The efficacy and safety of PARP inhibitors in mCRPC with HRR mutation in second-line treatment: a systematic review and bayesian network meta-analysis.

BACKGROUND: Poly (ADP- ribose) polymerase inhibitors (PARPi) has been increasingly adopted for metastatic castration-resistance prostate cancer (mCRPC) patients with homologous recombination repair deficiency (HRD). However, it is unclear which PARPi is optimal in mCRPC patients with HRD in 2nd -line setting. METHOD: We conducted a systematic review of trials regarding PARPi- based therapies on mCRPC in 2nd -line setting and performed a Bayesian network meta-analysis (NMA). Radiographic progression-free survival (rPFS) was assessed as primary outcome. PSA response and adverse events (AEs) were evaluated as secondary outcomes. Subgroup analyses were performed according to specific genetic mutation. RESULTS: Four RCTs comprised of 1024 patients (763 harbored homologous recombination repair (HRR) mutations) were identified for quantitative analysis. Regarding rPFS, olaparib monotherapy, rucaparib and cediranib plus olaparib showed significant improvement compared with ARAT. Olaparib plus cediranib had the highest surface under cumulative ranking curve (SUCRA) scores (87.5%) for rPFS, followed by rucaparib, olaparib and olaparib plus abiraterone acetate prednisone. For patients with BRCA 1/2 mutations, olaparib associated with the highest probability (98.1%) of improved rPFS. For patients with BRCA-2 mutations, olaparib and olaparib plus cediranib had similar efficacy. However, neither olaparib nor rucaparib showed significant superior effectiveness to androgen receptor-axis-targeted therapy (ARAT) in patients with ATM mutations. For safety, olaparib showed significantly lower ≥ 3 AE rate compared with cediranib plus olaparib (RR: 0.72, 95% CI: 0.51, 0.97), while olaparib plus cediranib was associated with the highest risk of all-grade AE. CONCLUSION: PARPi-based therapy showed considerable efficacy for mCRPC patients with HRD in 2nd -line setting. However, patients should be treated accordingly based on their genetic background as well as the efficacy and safety of the selected regimen. TRIAL REGISTRATION: CRD42023454079.

Current therapy and drug resistance in metastatic castration-resistant prostate cancer.

Castration-resistant prostate cancer (CRPC), especially metastatic castration-resistant prostate cancer (mCRPC) is one of the most prevalent malignancies and main cause of cancer-related death among men in the world. In addition, it is very difficult for clinical treatment because of the natural or acquired drug resistance of CRPC. Mechanisms of drug resistance are extremely complicated and how to overcome it remains an urgent clinical problem to be solved. Thus, a comprehensive and thorough understanding for mechanisms of drug resistance in mCRPC is indispensable to develop novel and better therapeutic strategies. In this review, we aim to review new insight of the treatment of mCRPC and elucidate mechanisms governing resistance to new drugs: taxanes, androgen receptor signaling inhibitors (ARSIs) and poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi). Most importantly, in order to improve efficacy of these drugs, strategies of overcoming drug resistance are also discussed based on their mechanisms respectively.

The prevalence of gene mutations in homologous recombination repair pathways in Japanese patients with metastatic castration-resistant prostate cancer in real-world clinical practice: The multi-institutional observational ZENSHIN study.

BACKGROUND: Metastatic castration-resistant prostate cancer (mCRPC) is a genetically heterogeneous disease with a poor prognosis. The prevalence of mutations in homologous recombination repair (HRR) pathway genes, including BRCA1/2, as well as treatment patterns and clinical outcomes, are not well characterized among Japanese men with mCRPC. METHODS: This multicenter, noninterventional cohort study enrolled Japanese men with mCRPC from 24 institutions between 2014 and 2018. Mutations in the 15 HRR-related genes were assessed using archival primary or metastatic tumor samples. Patterns of sequential therapies for mCRPC were investigated. Patients were followed up for survival evaluation including prostate-specific antigen progression-free survival (PSA-PFS) and overall survival (OS). RESULTS: Of the 143 patients analyzed, HRR-related mutations were detected in 51 patients (35.7%). The most frequently mutated genes were CDK12 (N = 19, 13.3%), followed by BRCA2 (N = 18, 12.6%), ATM (N = 8, 5.6%), and CHEK2 (N = 3, 2.1%). The most common type of first-line therapy for mCRPC was next-generation hormonal agents (NHA, 44.4%), followed by first-generation antiandrogens (FGA, 30.3%), and taxanes (22.5%). Commonly prescribed first-/second-line sequential regimens included FGA/NHA (17.6%), NHA/NHA (15.5%), and NHA/taxanes (14.1%). The median PSA-PFS and OS for the entire cohort were 5.6 and 26.1 months, respectively. Patients carrying BRCA1/2 mutations had numerically shorter PSA-PFS (median 3.3 vs. 5.9 months) and OS (median 20.7 vs. 27.3 months) than those without mutations. CONCLUSIONS: In conclusion, approximately one-third of Japanese patients with mCRPC carried mutations in HRR-related genes in this study. The real-world outcomes of mCRPC are poor with conventional therapy, warranting an expansion of treatment options based on genetic abnormalities of the disease.

