TFE3-Rearranged PEComa/PEComa-like Neoplasms: Report of 25 New Cases Expanding the Clinicopathologic Spectrum and Highlighting its Association With Prior Exposure to Chemotherapy

Since their original description as a distinctive neoplastic entity, ~50 TFE3-rearranged perivascular epithelioid cell tumors (PEComas) have been reported. We herein report 25 new TFE3-rearranged PEComas and review the published literature to further investigate their clinicopathologic spectrum. Notably, 5 of the 25 cases were associated with a prior history of chemotherapy treatment for cancer. This is in keeping with prior reports, based mainly on small case series, with overall 11% of TFE3-rearranged PEComas being diagnosed postchemotherapy. The median age of our cohort was 38 years. Most neoplasms demonstrated characteristic features such as nested architecture, epithelioid cytology, HMB45 positive, and muscle marker negative immunophenotype. SFPQ was the most common TFE3 fusion partner present in half of the cases, followed by ASPSCR1 and NONO genes. Four of 7 cases in our cohort with meaningful follow-up presented with or developed systemic metastasis, while over half of the reported cases either recurred locally, metastasized, or caused patient death. Follow-up for the remaining cases was limited (median 18.5 months), suggesting that the prognosis may be worse. Size, mitotic activity, and necrosis were correlated with aggressive behavior. There is little evidence that treatment with MTOR inhibitors, which are beneficial against TSC-mutated PEComas, is effective against TFE3-rearranged PEComas: only one of 6 reported cases demonstrated disease stabilization. As co-expression of melanocytic and muscle markers, a hallmark of conventional TSC-mutated PEComa is uncommon in the spectrum of TFE3-rearranged PEComa, an alternative terminology may be more appropriate, such as "TFE3-rearranged PEComa-like neoplasms," highlighting their distinctive morphologic features and therapeutic implications.

Prostate Cancer, Version 3.2024

The NCCN Guidelines for Prostate Cancer include recommendations for staging and risk assessment after a prostate cancer diagnosis and for the care of patients with localized, regional, recurrent, and metastatic disease. These NCCN Guidelines Insights summarize the panel's discussions for the 2024 update to the guidelines with regard to initial risk stratification, initial management of very-low-risk disease, and the treatment of nonmetastatic recurrence.

Divergent immune microenvironments in two tumor nodules from a patient with mismatch repair-deficient prostate cancer

Patients with prostate cancer (PC) generally do not respond favorably to immune checkpoint inhibitors, which may be due to a low abundance of tumor-infiltrating lymphocytes even when mutational load is high. Here, we identified a patient who presented with high-grade primary prostate cancer with two adjacent tumor nodules. While both nodules were mismatch repair-deficient (MMRd), exhibited pathogenic MSH2 and MSH6 alterations, had a high tumor mutational burden (TMB), and demonstrated high microsatellite instability (MSI), they had markedly distinct immune phenotypes. The first displayed a dense infiltrate of lymphocytes ("hot nodule"), while the second displayed significantly fewer infiltrating lymphocytes ("cold nodule"). Whole-exome DNA analysis found that both nodules shared many identical mutations, indicating that they were derived from a single clone. However, the cold nodule appeared to be sub-clonal relative to the hot nodule, suggesting divergent evolution of the cold nodule from the hot nodule. Whole-transcriptome RNA analysis found that the cold nodule demonstrated lower expression of genes related to antigen presentation (HLA) and, paradoxically, classical tumor immune tolerance markers such as PD-L1 (CD274) and CTLA-4. Immune cell deconvolution suggested that the hot nodule was enriched not only in CD8+ and CD4 + T lymphocytes, but also in M1 macrophages, activated NK cells, and γδ T cells compared to the cold nodule. This case highlights that MMRd/TMB-high PC can evolve to minimize an anti-tumor immune response, and nominates downregulation of antigen presentation machinery (HLA loss) as a potential mechanism of adaptive immune evasion in PC.

LSD1 inhibition suppresses ASCL1 and de-represses YAP1 to drive potent activity against neuroendocrine prostate cancer

Lysine-specific demethylase 1 (LSD1 or KDM1A ) has emerged as a critical mediator of tumor progression in metastatic castration-resistant prostate cancer (mCRPC). Among mCRPC subtypes, neuroendocrine prostate cancer (NEPC) is an exceptionally aggressive variant driven by lineage plasticity, an adaptive resistance mechanism to androgen receptor axis-targeted therapies. Our study shows that LSD1 expression is elevated in NEPC and associated with unfavorable clinical outcomes. Using genetic approaches, we validated the on-target effects of LSD1 inhibition across various models. We investigated the therapeutic potential of bomedemstat, an orally bioavailable, irreversible LSD1 inhibitor with low nanomolar potency. Our findings demonstrate potent antitumor activity against CRPC models, including tumor regressions in NEPC patient-derived xenografts. Mechanistically, our study uncovers that LSD1 inhibition suppresses the neuronal transcriptional program by downregulating ASCL1 through disrupting LSD1:INSM1 interactions and de-repressing YAP1 silencing. Our data support the clinical development of LSD1 inhibitors for treating CRPC - especially the aggressive NE phenotype.

Statement of Significance

Neuroendocrine prostate cancer presents a clinical challenge due to the lack of effective treatments. Our research demonstrates that bomedemstat, a potent and selective LSD1 inhibitor, effectively combats neuroendocrine prostate cancer by downregulating the ASCL1- dependent NE transcriptional program and re-expressing YAP1.

"Oncocytoid Renal Cell Carcinomas After Neuroblastoma" Represent TSC -mutated Eosinophilic Solid and Cystic Renal Cell Carcinomas : Association With Prior Childhood Malignancy and Multifocality With Therapeutic Implications

The concept of oncocytoid renal cell carcinoma in patients who have survived neuroblastoma as a distinct biologic entity has been controversial since its original description in 1999. This is in part because similar oncocytoid renal cell carcinomas have been described in association with other pediatric cancers, and also because other renal cell carcinoma subtypes (such as MiT family translocation renal cell carcinoma) have been described in children who have survived neuroblastoma. We identified an index case of a child who survived medulloblastoma and developed multifocal bilateral oncocytoid renal cell carcinomas with morphology and immunophenotype compatible with eosinophilic solid and cystic renal cell carcinoma (ESC RCC) and demonstrated that both neoplasms harbored distinctive mutations in the TSC1/TSC2 genes. Remarkably, the child's remaining bilateral multifocal renal neoplasms completely responded to MTOR inhibitor therapy without need for further surgery. To confirm our hypothesis that oncocytoid renal cell carcinomas after childhood cancer represent ESC RCC, we obtained formalin-fixed paraffin-embedded tissue blocks from 2 previously published cases of oncocytoid renal cell carcinoma after neuroblastoma, confirmed that the morphology and immunophenotype was consistent with ESC RCC, and demonstrated that both cases harbored somatic TSC gene mutations. Both expressed markers previously associated with neoplasms harboring TSC gene mutations, glycoprotein nonmetastatic B, and cathepsin K. Of note, one of these patients had 2 ESC RCC which harbored distinctive TSC2 mutations, while the background kidney of the other patient had multiple small cysts lined by similar oncocytoid cells which showed loss of TSC2 protein. We then reviewed 3 of 4 cases from the original 1999 report of oncocytoid renal cell carcinomas after neuroblastoma, found that all 3 demonstrated morphology (including basophilic cytoplasmic stippling) that is characteristic of ESC RCC, showed that all 3 overexpressed glycoprotein nonmetastatic B, and showed that both cases with adequate material demonstrated loss of TSC2 protein and expressed cytokeratin 20 and cathepsin K by immunohistochemistry. In summary, "oncocytoid renal cell carcinomas after neuroblastoma" represent ESC RCC which are often multifocal in patients who have survived childhood cancer, likely representing an incompletely characterized tumor predisposition syndrome. MTOR-targeted therapy represents an effective therapeutic option for such patients to preserve functional nephrons.

Clinical and Genomic Differences Between Advanced Molecular Imaging-detected and Conventional Imaging-detected Metachronous Oligometastatic Castration-sensitive Prostate Cancer

In metastatic castration-sensitive prostate cancer (mCSPC), disease volume plays an integral role in guiding treatment recommendations, including selection of docetaxel therapy, metastasis-directed therapy, and radiation to the prostate. Although there are multiple definitions of disease volume, they have commonly been studied in the context of metastases detected via conventional imaging (CIM). One such numeric definition of disease volume, termed oligometastasis, is heavily dependent on the sensitivity of the imaging modality. We performed an international multi-institutional retrospective review of men with metachronous oligometastatic CSPC (omCSPC), detected via either advanced molecular imaging alone (AMIM) or CIM. Patients were compared with respect to clinical and genomic features using the Mann-Whitney U test, Pearson's χ2 test, and Kaplan-Meier overall survival (OS) analyses with a log-rank test. A total of 295 patients were included for analysis. Patients with CIM-omCSPC had significantly higher Gleason grade group (p = 0.032), higher prostate-specific antigen at omCSPC diagnosis (8.0 vs 1.7 ng/ml; p < 0.001), more frequent pathogenic TP53 mutations (28% vs 17%; p = 0.030), and worse 10-yr OS (85% vs 100%; p < 0.001). This is the first report of clinical and biological differences between AMIM-detected and CIM-detected omCSPC. Our findings are particularly important for ongoing and planned clinical trials in omCSPC. PATIENT SUMMARY: Metastatic prostate cancer with just a few metastases only detected via newer scanning methods (called molecular imaging) is associated with fewer high-risk DNA mutations and better survival in comparison to metastatic cancer detected via conventional scan methods.

