Randomized Phase II Study Evaluating the Addition of Pembrolizumab to Radium-223 in Metastatic Castration-resistant Prostate Cancer.

The checkpoint immunotherapeutic pembrolizumab induces responses in a small minority of patients with metastatic castration-resistant prostate cancer (mCRPC). Radium-223 (R223) may increase immunogenicity of bone metastases and increase pembrolizumab (P) activity. In a randomized phase II study, we assessed the effect of R223+P compared with R223 on tumor immune infiltration, safety, and clinical outcomes in patients with mCRPC. The primary endpoint was differences in CD4+ and CD8+ T-cell infiltrate in 8-week versus baseline bone metastasis biopsies; secondary endpoints were safety, radiographic progression-free survival (rPFS), and overall survival (OS). Of the 42 treated patients (29 R223+P, 13 R223), 18 R223+P and 8 R223 patients had evaluable paired tumor biopsies. Median fold-change of CD4+ T cells was -0.7 (range: -9.3 to 4.7) with R223+P and 0.1 (-11.1 to 3.7) with R223 (P = 0.66); for CD8+ T cells, median fold-change was -0.6 (-7.4 to 5.3) with R223+P and -1.3 (-3.1 to 4.8) with R223 (P = 0.66). Median rPFS and OS was 6.1 (95% confidence interval: 2.7-11.0) and 16.9 months [12.7-not reached (NR)], respectively, with R223+P and 5.7 (2.6-NR) and 16.0 (9.0-NR), respectively, with R223. Although R223+P was well tolerated with no unexpected toxicity, the combination did not improve efficacy. High-dimensional flow cytometry demonstrated minimal immune modulation with R223, whereas R223+P induced CTLA-4 expression on circulating CD4+ T cells. Clinical responders possessed lower circulating frequencies of Ki67+ T and myeloid cells at baseline and higher circulating frequencies of TIM-3+ T and myeloid cells by week 9. Although R223+P did not induce T-cell infiltration into the tumor microenvironment, exhaustion of induced peripheral T-cell immune responses may dampen the combination's clinical activity.

Postradical prostatectomy prostate-specific antigen outcomes after 6 versus 18 months of perioperative androgen-deprivation therapy in men with localized, unfavorable intermediate-risk or high-risk prostate cancer: Results of part 2 of a randomized phase 2 trial.

BACKGROUND: Patients with localized, unfavorable intermediate-risk and high-risk prostate cancer have an increased risk of relapse after radical prostatectomy (RP). The authors previously reported on part 1 of this phase 2 trial testing neoadjuvant apalutamide, abiraterone, prednisone, plus leuprolide (AAPL) or abiraterone, prednisone, and leuprolide (APL) for 6 months followed by RP. The results demonstrated favorable pathologic responses (tumor <5 mm) in 20.3% of patients (n = 24 of 118). Herein, the authors report the results of part 2. METHODS: For part 2, patients were randomized 1:1 to receive either AAPL for 12 months (arm 2A) or observation (arm 2B), stratified by neoadjuvant therapy and pathologic tumor classification. The primary end point was 3-year biochemical progression-free survival. Secondary end points included safety and testosterone recovery (>200 ng/dL). RESULTS: Overall, 82 of 118 patients (69%) enrolled in part 1 were randomized to part 2. A higher proportion of patients who were not randomized to adjuvant therapy had a favorable prostatectomy pathologic response (32.3% in nonrandomized patients compared with 17.1% in randomized patients). In the intent-to-treat analysis, the 3-year biochemical progression-free survival rate was 81% for arm 2A and 72% for arm 2B (hazard ratio, 0.81; 90% confidence interval, 0.43-1.49). Of the randomized patients, 81% had testosterone recovery in the AAPL group compared with 95% in the observation group, with a median time to recovery of <12 months in both arms. CONCLUSIONS: In this study, because 30% of patients declined adjuvant treatment, part B was underpowered to detect differences between arms. Future perioperative studies should be biomarker-directed and include strategies for investigator and patient engagement to ensure compliance with protocol procedures.

