Developing Folate-Conjugated miR-34a Therapeutic for Prostate Cancer: Challenges and Promises.

Prostate cancer (PCa) remains a common cancer with high mortality in men due to its heterogeneity and the emergence of drug resistance. A critical factor contributing to its lethality is the presence of prostate cancer stem cells (PCSCs), which can self-renew, long-term propagate tumors, and mediate treatment resistance. MicroRNA-34a (miR-34a) has shown promise as an anti-PCSC therapeutic by targeting critical molecules involved in cancer stem cell (CSC) survival and functions. Despite extensive efforts, the development of miR-34a therapeutics still faces challenges, including non-specific delivery and delivery-associated toxicity. One emerging delivery approach is ligand-mediated conjugation, aiming to achieve specific delivery of miR-34a to cancer cells, thereby enhancing efficacy while minimizing toxicity. Folate-conjugated miR-34a (folate-miR-34a) has demonstrated promising anti-tumor efficacy in breast and lung cancers by targeting folate receptor α (FOLR1). Here, we first show that miR-34a, a TP53 transcriptional target, is reduced in PCa that harbors TP53 loss or mutations and that miR-34a mimic, when transfected into PCa cells, downregulated multiple miR-34a targets and inhibited cell growth. When exploring the therapeutic potential of folate-miR-34a, we found that folate-miR-34a exhibited impressive inhibitory effects on breast, ovarian, and cervical cancer cells but showed minimal effects on and targeted delivery to PCa cells due to a lack of appreciable expression of FOLR1 in PCa cells. Folate-miR-34a also did not display any apparent effect on PCa cells expressing prostate-specific membrane antigen (PMSA) despite the reported folate's binding capability to PSMA. These results highlight challenges in the specific delivery of folate-miR-34a to PCa due to a lack of target (receptor) expression. Our study offers novel insights into the challenges and promises within the field and casts light on the development of ligand-conjugated miR-34a therapeutics for PCa.

Androgen deprivation triggers a cytokine signaling switch to induce immune suppression and prostate cancer recurrence.

Androgen deprivation therapy (ADT) is an effective but not curative treatment for advanced and recurrent prostate cancer (PC). We investigated the mechanisms controlling the response to androgen-deprivation by surgical castration in genetically-engineered mouse models (GEMM) of PC, using high frequency ultrasound imaging to rigorously measure tumor volume. Castration initially causes almost all tumors to shrink in volume, but many tumors subsequently recur within 5-10 weeks. Blockade of tumor necrosis factor (TNF) signaling a few days in advance of castration surgery, using a TNFR2 ligand trap, prevents regression in a PTEN-deficient GEMM. Following tumor regression, a basal stem cell-like population within the tumor increases along with TNF protein levels. Tumor cell lines in culture recapitulate these in vivo observations, suggesting that basal stem cells are the source of TNF. When TNF signaling blockade is administered immediately prior to castration, tumors regress but recurrence is prevented, implying that a late wave of TNF secretion within the tumor, which coincides with the expression of NFkB regulated genes, drives recurrence. The inhibition of signaling downstream of one NFkB-regulated protein, chemokine C-C motif ligand 2 (CCL2), prevents post-castration tumor recurrence, phenocopying post-castration (late) TNF signaling blockade. CCL2 was originally identified as a macrophage chemoattractant and indeed at late times after castration gene sets related to chemotaxis and migration are up-regulated. Importantly, enhanced CCL2 signaling during the tumor recurrence phase coincides with an increase in pro-tumorigenic macrophages and a decrease in CD8 T cells, suggesting that recurrence is driven at least in part by tumor immunosuppression. In summary, we demonstrate that a therapy-induced switch in TNF signaling, a consequence of the increased stem cell-like character of the residual tumor cells surviving ADT, induces an immunosuppressive tumor microenvironment and concomitant tumor recurrence.

Psychological Distress, Emergency Room Utilization, and Mortality Risk Among US Adults With History of Prostate Cancer.