Metastasic Prostate Cancer: Predictive Factors of Earlier Progression to Castration-Resistance.

INTRODUCTION: Prostate cancer (PCa) can progress to the lethal phenotype of metastatic castration resistance (mCRPC), either from initially localized disease or de novo metastatic cancer. New drugs improving overall survival are now the cornerstone of treatment. Nevertheless, there are no defined sequences or established timing to initiate or discontinue treatments; besides, not all patients end in CRPC or reach this stage at the same time. OBJECTIVE: To evaluate characteristics of patients who progress to mCRPC and establish an association with time to mCRPC diagnosis. MATERIAL AND METHODS: Retrospective, descriptive and observational study of 35 mCRPC patients, performed from 2013 to 2017. Variables analyzed were age, Gleason score and prostate-specific antigen (PSA) at diagnosis, initial stage, response time to androgen deprivation therapy (ADT), PSA nadir on ADT and time until mCRPC progression. Statistical analysis comparing variables with time to mCRPC diagnosis was performed. RESULTS: Average age at diagnosis was 68.9 years; PSA values were classified into 3 categories: <20 ng/ml, 20-50 and >50. Gleason score was 7 in 50%, and 8-9 in the rest. Tumor was initially localized in 46% of the patients and metastatic in the rest. PSA nadir on ADT was <1 ng/ml in 67%. Average time to androgen deprivation: 5.5 years, time to mCRPC diagnosis: 6.9 years. Significant associations between time to mCRPC and time of androgen deprivation, PSA nadir during ADT and stage at diagnosis were found. CONCLUSION: Response time to ADT <1 year, PSA nadir value >5 ng/ml during treatment and metastatic stage at diagnosis were associated with earlier progression to mCRPC.

Metastasic Prostate Cancer: Predictive Factors of Earlier Progression to Castration-Resistance

Introduction: Prostate cancer (PCa) can progress to the lethal phenotype of metastatic castration resistance (mCRPC), either from initially localized disease or de novo metastatic cancer. New drugs improving overall survival are now the cornerstone of treatment. Nevertheless, there are no defined sequences or established timing to initiate or discontinue treatments; besides, not all patients end in CRPC or reach this stage at the same time. Objective: To evaluate characteristics of patients who progress to mCRPC and establish an association with time to mCRPC diagnosis. Material and Methods: Retrospective, descriptive and observational study of 35 mCRPC patients, performed from 2013 to 2017. Variables analyzed were age, Gleason score and prostate-specific antigen (PSA) at diagnosis, initial stage, response time to androgen deprivation therapy (ADT), PSA nadir on ADT and time until mCRPC progression. Statistical analysis comparing variables with time to mCRPC diagnosis was performed. Results: Average age at diagnosis was 68.9 years; PSA values were classified into 3 categories: <20 ng/ml, 20-50 and >50. Gleason score was 7 in 50%, and 8-9 in the rest. Tumor was initially localized in 46% of the patients and metastatic in the rest. PSA nadir on ADT was <1 ng/ml in 67%. Average time to androgen deprivation: 5.5 years, time to mCRPC diagnosis: 6.9 years. Significant associations between time to mCRPC and time of androgen deprivation, PSA nadir during ADT and stage at diagnosis were found. Conclusion: Response time to ADT <1 year, PSA nadir value >5 ng/ml during treatment and metastatic stage at diagnosis were associated with earlier progression to mCRPC (AU)