Adjuvant and salvage radiotherapy after neoadjuvant therapy and radical prostatectomy for high-risk localized prostate cancer.

BACKGROUND: We sought to describe patterns of delivery of adjuvant (aRT) and salvage RT (sRT) in patients who underwent RP after receiving neoadjuvant androgen receptor pathway inhibitor (ARPI) before radical prostatectomy (RP) for high-risk localized prostate cancer (HRLPC). METHODS: Two hundred eighteen patients treated on phase 2 neoadjuvant trials between 2006 and 2018 at two academic centers were evaluated. aRT and sRT were defined as receipt of RT with a PSA of ≤0.1 or >0.1 ng/mL, respectively. Primary outcomes were biochemical recurrence (BCR), defined as time from aRT/sRT to a PSA rising to >0.1 ng/mL, and metastasis-free survival (MFS) after RT. RESULTS: Twenty-three (11%) and 55 (25%) patients received aRT and sRT respectively. Median PSA at start of aRT and sRT was 0.01 and 0.16 ng/mL, and median duration from RP to RT was 5 and 14 months, respectively. All aRT patients had NCCN high-risk disease, 30% were pN1 and 43% had positive surgical margins; 52% had prostate bed RT. Fifty-one percent of sRT patients had biopsy Gleason 9-10, 29% were pT2 and 9% had positive surgical margins; 63% had RT to the prostate bed/pelvis. At a median follow-up of 5.3 and 3.0 years after aRT and sRT, 3-year freedom from BCR was 55% and 47%, and 3-year MFS was 56% and 53%, respectively. CONCLUSIONS: aRT was infrequently used in patients who received neoadjuvant ARPI before RP for HRLPC. Outcomes of aRT and sRT were similar but generally poor. Studies evaluating intensified systemic therapy approaches with postoperative RT in this high-risk population are needed.

Randomized Trial of Olaparib With or Without Cediranib for Metastatic Castration-Resistant Prostate Cancer: The Results From National Cancer Institute 9984.

PURPOSE: Cediranib, a pan-vascular endothelial growth factor receptor inhibitor, suppresses expression of homologous recombination repair (HRR) genes and increases sensitivity to poly-(ADP-ribose) polymerase inhibition in preclinical models. We investigated whether cediranib combined with olaparib improves the clinical outcomes of patients with prostate cancer. METHODS: Patients with progressive metastatic castration-resistant prostate cancer (mCRPC) were randomly assigned 1:1 to arm A: cediranib 30 mg once daily plus olaparib 200 mg twice daily or arm B: olaparib 300 mg twice daily alone. The primary end point was radiographic progression-free survival (rPFS) in the intention-to-treat patients. The secondary end points were rPFS in patients with HRR-deficient and HRR-proficient mCRPC. RESULTS: In the intention-to-treat set of 90 patients, median rPFS was 8.5 (95% CI, 5.4 to 12.0) and 4.0 (95% CI, 3.2 to 8.5) months in arms A and B, respectively. Cediranib/olaparib significantly improved rPFS versus olaparib alone (hazard ratio [HR], 0.617; 95% CI, 0.392 to 0.969; P = .0359). Descriptive analyses showed a median rPFS of 10.6 (95% CI, 5.9 to not assessed [NA]) and 3.8 (95% CI, 2.33 to NA) months (HR, 0.64; 95% CI, 0.272 to 1.504) among patients with HRR-deficient mCRPC, and 13.8 (95% CI, 3.3 to NA) and 11.3 (95% CI, 3.8 to NA) months (HR, 0.98; 95% CI, 0.321 to 2.988) among patients with BRCA2-mutated mCRPC in arms A and B, respectively. The incidence of grades 3-4 adverse events was 61% and 18% in arms A and B, respectively. CONCLUSION: Cediranib combined with olaparib improved rPFS compared with olaparib alone in men with mCRPC. This combination was associated with an increased incidence of grades 3-4 adverse events. BRCA2-mutated subgroups treated with olaparib with or without cediranib were associated with a numerically longer median rPFS.

Radiation and Androgen Deprivation Therapy With or Without Docetaxel in the Management of Nonmetastatic Unfavorable-Risk Prostate Cancer: A Prospective Randomized Trial.