PURPOSE: Adults with a history of prostate cancer experience several physical and mental stressors. However, limited information is available about the prevalence of psychological distress in this population and its association with clinical outcomes in a nationally representative sample. METHODS: We identified adults with history of prostate cancer from a nationally representative cohort (2000-2018 US National Health Interview Survey) and its linked mortality files through December 31, 2019. The six-item Kessler Psychological Distress Scale (K6) was used to assess psychological distress. The associations between psychological distress severity, emergency room (ER) usage, and mortality risk were estimated using multivariable logistic and Cox proportional hazards models, which were both adjusted for age, survey year, race/ethnicity, region, education, health insurance, comorbidities, functional limitations, and time since cancer diagnosis. RESULTS: Among the 3,451 adults with history of prostate cancer surveyed, 96 (2.4%), 434 (11.3%), and 2,921 (86.3%) reported severe, moderate, or low/no mental distress, respectively. During the 12 months preceding the survey, 812 (22.8%) adults with history of prostate cancer visited the ER. After a median follow-up of 81 months, 937 (25.5%) deaths occurred. Compared with participants with low/no mental distress, those with severe mental distress reported the highest utilization of the ER (adjusted odds ratio [aOR], 2.57 [95% CI, 1.51 to 4.37]) and exhibited the highest all-cause mortality (adjusted hazard ratio [aHR], 1.83 [95% CI, 1.29 to 2.60]), followed by those with moderate mental distress (ER use aOR, 1.76 [95% CI, 1.29 to 2.42]; all-cause mortality aHR, 1.22 [95% CI, 0.92 to 1.62]). CONCLUSION: Among US adults with history of prostate cancer, psychological distress was associated with increased ER use and mortality risk. Notably, severe psychological distress was correlated with the highest rates of ER visits and mortality risk. However, given the retrospective nature of this study, uncontrolled confounding variables need to be considered when interpreting the findings.

Developing folate-conjugated miR-34a therapeutic for prostate cancer treatment: Challenges and promises.

Prostate cancer (PCa) remains a common cancer with high mortality in men due to its heterogeneity and the emergence of drug resistance. A critical factor contributing to its lethality is the presence of prostate cancer stem cells (PCSCs), which can self-renew, long-term propagate tumors and mediate treatment resistance. MicroRNA-34a (miR-34a) has shown promise as an anti-PCSC therapeutic by targeting critical molecules involved in cancer stem cell (CSC) survival and functions. Despite extensive efforts, the development of miR-34a therapeutics still faces challenges, including non-specific delivery and delivery-associated toxicity. One emerging delivery approach is ligand-mediated conjugation, aiming to achieve specific delivery of miR-34a to cancer cells, thereby enhancing efficacy while minimizing toxicity. Folate-conjugated miR-34a (folate-miR-34a) has demonstrated promising anti-tumor efficacy in breast and lung cancers by targeting folate receptor α (FOLR1). Here, we first show that miR-34a, a TP53 transcriptional target, is reduced in PCa that harbors TP53 loss or mutations and that miR-34a mimic, when transfected into PCa cells, downregulated multiple miR-34a targets and inhibited cell growth. When exploring the therapeutic potential of folate-miR-34a, we found that folate-miR-34a exhibited impressive inhibitory effects on breast, ovarian and cervical cancer cells but showed minimal effects on and targeted delivery to PCa cells due to a lack of appreciable expression of FOLR1 in PCa cells. Folate-miR-34a also did not display any apparent effect on PCa cells expressing prostate-specific membrane antigen (PMSA) despite the reported folate's binding capability to PSMA. These results highlight challenges in specific delivery of folate-miR-34a to PCa due to lack of target (receptor) expression. Our study offers novel insights on the challenges and promises within the field and cast light on the development of ligand-conjugated miR-34a therapeutics for PCa.

Phase II Trial of Concurrent Nivolumab and Radiation Therapy for Muscle-Invasive Bladder Cancer of Older or Chemotherapy-Ineligible Patients.

