The 2019 Coffey-Holden Prostate Cancer Academy (CHPCA) Meeting, "Prostate Cancer Research: The Next Generation," was held 20 to 23 June, 2019, in Los Angeles, California.
The CHPCA Meeting is an ...annual conference held by the Prostate Cancer Foundation, that is uniquely structured to stimulate intense discussion surrounding topics most critical to accelerating prostate cancer research and the discovery of new life-extending treatments for patients. The 7th Annual CHPCA Meeting was attended by 86 investigators and concentrated on many of the most promising new treatment opportunities and next-generation research technologies.
The topics of focus at the meeting included: new treatment strategies and novel agents for targeted therapies and precision medicine, new treatment strategies that may synergize with checkpoint immunotherapy, next-generation technologies that visualize tumor microenvironment (TME) and molecular pathology in situ, multi-omics and tumor heterogeneity using single cells, 3D and TME models, and the role of extracellular vesicles in cancer and their potential as biomarkers.
This meeting report provides a comprehensive summary of the talks and discussions held at the 2019 CHPCA Meeting, for the purpose of globally disseminating this knowledge and ultimately accelerating new treatments and diagnostics for patients with prostate cancer.
Patient-derived xenografts (PDX) are tumor-in-mouse models for cancer. PDX collections, such as the NCI PDXNet, are powerful resources for preclinical therapeutic testing. However, variations in ...experimental and analysis procedures have limited interpretability. To determine the robustness of PDX studies, the PDXNet tested temozolomide drug response for three prevalidated PDX models (sensitive, resistant, and intermediate) across four blinded PDX Development and Trial Centers using independently selected standard operating procedures. Each PDTC was able to correctly identify the sensitive, resistant, and intermediate models, and statistical evaluations were concordant across all groups. We also developed and benchmarked optimized PDX informatics pipelines, and these yielded robust assessments across xenograft biological replicates. These studies show that PDX drug responses and sequence results are reproducible across diverse experimental protocols. In addition, we share the range of experimental procedures that maintained robustness, as well as standardized cloud-based workflows for PDX exome-sequencing and RNA-sequencing analyses and for evaluating growth. SIGNIFICANCE: The PDXNet Consortium shows that PDX drug responses and sequencing results are reproducible across diverse experimental protocols, establishing the potential for multisite preclinical studies to translate into clinical trials.
Histone acetyltransferase (HAT) p300 and its paralog CBP acetylate histone lysine side chains and play critical roles in regulating gene transcription. The HAT domain of p300/CBP is a potential drug ...target for cancer. Through compound screening and medicinal chemistry, novel inhibitors of p300/CBP HAT with their IC50 values as low as 620 nM were discovered. The most potent inhibitor is competitive against histone substrates and exhibits a high selectivity for p300/CBP. It inhibited cellular acetylation and had strong activity with EC50 of 1–3 μM against proliferation of several tumor cell lines. Gene expression profiling in estrogen receptor (ER)-positive breast cancer MCF-7 cells showed that inhibitor treatment recapitulated siRNA-mediated p300 knockdown, inhibited ER-mediated gene transcription, and suppressed expression of numerous cancer-related gene signatures. These results demonstrate that the inhibitor is not only a useful probe for biological studies of p300/CBP HAT but also a pharmacological lead for further drug development targeting cancer.
Large-scale changes (gross chromosomal rearrangements GCRs) are common in genomes, and are often associated with pathological disorders. We report here that a specific pair of nearby inverted repeats ...in budding yeast fuse to form a dicentric chromosome intermediate, which then rearranges to form a translocation and other GCRs. We next show that fusion of nearby inverted repeats is general; we found that many nearby inverted repeats that are present in the yeast genome also fuse, as does a pair of synthetically constructed inverted repeats. Fusion occurs between inverted repeats that are separated by several kilobases of DNA and share >20 base pairs of homology. Finally, we show that fusion of inverted repeats, surprisingly, does not require genes involved in double-strand break (DSB) repair or genes involved in other repeat recombination events. We therefore propose that fusion may occur by a DSB-independent, DNA replication-based mechanism (which we term "faulty template switching"). Fusion of nearby inverted repeats to form dicentrics may be a major cause of instability in yeast and in other organisms.