PURPOSE: Although docetaxel is not recommended when managing men with unfavorable-risk prostate cancer (PC) given negative or inconclusive results from previous randomized trials, unstudied benefits may exist. METHODS: Between September 21, 2005, and January 13, 2015, we randomly assigned 350 men 1:1 with T1c-4N0M0 unfavorable-risk PC to receive radiation therapy (RT) and androgen deprivation therapy (ADT) plus docetaxel (60 mg/m2 once every 3 weeks for three cycles before RT and 20 mg/m2 once weekly during RT) versus ADT + RT. We evaluated the treatment effect of adding docetaxel to ADT + RT on the primary end point of overall survival (OS) and the incidence of RT-induced cancers and explored whether the impact of the treatment effect on OS differed within prostate-specific antigen (PSA) subgroups (< 4, > 20 v 4-20 ng/mL) using the interaction test for heterogeneity adjusted for age and PC prognostic factors. RESULTS: After a median follow-up of 10.2 years, 89 men died (25.43%); of these, 42 from PC (47.19%). Although OS was not significantly increased in the docetaxel arm (the restricted mean survival time over 10 years was 9.11 v 8.82 years; P = .22), significantly fewer RT-induced cancers were observed (10-year estimates: 0.61% v 4.90%; age-adjusted hazard ratio of 0.13; 95% CI, 0.02 to 0.97; P = .046). The treatment effect of adding docetaxel to ADT + RT on OS significantly differed in men with a PSA < 4 ng/mL versus 4-20 ng/mL (adjusted hazard ratio: 0.27 and 1.51, respectively) because of less PC-specific mortality on the docetaxel arm (0.00% v 28.57%) among men with PSA < 4 ng/mL. CONCLUSION: Adding docetaxel to ADT + RT did not prolong OS in men with unfavorable-risk PC, but decreased RT-induced cancer incidence, and may prolong OS in the subgroup of men with a PSA < 4 ng/mL by reducing PC-specific mortality.

Prospective Evaluation of Clinical Outcomes Using a Multiplex Liquid Biopsy Targeting Diverse Resistance Mechanisms in Metastatic Prostate Cancer.

PURPOSE: Nearly all men with prostate cancer treated with androgen receptor (AR) signaling inhibitors (ARSIs) develop resistance via diverse mechanisms including constitutive activation of the AR pathway, driven by AR genomic structural alterations, expression of AR splice variants (AR-Vs), or loss of AR dependence and lineage plasticity termed neuroendocrine prostate cancer. Understanding these de novo acquired ARSI resistance mechanisms is critical for optimizing therapy. MATERIALS AND METHODS: A novel liquid biopsy technology was used to collect mRNA from circulating tumor cells (CTCs) to measure expression of AR-Vs, AR targets, and neuroendocrine prostate cancer markers. An institutional review board-approved prospective cohort (N = 99) was used to identify patterns of gene expression. Two prospective multicenter phase II clinical trials of ARSIs for men with castration-resistant prostate cancer (ClinicalTrials.gov: NCT01942837 [enzalutamide, N = 21] and NCT02025010 [abiraterone, N = 27]) were used to further validate these findings. RESULTS: Hierarchical clustering of CTC transcripts identified two distinct clusters. Cluster 2 (C2) exhibited increased expression of AR-regulated genes and was associated with worse overall survival (median 8.6 v 22.4 months; P < .01; hazard ratio [HR] = 3.45 [1.9 to 6.14]). In multivariable analysis, C2 was prognostic independent of other clinicopathologic variables. AR-V status was not significant when accounting for C2. Upon further validation in pooled multicenter phase II trials, C2 was associated with worse overall survival (15.2 months v not reached; P < .01; HR = 8.43 [2.74 to 25.92]), prostate-specific antigen progression-free survival (3.6 v 12 months; P < .01; HR = 4.64 [1.53 to 14.11]), and radiographic progression-free survival (2.7 v 40.6 months; P < .01; HR = 4.64 [1.82 to 17.41]). CONCLUSION: We demonstrate that a transcriptional profile detectable in CTCs obtained from liquid biopsies can serve as an independent prognostic marker beyond AR-V7 in patients with metastatic prostate cancer and can be used to identify the emergence of multiple ARSI resistance mechanisms. This is currently being investigated in additional prospective trials.

