; nominal P = 0.5505); the prespecified inverse probability censoring weighting analysis of OS, accounting for imbalances in subsequent use of poly adenosine diphosphate-ribose polymerase inhibitors and other life-prolonging therapies, demonstrated an HR of 0.54 (95% CI 0.33-0.90; nominal P = 0.0181). No new safety signals were observed.

CONCLUSIONS

MAGNITUDE, enrolling the largest BRCA1/2 cohort in first-line mCRPC to date, demonstrated improved rPFS and other clinically relevant outcomes with niraparib plus AAP in patients with BRCA1/2-altered mCRPC, emphasizing the importance of identifying this molecular subset of patients.

Molecular Targeted Therapies in Metastatic Prostate Cancer: Recent Advances and Future Challenges

Prostate cancer is the most frequent malignant tumor in men, and, despite the great improvements in survival in patients with localized cancer, the prognosis for metastatic disease remains poor. Novel molecular targeted therapies, which block specific molecules or signaling pathways in tumor cells or in their microenvironment, have shown encouraging results in metastatic castration-resistant prostate cancer. Among these therapeutic approaches, prostate-specific membrane antigen-targeted radionuclide therapies and DNA repair inhibitors represent the most promising ones, with some therapeutic protocols already approved by the FDA, whereas therapies targeting tumor neovascularization and immune checkpoint inhibitors have not yet demonstrated clear clinical benefits. In this review, the most relevant studies and clinical trials on this topic are illustrated and discussed, together with future research directions and challenges.

Applications for open access normalized synthesis in metastatic prostate cancer trials

Recent metastatic castration-resistant prostate cancer (mCRPC) clinical trials have integrated homologous recombination and DNA repair deficiency (HRD/DRD) biomarkers into eligibility criteria and secondary objectives. These trials led to the approval of some PARP inhibitors for mCRPC with HRD/DRD indications. Unfortunately, biomarker-trial outcome data is only discovered by reviewing publications, a process that is error-prone, time-consuming, and laborious. While prostate cancer researchers have written systematic evidence reviews (SERs) on this topic, given the time involved from the last search to publication, an SER is often outdated even before publication. The difficulty in reusing previous review data has resulted in multiple reviews of the same trials. Thus, it will be useful to create a normalized evidence base from recently published/presented biomarker-trial outcome data that one can quickly update. We present a new approach to semi-automating normalized, open-access data tables from published clinical trials of metastatic prostate cancer using a data curation and SER platform. Clinicaltrials.gov and Pubmed.gov were used to collect mCRPC clinical trial publications with HRD/DRD biomarkers. We extracted data from 13 publications covering ten trials that started before 22nd Apr 2021. We extracted 585 hazard ratios, response rates, duration metrics, and 543 adverse events. Across 334 patients, we also extracted 8,180 patient-level survival and biomarker values. Data tables were populated with survival metrics, raw patient data, eligibility criteria, adverse events, and timelines. A repeated strong association between HRD and improved PARP inhibitor response was observed. Several use cases for the extracted data are demonstrated via analyses of trial methods, comparison of treatment hazard ratios, and association of treatments with adverse events. Machine learning models are also built on combined and normalized patient data to demonstrate automated discovery of therapy/biomarker relationships. Overall, we demonstrate the value of systematically extracted and normalized data. We have also made our code open-source with simple instructions on updating the analyses as new data becomes available, which anyone can use even with limited programming knowledge. Finally, while we present a novel method of SER for mCRPC trials, one can also implement such semi-automated methods in other clinical trial domains to advance precision medicine.