PURPOSE: Bladder cancer is predominantly a disease of older individuals. Concurrent chemotherapy and radiation is a bladder-sparing strategy for management of muscle-invasive bladder cancer; however, many patients are not candidates for chemotherapy due to comorbidities or impaired performance status. We conducted a study in a chemotherapy-ineligible patient population with the objectives of evaluating the safety, efficacy, and quality-of-life effect of the combination of nivolumab and radiation therapy in patients with localized/locally advanced urothelial cancer. METHODS AND MATERIALS: Eligible patients had muscle-invasive bladder cancer and were not candidates for standard chemoradiation strategy due to at least one of the following: performance status of 2, creatinine clearance ≤60 mL/min, cardiac disease, neuropathy, and intolerance to previous treatment. Creatinine clearance ≥40 mL/min, normal marrow, and liver function were required. The primary endpoint was progression-free survival at 12 months. Nivolumab was started within 3 days of radiation therapy and administered at a dose of 240 mg intravenously every 2 weeks for a maximum of 6 months. Radiation therapy was per standard of care for bladder cancer. Imaging and cystoscopy and biopsy evaluation were required at months 3, 6, and 12 and then annually until progression. RESULTS: Twenty patients were enrolled, with a median age of 78.5 years (range, 58-95 years); 80% of patients were >70 years of age, and 8 (40%) were >80 years of age. Median creatinine clearance was 52 mL/min. Nine patients (48%) were progression free at 12 months. Median progression-free survival was 11.4 months (90% CI, 7.5-23.7 months), and median overall survival was 15.6 months (90% CI, 9.1-26.1 months). CONCLUSIONS: Concurrent nivolumab and radiation therapy is tolerable but demonstrated limited efficacy in an older population with multiple comorbidities. Immune correlates demonstrated that patients with baseline programmed cell death ligand 1 combined prognostic score ≥5% had numerically longer progression-free survival.

Nivolumab plus Gemcitabine-Cisplatin in Advanced Urothelial Carcinoma.

BACKGROUND: No new agent has improved overall survival in patients with unresectable or metastatic urothelial carcinoma when added to first-line cisplatin-based chemotherapy. METHODS: In this phase 3, multinational, open-label trial, we randomly assigned patients with previously untreated unresectable or metastatic urothelial carcinoma either to receive intravenous nivolumab (at a dose of 360 mg) plus gemcitabine-cisplatin (nivolumab combination) every 3 weeks for up to six cycles, followed by nivolumab (at a dose of 480 mg) every 4 weeks for a maximum of 2 years, or to receive gemcitabine-cisplatin alone every 3 weeks for up to six cycles. The primary outcomes were overall and progression-free survival. The objective response and safety were exploratory outcomes. RESULTS: A total of 608 patients underwent randomization (304 to each group). At a median follow-up of 33.6 months, overall survival was longer with nivolumab-combination therapy than with gemcitabine-cisplatin alone (hazard ratio for death, 0.78; 95% confidence interval [CI], 0.63 to 0.96; P = 0.02); the median survival was 21.7 months (95% CI, 18.6 to 26.4) as compared with 18.9 months (95% CI, 14.7 to 22.4), respectively. Progression-free survival was also longer with nivolumab-combination therapy than with gemcitabine-cisplatin alone (hazard ratio for progression or death, 0.72; 95% CI, 0.59 to 0.88; P = 0.001). The median progression-free survival was 7.9 months and 7.6 months, respectively. At 12 months, progression-free survival was 34.2% and 21.8%, respectively. The overall objective response was 57.6% (complete response, 21.7%) with nivolumab-combination therapy and 43.1% (complete response, 11.8%) with gemcitabine-cisplatin alone. The median duration of complete response was 37.1 months with nivolumab-combination therapy and 13.2 months with gemcitabine-cisplatin alone. Grade 3 or higher adverse events occurred in 61.8% and 51.7% of the patients, respectively. CONCLUSIONS: Combination therapy with nivolumab plus gemcitabine-cisplatin resulted in significantly better outcomes in patients with previously untreated advanced urothelial carcinoma than gemcitabine-cisplatin alone. (Funded by Bristol Myers Squibb and Ono Pharmaceutical; CheckMate 901 ClinicalTrials.gov number, NCT03036098.).

Medicaid expansion and racial disparity in timely multidisciplinary treatment in muscle invasive bladder cancer.

BACKGROUND: Multidisciplinary cancer care (neoadjuvant chemotherapy followed by radical cystectomy or trimodality therapy) is crucial for outcome of muscle-invasive bladder cancer (MIBC), a potentially curable illness. Medicaid expansion through Affordable Care Act (ACA) increased insurance coverage especially among patients of racial minorities. This study aims to investigate the association between Medicaid expansion and racial disparity in timely treatment in MIBC. METHODS: This quasi-experimental study analyzed Black and White individuals aged 18-64 years with stage II and III bladder cancer treated with neoadjuvant chemotherapy followed by radical cystectomy or trimodality therapy from National Cancer Database 2008-2018. Primary outcome was timely treatment started within 45 days following cancer diagnosis. Racial disparity is the percentage-point difference between Black and White patients. Patients in expansion and nonexpansion states were compared using difference-in-differences and difference-in-difference-in-differences analyses, controlling for age, sex, area-level income, clinical stage, comorbidity, metropolitan status, treatment type, and year of diagnosis. RESULTS: The study included 4991 (92.3% White, n = 4605; 7.7% Black, n = 386) patients. Percentage of Black patients who received timely care increased following the ACA in Medicaid expansion states (54.5% pre-ACA vs 57.4% post-ACA) but decreased in nonexpansion states (69.9% pre-ACA vs 53.7% post-ACA). After adjusting covariates, Medicaid expansion was associated with a net 13.7 percentage-point reduction of Black-White patient disparity in timely receipt of MIBC treatment (95% confidence interval = 0.5% to 26.8%; P < .01). CONCLUSIONS: Medicaid expansion was associated with statically significant reduction in racial disparity between Black and White patients in timely multidisciplinary treatment for MIBC.