The impact of pretreatment PSA on risk stratification in men with Gleason 6 prostate cancer: Implications for active surveillance.

BACKGROUND: There are limited data to support the safety of active surveillance in men with favorable-intermediate risk prostate cancer due only to a prostate specific antigen (PSA) above 10 ng/ml. We therefore evaluated the impact of pretreatment PSA on risk-stratification in men with Gleason 6 prostate cancer. METHODS: We identified men aged 18 to 75 with cT1-2cN0cM0, pre-treatment PSA < 20 ng/ml, Gleason 6 prostate cancer diagnosed from 2010 to 2016 in the National Cancer Database who underwent radical prostatectomy. The associations of patient and disease features with Gleason score upgrading or adverse pathologic features at prostatectomy were evaluated using logistic regression. To evaluate for non linear relationships between PSA and each outcome, we examined predicted marginal event rates standardized for baseline characteristics with PSA modeled using restricted cubic splines RESULTS: A total of 75,566 patients were included in the cohort. In unadjusted analyses, patients with pretreatment PSA ≥ 10 ng/ml had higher rates of Gleason core upgrading (58.8% vs. 47.9%; P< 0.001) and adverse pathologic features (19.7% vs. 10.0%; P< 0.001) compared to patients with PSA < 10 ng/ml. In multivariable analyses, PSA ≥ 10 ng/ml was associated with statistically significantly increased risks of Gleason score upgrading (OR 1.47;95%CI 1.39 - 1.55) and adverse pathologic features (OR 2.15;95%CI 2.01 - 2.30). When modeled as a non linear continuous covariate, PSA was associated with increased adjusted rates of Gleason score upgrading and adverse pathologic features without a clear dichotomization at a threshold of 10 ng/ml. CONCLUSION: Higher pretreatment PSA was independently associated with increased risks of Gleason score upgrading and adverse pathologic features at prostatectomy. Flexible modeling of the relationship between PSA and each outcome did not support dichotomization at a threshold of 10 ng/ml. These results can be used to improve patient risk-stratification for active surveillance.

Phase II Multicenter Study of Enzalutamide in Metastatic Castration-Resistant Prostate Cancer to Identify Mechanisms Driving Resistance.

PURPOSE: Enzalutamide is a second-generation androgen receptor (AR) inhibitor that has improved overall survival (OS) in metastatic castration-resistant prostate cancer (CRPC). However, nearly all patients develop resistance. We designed a phase II multicenter study of enzalutamide in metastatic CRPC incorporating tissue and blood biomarkers to dissect mechanisms driving resistance. PATIENTS AND METHODS: Eligible patients with metastatic CRPC underwent a baseline metastasis biopsy and then initiated enzalutamide 160 mg daily. A repeat metastasis biopsy was obtained at radiographic progression from the same site when possible. Blood for circulating tumor cell (CTC) analysis was collected at baseline and progression. The primary objective was to analyze mechanisms of resistance in serial biopsies. Whole-exome sequencing was performed on tissue biopsies. CTC samples underwent RNA sequencing. RESULTS: A total of 65 patients initiated treatment, of whom 22 (33.8%) had received prior abiraterone. Baseline biopsies were enriched for alterations in AR (mutations, amplifications) and tumor suppression genes (PTEN, RB1, and TP53), which were observed in 73.1% and 92.3% of baseline biopsies, respectively. Progression biopsies revealed increased AR amplifications (64.7% at progression vs. 53.9% at baseline) and BRCA2 alterations (64.7% at progression vs. 38.5% at baseline). Genomic analysis of baseline and progression CTC samples demonstrated increased AR splice variants, AR-regulated genes, and neuroendocrine markers at progression. CONCLUSIONS: Our results demonstrate that a large proportion of enzalutamide-treated patients have baseline and progression alterations in the AR pathway and tumor suppressor genes. We demonstrate an increased number of BRCA2 alterations post-enzalutamide, highlighting the importance of serial tumor sampling in CRPC.