Abstract
Background: AA men have higher PC incidence and mortality than white men. Healthcare access and other socioeconomic factors contribute to these disparities. The high cost of NGS can become ...an additional factor for disparity. Indeed, minority and uninsured pts were underrepresented in prior NGS studies and NGS-based Precision Oncology clinical trials.
Methods: Ben Taub Hospital (BTH) is a safety net hospital serving a racially/ethnically diverse pt population (91% minorities). We retrospectively analyzed NGS data obtained via Tempus|xT tissue assay (DNA sequencing of 648 genes in tumor tissue at 500x depth) and/or Tempus|xF liquid biopsy assay (ctDNA sequencing of 105 genes at 5,000x depth) for germline and/or somatic mutations detected in 117 BTH pts 61 self-identified AA and 56 white (including white Hispanic) receiving treatment for locally advanced, biochemically recurrent or metastatic PC. We also analyzed de-identified NGS data from a nationwide cohort of 2090 metastatic PC pts (225 AA) previously sequenced with xT and/or xF by Tempus Labs (Chicago, IL).
Results: AA BTH PC pts exhibited high frequencies of BRCA2 (14.8%), SPOP (19.7%), AR (16.4%) and TP53 (49.1%) mutations (respective frequencies in white BTH pts were 9%, 7%, 3.6% and 12.5%). TMPRSS2 fusions were less frequent in AA than white pts. Upon treatment with active therapy (hormonal or taxane), the allele frequency of PC-derived ctDNA mutations in the liquid biopsy declined significantly and concordantly to the biochemical (PSA) response. In addition, two out of 61 (3.3%) AA BTH PCs had microsatellite instability a frequency comparable to that seen in white BTH PC pts (3.6%) and in the nationwide Tempus Labs cohort (3.6% of AA PC pts), and experienced prompt and durable clinical, biochemical and molecular responses to pembrolizumab, including disappearance of PC-derived mutant ctDNA. On the other hand, four AA PC pts who had progressed on abiraterone or enzalutamide with ctDNA findings of AR mutations previously reported as sensitive in vitro to the newest FDA-approved AR antagonist darolutamide, did not achieve clinical or biochemical response on darolutamide treatment and that was paralleled by lack of molecular (ctDNA fraction) response.
Conclusions: The high mutation frequency in key PC drivers in AA pts at our safety net hospital can be attributed to underlying disease biology or the more advanced disease at presentation in AA pts with socioeconomic factors delaying access to healthcare. Wide use of NGS testing is necessary to improve early access of underserved minority populations to novel targeted therapies and to biomarker-based Precision Oncology clinical trials. Liquid biopsy is a minimally invasive tool that allows longitudinal monitoring of response (or lack thereof) to treatment.
Citation Format: Tamer Khashab, Salma Kaochar, Alexander D. Le, Samantha Cohen, Attiya B. Noor, Heidi Dowst, Neda Zarrin-Khameh, Michael A. Brooks, Guilherme Godoy, Maria A. Berezina, Anna E. Schwarzbach, Michael E. Scheurer, Martha P. Mims, Nicholas Mitsiades. Genomic characterization and monitoring molecular response to treatment in African American (AA) advanced prostate cancer (PC) patients (pts) via next-generation sequencing (NGS): Real-world experience in a safety net hospital Oncology clinic abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 549.
African-American (AA) men are more likely to be diagnosed with and die from prostate cancer than European American (EA) men. Despite the central role of the androgen receptor (AR) transcription ...factor in prostate cancer, little is known about the contribution of epigenetics to observed racial disparities. We performed AR chromatin immunoprecipitation sequencing on primary prostate tumors from AA and EA men, finding that sites with greater AR binding intensity in AA relative to EA prostate cancer are enriched for lipid metabolism and immune response genes. Integration with transcriptomic and metabolomic data demonstrated coinciding upregulation of lipid metabolism gene expression and increased lipid levels in AA prostate cancer. In a metastatic prostate cancer cohort, upregulated lipid metabolism associated with poor prognosis. These findings offer the first insights into ancestry-specific differences in the prostate cancer AR cistrome. The data suggest a model whereby increased androgen signaling may contribute to higher levels of lipid metabolism, immune response, and cytokine signaling in AA prostate tumors. Given the association of upregulated lipogenesis with prostate cancer progression, our study provides a plausible biological explanation for the higher incidence and aggressiveness of prostate cancer observed in AA men.
