High-volume Metastatic Disease Research Articles

High-volume mCRPC is associated with decreased cancer specific survival in patients on second-generation hormone therapy in the post docetaxel setting.

192 Background: In the setting of disease progression of metastatic castrate resistant prostate cancer (mCRPC) on docetaxel, abiraterone acetate (AA) and enzalutamide are two commonly used second line therapies with data demonstrating survival benefits. Less is known about patient specific factors that contribute to success with these therapies. The objective of this study is to improve patient selection for post-docetaxel second generation hormone therapy (AA or enzalutamide) by evaluating whether overall metastatic burden is associated with treatment response in this setting. Methods: By retrospective chart review, patients with mCRPC treated with AA or enzalutamide following docetaxel failure (defined as PSA rise and radiographic progression) were identified. Patients were categorized into low volume and high volume metastatic disease based on the number of pre-treatment metastatic lesions; where low volume disease describes patients with ≤ 5 metastatic lesions (e.g. oligometastatic disease), and high volume disease represents patients with > 5 individual lesions. The primary endpoint was cancer-specific mortality and the secondary endpoint was radiographic progression free survival. Median follow-up time was 29.5 months. Results: 75 patients were identified and included in our analysis: 39 with high volume metastatic disease, and 36 with low volume metastatic disease. Baseline characteristics of age and pre-treatment ECOG were not statistically different between these groups. Pre-treatment high-volume disease burden was significantly associated with increased risk of radiographic disease progression (HR 4.21, 95%CI 1.97-8.99, p < 0.0001) and cancer specific mortality (HR 5.84, 95% CI 1.58-21.53, p = 0.0026) during treatment with second generation androgen deprivation therapy. Conclusions: High volume metastatic disease burden is associated with significantly increased cancer specific mortality and decreased progression free survival for patients on second line therapy with AA or enzalutamide following docetaxel treatment failure.

The Swedish national guidelines on prostate cancer, part 2: recurrent, metastatic and castration resistant disease

Objective There is now an unprecedented amount of evidence to consider when revising prostate cancer guidelines. We believe that there is a value in publishing summaries of national clinical guidelines in English for others to read and comment on. Methods This is part 2 of a summary of the Swedish prostate cancer guidelines that were published in June 2022. This part covers recurrence after local treatment and management of metastatic and castration resistant disease. Part 1 covers early detection, diagnostics, staging, patient support and management of non-metastatic disease. Results The 2022 Swedish guidelines include several new recommendations. Among these is a recommendation of a period of observation with repeated PSA tests for patients with approximately 10 years’ life expectancy who experience a BCR more than 2–5 years after radical prostatectomy, to allow for estimating the PSA doubling time before deciding whether to give salvage radiotherapy or not. Recent results from the PEACE-1 trial led to the recommendation of triple-treatment with a GnRH agonist, abiraterone plus prednisolone and 6 cycles of docetaxel for patients with high-volume metastatic disease who are fit for chemotherapy. The Swedish guidelines differ from the European ones by having more restrictive recommendations about genetic testing of and high-dose zoledronic acid or denosumab treatment for men with metastatic prostate cancer, and by recommending considering bicalutamide monotherapy for selected patients with low-volume metastatic disease. Conclusions The 2022 Swedish prostate cancer guidelines include several new recommendations and some that differ from the European guidelines.

Achieving Consensus for Management of Hormone-Sensitive, Low-Volume Metastatic Prostate Cancer in Italy.