An up-to-date evaluation of abiraterone for the treatment of prostate cancer.

Introduction: Abiraterone acetate, an oral 17-alpha-hydroxylase inhibitor, effectively prevents the synthesis of androgens from steroid precursors. Abiraterone has become a standard of care in patients with metastatic prostate cancer due to its efficacy in both castrate-sensitive and castrate-resistant disease when given in combination with androgen deprivation therapy (ADT). Abiraterone may have a role in additional aspects of prostate cancer treatment in the future.Areas covered: The present article focuses on the development and establishment of abiraterone among the available treatment options for prostate cancer. A literature search was performed in PubMed/Medline for prior studies and reviews of the drug. Current clinical trials were examined in the Clinicaltrials.gov database.Expert opinion: Abiraterone has shown efficacy in castrate-resistant metastatic prostate cancer, providing an additional degree of hormonal sensitivity for tumors resistant to ADT. Impressively, abiraterone in conjunction with ADT as a first-line treatment for castrate-sensitive prostate cancer also confers a significant overall survival benefit compared to ADT alone. With minimal additional toxicity, abiraterone has established itself as a well-tolerated, convenient, and effective treatment option. Ongoing studies are expected to broaden the drug's indications as well as its preference among other prostate cancer therapies.

Results of a Randomized Phase II Trial of Intense Androgen Deprivation Therapy prior to Radical Prostatectomy in Men with High-Risk Localized Prostate Cancer.

PURPOSE: This multicenter randomized phase 2 trial investigates the impact of intense androgen deprivation on radical prostatectomy pathologic response and radiographic and tissue biomarkers in localized prostate cancer (NCT02903368). MATERIALS AND METHODS: Eligible patients had a Gleason score ≥4+3=7, prostate specific antigen >20 ng/mL or T3 disease and lymph nodes <20 mm. In Part 1, patients were randomized 1:1 to apalutamide, abiraterone acetate, prednisone and leuprolide (AAPL) or abiraterone, prednisone, leuprolide (APL) for 6 cycles (1 cycle=28 days) followed by radical prostatectomy. Surgical specimens underwent central review. The primary end point was the rate of pathologic complete response or minimum residual disease (minimum residual disease, tumor ≤5 mm). Secondary end points included prostate specific antigen response, positive margin rate and safety. Magnetic resonance imaging and tissue biomarkers of pathologic outcomes were explored. RESULTS: The study enrolled 118 patients at 4 sites. Median age was 61 years and 94% of patients had high-risk disease. The combined pathologic complete response or minimum residual disease rate was 22% in the AAPL arm and 20% in the APL arm (difference: 1.5%; 1-sided 95% CI -11%, 14%; 1-sided p=0.4). No new safety signals were observed. There was low concordance and correlation between posttherapy magnetic resonance imaging assessed and pathologically assessed tumor volume. PTEN-loss, ERG positivity and presence of intraductal carcinoma were associated with extensive residual tumor. CONCLUSIONS: Intense neoadjuvant hormone therapy in high-risk prostate cancer resulted in favorable pathologic responses (tumor <5 mm) in 21% of patients. Pathologic responses were similar between treatment arms. Part 2 of this study will investigate the impact of adjuvant hormone therapy on biochemical recurrence.

Enzalutamide With Radiation Therapy for Intermediate-Risk Prostate Cancer: A Phase 2 Study.