With immunotherapies and inhibitors of metabolic enzymes in clinical development, the altered lipid metabolism and immune response in African-American men provides potential therapeutic opportunities to attenuate racial disparities in prostate cancer.
Abstract Androgen receptor- (AR-) indifference is a mechanism of resistance to hormonal therapy in prostate cancer (PC). Here we demonstrate that ONECUT2 (OC2) activates resistance through multiple ...drivers associated with adenocarcinoma, stem-like and neuroendocrine (NE) variants. Direct OC2 gene targets include the glucocorticoid receptor (GR; NR3C1) and the NE splicing factor SRRM4, which are key drivers of lineage plasticity. Thus, OC2, despite its previously described NEPC driver function, can indirectly activate a portion of the AR cistrome through epigenetic activation of GR. Mechanisms by which OC2 regulates gene expression include promoter binding, enhancement of genome-wide chromatin accessibility, and super-enhancer reprogramming. Pharmacologic inhibition of OC2 suppresses lineage plasticity reprogramming induced by the AR signaling inhibitor enzalutamide. These results demonstrate that OC2 activation promotes a range of drug resistance mechanisms associated with treatment-emergent lineage variation in PC and support enhanced efforts to therapeutically target OC2 as a means of suppressing treatment-resistant disease.
Abstract
Background: Prostate cancer (PC) is the single most common and second-most lethal cancer in men, with over 268,000 estimated cases and over 34,500 estimated deaths in the US in 2022. The ...Speckle-Type POZ protein (SPOP) mutant subclass of PC accounts for 10% to 15% of all primary PC cases. SPOP is an adaptor for Cullin3/Ring (CUL3-RING)-type E3 ubiquitin ligase complexes and provides substrate specificity. The Cancer Genome Atlas (TCGA) studies show that SPOP is the most frequently mutated gene in primary prostate cancer (PC). Interestingly, PC-associated SPOP mutations are always missense and occur in a heterozygous fashion. The current gap in knowledge is the lack of understanding of the role of wildtype SPOP in PC. Methods: By utilizing prostate specific SPOP knockout (KO) mice, we recently reported increased levels of AR and MYC protein and increased cellular turnover (both proliferation and apoptosis) in the prostate luminal epithelium compared to wildtype prostates. We now characterized these mice for the expression of Cre protein and SPOP mRNA at different age using immunohistochemistry and RNA in situ hybridization. Furthermore, we performed RNA-sequencing analysis in the SPOP knockout mice and matched control littermates. Moreover, we performed RNA-seq in LNCaP, LNCaP-Abl, and RWPE1 cells following SPOP inhibition via siRNA targeting SPOP. Finally, we compared our SPOP inhibition signature from in vitro cell lines and prostate specific SPOP knockout murine model to gain insights about the role of wildtype SPOP protein in the prostate epithelium. Result: Using our Spopfl/fl;PBCre+ model, we observed SPOP floxed cells are rapidly lost and the murine prostate epithelium was repopulated with SPOP wildtype carrying cells. Similarly, knockdown (KD) of SPOP through siRNA treatment in a panel of PC cell lines resulted in a significant reduction in cell viability. These observations suggest that SPOP is important for the normal prostate cell viability. Further transcriptomic profiling of SPOP KO (from transgenic murine model) as well as siSPOP treated in vitro prostate cell lines revealed a significant reduction in the transcriptional activity of the AR. Conclusion: Our data illustrate for the first time a critical role for SPOP in the growth and survival of the prostate epithelium and prostate cancer cell. Our findings further validates SPOP as a important therapeutic target for the treatment of prostate cancer.
Citation Format: Kinza Rizwan, Darlene Skapura, Cammy Mason, Cristian Coarfa, Nicholas Mitsiades, Damian Young, Salma Kaochar. SPOP loss places the prostate luminal epithelial cells at a selective disadvantage abstract. In: Proceedings of the AACR Special Conference: Advances in Prostate Cancer Research; 2023 Mar 15-18; Denver, Colorado. Philadelphia (PA): AACR; Cancer Res 2023;83(11 Suppl):Abstract nr B069.