Metastatic hormone-sensitive prostate cancer (mHSPC) is usually categorized as high- or low-volume disease. This is relevant because low- and high-volume metastatic disease are associated with different outcomes, and thus management of the two forms should differ. Although some definitions have been reported, the concept of oligometastatic disease is not so clearly defined, giving rise to further variability in the choice of treatment, mainly between systemic agents and radiotherapy, especially in the era of metastasis-directed therapy. With the aim of providing clinicians with guidance on best practice, a group of medical and radiation oncologists, experts in prostate cancer, used the round robin method to generate a series of consensus statements on management of low-volume mHSPC. Consensus was obtained on three major areas of controversy: (1) with regard to clinical definitions of mHSPC, it was held that oligometastatic and low-volume disease refer to different concepts and should not be used interchangeably; (2) regarding therapy of de novo low-volume metastatic disease, androgen deprivation therapy alone can be considered undertreatment, and all patients should be evaluated for systemic treatment combinations; local therapy should not be denied in patients with mHSPC, regardless of the intensity of systemic therapy, and metastasis-directed therapy can be proposed in selected cases; (3) with regard to treatment of metachronous metastatic disease, patients should be evaluated for systemic treatment combinations. Metastasis-directed therapy can be proposed to delay systemic treatment in selected cases, especially if prostate-specific membrane antigen positron emission tomography staging has been performed and when indolent disease occurs. It is hoped that clinicians treating patients with mHSPC in daily practice will find this expert opinion of value.

Updated overall survival outcomes in ENZAMET (ANZUP 1304), an international, cooperative group trial of enzalutamide in metastatic hormone-sensitive prostate cancer (mHSPC).

LBA5004 Background: The first planned interim analysis of ENZAMET, with 243 deaths after a median follow-up of 34 months, revealed a clinically meaningful overall survival benefit in mHSPC with the addition of enzalutamide to standard of care (hazard ratio 0.67, 95% CI 0.52 to 0.86, p=0.002, Davis et al, NEJM 2019). We now present updated overall survival (OS) findings from the prespecified analysis triggered to occur after 470 deaths. Methods: We randomly assigned participants (pts) with mHSPC to treatment with testosterone suppression (TS) plus either a conventional non-steroidal anti-androgen (NSAA) or enzalutamide. Stratification factors included age, volume of disease (high vs low according to the CHAARTED definition), and planned use of concurrent docetaxel assigned by the treating physician (docetaxel yes vs no). Results: We randomized 1125 pts with a median age of 69 years, including 503 in the docetaxel stratum, and 602 with high volume metastatic disease. OS results in the table below are based on 476 deaths, a median follow-up of 68 months, and a cut-off date of 19JAN2022. The hazard rate for death was 30% lower among all those assigned enzalutamide versus control (p<0.0001). Outcomes by volume status are shown (Table) as well as the subgroups of interest with M1 high or low volume disease at diagnosis selected for concurrent docetaxel. Conclusions: Enzalutamide added to TS, compared with an active comparator of NSAA, provided clinically meaningful improvements in OS for the combined overall cohort, which persisted with an additional 3 years of follow-up. The benefits were more pronounced in pts with low volume disease, and were also seen in the subgroup with M1 high volume mHSPC despite the relatively high survival with TS+docetaxel+NSAA. ENZAMET was led by ANZUP Cancer Trials Group and the University of Sydney NHMRC Clinical Trials Centre, with funding support from Astellas. Clinical trial information: NCT02446405. [Table: see text]

Is Triple Therapy the New Standard for Metastatic Hormone-sensitive Prostate Cancer?

The treatment of metastatic hormone-sensitive prostate cancer has rapidly changed over the last decade. Currently, standard of care (SOC) options for first-line treatment are androgen deprivation therapy (ADT) in combination with either docetaxel chemotherapy or an androgen receptor pathway inhibitor such as abiraterone, enzalutamide or apalutamide. Recent results from both the PEACE-1 and ARASENS trials show an overall survival and progression-free survival benefit from the addition of an androgen-receptor pathway inhibitor for patients in whom the SOC option of ADT plus docetaxel has been chosen in de novo metastatic hormone-sensitive prostate cancer, with a more pronounced benefit in those with high-volume metastatic disease. However, many clinicians now preferentially use ADT plus an androgen-receptor pathway inhibitor as SOC first-line treatment, and no prospective trial has addressed whether there is a benefit from the addition of docetaxel to this version of SOC combination therapy. The benefit of triplet combination therapy in those with recurrent or low-volume metastatic disease is less clear and longer follow-up is required before conclusions can be drawn about these patient groups.

Management of newly diagnosed metastatic hormone-sensitive prostate cancer: A survey of UK Uro-oncologists.