PURPOSE: Androgen deprivation therapy (ADT) is often used as adjuvant treatment with radiation therapy (RT) for intermediate-risk prostate cancer. ADT is associated with multiple side effects, including weight gain, loss of libido, and hot flashes. In contrast, antiandrogen monotherapy has been generally better tolerated. This study aimed to assess the effectiveness of enzalutamide (an antiandrogen) monotherapy with RT for the treatment of intermediate-risk prostate cancer. METHODS AND MATERIALS: This trial was an open-label, phase 2 study of 6 months of enzalutamide monotherapy with external beam RT for intermediate-risk prostate cancer. Enzalutamide was initiated 2 months before external beam RT. The primary endpoint was prostate-specific antigen (PSA) response measured at the end of enzalutamide administration at the 6-month timepoint. Secondary endpoints included assessment of toxicity and changes in anthropomorphic body measurement, sexual function, and metabolism. The sample size was 64 patients. The hypothesis was that if ≥60% of the patients did not achieve a PSA nadir of ≤0.2 ng/mL, the study results would be deemed negative. RESULTS: The results met the prespecified endpoint for efficacy in that PSA values ≤0.2 ng/mL were observed in 49 of 64 patients (77%), and 60 of 64 patients (94%) had PSA values ≤0.5ng/mL. The most frequent adverse events were hypertension and gynecomastia. There were no changes in anthropomorphic body measurements and only modest erectile dysfunction. CONCLUSIONS: Using PSA response as an endpoint, enzalutamide monotherapy may be as effective as ADT in combination with external beam RT for patients with intermediate-risk prostate cancer, and it is associated with fewer side effects. Randomized trials comparing enzalutamide with ADT are justified.

Outcomes of Post-Neoadjuvant Intense Hormone Therapy and Surgery for High Risk Localized Prostate Cancer: Results of a Pooled Analysis of Contemporary Clinical Trials.

PURPOSE: We report on the post-radical prostatectomy outcomes of patients enrolled in 3 randomized, multicenter, clinical trials of intense neoadjuvant androgen deprivation therapy prior radical prostatectomy. MATERIALS AND METHODS: All patients included were enrolled in trials evaluating intense androgen deprivation therapy followed by radical prostatectomy. The primary end point was time to biochemical recurrence, defined as the time from radical prostatectomy to prostate specific antigen >0.1 ng/ml or start of first post-radical prostatectomy therapy, stratified by pathological response at radical prostatectomy (presence or absence of exceptional pathological response defined as residual tumor at radical prostatectomy measuring 0-5 mm). Secondary end points included metastasis-free survival, overall survival, and time to testosterone recovery. RESULTS: Overall, 117 patients were included in the analysis, of whom 78.6% (92) had high risk disease. Following neoadjuvant therapy, 21.4% (25) had 0-5 mm of residual tumor, including 9.4% (11) with a pathological complete response. Overall, 49 patients (41.9%) experienced biochemical recurrence and the 3-year biochemical recurrence-free rate was 59.1% (95% CI 49.0-67.9). Of the 25 patients with an exceptional pathological response, 2 patients (8.0%) developed biochemical recurrence while 51.1% of nonresponders (47/92) developed biochemical recurrence. Testosterone recovery was observed in 93.8% of patients (106/113). PTEN loss and intraductal carcinoma were associated with shorter time to biochemical recurrence. CONCLUSIONS: In this pooled analysis of prospective trials, we demonstrate that exceptional pathological response following neoadjuvant therapy is associated with a favorable impact on biochemical recurrence. PTEN loss and intraductal carcinoma were associated with biochemical recurrence. Additional followup is warranted to evaluate the impact on long-term outcomes.

Results of a multicenter, phase 2 study of nivolumab and ipilimumab for patients with advanced rare genitourinary malignancies.