Prostate Cancer, Version 4.2023, NCCN Clinical Practice Guidelines in Oncology

The NCCN Guidelines for Prostate Cancer provide a framework on which to base decisions regarding the workup of patients with prostate cancer, risk stratification and management of localized disease, post-treatment monitoring, and treatment of recurrence and advanced disease. The Guidelines sections included in this article focus on the management of metastatic castration-sensitive disease, nonmetastatic castration-resistant prostate cancer (CRPC), and metastatic CRPC (mCRPC). Androgen deprivation therapy (ADT) with treatment intensification is strongly recommended for patients with metastatic castration-sensitive prostate cancer. For patients with nonmetastatic CRPC, ADT is continued with or without the addition of certain secondary hormone therapies depending on prostate-specific antigen doubling time. In the mCRPC setting, ADT is continued with the sequential addition of certain secondary hormone therapies, chemotherapies, immunotherapies, radiopharmaceuticals, and/or targeted therapies. The NCCN Prostate Cancer Panel emphasizes a shared decision-making approach in all disease settings based on patient preferences, prior treatment exposures, the presence or absence of visceral disease, symptoms, and potential side effects.

Somatic loss of ATM is a late event in pancreatic tumorigenesis

Understanding the timing and spectrum of genetic alterations that contribute to the development of pancreatic cancer is essential for effective interventions and treatments. The aim of this study was to characterize somatic ATM alterations in noninvasive pancreatic precursor lesions and invasive pancreatic adenocarcinomas from patients with and without pathogenic germline ATM variants. DNA was isolated and sequenced from the invasive pancreatic ductal adenocarcinomas and precursor lesions of patients with a pathogenic germline ATM variant. Tumor and precursor lesions from these patients as well as colloid carcinoma from patients without a germline ATM variant were immunolabeled to assess ATM expression. Among patients with a pathogenic germline ATM variant, somatic ATM alterations, either mutations and/or loss of protein expression, were identified in 75.0% of invasive pancreatic adenocarcinomas but only 7.1% of pancreatic precursor lesions. Loss of ATM expression was also detected in 31.0% of colloid carcinomas from patients unselected for germline ATM status, significantly higher than in pancreatic precursor lesions [pancreatic intraepithelial neoplasms (p = 0.0013); intraductal papillary mucinous neoplasms, p = 0.0040] and pancreatic ductal adenocarcinoma (p = 0.0076) unselected for germline ATM status. These data are consistent with the second hit to ATM being a late event in pancreatic tumorigenesis. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Transcriptomic and clinical heterogeneity of metastatic disease timing within metastatic castration-sensitive prostate cancer

BACKGROUND

Metastatic castration-sensitive prostate cancer (mCSPC) is commonly classified into high- and low-volume subgroups which have demonstrated differential biology, prognosis, and response to therapy. Timing of metastasis has similarly demonstrated differences in clinical outcomes; however, less is known about any underlying biologic differences between these disease states. Herein, we aim to compare transcriptomic differences between synchronous and metachronous mCSPC and identify any differential responses to therapy.

PATIENTS AND METHODS

We performed an international multi-institutional retrospective review of men with mCSPC who completed RNA expression profiling evaluation of their primary tumor. Patients were stratified according to disease timing (synchronous versus metachronous). The primary endpoint was to identify differences in transcriptomic profiles between disease timing. The median transcriptomic scores between groups were compared with the Mann-Whitney U test. Secondary analyses included determining clinical and transcriptomic variables associated with overall survival (OS) from the time of metastasis. Survival analysis was carried out with the Kaplan-Meier method and multivariable Cox regression.

RESULTS

A total of 252 patients were included with a median follow-up of 39.6 months. Patients with synchronous disease experienced worse 5-year OS (39% versus 79%; P < 0.01) and demonstrated lower median androgen receptor (AR) activity (11.78 versus 12.64; P < 0.01) and hallmark androgen response (HAR; 3.15 versus 3.32; P < 0.01). Multivariable Cox regression identified only high-volume disease [hazard ratio (HR) = 4.97, 95% confidence interval (CI) 2.71-9.10; P < 0.01] and HAR score (HR = 0.51, 95% CI 0.28-0.88; P = 0.02) significantly associated with OS. Finally, patients with synchronous (HR = 0.47, 95% CI 0.30-0.72; P < 0.01) but not metachronous (HR = 1.37, 95% CI 0.50-3.92; P = 0.56) disease were found to have better OS with AR and non-AR combination therapy as compared with monotherapy (P value for interaction = 0.05).

CONCLUSIONS

We have demonstrated a potential biologic difference between metastatic timing of mCSPC. Specifically, for patients with low-volume disease, those with metachronous low-volume disease have a more hormone-dependent transcriptional profile and exhibit a better prognosis than synchronous low-volume disease.

Abstract 1896: Dysregulation of DNA methylation in prostate cancer among African American men

Men of African ancestry have the higher incidence and mortality rates of prostate cancer (PCa) worldwide. These health disparities may be contributed by environmental or biological factors, such as epigenomics. Differential DNA methylation can influence carcinogenesis and disease progression. Indeed, the most common molecular event in PCa is dysregulation of DNA methylation. Among these epigenetic changes, some specific changes may be associated with poor outcomes. Numerous studies reported that differential DNA methylation influences the likelihood of developing PCa and affects its progression. However, most studies were based on European American patients. There is a need to investigate methylation profiles to evaluate potential African American-specific methylated genes, since differential DNA methylation may influence health disparities in PCa. This study aimed to investigate differentially DNA methylated genes between tumor vs. adjacent normal, and aggressive vs. indolent PCa (based on Gleason Score) in 120 African American patients from Florida. Genomic DNA samples were extracted by macro-dissection from FFPE. DNA methylation patterns were assessed using the human Illumina Infinium Methylation EPIC array. We identified 5,097 differentially methylated CpG-sites (q&lt;0.01, lΔβl &gt; 0.2) A few representative differentially methylated regions (DMRs) include immune genes, such as CD40, OX40L, Galectin 3, and STING, in prostate tumor tissues as compared with normal tissues. There was also a clear global increase of methylation level in the tumor samples compared to the normal tissues. Regarding PCa aggressiveness, 6,775 (Hypo:4,252, and Hyper: 2,523) differentially methylated CpG-sites (q&lt;0.05, lΔβl &gt; 0.1) were identified when two groups GG1 (Gleason score 6) vs GG4/5 (Gleason score 8≤) were compared. Among these 6,775 CpG-sites, many CpG-probes are consistently significant in more than one comparison. For example, 1,182 hyper and 1,660 hypo-methylation sites were identified in the comparison between GG1 and GG2/3 (Gleason score 7), while 362 hyper- and 1,640 hypo-methylation sites were found in the GG2/3 vs GG4/5 comparison. A small fraction of probes (51 hyper and 155 hypomethylated probes) was consistently found in all comparisons. These genes, MMP16, CDH13, CCND2, and SEPT9, were previously reported to have a role in PCa progression. This study identified several differentially methylated genes, associated with risk or aggressiveness. Most of these changes appear to overlap in different comparisons, thus GG1 vs. GG2/3 or GG2/3 vs. GG4/5 comparison. Many differentially methylated genes identified here have previously been associated with PCa risk or tumor aggressiveness. These results will shed light on potential mechanisms contributing to PCa disparities in African American population.

Citation Format: Anders Berglund, Kosj Yamoah, Carlos Diaz Osterman, Julie Dutil, Jaime Matta, Gilberto Ruiz-Deya, Liang Wang, Hyun Park, Tamara Lotan, Ryan Putney, Sungjune Kim, Seung Joon Kim, Clement Gwede, Rana Falahat, James Mule, Youngchul Kim, Ratna Chakrabarti, Jong Y. Park. Dysregulation of DNA methylation in prostate cancer among African American men [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1896.