Integrated single-cell analysis defines the epigenetic basis of castration-resistant prostate luminal cells.

Understanding prostate response to castration and androgen receptor signaling inhibitors (ARSI) is critical to improving long-term prostate cancer (PCa) patient survival. Here we use a multi-omics approach on 229,794 single cells to create a mouse single-cell reference atlas better suited to interpreting mouse prostate biology and castration response. Our reference atlas refines single-cell annotations and provides chromatin context, which, when coupled with mouse lineage tracing demonstrates that the castration-resistant luminal cells are distinct from the pre-existent urethra-proximal stem/progenitor cells. Molecular pathway analysis and therapeutic studies further implicate JUN/FOS, WNT/B-Catenin, FOXQ1, NFkB, and JAK/STAT pathways as the major drivers of castration-resistant luminal populations with high relevance to human PCa. Importantly, we demonstrate the utility of our datasets, which can be explored through an interactive portal (https://visportal.roswellpark.org/data/tang/), to aid in developing novel combination treatments with ARSI for advanced PCa patients.

Emergence of BRCA Reversion Mutations in Patients with Metastatic Castration-resistant Prostate Cancer After Treatment with Rucaparib.

BACKGROUND: Poly(adenosine diphosphate-ribose) polymerase (PARP) inhibitors are approved in the USA for the treatment of patients with BRCA1 or BRCA2 (BRCA) mutated (BRCA+) metastatic castration-resistant prostate cancer (mCRPC). BRCA reversion mutations are a known mechanism of acquired resistance to PARP inhibitors in multiple cancer types, although their impact and prevalence in mCRPC remain unknown. OBJECTIVE: To examine the prevalence of BRCA reversion mutations in the plasma of patients with BRCA+ mCRPC after progression on rucaparib. DESIGN, SETTING, AND PARTICIPANTS: Men with BRCA+ mCRPC enrolled in Trial of Rucaparib in Prostate Indications 2 (TRITON2) were treated with rucaparib after progressing on one to two lines of androgen receptor-directed and one taxane-based therapy. Cell-free DNA from the plasma of 100 patients, collected at the end of treatment after confirmed progression before May 5, 2020, was queried for BRCA reversion mutations using next-generation sequencing (NGS). OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The association of clinical efficacy and postprogression genomics was measured in 100 patients with BRCA+ mCRPC treated with rucaparib. RESULTS AND LIMITATIONS: No baseline BRCA reversion mutations were observed in 100 BRCA+ patients. NGS identified somatic BRCA reversion mutations in 39% (39/100) of patients after progression. Reversion rates were similar for BRCA2 and BRCA1, irrespective of germline or somatic status, but higher in samples with a high tumor DNA fraction. Most patients with reversions (74%, 29/39) had two or more reversion mutations occurring subclonally at lower allele frequencies than the original BRCA mutations. The incidence of BRCA reversion mutations increased with the duration of rucaparib treatment. The frequency of reversion mutations was higher in patients with an objective (58%) or a prostate-specific antigen (69%) response compared with those without either (39% and 29%, respectively). CONCLUSIONS: These findings suggest that BRCA reversion mutations are a significant mechanism of acquired resistance to rucaparib in patients with BRCA+ mCRPC, with evidence of subclonal convergence promoting systemic resistance. PATIENT SUMMARY: Men with BRCA mutated metastatic castration-resistant prostate cancer enrolled in TRITON2 were treated with rucaparib after progressing on one to two lines of androgen receptor-directed and one taxane-based therapy. Cell-free DNA from the plasma of 100 patients, collected after radiographic or prostate-specific antigen progression before May 5, 2020, was analyzed by next-generation sequencing and queried for BRCA reversion mutations.