Abstract
Purpose- BIN1 is in deleted in ~5% of all prostate cancer (PC) patients and interestingly is highly enriched in the Speckle-type POZ protein (SPOP) mutant subclass (15%) of PC. BIN1 was ...originally identified as a repressor of cMYC activity and our lab has shown that patients with SPOPmut;MYChigh PC have worse clinical outcomes. Our observation of BIN1 deletion in the SPOP mutant subclass leads us to hypothesize that BIN1 deletion leads to enhanced AR signaling and more aggressive PC. Experimental Procedures- We analyzed baseline protein and mRNA levels of BIN1 in 13 PC cell lines via quantitative polymerase chain reaction (qPCR) and immunoblot. To understand the role of BIN1 in PC cells, we overexpressed BIN1 and evaluated changes in cell proliferation, migration, and AR target gene expression. To elucidate the role of BIN1 in vivo prostate development, we also generated a prostate-specific knockout of BIN1 and investigated changes in prostate development and AR signaling axis over time in this mouse model. Results- Our results show that none of the 13 PC cell lines analyzed had strong protein expression at baseline, but all had detectable mRNA levels. Interestingly, the three cell lines with the highest mRNA expression were AR negative (DU-145), AR independent (LN95) or castration resistant (MDVR). We also saw a decrease in downstream AR target genes (KLK3 and NKX3.1) measured using qPCR after BIN1 overexpression in 22Rv1 cells. We further corroborated this finding by measuring KLK3 expression using a KLK3-luc reporter assay after BIN1 overexpression. BIN1 overexpression also reduced invasive activity of 22Rv1 measured using a Matrigel invasion assay system. Since BIN1 deletion was enriched in SPOP mutant PC clinical data, we evaluated changes in cell proliferation in the wildtype and mutant SPOP cell lines with and without BIN1OE and found that BIN1OEhindered growth of SPOP mutant PC cells. Analysis of the TCGA primary PC dataset illustrate that PC patients harboring BIN1 deletion had higher AR activity compared to PC patients expressing wildtype BIN1. Importantly, mice with prostate specific BIN1 deletion had larger prostate mass at 2 months of age compared to age matched controls and several mice at the 6&9 month had severely enlarged prostates. Conclusion- Our findings show for the first time that BIN1 functions as an inhibitor of the AR signaling axis and deletion of BIN1 leads to higher levels of AR signaling. We also show that BIN1 deletion in mice affects prostate development and leads to enlarged prostates. These novel findings illustrate the clinical significance of BIN1 deletion in PC patients and highlights the AR-signaling axis as a potential target for PC patients with BIN1 deletion
Citation Format: Collin McColl, Darlene Skapura, Elisa Echartea, Jenny Deng, Cristian Coarfa, Salma Kaochar, Brian Simons, Aleksandra Rusin. Elucidating the effects of the Alzheimer's disease associated gene BIN1 on cancer tumorigenesis abstract. In: Proceedings of the AACR Special Conference: Advances in Prostate Cancer Research; 2023 Mar 15-18; Denver, Colorado. Philadelphia (PA): AACR; Cancer Res 2023;83(11 Suppl):Abstract nr A008.
3D patient tumor avatars (3D-PTAs) hold promise for next-generation precision medicine. Here, we describe the benefits and challenges of 3D-PTA technologies and necessary future steps to realize ...their potential for clinical decision making. 3D-PTAs require standardization criteria and prospective trials to establish clinical benefits. Innovative trial designs that combine omics and 3D-PTA readouts may lead to more accurate clinical predictors, and an integrated platform that combines diagnostic and therapeutic development will accelerate new treatments for patients with refractory disease.
3D patient tumor avatars (3D-PTAs) hold promise for next-generation precision medicine. Here, we describe the benefits and challenges of 3D-PTA technologies and necessary future steps to realize their potential for clinical decision making. 3D-PTAs require standardization criteria and prospective trials to establish clinical benefits. Innovative trial designs that combine omics and 3D-PTA readouts may lead to more accurate clinical predictors, and an integrated platform that combines diagnostic and therapeutic development will accelerate new treatments for patients with refractory disease.
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