Impact of homologous recombination repair/BReast CAncer (BRCA) gene alterations on survival in a real-world setting of metastatic prostate cancer.

OBJECTIVE: To investigate alterations of homologous recombination repair (HRR) and especially BReast CAncer 1/2 (BRCA1/2) gene on overall survival (OS). Moreover, to explore the effect of inhibition of poly(ADP-ribose)-polymerase (PARPi) as systemic therapy for metastatic castration-resistant prostate cancer (mCRPC). PATIENTS AND METHODS: Of all HRR-screened patients with metastatic prostate cancer, baseline characteristics were sampled. Kaplan-Meier estimates and multivariable Cox regression models predicted the effect of HRR/BRCA1/2 alterations on OS. RESULTS: Of 196 eligible patients, 61 (31%) harboured any HRR and 40 (20%) BRCA1/2 alterations. Of HRR alterations, 40 (66%) vs six (10%) vs five (8.2%) vs four (6.6%) vs two (3.3%) vs four (6.6%) were BRCA1/2 vs Ataxia-telangiectasia mutated kinase (ATM) vs checkpoint kinase 2 (CHEK2) vs cyclin-dependent kinase 12 (CDK12) vs Fanconi anaemia complementation Group A (FANCA) vs positive for other mutations. Of these, 30% received a PARPi. OS differed significantly between HRR-positive vs -negative patients. Specifically in hormone-sensitive prostate cancer, the median OS was 63 (HRR positive) vs 57 (BRCA1/2 positive) vs 113 months (HRR negative) (P ≤ 0.01). In mCRPC, OS was 42 (HRR positive) vs 41 (BRCA1/2 positive) vs 70 months (HRR negative) (P ≤ 0.01). HRR and BRCA1/2 alterations were associated with worse OS after multivariable adjustment. Finally, patients with mCRPC with BRCA1/2 mutation treated without PARPi harboured worse OS than patients with BRCA1/2 mutation and PARPi therapy (median OS: 33 vs 48 months, P < 0.03). CONCLUSION: Incidence of HRR alteration in a clinical real-world setting is high when using blood- and tissue-based tests. Patients with HRR/BRCA alterations have worse outcomes resulting in significant OS differences between HRR/BRCA-positive patients with mCRPC with and without PARPi usage vs HRR/BRCA-negative patients.

PC4: A new regulator of cyclin D1 transcript levels.

The expression of cyclin proteins is tightly regulated during the cell cycle, to allow precise activation of cyclin-dependent kinases. In this issue, Pan et al. (https://doi.org/10.1083/jcb.202308066) identify an RNA-binding protein, PC4, as a regulator of cyclin D1 mRNA stability in hepatocellular carcinoma cells. This study provides a new mechanism regulating the levels of a key cell cycle protein, cyclin D1, in human cells.

[Fluorescence confocal microscopy-complete digitization of pathology]. / Fluoreszenzbasierte Konfokalmikroskopie ­ vollständige Digitalisierung der Pathologie.

BACKGROUND: Fluorescence-based confocal microscopy (FCM) can be used to create virtual H&E sections in real time. So far, FCM has been used in dermato-, uro-, and gynecopathology. FCM allows the creation of a completely digitized frozen section, which could potentially replace conventional frozen sections in the future. OBJECTIVE: The aim of the current work is to implement FCM technology as a component of fully digitized processes in the pathological workflow. For this purpose, the current use of FCM in liver transplant pathology will be extended to other disciplines such as urology and otorhinolaryngology. MATERIALS AND METHODS: The FCM technique continues to be used prospectively on native tissue samples from potential donor livers. Conventional frozen sections are used comparatively to virtual FCM scans. RESULTS: The data show a nearly perfect agreement for the detection of cholangitis, fibrosis, and malignancy, and a high level of agreement for, e.g., macrovesicular steatosis, inflammation, steatohepatitis, and necrosis between virtual FCM scans and conventional routine diagnostic frozen sections. CONCLUSION: Since the availability of time- and cost-intensive frozen section diagnostics in the context of transplant pathology in continuous operation (24/7) is now only established at very few university centers in Germany due to an increasing shortage of specialists, the use of FCM could be an important building block in the current process leading towards a fully digitized pathology workflow and should thus be extended to various disciplines.

Acute BRCAness Induction and AR Signaling Blockage through CDK12/7/9 Degradation Enhances PARP Inhibitor Sensitivity in Prostate Cancer.