Phase II Randomized Study of Salvage Radiation Therapy Plus Enzalutamide or Placebo for High-Risk Prostate-Specific Antigen Recurrent Prostate Cancer After Radical Prostatectomy: The SALV-ENZA Trial

PURPOSE

We sought to investigate whether enzalutamide (ENZA), without concurrent androgen deprivation therapy, increases freedom from prostate-specific antigen (PSA) progression (FFPP) when combined with salvage radiation therapy (SRT) in men with recurrent prostate cancer after radical prostatectomy (RP).

PATIENTS AND METHODS

Men with biochemically recurrent prostate cancer after RP were enrolled into a randomized, double-blind, phase II, placebo-controlled, multicenter study of SRT plus ENZA or placebo (ClinicalTrials.gov identifier: NCT02203695). Random assignment (1:1) was stratified by center, surgical margin status (R0 v R1), PSA before salvage treatment (PSA ≥ 0.5 v < 0.5 ng/mL), and pathologic Gleason sum (7 v 8-10). Patients were assigned to receive either ENZA 160 mg once daily or matching placebo for 6 months. After 2 months of study drug therapy, external-beam radiation (66.6-70.2 Gy) was administered to the prostate bed (no pelvic nodes). The primary end point was FFPP in the intention-to-treat population. Secondary end points were time to local recurrence within the radiation field, metastasis-free survival, and safety as determined by frequency and severity of adverse events.

RESULTS

Eighty-six (86) patients were randomly assigned, with a median follow-up of 34 (range, 0-52) months. Trial arms were well balanced. The median pre-SRT PSA was 0.3 (range, 0.06-4.6) ng/mL, 56 of 86 patients (65%) had extraprostatic disease (pT3), 39 of 86 (45%) had a Gleason sum of 8-10, and 43 of 86 (50%) had positive surgical margins (R1). FFPP was significantly improved with ENZA versus placebo (hazard ratio [HR], 0.42; 95% CI, 0.19 to 0.92; P = .031), and 2-year FFPP was 84% versus 66%, respectively. Subgroup analyses demonstrated differential benefit of ENZA in men with pT3 (HR, 0.22; 95% CI, 0.07 to 0.69) versus pT2 disease (HR, 1.54; 95% CI, 0.43 to 5.47; Pinteraction = .019) and R1 (HR, 0.14; 95% CI, 0.03 to 0.64) versus R0 disease (HR, 1.00; 95% CI, 0.36 to 2.76; Pinteraction = .023). There were insufficient secondary end point events for analysis. The most common adverse events were grade 1-2 fatigue (65% ENZA v 53% placebo) and urinary frequency (40% ENZA v 49% placebo).

CONCLUSION

SRT plus ENZA monotherapy for 6 months in men with PSA-recurrent high-risk prostate cancer after RP is safe and delays PSA progression relative to SRT alone. The impact of ENZA on distant metastasis or survival is unknown at this time.

Clinical testing of transcriptome-wide expression profiles in high-risk localized and metastatic prostate cancer starting androgen deprivation therapy: an ancillary study of the STAMPEDE abiraterone Phase 3 trial

Metastatic and high-risk localized prostate cancer respond to hormone therapy but outcomes vary. Following a pre-specified statistical plan, we used Cox models adjusted for clinical variables to test associations with survival of multi-gene expression-based classifiers from 781 patients randomized to androgen deprivation with or without abiraterone in the STAMPEDE trial. Decipher score was strongly prognostic (p<2×10-5) and identified clinically-relevant differences in absolute benefit, especially for localized cancers. In metastatic disease, classifiers of proliferation, PTEN or TP53 loss and treatment-persistent cells were prognostic. In localized disease, androgen receptor activity was protective whilst interferon signaling (that strongly associated with tumor lymphocyte infiltration) was detrimental. Post-Operative Radiation-Therapy Outcomes Score was prognostic in localized but not metastatic disease (interaction p=0.0001) suggesting the impact of tumor biology on clinical outcome is context-dependent on metastatic state. Transcriptome-wide testing has clinical utility for advanced prostate cancer and identified worse outcomes for localized cancers with tumor-promoting inflammation.

NCCN Guidelines® Insights: Prostate Cancer, Version 1.2023

The NCCN Guidelines for Prostate Cancer address staging and risk assessment after a prostate cancer diagnosis and include management options for localized, regional, recurrent, and metastatic disease. The NCCN Prostate Cancer Panel meets annually to reevaluate and update their recommendations based on new clinical data and input from within NCCN Member Institutions and from external entities. These NCCN Guidelines Insights summarizes much of the panel's discussions for the 4.2022 and 1.2023 updates to the guidelines regarding systemic therapy for metastatic prostate cancer.

Prostate multi-parametric magnetic resonance imaging appearance of diffuse adenosis of the peripheral zone (DAPZ)

Imaging specialists must recognize potential mimics of prostate cancer (PCa) on multi-parametric magnetic resonance imaging (mpMRI). We describe the appearance of diffuse adenosis of the peripheral zone (DAPZ) on mpMRI. The features of DAPZ parallel those of diffuse PCa, with low signal on T2-weighted images, rapid enhancement on dynamic contrast-enhanced sequences, and restricted diffusion. DAPZ is typically encountered in younger men with elevated prostate specific antigen (PSA) levels and portends an increased risk of the development of PCa. Recognition of the imaging appearance of DAPZ may reassure patients with concordant pathologic findings and may aid in selecting patients for follow-up.

De Novo Neuroendocrine Features in Prostate Cancer

Neuroendocrine tumors of the prostate are rare and encompass a group of entities that are classified based on a combination of morphological and immunohistochemical features. Despite the 2016 World Health Organization classification of prostatic neuroendocrine tumors, variants have been reported that do not fit well in the categorization scheme. While the majority of these tumors arise in the setting of castration-resistant prostate cancer (postandrogen deprivation therapy), de novo cases may occur. In this review, we highlight the most significant pathological and immunohistochemical features, emerging biomarkers, and molecular features of such tumors.

Antizyme Inhibitor 1 regulates matrikine expression and enhances the metastatic potential of aggressive primary prostate cancer

Molecular drivers of metastasis in patients with high-risk localized prostate cancer (PCa) are poorly understood. Therefore, we aim to study molecular drivers of metastatic progression in high-risk PCa patients. A retrospective matched case-control study of two clinico-pathologically identical groups of high-risk PCa patients was undertaken. One group developed metastatic recurrence (n=19) while the other did not (n=25). The primary index tumor was identified by a uro-pathologist, followed by DNA and RNA extraction for somatic copy number aberration (CNA) analysis and whole-transcriptome gene expression analysis. In vitro and in vivo studies included cell line manipulation and xenograft models. The integrative CNA and gene expression analyses identified an increase in AZIN1 gene expression within a focal amplification of 8q22.3, which was associated with metastatic recurrence of high-risk PCa patients in four independent cohorts. The effects of AZIN1 knockdown were evaluated, due to its therapeutic potential. AZIN1 knockdown effected proliferation and metastatic potential of PCa cells and xenograft models. RNA sequencing after AZIN1 knockdown in PCa cells revealed upregulation of genes coding for collagen subunits. The observed effect on cell migration after AZIN1 knockdown was mimicked when exposing PCa cells to bio-active molecules deriving from COL4A1 and COL4A2. Our integrated CNA and gene expression analysis of primary high-risk PCa identified the AZIN1 gene as a novel driver of metastatic progression, by altering collagen subunit expression. Future research should further investigate its therapeutic potential in preventing metastatic recurrence. Implications: AZIN1 was identified as driver of metastatic progression in high-risk PCa through matrikine regulation.

Transcriptional landscape of PTEN loss in primary prostate cancer

BACKGROUND

PTEN is the most frequently lost tumor suppressor in primary prostate cancer (PCa) and its loss is associated with aggressive disease. However, the transcriptional changes associated with PTEN loss in PCa have not been described in detail. In this study, we highlight the transcriptional changes associated with PTEN loss in PCa.

METHODS

Using a meta-analysis approach, we leveraged two large PCa cohorts with experimentally validated PTEN and ERG status by Immunohistochemistry (IHC), to derive a transcriptomic signature of PTEN loss, while also accounting for potential confounders due to ERG rearrangements. This signature was expanded to lncRNAs using the TCGA quantifications from the FC-R2 expression atlas.

RESULTS

The signatures indicate a strong activation of both innate and adaptive immune systems upon PTEN loss, as well as an expected activation of cell-cycle genes. Moreover, we made use of our recently developed FC-R2 expression atlas to expand this signature to include many non-coding RNAs recently annotated by the FANTOM consortium. Highlighting potential novel lncRNAs associated with PTEN loss and PCa progression.

CONCLUSION

We created a PCa specific signature of the transcriptional landscape of PTEN loss that comprises both the coding and an extensive non-coding counterpart, highlighting potential new players in PCa progression. We also show that contrary to what is observed in other cancers, PTEN loss in PCa leads to increased activation of the immune system. These findings can help the development of new biomarkers and help guide therapy choices.