Prostate cancer as a dedifferentiated organ: androgen receptor, cancer stem cells, and cancer stemness.

Cancer progression is characterized and driven by gradual loss of a differentiated phenotype and gain of stem cell-like features. In prostate cancer (PCa), androgen receptor (AR) signaling is important for cancer growth, progression, and emergence of therapy resistance. Targeting the AR signaling axis has been, over the decades, the mainstay of PCa therapy. However, AR signaling at the transcription level is reduced in high-grade cancer relative to low-grade PCa and loss of AR expression promotes a stem cell-like phenotype, suggesting that emergence of resistance to AR-targeted therapy may be associated with loss of AR signaling and gain of stemness. In the present mini-review, we first discuss PCa from the perspective of an abnormal organ with increasingly deregulated differentiation, and discuss the role of AR signaling during PCa progression. We then focus on the relationship between prostate cancer stem cells (PCSCs) and AR signaling. We further elaborate on the current methods of using transcriptome-based stemness-enriched signature to evaluate the degree of oncogenic dedifferentiation (cancer stemness) in pan-cancer datasets, and present the clinical significance of scoring transcriptome-based stemness across the spectrum of PCa development. Our discussions highlight the importance to evaluate the dynamic changes in both stem cell-like features (stemness score) and AR signaling activity across the PCa spectrum.

A Preclinical Study to Repurpose Spironolactone for Enhancing Chemotherapy Response in Bladder Cancer.

Neoadjuvant chemotherapy (NAC) followed by radical cystectomy is the standard-of-care for patients with muscle-invasive bladder cancer (MIBC). Defects in nucleotide excision repair (NER) are associated with improved responses to NAC. Excision Repair Cross-Complementation group 3 (ERCC3) is a key component of NER process. No NER inhibitors are available for treating patients with bladder cancer. We have developed an ex vivo cell-based assay of 6-4 pyrimidine-pyrimidinone (6-4PP) removal as a surrogate measure of NER capacity in human bladder cancer cell lines. The protein expression of ERCC3 was examined in human MIBC specimens and cell lines. Small molecule inhibitors were screened for NER inhibition in bladder cancer cell lines. Spironolactone was identified as a potent NER inhibitor. Combined effects of spironolactone with chemo-drugs were evaluated in vitro and in vivo. The efficacy between platinum and spironolactone on cytotoxicity was determined by combination index. A correlation between NER capacity and cisplatin sensitivity was demonstrated in a series of bladder cancer cell lines. Further, siRNA-mediated knockdown of ERCC3 abrogated NER capacity and enhanced cisplatin cytotoxicity. Spironolactone inhibited ERCC3 protein expression, abrogated NER capacity, and increased platinum-induced cytotoxicity in bladder cancer cells in vivo and in patient-derived organoids. Moreover, spironolactone exhibited the potential synergism effects with other clinical chemotherapy regimens in bladder cancer cell lines. Our data support the notion of repurposing spironolactone for improving the chemotherapy response of NAC in patients with MIBC. Further clinical trials are warranted to determine the safety and efficacy of spironolactone in combination with chemotherapy.

Loss of MAGEC3 Expression Is Associated with Prognosis in Advanced Ovarian Cancers.

Rare variants in MAGEC3 are associated with BRCA negative, early-onset ovarian cancers. Given this association, we evaluated the impact of MAGEC3 protein expression on prognosis and transcription. We quantified normal and tumor protein expression of MAGEC3 via immunohistochemistry in n = 394 advanced ovarian cancers, assessed the correlation of these values with clinicopathologic and immunological features and modeled survival using univariate and multivariate models. To extend these results, we quantified MAGEC3 protein expression in n = 180 cancers and used matching RNA sequencing data to determine MAGEC3-associated differentially expressed genes and to build an RNA-based model of MAGEC3 protein levels. This model was tested in a third independent cohort of patients from TCGA's OV dataset (n = 282). MAGEC3 protein was sporadically lost in ovarian cancers, with half of the cases falling below the 9.5th percentile of normal tissue expression. Cases with MAGEC3 loss demonstrated better progression-free survival [HR = 0.71, p = 0.004], and analyses performed on predicted protein scores were consistent [HR = 0.57 p = 0.002]. MAGEC3 protein was correlated with CD8 protein expression [Pearson's r = 0.176, p = 0.011], NY-ESO-1 seropositivity, and mRNA expression of tumor antigens at Xq28. Results of gene set enrichment analysis showed that genes associated with MAGEC3 protein expression cluster around G2/M checkpoint (NES = 3.20, FDR < 0.001) and DNA repair (NES = 2.28, FDR < 0.001) hallmark pathways. These results show that MAGEC3 is a prognostic biomarker in ovarian cancer.