Clinical Utility of Olaparib in the Treatment of Metastatic Castration-Resistant Prostate Cancer: A Review of Current Evidence and Patient Selection

Metastatic castration-resistant prostate cancer (mCRPC) is an aggressive and fatal disease with a median survival of 36 months. With the advent of genetic sequencing to identify individual genomic profiles and acquired tumor-specific pathways, targeted therapies have revolutionized cancer treatment, including the treatment strategy in mCRPC. Poly(adenosine 5'-diphosphate) ribose polymerase inhibitors (PARPi) are oral drugs that target mutations in the homologous recombination repair (HRR) pathway, which are found in approximately 27% of prostate cancer patients. In May 2020, the first PARP inhibitor, olaparib, was approved by the US Food and Drug Administration for men with mCRPC with HHR gene mutations based on the findings of the Phase III PROfound trial that showed improved overall survival in men with mCRPC who received olaparib and whose disease had progressed on a novel hormonal agent. This review summarizes the current evidence and clinical utility of olaparib as treatment in men with mCRPC. We describe the mechanism of action of PARPi, key clinical trials of olaparib in men with mCRPC, and ongoing Phase II and III clinical trials investigating olaparib in combination therapy and as front-line therapy in mCRPC.

Derivation and Application of Molecular Signatures to Prostate Cancer: Opportunities and Challenges

Prostate cancer is a high-incidence cancer that requires improved patient stratification to ensure accurate predictions of risk and treatment response. Due to the significant contributions of transcription factors and epigenetic regulators to prostate cancer progression, there has been considerable progress made in developing gene signatures that may achieve this. Some of these are aligned to activities of key drivers such as the androgen receptor, whilst others are more agnostic. In this review, we present an overview of these signatures, the strategies for their derivation, and future perspectives on their continued development and evolution.

Targetable gene fusions and aberrations in genitourinary oncology

Gene fusions result from either structural chromosomal rearrangement or aberrations caused by splicing or transcriptional readthrough. The precise and distinctive presence of fusion genes in neoplastic tissues and their involvement in multiple pathways central to cancer development, growth and survival make them promising targets for personalized therapy. In genitourinary malignancies, rearrangements involving the E26 transformation-specific family of transcription factors have emerged as very frequent alterations in prostate cancer, especially the TMPRSS2-ERG fusion. In renal malignancies, Xp11 and t(6;11) translocations are hallmarks of a distinct pathological group of tumours described as microphthalmia-associated transcription factor family translocation-associated renal cell carcinomas. Novel druggable fusion events have been recognized in genitourinary malignancies, leading to the activation of several clinical trials. For instance, ALK-rearranged renal cell carcinomas have shown responses to alectinib and crizotinib. Erdafitinib has been tested for the treatment of FGFR-rearranged bladder cancer. Other anti-fibroblast growth factor receptor 3 (FGFR3) compounds are showing promising results in the treatment of bladder cancer, including infigratinib and pemigatinib, and all are currently in clinical trials.

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.

[DNA damage repair: An emerging strategy in metastatic prostate cancer]

Genetic instability is one part of the oncogenic process. Gene mutations involved in DNA repair mechanisms can promote this genetic instability and participate in oncogenesis and metastatic progression. In prostate cancer, DNA repair abnormalities mainly correspond to somatic or constitutional mutations of the BRCA2 and ATM genes. Therapeutic management of metastatic castration-resistant prostate cancer (mCRPC) is currently based on new hormonal therapies (abiraterone, enzalutamide) and taxane-type chemotherapy (docetaxel or cabazitaxel). Preliminary data tend to indicate a specific activity of agents causing DNA breaks (platinum salts) and PARP inhibitors in patients with these DNA repair abnormalities. The frequency of DNA repair gene mutations in patients with prostate cancer (around 20%) and the antitumor response of PARP inhibitors make it a possible short-term therapeutic strategy with several registering clinical trials ongoing.

Incorporating Biomarker Stratification into STAMPEDE: an Adaptive Multi-arm, Multi-stage Trial Platform

The treatment and outcomes for advanced prostate cancer have experienced significant progress over recent years. Importantly, the additional benefits of ‘up front’ chemotherapy (docetaxel) and abiraterone, over and above conventional androgen deprivation, have been separately demonstrated in the multi-arm, multi-stage (MAMS) STAMPEDE protocol, which continues recruitment to other questions. Alongside this, insights into the underlying molecular biology and, inevitably, the molecular heterogeneity of prostate cancer are opening the door to new therapeutic approaches. Incorporating this understanding and testing these hypotheses within STAMPEDE brings new challenges to the MAMS approach, but has the potential to further improve the outlook for this disease.