To explore the practice and views of uro-oncologists in the United Kingdom regarding their use of chemotherapy and androgen receptor-targeted agents (ARTAs) in patients with newly diagnosed metastatic hormone-sensitive prostate cancer (mHSPC). An expert-devised paper or online questionnaire was completed by members of the British Uro-oncology Group. All respondents stated that they would offer patients with newly diagnosed mHSPC docetaxel and androgen deprivation therapy (ADT) if they were sufficiently fit to receive chemotherapy (this was the only option available at the time of the survey); 64% would strongly recommend docetaxel for those with high-volume metastatic disease and 31% for those with low-volume disease. Hypothetically, if both docetaxel and ARTAs were available in the United Kingdom for mHSPC, almost 65% of respondents would recommend an ARTA with ADT to these patients in at least one-half of all cases, with the strongest recommendations to patients with high-risk disease. Imaging for the response was conducted according to suspicion of disease progression, regardless of treatment, with the minority of clinicians recommending routine imaging. If a choice of therapy was available, docetaxel would be more likely to be offered to patients with liver or lung metastases, and ARTAs to patients with bone or lymph node only metastases. Almost all respondents would offer local radiotherapy to the primary tumour in patients with low-volume disease. All the UK uro-oncologists surveyed stated that they would offer docetaxel in combination with ADT to all newly diagnosed patients with mHSPC if fit enough for chemotherapy. ARTAs would be offered to many patients if available, especially those with high-risk disease or those unfit to receive chemotherapy. Scanning was typically conducted following treatment only at the suspicion of disease progression.

The cytoreductive prostatectomy in metastatic prostate cancer: what the individual trials are hoping to answer.

To review the ongoing randomised trials of cytoreductive prostatectomy (CRP) in de novo hormone-sensitive metastatic prostate cancer (HSPC) in order to identify their goals and assess their strengths and weaknesses. PubMed, MEDLINE and clinical trials websites searches were performed to identify currently ongoing trials of CRP in de novo HSPC. Nine randomised clinical trials in CRP were identified and included: Southwest Oncology Group (SWOG) 1802, Surgery in Metastatic Carcinoma of Prostate (SIMCAP), Adjuvant Treatments to the Local Tumour for Metastatic Prostate Cancer: Assessment of Novel Treatment Algorithms (IP2-ATLANTA), Testing Radical prostatectomy in men with prostate cancer and oligoMetastases to the bone (TRoMbone), Impact of Radical Prostatectomy as Primary Treatment in Patients with Prostate Cancer with Limited Bone Metastases (g-RAMPP), Cytoreductive Prostatectomy vs Cytoreductive Prostate Irradiation as a Local Treatment Option for Metastatic Prostate Cancer: a Multicentric Feasibility Trial (LoMP II), Androgen-Deprivation Therapy or Androgen-Deprivation Therapy Plus Definitive Treatment (Radiation or Surgery) (FUSCC-OMPCa), and the Testing Radical Prostatectomy in Chinese Men with Prostate Cancer and oligoMetastases to the Bone study. Each study was different; assessing various primary outcome measures including overall survival (OS), progression-free survival and feasibility to randomise between standard therapy and CRP or between radiation therapy and CRP in the metastatic setting. In the oligometastatic setting, the trials assess OS, feasibility to randomise and time to castration resistance. Similarly, a number of secondary endpoints ranging from cancer-specific outcomes to quality-of-life outcomes are being investigated. The inclusion criteria in these trials also varied in terms of volume of metastatic disease (oligometastatic to high-volume metastatic disease), diagnosis of metastases (imaging based vs biopsy confirmed), imaging modalities used (conventional to newer modalities), as well as outcomes and follow-up regimes. While there are differences in each protocol, each trial aims to address different aspects of CRP in de novo HSPC. Therefore, the specific goals of each study and the limitations have to be taken into consideration when interpreting the results of these trials.

Management of Metastatic Hormone-Sensitive Prostate Cancer (mHSPC): an Evolving Treatment Paradigm.