Impact of neoadjuvant chemotherapy on survival and recurrence patterns after robot-assisted radical cystectomy for muscle-invasive bladder cancer: Results from the International Robotic Cystectomy Consortium.

OBJECTIVES: To analyze the impact of neoadjuvant chemotherapy on survival and recurrence patterns in muscle-invasive bladder cancer after robot-assisted radical cystectomy. MATERIALS AND METHODS: The International Robotic Cystectomy Consortium database was reviewed to identify patients who underwent robot-assisted radical cystectomy for muscle-invasive bladder cancer between 2002 and 2019. Survival outcomes, response rates, and recurrence patterns were compared between patients who received neoadjuvant chemotherapy and those who did not. Survival distributions were estimated using Kaplan-Meier analyses and compared using the log-rank test. RESULTS: A total of 1370 patients with muscle-invasive bladder cancer were identified, of whom 353 (26%) received neoadjuvant chemotherapy. After a median follow-up of 27 months, neoadjuvant chemotherapy recipients had higher 3-year overall survival (74% vs 57%; log-rank P < 0.01), 3-year cancer-specific survival (83% vs 73%; log-rank P = 0.03), and 3-year relapse-free survival (64% vs 48%; log-rank P < 0.01). Neoadjuvant chemotherapy was a predictor of higher overall survival, cancer-specific survival, and relapse-free survival in univariate but not multivariate analysis. Pathological downstaging (46% vs 23%; P < 0.01), complete responses (24% vs 8%; P < 0.01), and margin negativity (95% vs 91%; P < 0.01) at robot-assisted radical cystectomy were more common in the neoadjuvant chemotherapy group. Neoadjuvant chemotherapy recipients had lower distant (15% vs 22%; P < 0.01) but similar locoregional (12% vs 13%; P = 0.93) recurrence rates. CONCLUSIONS: In this analysis from a large international database, patients with muscle-invasive bladder cancer who received neoadjuvant chemotherapy before robot-assisted radical cystectomy had higher rates of survival, pathological downstaging, and margin-negative resections. They also experienced fewer distant recurrences.

Androgen receptor (AR) heterogeneity in prostate cancer and therapy resistance.

Androgen receptor (AR), a ligand-dependent nuclear transcription factor and a member of steroid hormone receptor family, plays an important role in prostate organogenesis by regulating epithelial differentiation and restricting cell proliferation. Although rarely mutated or amplified in treatment-naïve prostate cancer (PCa), AR signaling drives tumor growth and as a result, therapies that aim to inhibit AR signaling, called ARSIs (AR signaling inhibitors), have been in clinical use for >70 years. Unfortunately, the clinical efficacy of ARSIs is short-lived and the majority of treated patients develop castration-resistant PCa (CRPC). Numerous molecular mechanisms have been proposed for castration resistance; however, the cellular basis for CRPC emergence has remained obscure. One under-appreciated cellular mechanism for CRPC development is the AR heterogeneity that pre-exists in treatment-naive primary tumors, i.e., although most PCa cells express AR (i.e., AR+), there is always a population of PCa cells that express no/low AR (i.e., AR-/lo). Importantly, this AR heterogeneity becomes accentuated during ARSI treatment and highly prominent in established CRPC. Here, we provide a succinct summary of AR heterogeneity across the PCa continuum and discuss its impact on PCa response to treatments. While AR+ PCa cells/clones exhibit exquisite sensitivities to ARSIs, AR-/lo PCa cells/clones, which are greatly enriched in stem cell signaling pathways, display de novo resistance to ARSIs. Finally, we offer several potential combinatorial strategies, e.g., ARSIs with stem cell targeting therapeutics, to co-target both AR+ and AR-/lo PCa cells and metastatic clones.

NFκB-Activated COX2/PGE2/EP4 Axis Controls the Magnitude and Selectivity of BCG-Induced Inflammation in Human Bladder Cancer Tissues.