Abstract 2431: mTORC1 paradoxically drives MiT/TFE activity and lysosomal biogenesis in tuberous sclerosis complex

Background: Tuberous Sclerosis Complex (TSC) is characterized by TSC1/2 loss, dysregulated mTORC1 signaling & renal tumors (angiomyolipomas (AML) & renal cell carcinoma (RCC)). The MiT/TFE transcription factors (MITF/TFE3/TFEB) drive autophagy/lysosomal biogenesis & are negatively regulated by mTORC1. However, this model raises a paradox in cancer, where elevated lysosomal activity must persist with mTORC1 activity. We recently showed that epidermal Tsc1 loss paradoxically increases MiT/TFE-activity (https://www.jci.org/articles/view/128287). Intriguingly, TFE3/TFEB gene rearrangements/amplifications and TSC1/2 loss are mutually exclusive drivers in PEComas & RCC. This raises the possibility that TSC1/2 loss & TFE3/TFEB gene rearrangements have overlapping cellular consequences. Here, we address the hypothesis that MiT/TFE-driven lysosomal biogenesis drives tumorigenesis in TSC.

Design: We used HEK293T cells +/- CRISPR deletion (KO) of TSC1, 2 or both, to examine: a) Lysosomal gene enrichment by RNA-seq/GSEA, b) Expression of MiT/TFE & lysosomal markers (immunoblotting, qRT-PCR & IF), c) MiT/TFE localization (IF & nuclear fraction immunoblots), d) MiT/TFE activity (4X-CLEAR luciferase assays, qRT-PCR, cathepsin processing, autophagic flux, LC3 puncta). We analysed spontaneous renal tumors in Tsc2 +/- mice for MIT/TFE protein/gene expression (IHC, IF & qRT-PCR analyses of laser capture micro-dissected (LCM) renal tumors). We examined MIT/TFE proteins/lysosomal markers in FFPE samples of renal PEComas & eosinophilic solid & cystic (ESC) RCC & normal kidney.

Results: RNA-seq/GSEA showed enrichment of lysosomal gene sets in TSC1/2 KO cells compared to controls. TSC2 KO cells had increased expression of lysosomal transcripts & proteins in cellular lysates & lysosomal fractions. TSC1, 2 & 1/2 KO cells showed increased nuclear TFEB/TFE3 (IF/nuclear-fraction immunoblots), compared to controls. MiT/TFE activity in 4X-CLEAR luciferase reporter assays was increased in TSC2 KO cells compared to controls. Treatment of TSC2 KO cells with chloroquine increased lipidated LC3-II, indicating increased autophagic flux. TSC2 KO cells also showed increased LC3-labelled puncta by IF. We analyzed renal tumors in Tsc2 +/- mice, where elevated mTORC1 signaling was confirmed by p-S6 IHC. Expression of lysosomal proteins (LAMP1, Lamtor 1, Rag C, Cathepsin B) & nuclear localization of TFE3 & TFEB was increased in these lesions by IF/IHC, compared to normal kidney. We performed LCM on renal tumors from Tsc2 +/- mice & found levels of MiT/TFE transcriptional targets to be significantly enriched in tumors compared to normal kidney. We analyzed TFE3 expression in 10 cases of ESC- RCC with sporadic bi-allelic TSC1/2 mutations & 2 cases of TSC-associated RCC; 8/10 cases showed elevated nuclear TFE3.

Conclusions: Elevated MiT/TFE levels & activity may represent oncogenic drivers in human & murine renal tumors in TSC.

Citation Format: Kaushal V. Asrani, Daniela Salles, Juhyung Woo, Adrianna Mendes, Sanjana Murali, Thiago Vidotto, Pedram Argani, Edward Gabrielson, Tamara Lotan. mTORC1 paradoxically drives MiT/TFE activity and lysosomal biogenesis in tuberous sclerosis complex [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 2431.

The 2019 Genitourinary Pathology Society (GUPS) White Paper on Contemporary Grading of Prostate Cancer

CONTEXT.—

Controversies and uncertainty persist in prostate cancer grading.

OBJECTIVE.—

To update grading recommendations.

DATA SOURCES.—

Critical review of the literature along with pathology and clinician surveys.

CONCLUSIONS.—

Percent Gleason pattern 4 (%GP4) is as follows: (1) report %GP4 in needle biopsy with Grade Groups (GrGp) 2 and 3, and in needle biopsy on other parts (jars) of lower grade in cases with at least 1 part showing Gleason score (GS) 4 + 4 = 8; and (2) report %GP4: less than 5% or less than 10% and 10% increments thereafter. Tertiary grade patterns are as follows: (1) replace "tertiary grade pattern" in radical prostatectomy (RP) with "minor tertiary pattern 5 (TP5)," and only use in RP with GrGp 2 or 3 with less than 5% Gleason pattern 5; and (2) minor TP5 is noted along with the GS, with the GrGp based on the GS. Global score and magnetic resonance imaging (MRI)-targeted biopsies are as follows: (1) when multiple undesignated cores are taken from a single MRI-targeted lesion, an overall grade for that lesion is given as if all the involved cores were one long core; and (2) if providing a global score, when different scores are found in the standard and the MRI-targeted biopsy, give a single global score (factoring both the systematic standard and the MRI-targeted positive cores). Grade Groups are as follows: (1) Grade Groups (GrGp) is the terminology adopted by major world organizations; and (2) retain GS 3 + 5 = 8 in GrGp 4. Cribriform carcinoma is as follows: (1) report the presence or absence of cribriform glands in biopsy and RP with Gleason pattern 4 carcinoma. Intraductal carcinoma (IDC-P) is as follows: (1) report IDC-P in biopsy and RP; (2) use criteria based on dense cribriform glands (>50% of the gland is composed of epithelium relative to luminal spaces) and/or solid nests and/or marked pleomorphism/necrosis; (3) it is not necessary to perform basal cell immunostains on biopsy and RP to identify IDC-P if the results would not change the overall (highest) GS/GrGp part per case; (4) do not include IDC-P in determining the final GS/GrGp on biopsy and/or RP; and (5) "atypical intraductal proliferation (AIP)" is preferred for an intraductal proliferation of prostatic secretory cells which shows a greater degree of architectural complexity and/or cytological atypia than typical high-grade prostatic intraepithelial neoplasia, yet falling short of the strict diagnostic threshold for IDC-P. Molecular testing is as follows: (1) Ki67 is not ready for routine clinical use; (2) additional studies of active surveillance cohorts are needed to establish the utility of PTEN in this setting; and (3) dedicated studies of RNA-based assays in active surveillance populations are needed to substantiate the utility of these expensive tests in this setting. Artificial intelligence and novel grading schema are as follows: (1) incorporating reactive stromal grade, percent GP4, minor tertiary GP5, and cribriform/intraductal carcinoma are not ready for adoption in current practice.

Role of specialized composition of SWI/SNF complexes in prostate cancer lineage plasticity

Advanced prostate cancer initially responds to hormonal treatment, but ultimately becomes resistant and requires more potent therapies. One mechanism of resistance observed in around 10–20% of these patients is lineage plasticity, which manifests in a partial or complete small cell or neuroendocrine prostate cancer (NEPC) phenotype. Here, we investigate the role of the mammalian SWI/SNF (mSWI/SNF) chromatin remodeling complex in NEPC. Using large patient datasets, patient-derived organoids and cancer cell lines, we identify mSWI/SNF subunits that are deregulated in NEPC and demonstrate that SMARCA4 (BRG1) overexpression is associated with aggressive disease. We also show that SWI/SNF complexes interact with different lineage-specific factors in NEPC compared to prostate adenocarcinoma. These data point to a role for mSWI/SNF complexes in therapy-related lineage plasticity, which may also be relevant for other solid tumors.

The differentiation of prostate adenocarcinoma to neuroendocrine prostate cancer (CRPC-NE) is a mechanism of resistance to androgen deprivation therapy. Here the authors show that SWI/SNF chromatin-remodeling complex is deregulated in CRPC-NE and that the complex interacts with different lineage specific factors throughout prostate cancer transdifferentiation.

Practice patterns related to prostate cancer grading: results of a 2019 Genitourinary Pathology Society clinician survey

PURPOSE

To survey urologic clinicians regarding interpretation of and practice patterns in relation to emerging aspects of prostate cancer grading, including quantification of high-grade disease, cribriform/intraductal carcinoma, and impact of magnetic resonance imaging-targeted needle biopsy.

MATERIALS AND METHODS

The Genitourinary Pathology Society distributed a survey to urology and urologic oncology-focused societies and hospital departments. Eight hundred and thirty four responses were collected and analyzed using descriptive statistics.