Introducción: El cáncer de próstata (CaP) puedeprogresar al fenotipo letal de resistencia a la castraciónmetastásica (CPRCm), ya sea por enfermedad inicialmentelocalizada o por cáncer metastásico de novo. Los nuevosmedicamentos que mejoran la supervivencia general sonahora la piedra angular del tratamiento. Sin embargo, nohay secuencias definidas ni tiempos establecidos para iniciar o suspender los tratamientos; además, no todos los pacientes terminan en CPRC o llegan a esta etapa al mismotiempo.Objetivo: Evaluar las características de los pacientesque progresan a CPRCm y establecer una asociación entreéstas y el tiempo hasta el diagnóstico de CPRCm.Material y Métodos: Estudio retrospectivo, descriptivo y observacional de 35 pacientes con CPRCm, realizado entre 2013 y 2017. Las variables analizadas fueronedad, puntaje de Gleason y antígeno prostático específico(PSA, por sus siglas en inglés) al diagnóstico, estadio inicial, tiempo de respuesta a la terapia de deprivación androgénica (TDA), Nadir de PSA en TDA y tiempo hastala progresión a CPRCm. Se realizó un análisis estadísticocomparando las variables con el tiempo hasta el diagnósticode CPRCm.Resultados: La edad promedio al diagnóstico fue de68,9 años; Los valores de PSA<20: 15% de los pacientes,PSA 20-50: 63% de los pacientes, y PSA>50 20%. La puntuación de Gleason fue de 7 en el 50% y de 8-9 en el resto.El tumor fue inicialmente localizado en el 46% de los pacientes y metastásico en el resto. El nadir de PSA en TDAfue <1 ng / ml en 67%. Tiempo medio de respuesta a TDA:5,5 años, tiempo hasta el diagnóstico de CPRCm: 6,9 años.Se encontraron asociaciones significativas entre el tiempohasta CPRCm y el tiempo de deprivación de andrógenos, elnadir de PSA durante el TDA y el estadio al momento deldiagnóstico.Conclusión: el tiempo de respuesta a TDA <1 año... (AU)

An exceptional response to 177LuPSMA undermined by neuroendocrine transformation.

Approximately 25% of patients who have undergone extensive systemic therapy for advanced metastatic castration-resistant prostate cancer (mCRPC) develop treatment associated neuroendocrine prostate cancer (NEPC). 177Lu-prostate specific membrane antigen (-PSMA) is an emerging alternative therapy for mCRPC patients who have exhausted other systemic therapy options; however, cells with neuroendocrine differentiation do not express PSMA and are not affected by this treatment. This case highlights an exceptional response of skeletal metastases to 177LuPSMA that is undermined by neuroendocrine transformation in the liver.

The emerging role of PARP inhibitors in prostate cancer.

INTRODUCTION: In prostate cancer , there has recently been an emerging interest in mutations in genes belonging to the homologous recombination repair (HRR) pathway and in the inhibition of poly (ADP-ribose) polymerase (PARP) proteins. AREAS COVERED: Mutations in the HRR genes, including BRCA1, BRCA2, and Ataxia-Telangiesctasia mutated (ATM), have been reported in prostate cancer, with different incidence in the localized and advanced settings. The PARP enzyme complex is involved in repair of DNA damage and its inhibition causes the accumulation of DNA mutations in HRR deficient cells. Several PARP inhibitors (PARPi) are under development, such as olaparib, talazoparib, niraparib, rucaparib, and veliparib. In metastatic castration resistant prostate cancer (mCRPC), olaparib has been the most studied and its clinical efficacy has been validated in a phase III clinical trial. Rucaparib and niraparib have also shown promising results in the preliminary analyzes of two phase II trials, while talazoparib is currently under development. EXPERT OPINION: PARPi have become part of the treatment of mCRPC. Early results of combination therapy with PARPi and new hormonal therapy are promising and are supported by a strong biological rationale. Current results need to be validated in randomized phase III-controlled trials in order to translate the use of PARPi into real world practice.

Molecular analysis of CD133-positive circulating tumor cells from patients with metastatic castration-resistant prostate cancer.

The function and clinical utility of stem cell markers in metastatic castration-resistant prostate cancer (mCRPC) remains unresolved, and their expression may confer important therapeutic opportunities for staging and therapy. In the adult human prostate, CD133 (PROM1) expression identifies infrequent prostate epithelial progenitor cells and putative cancer stem cells. Previous work demonstrated an association with CD133 and cancer cell proliferation using in vitro model systems. The primary objective here was to investigate the expression of CD133 in circulating tumor cells (CTCs) from patients with mCRPC and to test the hypothesis that patients with mCRPC had CD133-positive CTCs associated with increased cell proliferation, changes in the androgen receptor (AR) protein expression, or AR nuclear co-localization. We utilized ImageStreamX technology, which combines flow cytometry and fluorescence microscopy, to capture and analyze CD45-negative/EpCAM-positive CTCs for CD133, Ki-67, and AR. All patient samples (20/20) contained CD133-positive populations of CTCs, and on average 50.9 ± 28.2% (range of 18.2% to 100%) of CTCs were CD133-positive. CD133-positive CTCs have increased Ki-67 protein expression compared to CD133-negative CTCs, implying that CD133-positive CTCs may have greater proliferative potential when compared to their CD133-negative counterparts. CD133-positive and CD133-negative CTCs have similar levels of AR protein expression and cellular co-localization with nuclear markers, implying that CD133 expression is independent of AR pathway activity and an AR-independent marker of mCRPC proliferation. These studies demonstrate the presence of CD133-positive populations in CTCs from mCRPC with increased proliferative potential.