Combination systemic therapy is now standard of care for all men with metastatic, hormone-sensitive prostate cancer (mHSPC). Patients with mHSPC should be treated with standard androgen deprivation therapy (ADT) and abiraterone acetate with prednisone or docetaxel (chemohormoanl therapy) unless there are contraindications to combination therapy. Based on the Chemohormonal Therapy Versus Androgen Ablation Randomized Trial for Extensive Disease in Prostate Cancer (CHAARTED) study subgroup analysis, chemohormonal therapy may be most beneficial in men with high-volume disease burden, as men with low-volume metastatic disease do not appear to experience a survival benefit with chemohormonal therapy, while abiraterone in combination with ADT appears to be beneficial across both disease volume subgroups. Decisions regarding whether to use chemohormonal therapy or abiraterone and ADT for men with mHSPC should integrate consideration of volume of disease burden, quality of life effects, duration of therapy, and patient preferences for treatment as there is no formally powered prospective head-to-head comparison of these options demonstrating superiority of one approach over the other. Treatment of the primary tumor with radiation should be considered in men with de novo low-volume metastatic disease as radiation is associated with prolonged survival and a tolerable toxicity profile. Men with de novo high-volume metastatic disease do not appear to have improved survival with radiation of the primary tumor. Numerous clinical trials are ongoing to evaluate treatment approaches that may benefit men with mHSPC. Radical prostatectomy in men with mHSPC in combination with optimal systemic therapy is currently being assessed in a clinical trial, but should not be considered outside of a clinical trial. Metastasis-directed therapy with radiotherapy directed at metastatic lesions is still investigational, but can be considered in clinical trials in men with oligometastatic disease. Multiple studies are enrolling worldwide for men with mHSPC, and these should be considered for all interested patients.

Cost-effectiveness of docetaxel in high-volume hormone-sensitive metastatic prostate cancer.

Three pivotal trials have considered the addition of docetaxel (D) chemotherapy to conventional androgen-deprivation therapy (ADT) for the treatment of metastatic hormone- sensitive prostate cancer (HSPC). While an initial small trial was inconclusive, two larger trials demonstrated significant clinical benefit, including pronounced survival benefits (added 17 months) among patients with high-volume metastatic disease. Given the evolving clinical evidence, the cost-effectiveness of this approach warrants exploration. The cost-effectiveness of six cycles of ADT+D compared to ADT alone to treat patients with high-volume metastatic HSPC was assessed from a Canadian public payer perspective. We included three health states: HSPC, metastatic castration-resistant prostate cancer (CRPC), and death. Survival data were obtained from the CHAARTED trial, which reported outcomes specifically for high-volume disease. We used Ontario costs data and utilities from the literature. In the base case analysis, ADT+D cost an additional $25 757 and produced an extra 1.06 quality-adjusted life years (QALYs), resulting in an incremental cost-effectiveness ratio (ICER) of $24 226/QALY gained. Results from one-way sensitivity analysis across wide ranges of estimates and a range of scenarios, including an alternate model structure, produced ICERs below $35 000/QALY gained in all cases. The use of D with ADT in high-volume metastatic HSPC appears to be an economically attractive treatment approach. The findings were consistent with other studies and robust in sensitivity analysis across a variety of scenarios.

Plasma cell-free DNA-based prognosis in metastatic hormone sensitive prostate cancer.