RESULTS

Eighty percent of survey participants use quantity of Gleason pattern 4 on needle biopsy for clinical decisions, less frequently with higher Grade Groups. Fifty percent interpret "tertiary" grade as a minor/<5% component. Seventy percent of respondents would prefer per core grading as well as a global/overall score per set of biopsies, but 70% would consider highest Gleason score in any single core as the grade for management. Seventy five percent utilize Grade Group terminology in patient discussions. For 45%, cribriform pattern would affect management, while for 70% the presence of intraductal carcinoma would preclude active surveillance.

CONCLUSION

This survey of practice patterns in relationship to prostate cancer grading highlights similarities and differences between contemporary pathology reporting and its clinical application. As utilization of Gleason pattern 4 quantification, minor tertiary pattern, cribriform/intraductal carcinoma, and the incorporation of magnetic resonance imaging-based strategies evolve, these findings may serve as a basis for more nuanced communication and guide research efforts involving pathologists and clinicians.

Abstract 2535: Screening PTEN-loss associated lncRNAs in prostate cancer

Phosphatase and tensin homologue (PTEN) is a tumor suppressor gene that is frequently inactivated by deletion in prostate cancer (PCa). Occurring in around 20% of primary PCa tumors, and up to 50% in castration resistant tumors, it is the most frequent genomic aberration in PCa. Loss of PTEN activates the phosphoinositide 3-kinase-RAC-alpha serine/threonine-protein kinase (PI3K-AKT) pathway, which is associated with poor clinical outcomes. Despite the consequences of PTEN loss being well studied, most of what is known is restricted to protein-coding genes, with relatively little information about the role of non-coding genes. Using our recently created resource - the FC-R2 expression atlas, which encompasses expression levels for thousands of lncRNAs recently unveiled by the FANTOM consortium - we analyzed differential gene expression of PTEN-null vs PTEN-intact tumors with the goal of characterizing the molecular landscape of PTEN loss. First, we generated a consensus signature using two large PCa cohorts with experimentally validated PTEN status by Immunohistochemistry (IHC), applying a meta-analysis approach. This signature encompassed mainly protein coding genes due it being microarray based. In order to expand this signature beyond the coding genes, we relied on FC-R2-based TCGA-PRAD data. Since PTEN status was not available by IHC, we opted to call the status based on CNV. Then, we proceed to generate a PTEN-null signature using a generalized linear model approach. Both signatures were compared for concordance using correspondence-at-the-top plots and hypergeometric confidence intervals. Gene set enrichment analysis was performed in both signatures using a collection of obtained from the MSigDB database in order to characterize pathways involved in this event. Our results showed that the signature based on IHC validated samples agreed significantly with the CNV-based signature from TCGA for the genes in common. In the differential gene expression analysis on the TCGA cohort we observed 203 significant coding genes and 171 significant non-coding genes (FDR ≤ 0.01, LogFC ≥ 1). Notably, we identified several lncRNAs that have not been associated with PCa or PTEN loss, these include many classes of non-coding RNAs characterized by the FANTOM consortium such as: enhancers and promoters genes. Gene set enrichment analysis revealed that PTEN-null tumors are associated with epithelial-mesenchymal transition suggesting a possible role for these lncRNAs. In conclusion, by leveraging our resources, we were able to obtain comprehensive landscape of the PTEN loss in PCa for both the coding and non-coding counterpart. Furthermore, the association of many lncRNAs with PTEN loss was observed, many recently annotated by the FANTOM consortium, which can help us understand how genes are regulated in this event. In this work we show that despite being widely studied, there are still many components of PTEN loss in the form of lncRNAs highlighting potential markers for PTEN loss and clinical outcomes.

Citation Format: Eddie Luidy Imada, Diego Fernando Sanchez, Wikum Dinalankara, Tamara Lotan, Luigi Marchionni. Screening PTEN-loss associated lncRNAs in prostate cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2535.

Abstract 2959: Glycogen synthase kinase 3-β expression in prostate cancer (PCa) correlates with aggressive pathological features and its blockade with 9-ING-41 inhibits viability of PCa cell lines

Castration-resistant prostate cancer (CRPC) represents a lethal stage of disease with limited treatment options beyond androgen receptor (AR) inhibitors and chemotherapy. GSK-3β is a serine/threonine kinase established as a therapeutic target in several solid tumors. GSK-3β inhibitors reduce prostate cancer cell growth and inhibit AR-V7 transcriptional activity in vitro (Rinnab L et al 2008; Schütz SV et al 2011; Nakata et al 2017). This study aimed to characterize the GSK-3β expression in molecular subtypes of PCa and the antitumor activity of 9-ING-41, a selective small molecule GSK-3β inhibitor currently in phase 1/2 clinical studies (NCT03678883). We hypothesized that GSK3-β expression may correlate with sensitivity to GSK3-β inhibition as well as suppression of anti-apoptotic pathways. We evaluated the expression of GSK-3β in a tissue microarray of 134 specimens of PCa tumors from radical prostatectomies (median age 69, serum PSA 10.5 ± 7.6 ng/ml; grade groups (GG): 18 - GG 1 (13.4%), 67 - GG 2 (48.5%), 29 - GG 3 (21.4%), 7 - GG 4 (5.2%), 13 - GG 5 (9.7%); 72 patients (54.9%) had pT2 tumors, and 52 (39,1%) were pT3. Seven patients (5.7%) had positive lymph node (pN1 disease). ERG expression and PTEN loss were observed in 52% (71/134) and 42%, respectively. The GSK-3β histologic score (% of positive tumor cells multiplied by intensity 0-3) correlated with higher Gleason grade (p&lt;0.05), extraprostatic extension (pT3a, p&lt;0.05), but not with serum PSA, tumor volume, margin status or size of index nodule. Cases with predominant nuclear localization of GSK-3β (5%; N=7) had higher Gleason score, pathologic stage, and all but one had PTEN loss. The antiproliferative effect of 9-ING-41 in four PCa human cell lines (PC3, DU145, LNCAP and 22rV1) was investigated using Cell-Titer-Glo (CTG) viability assay. 9-ING-41 demonstrated a dose-dependent decrease in proliferation of AR positive (IC50s 0.3 μM LNCAP; 0.8 μM 22rV1) and AR negative cell lines (IC50 0.6 μM PC3, 0.2 μM DU145). 9-ING-41 induced robust apoptosis (cleaved PARP) in LNCAP and PC3 cells, but not in DU145. All four cell lines expressed GSK-3β, the target of 9-ING-41 and its level were not altered by treatment. 9-ING-41 decreased the expression of phosphorylated NF-kβ (Ser536), anti-apoptotic proteins MCL-1 and BCL-2 by western immunoblotting. Interestingly, the most sensitive cell line, DU145, had lower levels of NF-kβ and suppressed both MCL-1 and BCL-2 after exposure to 9-ING-41. Our current work is evaluating the extent of apoptosis versus growth arrest, especially in the DU145 cell line, where PARP cleavage was not observed. We are also evaluating the effects of the 9-ING-41 on cellular targets of GSK-3β as potential markers of drug efficacy. 9-ING-41 has potent anti-proliferative activity against PCa cell lines. These data support the inclusion of patients with CRPC in clinical studies of 9-ING-41 and its further investigation for the treatment of CRPC.

Citation Format: Fabio Tavora, Tamara Lotan, Marclesson Alves, Lanlan Zhou, Ali Amin, Navaraj Arunasalam, Andre De Souza, Anthony Mega, Dragan Golijanin, Frank Giles, Wafik El-Deiry, Benedito Carneiro. Glycogen synthase kinase 3-β expression in prostate cancer (PCa) correlates with aggressive pathological features and its blockade with 9-ING-41 inhibits viability of PCa cell lines [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2959.