Current treatments for advanced prostate cancer (PCa) primarily target androgen receptor (AR)-pathways. However, the emergence of castration-resistant prostate cancer (CRPC) and resistance to AR signaling inhibitors (ARSI) remains a significant clinical challenge. This study introduces BSJ-5-63, a novel triple degrader targeting cyclin-dependent kinases (CDKs) CDK12, CDK7, and CDK9, with potential to transform CRPC therapy. BSJ-5-63 effectively downregulates homologous recombination repair (HRR) genes, including BRCA1 and BRCA2, through CDK12 degradation, and attenuates AR signaling through CDK7 and CDK9 degradation, further enhancing its therapeutic impact. Importantly, BSJ-5-63 induces a "BRCAness" state that persists for a significant duration, enabling sequential combination therapy with PARP inhibitors (PARPis) while potentially minimizing drug-related toxicity and resistance. In both in vitro and in vivo studies, BSJ-5-63 exhibited potent antiproliferative effects in both AR-positive and AR-negative CRPC models. This study presents a promising multi-pronged approach for CRPC treatment, addressing both DNA repair mechanisms and AR signaling, with the potential to benefit a wide range of patients regardless of their BRCA1/2 mutational status. SIGNIFICANCE: This study introduces BSJ-5-63, a triple degrader designed to target CDK12, CDK7, and CDK9, making a significant advancement in CRPC therapy. The distinctive mechanism of BSJ-5-63 involves downregulating HRR genes and inhibiting AR signaling, thereby inducing a BRCAness state. This enhances sensitivity to PARP inhibition, effectively addressing ARSI resistance and improving the overall efficacy of treatment. The development of BSJ-5-63 represents a promising therapeutic approach, with the potential to benefit a broad spectrum of CRPC patients.

Feasibility of Next-generation Sequencing of Liquid Biopsy (Circulating Tumor DNA) Samples and Tumor Tissue from Patients with Metastatic Prostate Cancer in a Real-world Clinical Setting in Germany.

BACKGROUND AND OBJECTIVE: With European Medicines Agency approval of PARP inhibitors in metastatic castration-resistant prostate cancer and ongoing trials in metastatic hormone-sensitive prostate cancer, detection of genetic alterations in BRCA1/2 and other homologous recombination repair genes has gained an important role. Our aim was to investigate the feasibility and comparability of comprehensive next-generation sequencing (NGS) of liquid biopsy (LB; circulating tumor DNA) and tumor tissue (TT) samples in a real-world clinical setting. METHODS: The study cohort consisted of 50 patients with metastatic prostate cancer (mPC) who had TT NGS performed for BRCA1/2 alterations and consent for additional LB NGS. The Oncomine Comprehensive Assay v3 (Thermo Fisher Scientific, Waltham, MA, USA) was used for TT NGS. The Guardant360 83-gene assay (Guardant Health, Palo Alto, CA, USA) was used for LB NGS, including all types of somatic alterations, microsatellite instability, and blood tumor mutational burden. We calculated BRCA1/2 alteration rates and the negative percentage agreement (NPA) and positive percentage agreement (PPA) between TT and LB results. KEY FINDINGS AND LIMITATIONS: TT NGS was successful in 44/50 patients (88%), with pathogenic BRCA1/2 alterations detected in four (9%). LB NGS was successful in all 50 patients (100%), with BRCA1/2 alterations detected in ten (20%). In a subgroup analysis for the 44 patients with successful TT NGS, NPA was 85% and PPA was 50%. The median time between TT sample collection and blood sampling for NGS was 132 wk (IQR 94-186). The limited sample size and differences in the time of NGS assessment are limitations. CONCLUSIONS AND CLINICAL IMPLICATIONS: LB NGS resulted in a higher detection rate for BRCA1/2 alterations in comparison to conventional TT NGS (20% vs 9%). Ideally, BRCA1/2 testing should be based on both approaches to identify all patients with mPC eligible for PARP inhibitor therapy. PATIENT SUMMARY: Our study shows that genetic tests for both tumor tissue and blood samples results in higher rates of detection of BRCA1/2 gene alterations in patients with metastatic prostate cancer.

Heterogeneity and transcriptional drivers of triple-negative breast cancer.

Triple-negative breast cancer (TNBC) is a heterogeneous disease with limited treatment options. To characterize TNBC heterogeneity, we defined transcriptional, epigenetic, and metabolic subtypes and subtype-driving super-enhancers and transcription factors by combining functional and molecular profiling with computational analyses. Single-cell RNA sequencing revealed relative homogeneity of the major transcriptional subtypes (luminal, basal, and mesenchymal) within samples. We found that mesenchymal TNBCs share features with mesenchymal neuroblastoma and rhabdoid tumors and that the PRRX1 transcription factor is a key driver of these tumors. PRRX1 is sufficient for inducing mesenchymal features in basal but not in luminal TNBC cells via reprogramming super-enhancer landscapes, but it is not required for mesenchymal state maintenance or for cellular viability. Our comprehensive, large-scale, multiplatform, multiomics study of both experimental and clinical TNBC is an important resource for the scientific and clinical research communities and opens venues for future investigation.