242 Background: We evaluated plasma cell free based genomic aberrations for prognosticating survival of newly diagnosed metastatic hormone sensitive prostate cancer (mHSPC) patients (pts). Methods: Plasma was collected from mHSPC pts enrolled between 2009-2014. Platelet poor plasma (PPP) fractions were processed uniformly and cell free DNA (cfDNA) extracted using Qiagen kits. Pts were followed after initiating hormonal therapy until death. Next Gen Sequencing (NGS) of cfDNA was performed using Illumina HiSeq X for a preselected panel of 128 genes (PredicineDDR-77 cancer driver genes; 29 genes in BRCA-FA homologous recombination deficiency (HRD) pathway; 22 DNA damage repair pathway genes). Statistical analyses of plasma genome based aberrations with overall survival (OS) were performed in R 3.5.1. Cox proportional-hazard models were used for survival analysis. Results: An average of 2.5 ml PPP from 99 pts yielded a median of 10.5 ng (range: 2.8-702) cfDNA per sample. 15/99 pt samples with a yield < 5 ng were excluded from sequencing; 9/99 samples failed NGS. Median follow-up time was 80.2 months (mths) (Range: 74.7, 87]); median OS was 69.1 mths (range: 54,NR). 29 pts with full NGS data had high volume metastatic disease. cfDNA yield correlated with metastatic volume (P = 0.01). Univariate analysis revealed both variables prognostic for OS (Metastatic volume: log-rank P=0.01, HR=2.1, 95% CI: 1.1-3.8; cfDNA yield: P =0.04, HR = 1.3, 95% CI: 1.03-1.7). Multivariate regression showed prognostic value of cfDNA yield remained independent of metastatic volume (P = 0.03, HR = 1.34, 95% CI: 1.02-1.76). 54/67 samples with NGS data had at least one mutation/copy number variation detected. Top mutated genes included TP53 (N=18), ATM (N=9), CHEK2 (N=7), FANCM (N=6), RB1 (N=6), BRCA2 (N=5), PIK3CA (N=4) and 37/67 pts harbored 1≥ variant in HDR pathways. These pts had a shorter survival (median: 58.6 mths) (P=0.04, HR= 2.28, 95% CI: 1.01-5.18) and pts with ATM mutations did significantly worse (median survival: 47.4 mths) (HR=4.03, P=0.0005, 95% CI: 1.73-9.37). Conclusions: Plasma cfDNA yield is prognostic for survival in newly diagnosed mHSPC state and presence of HRD pathway genomic aberrations in plasma cfDNA are associated with poor survival.

Cost effectiveness of chemohormonal therapy in patients with metastatic hormone-sensitive and non-metastatic high-risk prostate cancer.

ABSTRACTObjective To assess the cost-effectiveness of chemohormonal therapy in patients with metastatic hormone-sensitive and non-metastatic high-risk prostate cancer.Methods An analytical decision model was developed to determine the cost-effectiveness of chemohormonal therapy versus androgen deprivation therapy alone in patients with metastatic hormone-sensitive prostate cancer and patients with non-metastatic high-risk prostate cancer. The cost-effectiveness in metastatic patients with a high-volume disease was assessed separately. The model used data from randomized clinical trials and drug acquisition costs in Brazil. In addition, the costs of post-progression therapies have been included in this model. The benefits to health are expressed as the quality-adjusted life-years, and the incremental cost-effectiveness ratios were calculated.Results Chemohormonal therapy may be associated with improved quality-adjusted life-years for all patient. The improvement was more than six times greater for patients with high-volume metastatic disease. In these patients, the incremental cost-effectiveness ratios were up to 74% lower than the incremental cost-effectiveness ratios of patients with non-metastatic disease.Conclusion Chemohormonal therapy has been more cost-effective in patients with high-volume metastatic disease.

Cytoreductive Prostatectomy for Metastatic Prostate Cancer: First Lessons Learned From the Multicentric Prospective Local Treatment of Metastatic Prostate Cancer (LoMP) Trial

To prospectively evaluate patients with newly diagnosed metastatic prostate cancer in the context of the LoMP trial (which investigates the role of cytoreductive radical prostatectomy [cRP] in addition to standard of care [SoC]) and to provide a preliminary analysis of patient's characteristics, safety of cRP, and early local symptoms. cRP was performed in asymptomatic patients with a resectable tumor and who were fit to undergo surgery (group A, n = 17). Only SoC was administered to patients with metastatic prostate cancer ineligible or unwilling to undergo cRP (group B, n = 29). At 3 months, surgical complications related to cRP and local symptoms for both groups were evaluated. Median operation time, blood loss, and hospital stay for cRP were 215 minutes (150-290), 250 mL (100-900), and 4 days (2-7), respectively. Respectively 5 (29.4%) and 2 (11.8%) patients suffered grades 1 and 2 complications within 3 months postoperatively. When compared with Group B, patients in group A were younger (64 vs 72 years, P = .005), had lower initial prostate-specific antigen (15.9 vs 156 µg/L, P = .002), and less high-volume metastatic disease (5.9% vs 69%, P <.001). At 3 months, 5 (29.4%) patients in group A reported stress urinary incontinence without any further local symptoms. In group B, respectively 2 (6.8%), 11 (37.9%), and 2 (6.8%) patients suffered urge incontinence, obstructive voiding needing medical intervention, and ureteric obstruction. In a group of well-selected patients, cRP is safe. These patients have more favorable characteristics compared with patients treated with only SoC. If only SoC can be offered, patients are at risk to suffer from local symptoms.