Abstract IA22: A comprehensive and integrated approach to identify factors associated with aggressive prostate cancer in African-Americans: The RESPOND Study

African American (AA) men have a &gt;60% higher incidence, are more likely to be diagnosed with aggressive and potentially lethal PCa, and are more than twice as likely to die from PCa than white (WH) men. Reasons for the greater burden of aggressive disease in AA men are unknown but are likely to include a multitude of factors including social factors such as lifetime stress, inherited susceptibility, and tumor-related features such as somatic alterations and local inflammation in the microenvironment. RESPOND (Research on Prostate Cancer in Men of African Ancestry: Defining the Roles of Genetics, Immunity and Social Stress) has been funded to study the reasons for increased risk of aggressive disease among AA and will include a comprehensive approach including the role of stress and the contextual environment (Project 1), germline susceptibility (Project 2), tumor somatic genetics (Project 3), inflammatory tumor microenvironment (Project 4), and, the integrated synergistic effects of these factors. Project 1: Social stress: AA men are uniquely exposed to high levels of social adversity such as discrimination, violence, crime, financial strain, and residence in poor-resourced environments, over their lifetime. These social stressors are experienced at multiple levels, including individual, neighborhood, and institutional, ultimately leading to chronic and long-term stress. Social stressors may be a contributor to the development of aggressive PCa and high mortality. Project 2: Germline genetic factors: There is evidence to suggest genetic differences in the allelic architecture of PCa across populations. We found a region of the genome (8q24) that harbored genetic risk alleles that may contribute to the greater risk of PCa in AA men. Substantially larger collections of AA cases are needed to reveal a common susceptibility locus that is specific to high-risk disease. We will be expanding genome-wide efforts to identify susceptibility alleles for aggressive PCa in AA men. Project 3: Somatic genetic factors. PCa is a heterogeneous and multifocal disease with a diverse genetic component. Few genetic or molecular drivers of aggressive disease have been identified, and studies in AA men are critically limited. This is due to the fact that the majority of PCa profiling studies have focused on localized disease and largely on men of European ancestry. We will address this issue through the comprehensive and integrated genomic and transcriptomic analysis of a large number of clinically annotated aggressive vs. nonaggressive PCas in AA men. We anticipate that this study will identify genomic markers of aggressive PCa in general and AA PCa in particular, with some of these somatic events being therapeutically actionable, leading to new treatment paradigms for this lethal disease. Project 4: Inflammatory tumor microenvironment. There is evidence to suggest that inflammation drives the formation of precursor lesions to PCa development and may contribute to PCa progression. The consistent observation of overexpression of genes involved in inflammatory pathways in PCa tumors from AA men points to a proinflammatory immune cell component in the tumors of these men that may contribute to PCa progression and their higher PCa mortality. Integration of social and genetic information: Independently evaluating germline, somatic genome, and tumor microenvironment characteristics of PCa ignores the potential for shared biologic mechanism(s). The integration of data across these domains will lead to the identification of shared genes and/or pathways that define more homogeneous, and clinically important, subsets of PCa tumors. The vast genomic and molecular data generated in the same individuals will facilitate the estimation of tumor subgroups as a function of somatic and tumor microenvironment and an assessment of their relationship with other potential PCa risk factors, such as socioeconomic factors, lifetime stress, and genomic germline variation. We will evaluate the association of integrated molecular profiles with recurrence and survival in the future. The RESPOND Cohort: We are in the process of recruiting a cohort of 10,000 incident AA PCa cases to support the four research projects. The men, diagnosed between 2015-2018, are being recruited through cancer registries in 7 states (California, Florida, Georgia, Louisiana, Michigan, New Jersey, and Texas). The fieldwork procedures include enrolling the men by completion of a mailed (or online) survey, followed by a request to obtain a saliva sample and HIPAA authorization to obtain tumor tissue. Of the ~23,000 AA PCa patients we will contact, we estimate to receive a survey from 45% (10,050), DNA from 33% (7,543), HIPAA release from 26% (6,030) and tumor samples for 13% (3,015). Impact: In Project 1, we are studying the impact of multilevel stressors over the lifecourse on risk of developing aggressive and lethal PCa, providing both a means of identifying high-risk men for targeted prevention and treatment, as well as informing the etiology by which tumor aggressiveness arises. In Project 2, the ability to better understand, based on inherited variation, which AA men are at greater risk of developing aggressive and lethal PCa will help in the development of targeted screening and prevention strategies. In Project 3, delineating the genomic events that are acquired during the development of PCa in AA men may guide the development of targeted therapeutic strategies for men whose tumors display aggressive molecular signatures. In Project 4, the ability to define immune profiles associated with aggressive PCa in AA men could inform the development of cancer prevention and/or treatment strategies. Altogether, this body of research will provide impactful information as to the underlying factors that contribute to aggressive PCa in AA men.

Citation Format: Ann S. Hamilton, Scarlett Gomez, Xiao-Cheng Wu, Kevin Ward, Melissa Bondy, Rosemary Cress, Jennifer Beebe-Dimmer, Karen Pawlish, Jong Park, Iona Cheng, Antoinette Stroup, Thomas Sellers, Susan Gundell, Angelo Demarzo, Denise Modjeski, Stephen Chanock, Salma Shariff-Marco, Mindy DeRouen, John Carpten, Franklin Huang, Karen Sfanos, Tamara Lotan, David Conti, Christopher Haiman. A comprehensive and integrated approach to identify factors associated with aggressive prostate cancer in African-Americans: The RESPOND Study [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr IA22.

Family history of prostate cancer and the incidence of ERG- and phosphatase and tensin homolog-defined prostate cancer

Family history is among the strongest known risk factors for prostate cancer (PCa). Emerging data suggest molecular subtypes of PCa, including two somatic genetic aberrations: fusions of androgen-regulated promoters with ERG and, separately, phosphatase and tensin homolog (PTEN) loss. We examined associations between family history and incidence of these subtypes in 44,126 men from the prospective Health Professionals Follow-up Study. ERG and PTEN status were assessed by immunohistochemistry. Multivariable competing risks models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for associations between self-reported family history of PCa and molecular subtypes of disease. Thirteen percent of men had a positive family history of PCa at baseline. During a median follow-up of 18.5 years, 5,511 PCa cases were diagnosed. Among them, 888 were assayed for ERG status (47% ERG-positive) and 715 were assayed for PTEN loss (14% PTEN null). Family history was more strongly associated with risk of ERG-negative (HR: 2.15; 95% CI: 1.71-2.70) than ERG-positive (HR: 1.49; 95% CI: 1.13-1.95) disease (p_{heterogeneity} : 0.04). The strongest difference was among men with an affected father (HR_ERG-negative : 2.09; 95% CI: 1.64-2.66; HR_ERG-positive : 1.30; 95% CI: 0.96-1.76; p_{heterogeneity} : 0.01). Family history of PCa was positively associated with both PTEN null (HR: 2.10; 95% CI: 1.26-3.49) and PTEN intact (HR: 1.72; 95% CI: 1.39-2.13) PCa (p_{heterogeneity} : 0.47). Our results indicate that PCa family history may be positively associated with PCa in all ERG and PTEN subtypes, suggesting a role of genetic susceptibility in their development. It is possible that ERG-negative disease could be especially associated with positive family history.

The Role of Lineage Plasticity in Prostate Cancer Therapy Resistance

Lineage plasticity has emerged as an important mechanism of treatment resistance in prostate cancer. Treatment-refractory prostate cancers are increasingly associated with loss of luminal prostate markers, and in many cases induction of developmental programs, stem cell-like phenotypes, and neuroendocrine/neuronal features. Clinically, lineage plasticity may manifest as low PSA progression, resistance to androgen receptor (AR) pathway inhibitors, and sometimes small cell/neuroendocrine pathologic features observed on metastatic biopsy. This mechanism is not restricted to prostate cancer as other malignancies also demonstrate lineage plasticity during resistance to targeted therapies. At present, there is no established therapeutic approach for patients with advanced prostate cancer developing lineage plasticity or small cell neuroendocrine prostate cancer (NEPC) due to knowledge gaps in the underlying biology. Few clinical trials address questions in this space, and the outlook for patients remains poor. To move forward, urgently needed are: (i) a fundamental understanding of how lineage plasticity occurs and how it can best be defined; (ii) the temporal contribution and cooperation of emerging drivers; (iii) preclinical models that recapitulate biology of the disease and the recognized phenotypes; (iv) identification of therapeutic targets; and (v) novel trial designs dedicated to the entity as it is defined. This Perspective represents a consensus arising from the NCI Workshop on Lineage Plasticity and Androgen Receptor-Independent Prostate Cancer. We focus on the critical questions underlying lineage plasticity and AR-independent prostate cancer, outline knowledge and resource gaps, and identify strategies to facilitate future collaborative clinical translational and basic studies in this space.

A phase II randomized placebo-controlled double-blind study of salvage radiation therapy plus placebo versus SRT plus enzalutamide with high-risk PSA-recurrent prostate cancer after radical prostatectomy (SALV-ENZA)

BACKGROUND

In men with a rising PSA following radical prostatectomy, salvage radiation therapy (SRT) offers a second chance for cure. Hormonal therapy can be combined with SRT in order to increase prostate tumor control, albeit with associated higher rates of treatment side effects. This trial studies the effectiveness of SRT combined with hormonal therapy using a more potent anti-androgen with a favorable side effect profile. Enzalutamide, a next generation selective androgen receptor antagonist, is approved by the Food and Drug Administration for the treatment of metastatic castrate-resistant prostate cancer (CRPC) where it has been shown to improve overall survival in combination with androgen deprivation therapy. The primary objective of this study is to evaluate the efficacy of combination SRT and enzalutamide for freedom-from-PSA-progression. Secondary objectives include time to local recurrence within the radiation field, metastasis-free survival and safety as determined by frequency and severity of adverse events.