BACKGROUND: In this multicenter, single-arm, multicohort, phase 2 trial, the efficacy of nivolumab and ipilimumab was evaluated in patients with advanced rare genitourinary cancers, including bladder and upper tract carcinoma of variant histology (BUTCVH), adrenal tumors, platinum-refractory germ cell tumors, penile carcinoma, and prostate cancer of variant histology (NCT03333616). METHODS: Patients with rare genitourinary malignancies and no prior immune checkpoint inhibitor exposure were enrolled. Patients received nivolumab at 3 mg/kg and ipilimumab at 1 mg/kg intravenously every 3 weeks for 4 doses, and this was followed by 480 mg of nivolumab intravenously every 4 weeks. The primary endpoint was the objective response rate (ORR) by the Response Evaluation Criteria in Solid Tumors (version 1.1). RESULTS: Fifty-five patients were enrolled at 6 institutions between April 2018 and July 2019 in 3 cohorts: BUTCVH (n = 19), adrenal tumors (n = 18), and other tumors (n = 18). The median follow-up was 9.9 months (range, 1 to 21 months). Twenty-eight patients (51%) received 4 doses of nivolumab and ipilimumab; 25 patients received nivolumab maintenance for a median of 4 cycles (range, 1-18 cycles). The ORR for the entire study was 16% (80% confidence interval, 10%-25%); the ORR in the BUTCVH cohort, including 2 complete responses, was 37%, and it was 6% in the other 2 cohorts. Twenty-two patients (40%) developed treatment-related grade 3 or higher toxicities; 24% (n = 13) required high-dose steroids (≥40 mg of prednisone or the equivalent). Grade 5 events occurred in 3 patients; 1 death was treatment related. CONCLUSIONS: Nivolumab and ipilimumab resulted in objective responses in a subset of patients with rare genitourinary malignancies, especially those with BUTCVH. An additional cohort exploring their activity in genitourinary tumors with neuroendocrine differentiation is ongoing. LAY SUMMARY: Patients with rare cancers are often excluded from studies and have limited treatment options. Fifty-five patients with rare tumors of the genitourinary system were enrolled from multiple sites and were treated with nivolumab and ipilimumab, a regimen used for kidney cancer. The regimen showed activity in some patients, particularly those with bladder or upper tract cancers of unusual or variant histology; 37% of those patients responded to therapy. Additional studies are ongoing to better determine who benefits the most from this combination.

Author Correction: A co-clinical approach identifies mechanisms and potential therapies for androgen deprivation resistance in prostate cancer.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Taxane resistance in prostate cancer is mediated by decreased drug-target engagement.

Despite widespread use of taxanes, mechanisms of action and resistance in vivo remain to be established, and there is no way of predicting who will respond to therapy. This study examined prostate cancer (PCa) xenografts and patient samples to identify in vivo mechanisms of taxane action and resistance. Docetaxel drug-target engagement was assessed by confocal anti-tubulin immunofluorescence to quantify microtubule bundling in interphase cells and aberrant mitoses. Tumor biopsies from metastatic PCa patients obtained 2 to 5 days after their first dose of docetaxel or cabazitaxel were processed to assess microtubule bundling, which correlated with clinical response. Microtubule bundling was evident in PCa xenografts 2 to 3 days after docetaxel treatment but was decreased or lost with acquired resistance. Biopsies after treatment with leuprolide plus docetaxel showed extensive microtubule bundling as did biopsies obtained 2 to 3 days after initiation of docetaxel or cabazitaxel in 2 patients with castration-resistant PCa with clinical responses. In contrast, microtubule bundling in biopsies 2 to 3 days after the first dose of docetaxel was markedly lower in 4 nonresponding patients. These findings indicate that taxanes target both mitotic and interphase cells in vivo and that resistance is through mechanisms that impair drug-target engagement. Moreover, the findings suggest that microtubule bundling after initial taxane treatment may be a predictive biomarker for clinical response.

TRA-1-60-positive/CD45low cells found in the peripheral blood of prostate cancer patients with metastatic disease - A proof-of-concept study.

PURPOSE: Over 90% of all cancer related deaths are due to metastasis. However, current diagnostic tools can't reliably discriminate between invasive and localized cancers. PATIENTS AND METHODS: In this proof-of-concept study, we employed the embryonic stem cell marker TRA-1-60 (TRA+) to identify TRA + cells within the blood of prostate cancer patients and searched for TRA + cells in men with metastatic and localized cancers. We isolated whole peripheral blood mononuclear cells from 26 metastatic prostate cancer patients, from 13 patients with localized prostate cancer and from 17 healthy controls. Cells were stained for DAPI, CD45 and TRA + by immunofluorescence and imaged by epi-fluorescence microscopy. Imaged-based software was used both to identify TRA + cells, and to analyze CD45 levels in TRA+ and negative cells. RESULTS: We found high numbers of TRA + cells within the blood of metastatic cancer patients, whereas healthy individuals or men with localized prostate cancer showed none or very low numbers of TRA + cells. Further analysis of the CD45 levels of TRA + cells revealed a small population of TRA + cells with almost undetectable CD45 levels that were found frequently in metastatic prostate cancer patients. By excluding CD45 positive cells from the TRA + cell pool, we were able to refine the assay to be highly specific in identifying men with metastatic disease. In fact, the difference of CD45 levels between TRA+ and negative cells was a robust measure to distinguish between men with localized and metastatic prostate cancers in this small patient cohort. CONCLUSIONS: The data suggest that metastatic prostate cancer patient have significant numbers of TRA+/CD45low cells which might represent a potential tool for diagnostic assessment in the future.