De novo metastatic prostate cancer: Patterns of PSA testing prediagnosis and disease characteristics.

271 Background: A small proportion of men with prostate cancer (PCa) will present with metastatic disease at first presentation, termed de novo metastatic PCa. PSA screening is not a national policy, yet PSA testing is commonly performed and national guidelines are available to guide subsequent management. We sought to investigate this group of men to determine if prior PSA testing had been previously performed, and if elevated, to determine if appropriate referrals were being made. We also sought to further characterise and analyse associated risk factors. Methods: A retrospective review of pts who presented with de novometastatic PCa over a three year period was performed in three cancer centres in Ireland. Characteristics such as demographics, Gleason score, symptoms at presentation and disease volume (high v low) were obtained. PSA results done in the primary care for a period of 12-24 months and &gt; 24 months prior to diagnosis were recorded. Results: 100 pts with de novo metastatic PCa were identified between 2013 and 2015. Median age at diagnosis was 72 years (49-90), 77 pts (77%) presented with high volume disease, 11 pts (11%) had evidence of visceral metastasis with a median age of 62 years (51-72). Median PSA level at diagnosis was 106, and 91% of pts (n = 74) had a Gleason score of ≥ 8. Symptoms at presentation were evaluable in 88 pts with the majority of pts presenting with pain (n = 49, 55.6%) and lower urinary tract symptoms (n = 33, 37.5%). 22 pts (22%) had a PSA level done within 12-24 months prior to diagnosis which was higher than 4.0 ng/ml in 18 pts (82%). 57 pts (57%) had a PSA level done over 24 months prior to diagnosis which was higher than 4.0 ng/ml in 35 pts (61.4%), PSA measurement was only repeated in 18 pts (51%) out of 35 pts with high PSA levels prior to diagnosis. Having elevated PSA levels over 4.0 ng/ml within 12-24 months and over 24 months prior to diagnosis was not associated high volume metastatic disease (P = 0.88). Conclusions: A sizeable proportion of pts diagnosed with de novo metastatic PCa had PSA measurements performed more than one year prior to diagnosis which was elevated. Optimization and adherence to national guidelines regarding PSA testing is needed to decrease the number of pts diagnosed with de novo disease.

Evolving Use of Androgen Deprivation Therapy in Prostate Cancer Management.

Since its introduction more than 70 years ago, the use of androgen deprivation therapy (ADT) for prostate cancer has evolved to become part of a multimodal management approach. In this presentation from the NCCN 21st Annual Conference, James L. Mohler, MD, reviewed data that inform these strategies and gave his bottom-line recommendations on issues such as ADT plus radiotherapy, continuous versus intermittent ADT, ADT for positive nodes, and ADT plus docetaxel. He suggested that ADT plus radiation therapy should be used in patients at high risk, intermittent ADT is more appropriate for most patients than continuous ADT, and docetaxel should be given with ADT for high-volume metastatic disease.

Effect of metastatic site biopsy on circulating tumor cell (CTC) count in castrate resistant prostate cancer (CRPC) stage.