Bacillus Calmette-Guérin (BCG) is commonly used in the immunotherapy of bladder cancer (BlCa) but its effectiveness is limited to only a fraction of patients. To identify the factors that regulate the response of human BlCa tumor microenvironment (TME) to BCG, we used the ex vivo whole-tissue explant model. The levels of COX2 in the BCG-activated explants closely correlated with the local production of Treg- and MDSCS attractants and suppressive factors, while the baseline COX2 levels did not have predictive value. Accordingly, we observed that BCG induced high levels of MDSC- and Treg-attracting chemokines (CCL22, CXCL8, CXCL12) and suppressive factors (IDO1, IL-10, NOS2). These undesirable effects were associated with the nuclear translocation of phosphorylated NFκB, induction of COX2, the key enzyme controlling PGE2 synthesis, and elevation of a PGE2 receptor, EP4. While NFκB blockade suppressed both the desirable and undesirable components of BCG-driven inflammation, the inhibitors of PGE2 synthesis (Celecoxib or Indomethacin) or signaling (EP4-selective blocker, ARY-007), selectively eliminated the induction of MDSC/Treg attractants and immunosuppressive factors but enhanced the production of CTL attractants, CCL5, CXCL9 and CXCL10. PGE2 blockade allowed for the selectively enhanced migration of CTLs to the BCG-treated BlCa samples and eliminated the enhanced migration of Tregs. Since the balance between the CTLs and suppressive cells in the TME predicts the outcomes in patients with BlCa and other diseases, our data help to elucidate the mechanisms which limit the effectiveness of BCG therapies and identify new targets to enhance their therapeutic effects.

T-cell CX3CR1 expression as a dynamic blood-based biomarker of response to immune checkpoint inhibitors.

Immune checkpoint inhibitors (ICI) have revolutionized treatment for various cancers; however, durable response is limited to only a subset of patients. Discovery of blood-based biomarkers that reflect dynamic change of the tumor microenvironment, and predict response to ICI, will markedly improve current treatment regimens. Here, we investigate CX3C chemokine receptor 1 (CX3CR1), a marker of T-cell differentiation, as a predictive correlate of response to ICI therapy. Successful treatment of tumor-bearing mice with ICI increases the frequency and T-cell receptor clonality of the peripheral CX3CR1+CD8+ T-cell subset that includes an enriched repertoire of tumor-specific and tumor-infiltrating CD8+ T cells. Furthermore, an increase in the frequency of the CX3CR1+ subset in circulating CD8+ T cells early after initiation of anti-PD-1 therapy correlates with response and survival in patients with non-small cell lung cancer. Collectively, these data support T-cell CX3CR1 expression as a blood-based dynamic early on-treatment predictor of response to ICI therapy.

Phase II study of the histone deacetylase inhibitor vorinostat (Suberoylanilide Hydroxamic Acid; SAHA) in recurrent or metastatic transitional cell carcinoma of the urothelium - an NCI-CTEP sponsored: California Cancer Consortium trial, NCI 6879.

BACKGROUND: Until the advent of T cell check point inhibitors standard second-line therapy for patients with metastatic urothelial cancer (mUC) was undefined. Histone deacetylase inhibitors (HDACi) have anti-cancer activity in a variety of tumor models including modulation of apoptosis in bladder cancer cell lines. We evaluated the efficacy and toxicity of the HDACi vorinostat in patients with mUC failing first-line platinum-based therapy either in the adjuvant/neoadjuvant setting or for recurrent/advanced disease. METHODS: Vorinostat was given orally 200 mg twice daily continuously until progression or unacceptable toxicity. The primary end point was RECIST response rate (RR); a RR > 20% was deemed interesting in a 2-stage design requiring one response in the first 12 patients to proceed to 2nd stage for a total of 37 subjects. CT or MRI scan imaging occurred every 6 weeks. RESULTS: Fourteen patients were accrued characterized by: median age 66 years (43-84); Caucasian (79%); males (86%); and Karnofsky performance status ≥90 (50%). Accrual was terminated in the first stage as no responses were observed. Best response was stable disease (3 patients). Progression was observed in 8 patients. Two patients came off therapy prior to re-imaging and a 3rd patient died while on treatment and was not assessed for response. Median number of cycles was 2 (range 1-11). Median disease-free survival and overall survival times were 1.1 (0.8, 2.1) & 3.2 (2.1, 14.5) months, respectively. Toxicities were predominantly cytopenias and thrombocytopenic bleeding. Two pts. had grade 5 toxicity unlikely related to treatment. Two pts. had grade 4 and 6 had grade 3 toxicities observed. Two patients with stable disease remained on therapy for 6+ cycles. CONCLUSIONS: Vorinostat on this dose-schedule had limited efficacy and significant toxicity resulting in a unfavorable risk:benefit ratio in patients with mUC. NCT00363883.