Low Abundance of Circulating Tumor DNA in Localized Prostate Cancer.

PURPOSE: Despite decreased screening-based detection of clinically insignificant tumors, most diagnosed prostate cancers are still indolent, indicating a need for better strategies for detection of clinically significant disease before treatment. We hypothesized that patients with detectable circulating tumor DNA (ctDNA) were more likely to harbor aggressive disease. METHODS: We applied ultra-low-pass whole-genome sequencing to profile cell-free DNA from 112 patients diagnosed with localized prostate cancer and performed targeted resequencing of plasma DNA for somatic mutations previously identified in matched solid tumor in nine cases. We also performed similar analyses of data from patients with metastatic prostate cancer. RESULTS: In all cases of localized prostate cancer, even in clinically high-risk patients who subsequently had recurrent disease, ultra-low-pass whole-genome sequencing and targeted resequencing did not detect ctDNA in plasma acquired before surgery or before recurrence. In contrast, using both approaches, ctDNA was detected in patients with metastatic prostate cancer. CONCLUSION: Our findings demonstrate clear differences between localized and advanced prostate cancer with respect to the dissemination and detectability of ctDNA. Because allele-specific alterations in ctDNA are below the threshold for detection in localized prostate cancer, other approaches to identify cell-free nucleic acids of tumor origin may demonstrate better specificity for aggressive disease.

Evaluation of Intense Androgen Deprivation Before Prostatectomy: A Randomized Phase II Trial of Enzalutamide and Leuprolide With or Without Abiraterone.

PURPOSE: Patients with locally advanced prostate cancer have an increased risk of cancer recurrence and mortality. In this phase II trial, we evaluate neoadjuvant enzalutamide and leuprolide (EL) with or without abiraterone and prednisone (ELAP) before radical prostatectomy (RP) in men with locally advanced prostate cancer. PATIENTS AND METHODS: Eligible patients had a biopsy Gleason score of 4 + 3 = 7 or greater, prostate-specific antigen (PSA) greater than 20 ng/mL, or T3 disease (by prostate magnetic resonance imaging). Lymph nodes were required to be smaller than 20 mm. Patients were randomly assigned 2:1 to ELAP or EL for 24 weeks followed by RP. All specimens underwent central pathology review. The primary end point was pathologic complete response or minimal residual disease (residual tumor ≤ 5 mm). Secondary end points were PSA, surgical staging, positive margins, and safety. Biomarkers associated with pathologic outcomes were explored. RESULTS: Seventy-five patients were enrolled at four centers. Most patients had high-risk disease by National Comprehensive Cancer Network criteria (n = 65; 87%). The pathologic complete response or minimal residual disease rate was 30% (n = 15 of 50) in ELAP-treated patients and 16% (n = four of 25) in EL-treated patients (two-sided P = .263). Rates of ypT3 disease, positive margins, and positive lymph nodes were similar between arms. Treatment was well-tolerated. Residual tumors in the two arms showed comparable levels of ERG, PTEN, androgen receptor PSA, and glucocorticoid receptor expression. Tumor ERG positivity and PTEN loss were associated with more extensive residual tumors at RP. CONCLUSION: Neoadjuvant hormone therapy followed by RP in locally advanced prostate cancer resulted in favorable pathologic responses in some patients, with a trend toward improved pathologic outcomes with ELAP. Longer follow-up is necessary to evaluate the impact of therapy on recurrence rates. The potential association of ERG and PTEN alterations with worse outcomes warrants additional investigation.