190 Background: It is not known if biopsy of CRPC stage metastases alters CTC results. We evaluated pre &amp; post biopsy CTC counts in a prospective cohort undergoing pre-chemotherapy abiraterone acetate/prednisone (AA/P). Methods: CTC enumeration was performed on 7.5mL blood using the FDA cleared immunomagnetic/immunofluorescence assay (CellSearch). Time of blood draw for CTC counts pre/post biopsy was recorded for each biopsy. Biopsies were performed using 11/13 gauge core biopsy device for bone lesions and 18 gauge core needle biopsy device for soft tissue/nodal metastases. All patients (pts) underwent two serial biopsies 3 months apart. Change in CTC counts pre/post biopsy for visits 1 and 2 were evaluated using Wilcoxon signed rank test (significance at p&lt;0.05). Differences in CTC count change (visit1) pre/post biopsy based on metastatic site (skeletal vs. non-skeletal) was compared using Wilcoxon rank-sum test. Results: Median age of the cohort was 74 years (IQR: 68-78); median PSA at V1 was 16.4 ng/ml (IQR: 6.4-87.6); at V2 was 11.5 ng/ml (IQR: 1.8-23.7). Of 59 pts undergoing biopsies 42 were in bone and 17 in nodal/soft tissue masses. At V1, pre/post biopsy CTC counts were measured on 50 and 49 pts, respectively; at V2, pre/post CTC counts were measured on 43 and 36 pts. High volume metastatic disease at V1 was observed in 67.8 % of all pts. Table lists CTC counts and time of collection pre/post biopsy for both visits. Mean change in pre/post biopsy CTC counts for skeletal sites was 0.7 (range: -12 to 64) compared to 12.1 (range: -21 to 13) for non-skeletal sites (p=0.23). Conclusions: An increase in mean CTC counts after biopsy of CRPC metastases was observed. No significant differences in change of CTC counts based on site biopsied (skeletal versus non-skeletal) was noted. Correlation with clinical outcomes is on-going. Clinical trial information: NCT# 01953640. [Table: see text]

Serum insulin to predict time to castration-resistant progression and overall survival in metastatic androgen-dependent prostate cancer (mADPCa).

e16038 Background: Duration of response to androgen-deprivation therapy (ADT) is highly variable in patients with mADPC and prognostic markers are needed. Insulin resistance and hyperinsulinemia may contribute to prostate cancer progression. We hypothesized that pretreatment serum insulin levels would predict time to castration-resistant progression (PFS) and overall survival (OS). Methods: Sera from men treated on a randomized phase 3 trial of first line ADT vs. ADT plus chemotherapy were retrospectively analyzed using a multiplex ELISA for cytokines and angiogenic factors (CAFs). Univariate and multivariate Cox proportional hazards regression models were used to identify associations between CAFs and PFS/OS. Results: 66 pts were evaluable, 86% Caucasian, median age 72 yrs, median PSA 31.5ng/mL, 77% Gleason score of ≥8, and 53% high volume metastatic disease (HVM). Thirty-five pts received ADT; 31 pts received ADT+chemo. In univariate analysis, higher pretreatment insulin and C-peptide were positively correlated with PFS, whereas higher hepatocyte-growth factor (HGF), osteopontin (OPN) and HVM were negatively correlated with PFS. In multivariate analysis, only higher insulin was associated with longer PFS (HR=0.72, 95%CI 1.32 -0.87; p&lt;0.001), whereas higher HGF and OPN were associated with reduced PFS (HR=1.82, 95%CI 0.59-2.83, p&lt;0.01 and HR=1.81, 95%CI 1.18-2.47, p&lt;0.001, respectively). Higher Insulin and Program Death 1 (PD1) were associated with longer OS on multivariate analysis (HR=0.78 p&lt;0.02 and HR=0.55 p&lt;0.02, respectively), whereas HVM and higher OPN were associated with reduced OS (HR=2.28 p&lt;0.01 and HR=1.60 p&lt;0.02). Using low insulin, high HGF and high OPN as 3 independent risk factors (RF), 3 distinct risk groups could predict PFS: good (zero RF), intermediate (1 or 2 RF) and poor risk (3 RF), with median PFS of 6.90, 1.97, and 0.86 years, respectively (p&lt;0.001). Conclusions: Higher pretreatment insulin was associated with prolonged PFS and OS in men with mADPC treated with ADT. Our data suggest that insulin levels are a biomarker for sensitivity to ADT and highlight the complex interactions between metabolism and PCa progression.