Patient derived models of bladder cancer enrich the signal of the tumor cell transcriptome facilitating the analysis of the tumor cell compartment.

The evolving paradigm of the molecular classification of bladder cancer requires models that represent the classifications with less heterogeneity. Robust transcriptome based molecular classifications are essential to address tumor heterogeneity. Patient derived models (PDMs) are a powerful preclinical tool to study specific tumor compartments. We tested if the consensus molecular subtype analysis was applicable to PDMs and evaluated the tumor compartment each model represents. PDMs derived from surgical specimens were established as xenografts (PDX), organoids (PDO), and spheroids (PDS). The surgical specimens and PDMs were molecularly characterized by RNA sequencing. PDMs that were established in immune deficient mice or in vitro significantly downregulated transcripts related to the immune and stromal compartments compared to the surgical specimens. However, PDMs upregulate a patient-specific bladder cancer cell signal which allowed for analysis of cancer cell pathways independent of the tumor microenvironment. Based on transcriptomic signatures, PDMs are more similar to their surgical specimen than the model type; indicating that the PDMs retained unique features of the tumor from which the PDM was derived. When comparing models, PDX models were the most similar to the surgical specimen, while PDO and PDS models were most similar to each other. When the consensus molecular subtype classification system was applied to both the surgical samples and the three PDMs, good concordance was found between all samples indicating that this system of classification can be applied to PDO and PDS models. PDMs reduce tumor heterogeneity and allow analysis of tumor cells while maintaining the gene expression profile representative of the original tumor.

High intratumoral CD8+ T-cell infiltration is associated with improved survival in prostate cancer patients undergoing radical prostatectomy.

BACKGROUND: A high density of CD8+ tumor infiltrating lymphocytes (TILs) is associated with improved survival in multiple cancers, but its prognostic role in prostate cancer remains controversial. The aim of our study was to evaluate the prognostic value of CD8+ TILs in prostate cancer patients undergoing radical prostatectomy (RP). We hypothesized that elevated density of CD8+ TILs in the RP specimen would correlate with improved clinical outcomes. This information may be helpful for future immunotherapy clinical trial design and treatment selection. METHODS: Tumor microarrays constructed from 230 patients with localized prostate cancers who underwent RP from 2006 to 2012 at Roswell Park Comprehensive Cancer Center were analyzed retrospectively using immunohistochemistry. CD8+ cell density was evaluated using a computerized scoring system. The cohorts were separated by CD8+ TIL density at the 25th percentile (i.e., low 7 or pT3/4). The median follow-up time was 8.4 years. High CD8+ TIL density was associated with improved 5-year overall survival (98% vs. 91%, p = .01) and prostate cancer-specific survival (99% vs. 95%, p = .04) compared with patients with low CD8+ TIL density. There was a trend toward higher 5-year biochemical recurrence-free survival and metastasis-free survival in the cohort of patients with high CD8+ TIL density (52% vs. 38% and 86% vs. 73%, respectively), although the difference did not reach statistical significance (p = .18 and p = .05, respectively). In a multivariate analysis high CD8+ TIL density was an independent favorable prognostic factor for overall survival (hazards ratio = 0.38; 95% confidence interval: 0.17-0.87; p = .02). In contrast to the prognostic value of CD8+ TIL density, the CD8+ cell density in the matched normal prostate tissue was not associated with any clinical outcomes. CONCLUSION: Intratumoral CD8+ T-cell infiltration in the RP specimen is independently associated with improved survival after RP in this high-risk prostate cancer cohort. Pre-RP immunomodulation that promotes intratumoral CD8+ cytotoxic T-cell infiltration may be beneficial for this population.

Role of tumor microenvironment in the efficacy of BCG therapy.

Despite its significant overall efficacy, BCG fails to benefit a substantial proportion of bladder cancer (BlCa) patients. Here, we review recent data highlighting the role of tumor microenvironment (TME) in limiting antitumoral activity of BCG treatment and emerging opportunities to target TME to enhance the overall outcomes in BCG-treated BlCa patients.