METHODS/DESIGN

This is a randomized, double-blind, phase II, prospective, multicenter study in adult males with biochemically recurrent prostate cancer following radical prostatectomy. Following registration, enzalutamide 160 mg or placebo by mouth (PO) once daily will be administered for 6 months. Following two months of study drug, external beam radiotherapy to 66.6-70.2 Gray (Gy) will be administered to the prostate bed over 7-8 weeks while continuing daily placebo/enzalutamide. This is followed by two additional months of placebo/enzalutamide.

DISCUSSION

The SALV-ENZA trial is the first phase II placebo-controlled double-blinded randomized study to test SRT in combination with a next generation androgen receptor antagonist in men with high-risk recurrent prostate cancer after radical prostatectomy. The primary hypothesis of this study is that clinical outcomes will be improved by the addition of enzalutamide compared to standard-of-care SRT alone and pave the path for phase III evaluation of this combination.

TRIAL REGISTRATIONS

ClinicaltTrials.gov Identifier: NCT02203695 Date of Registration: 06/16/2014. Date of First Participant Enrollment: 04/16/2015.

Asporin Restricts Mesenchymal Stromal Cell Differentiation, Alters the Tumor Microenvironment, and Drives Metastatic Progression

Tumor progression to metastasis is not cancer cell autonomous, but rather involves the interplay of multiple cell types within the tumor microenvironment. Here we identify asporin (ASPN) as a novel, secreted mesenchymal stromal cell (MSC) factor in the tumor microenvironment that regulates metastatic development. MSCs expressed high levels of ASPN, which decreased following lineage differentiation. ASPN loss impaired MSC self-renewal and promoted terminal cell differentiation. Mechanistically, secreted ASPN bound to BMP-4 and restricted BMP-4-induced MSC differentiation prior to lineage commitment. ASPN expression was distinctly conserved between MSC and cancer-associated fibroblasts (CAF). ASPN expression in the tumor microenvironment broadly impacted multiple cell types. Prostate tumor allografts in ASPN-null mice had a reduced number of tumor-associated MSCs, fewer cancer stem cells, decreased tumor vasculature, and an increased percentage of infiltrating CD8⁺ T cells. ASPN-null mice also demonstrated a significant reduction in lung metastases compared with wild-type mice. These data establish a role for ASPN as a critical MSC factor that extensively affects the tumor microenvironment and induces metastatic progression. SIGNIFICANCE: These findings show that asporin regulates key properties of mesenchymal stromal cells, including self-renewal and multipotency, and asporin expression by reactive stromal cells alters the tumor microenvironment and promotes metastatic progression.

Abstract B024: Family history of prostate cancer and the incidence of ERG- and PTEN-defined prostate cancer

Introduction: Family history is among the strongest known risk factors for prostate cancer. Emerging data suggest unique molecular subtypes of disease, including common somatic genetic aberrations: fusions of androgen-regulated promoters with ERG and, separately, PTEN loss. We examined associations between family history and incidence of these subtypes under the hypothesis that family history could be differentially associated with their occurrence.

Methods: We studied 47,115 men in the prospective Health Professionals Follow-up Study from 1986 to 2009. ERG and PTEN status were assessed with immunohistochemistry. Multivariable competing risk models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for associations between self-reported family history of prostate cancer and disease defined by molecular subtypes.

Results: During a median follow-up of 22.3 years, 5,606 prostate cancer cases were diagnosed. Among them, 889 and 711 were assayed for ERG status (48% ERG+) and PTEN loss (14% PTEN null), respectively. Prostate cancer family history was positively associated with both ERG+ (HR=1.85; 95% CI: 1.47-2.33) and ERG- (HR=2.20; 95% CI: 1.78-2.72) disease (P-heterogeneity=0.29). High-grade ERG+ disease suggested a pronounced association (HR=2.58; 95% CI: 1.85-3.61; P-heterogeneity versus high-grade ERG-: 0.08). Family history was also positively associated with PTEN null (HR=2.39; 95% CI: 1.53-3.71) and PTEN intact (HR=1.88; 95% CI: 1.54-2.28) prostate cancer (P-heterogeneity=0.34).

Conclusion: Prostate cancer family history is positively associated with prostate cancer defined by ERG and PTEN, suggesting a similar role of genetic susceptibility for these subtypes. It is possible that high-grade ERG+ disease could be uniquely associated with positive family history.

Citation Format: Dana Hashim, Amparo G. Gonzalez-Feliciano, Thomas U. Ahearn, Andreas Pettersson, Lauren Barber, Claire H. Pernar, Ericka M. Ebot, Stephen Finn, Edward L. Giovannucci, Rosina T. Lis, Massimo Loda, Giovanni Parmigiani, Kathryn L. Penney, Tamara Lotan, Philip W. Kantoff, Lorelei A. Mucci, Rebecca E. Graff. Family history of prostate cancer and the incidence of ERG- and PTEN-defined prostate cancer [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr B024.

Ultrasound elastography as a tool for imaging guidance during prostatectomy: initial experience

BACKGROUND

During laparoscopic or robotic assisted laparoscopic prostatectomy, the surgeon lacks tactile feedback which can help him tailor the size of the excision. Ultrasound elastography (USE) is an emerging imaging technology which maps the stiffness of tissue. In the paper we are evaluating USE as a palpation equivalent tool for intraoperative image guided robotic assisted laparoscopic prostatectomy.

MATERIAL/METHODS

Two studies were performed: 1) A laparoscopic ultrasound probe was used in a comparative study of manual palpation versus USE in detecting tumor surrogates in synthetic and ex-vivo tissue phantoms; N=25 participants (students) were asked to provide the presence, size and depth of these simulated lesions, and 2) A standard ultrasound probe was used for the evaluation of USE on ex-vivo human prostate specimens (N=10 lesions in N=6 specimens) to differentiate hard versus soft lesions with pathology correlation. Results were validated by pathology findings, and also by in-vivo and ex-vivo MR imaging correlation.

RESULTS

In the comparative study, USE displayed higher accuracy and specificity in tumor detection (sensitivity=84%, specificity=74%). Tumor diameters and depths were better estimated using USE versus with manual palpation. USE also proved consistent in identification of lesions in ex-vivo prostate specimens; hard and soft, malignant and benign, central and peripheral.

CONCLUSIONS

USE is a strong candidate for assisting surgeons by providing palpation equivalent evaluation of the tumor location, boundaries and extra-capsular extension. The results encourage us to pursue further testing in the robotic laparoscopic environment.

A broad survey of cathepsin K immunoreactivity in human neoplasms

Cathepsin K is consistently and diffusely expressed in alveolar soft part sarcoma (ASPS) and a subset of translocation renal cell carcinomas (RCCs). However, cathepsin K expression in human neoplasms has not been systematically analyzed. We constructed tissue microarrays (TMA) from a wide variety of human neoplasms, and performed cathepsin K immunohistochemistry (IHC). Only 2.7% of 1,140 carcinomas from various sites exhibited cathepsin K labeling, thus suggesting that among carcinomas, cathepsin K labeling is highly specific for translocation RCC. In contrast to carcinomas, cathepsin K labeling was relatively common (54.6%) in the 414 mesenchymal lesions studied, including granular cell tumor, melanoma, and histiocytic lesions, but not paraganglioma, all of which are in the morphologic differential diagnosis of ASPS. Cathepsin K IHC can be helpful in distinguishing ASPS and translocation RCC from some but not all of the lesions in their differential diagnosis.

Increased gene copy number of ERG on chromosome 21 but not TMPRSS2-ERG fusion predicts outcome in prostatic adenocarcinomas

The role of TMPRSS2-ERG gene fusion in prostate cancer prognostication remains controversial. We evaluated the prognostic role of TMPRSS2-ERG fusion using fluorescence in situ hybridization analysis in a case-control study nested in The Johns Hopkins retropubic radical prostatectomy cohort. In all, 10 tissue microarrays containing paired tumors and normal tissues obtained from 172 cases (recurrence) and 172 controls (non-recurrence) matched on pathological grade, stage, race/ethnicity, and age at the time of surgery were analyzed. All radical prostatectomies were performed at our institution between 1993 and 2004. Recurrence was defined as biochemical recurrence, development of clinical evidence of metastasis, or death from prostate carcinoma. Each tissue microarray spot was scored for the presence of TMPRSS2-ERG gene fusion and for ERG gene copy number gains. The odds ratio of recurrence and 95% confidence intervals were estimated from conditional logistic regression. Although the percentage of cases with fusion was slightly lower in cases than in controls (50 vs 57%), the difference was not statistically significant (P=0.20). The presence of fusion due to either deletion or split event was not associated with recurrence. Similarly, the presence of duplicated ERG deletion, duplicated ERG split, or ERG gene copy number gain with a single ERG fusion was not associated with recurrence. ERG gene polysomy without fusion was significantly associated with recurrence (odds ratio 2.0, 95% confidence interval 1.17-3.42). In summary, TMPRSS2-ERG fusion was not prognostic for recurrence after retropubic radical prostatectomy for clinically localized prostate cancer, although men with ERG gene copy number gain without fusion were twice more likely to recur.

MKK4 suppresses metastatic colonization by multiple highly metastatic prostate cancer cell lines through a transient impairment in cell cycle progression

Metastatic dissemination in prostate cancer is often early, but not all cancer cells form clinical metastases. Map kinase kinase 4 (MKK4) suppresses metastasis in a preclinical prostate cancer model. We hypothesize that MKK4 will specifically inhibit metastatic colonization through impaired proliferation. Three highly metastatic rat prostate cancer cell lines (AT6.1, Mat-Lu and AT3.1) were employed. Stably over-expressing HA-MKK4 or vector control lines were injected into immunocompromised mice. These experiments validated that HA-MKK4 specifically affects metastatic colonization and increases survival. Median survival (days) with HA-MKK4 vs. vector was 42 vs. 28 (p < 0.0001) for AT6.1, 25 vs. 19 (p < 0.0001) for Mat-Lu and 27 vs. 20 (p < 0.0001) for AT3.1. HA-MKK4 suppresses colonization within 14 days post dissemination, after which exponential proliferation resumes. Although overt metastases retain HA-MKK4, it is inactive within these lesions. Nonetheless, metastasis-derived cell lines were shown to retain functional HA-MKK4 and like their parental HA-MKK4 line are suppressed for experimental metastasis formation in vivo. Disseminated AT6.1-HA-MKK4 cells were analyzed and were found to have an alteration in cell cycle. Specifically, there was an accumulation of cells in G1-phase (p = 0.024) and decrease in S-phase (p = 0.037) compared with vector. In multiple prostate cancer lines, HA-MKK4 suppresses an early step in metastatic colonization. These data support a model in which MKK4 activation at the metastatic site causes a cell-cycle arrest, which is eventually overcome despite presence of functional HA-MKK4. Further studies will specifically interrogate the regulation of MKK4 activation within the metastatic microenvironment and the down-stream molecular events critical for metastasis suppression.

Association of PTEN loss with outcome of patients (pts) with early high-risk prostate cancer (CaP) treated with adjuvant docetaxel following radical prostatectomy (RP)

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Background: Loss of the PTEN tumor suppressor and subsequent activation of the PI3K pathway is common and has potential clinical and therapeutic value in CaP. We examined the PTEN status of primary tumors in pts who underwent adjuvant docetaxel tx in a prospective clinical trial.

Methods: Of the 77 pts enrolled in a prospective multi-institutional adjuvant docetaxel trial (TAX 2501, J Urol 2007), we prospectively collected 56 primary tumor pathology specimens suitable for analysis of PTEN status by immunoreactivity (IHC) and/or fluorescence in situ hybridisation (FISH) assay. Protocol defined progression included a PSA of ≥ 0.4 ng/mL, radiological/pathological evidence of recurrent disease or death from any cause. Univariate and multivariable analyses based on the Cox proportional hazards regression model were used to analyze the independent association of PTEN and other known prognostic factors with progression free survival (PFS).

Results: PTEN loss was observed in 37/56 pts (66%). Pts with PTEN loss vs detectable PTEN were balanced regarding clinical stage, combined Gleason score, seminal vesicles and surgical margins involvement, and lymph nodes status. Pts with a detectable PTEN had a significantly higher pre-RP PSA (median 14 vs 8.6 ng/mL, p=0.015). 41/56 (73.2%, median followup of 37.5 months, range 10.4 to 44.5) progressed with an overall median PFS of 13 months (mos) (95% CI 9.8–15.8). Independent prognostic factors of progression by multivariate analysis were: seminal vesicles involvement (HR 2.19, p=0.024), combined Gleason score 9–10 (HR 2.46, p=0.027) and PTEN loss (HR 2.36, p=0.037). PFS on pts without PTEN loss (median not reached at a followup time of 37.5 mos, range 10.4–44.5 mos) was significantly longer (log rank test, p = 0.026) compared to those with undetectable PTEN (median PFS 12.9 mos, 95% CI 9.7–15.3).

Conclusions: PTEN loss may be an independent prognostic factor associated with poorer outcome of pts with early high-risk CaP treated with adjuvant docetaxel following RP. These findings may have important prognostic and therapeutic implications in CaP.

No significant financial relationships to disclose.

Efficacy of the argon beam coagulator alone in obtaining hemostasis after laparoscopic porcine heminephrectomy: a pilot study

INTRODUCTION

The argon beam coagulator (ABC) is used in combination with other hemostatic agents and suture renorrhaphy to obtain hemostasis after laparoscopic partial nephrectomy. We performed a pilot study evaluating the efficacy of the ABC-alone in obtaining hemostasis during laparoscopic heminephrectomy (LHN) in a porcine model.

METHODS

Eight pigs (4 small (30 kg-40 kg) and 4 large (70 kg-80 kg)), underwent bilateral LHN. Hemostasis then was obtained by using the ABC at 120W as a single modality. The collecting system was not repaired. The hilum was unclamped and the renal defect observed for 20 minutes with pneumoperitoneum pressure of 4 mmHg. The animals were survived for 24 hours at which time they were sacrificed and necropsy performed.

RESULTS

All small pigs underwent LHN successfully. Mean pre- and post-op Hgb were 11.2 g/dl and 9.8 g/dl, respectively (p=0.12). In one of the animals, ABC at 150W was required to obtain hemostasis. All but one of the large pigs underwent LHN successfully. One of the animals had continuous bleeding despite ABC after right LHN and a completion nephrectomy was performed. Pre and postoperative Hgb for the large pigs were 9.9 g/dl and 9.3 g/dl, respectively (p=0.24).

CONCLUSIONS

The ABC-alone was successful in obtaining hemostasis in all but two of the renal units in both small and large pigs. The two hemostatic failures were noticeable immediately after hilar unclamping. Our data suggest that ABC-alone provides adequate hemostasis when applied to small-caliber vessels. Further long term studies are needed to fully evaluate the efficacy of the ABC.

c-Jun NH2-terminal kinase activating kinase 1/mitogen-activated protein kinase kinase 4-mediated inhibition of SKOV3ip.1 ovarian cancer metastasis involves growth arrest and p21 up-regulation

In many patients without clinical metastases, cancer cells have already escaped from the primary tumor and entered a distant organ. A long-standing question in metastasis research is why some disseminated cancer cells fail to complete steps of metastatic colonization for extended periods of time. Our laboratory identified c-Jun NH(2)-terminal kinase activating kinase 1/mitogen-activated protein kinase kinase 4 (JNKK1/MKK4) as a metastasis suppressor protein in a mouse xenograft model of experimental i.p. ovarian cancer metastasis. In this model, expression of JNKK1/MKK4 via activation of p38 delays formation of >or=1-mm implants and prolongs animal survival. Here, we elucidate the time course of this delay as well as the biological mechanisms underpinning it. Using the Gompertz function to model the net accumulation of experimental omental metastases, we show that MKK4-expressing implants arise, on average, 30 days later than controls. Quantitative real-time PCR shows that MKK4 expression does not have a substantial effect on the number of cancer cells initially adhering to the omentum, and terminal deoxyribonucleotidyl transferase-mediated dUTP nick end labeling analysis shows that there is no increase in apoptosis in these cells. Instead, immunohistochemical quantitation of cell cycle proteins reveals that MKK4-expressing cells fail to proliferate once they reach the omentum and up-regulate p21, a cell cycle inhibitor. Consistent with the time course data, in vitro kinase assays and in vivo passaging of cell lines derived from macroscopic metastases show that the eventual outgrowth of MKK4-expressing cells is not due to a discrete selection event. Rather, the population of MKK4-expressing cells eventually uniformly adapts to the consequences of up-regulated MKK4 signaling.

Using metastasis suppressor proteins to dissect interactions among cancer cells and their microenvironment

Cancer metastasis is a complex, dynamic process that begins with dissemination of cells from the primary tumor and culminates in the formation of clinically detectable, overt metastases at one or more discontinuous secondary sites. Evidence from in vivo video microscopy as well as PCR and immunohistochemical studies suggest that cancer cell dissemination is an early event in tumor progression and that cells may persist in a potentially dormant state for a prolonged period. Similarly, the mechanisms by which these disseminated cells initiate growth and complete the process of metastatic colonization remain largely unknown. Understanding signal transduction pathways regulating this final step of metastasis is therefore critical for successful clinical management. While genetic mutations or epigenetic changes may be required for a cell or group of cells to separate and survive distant from the primary tumor, the microenvironment within secondary tissues plays a substantial role in influencing whether disseminated cells survive and proliferate. Our work is focused on using metastasis suppressor proteins to gain insight into why the majority of disseminated cells, which should be fully malignant, do not proliferate immediately at secondary sites. The translational goal of this work is to identify targets for inhibiting metastatic growth and prolonging disease-free survival.