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123 Background: QOL outcomes have been associated with specific genetic variants in neurotransmitter metabolism. One such variant associated with reduced symptoms in placebo studies is in the rs4680 SNP of Carboxy-O-Methyltransferase (COMT). This variant is associated with reduced COMT enzymatic activity, higher cerebral dopamine levels, and improved mood. The interaction between this germline variant and cancer-directed treatment on QOL is undefined. A priori, we hypothesized that the COMT rs4680 SNP would be associated with better pain and QOL patient reported outcomes (PROs), than wildtype (WT) COMT within the E3805 CHAARTED Trial. Methods: E3805 compared docetaxel + androgen deprivation therapy (ADT+D) vs ADT in patients with metastatic hormone sensitive prostate cancer (mHSPC). PROs were collected at baseline, 3, 6, 9, and 12 months. Blood samples were genotyped prior to treatment. We compared PROs between patients with COMT WT vs rs4680 SNP within treatment arms longitudinally. PROs include Brief Pain Inventory (BPI) classified as: no (0), minimal (1), or more (≥2) pain, and BPI interference (range 0-10, 0= no pain or interference), and the Functional Assessment of Cancer Therapy-Prostate (FACT-P, higher score= better QOL, clinically important difference (CID)= 6). Descriptive statistics were used to characterize QOL over time. Fisher’s exact test, Wilcoxon rank sum test and mixed effects models were used to evaluate the associations between SNP and QOL in each arm. Results: Of 790 participants, 550 with SNP data were included. In the ADT+D arm, SNPs were not associated with PROs at any time point. In contrast, in the ADT alone arm, when compared to WT, rs4680 was associated with less pain at 3 months, less interference at 3, 6 and 9 months, and better QOL at 6 months (met criteria for CID). Conclusions: The rs4680 SNP, often associated with higher cerebral dopamine levels and improved QOL, was associated with less pain and superior QOL among patients with mHSPC treated with ADT, but not chemohormonal therapy. This is the first hypothesis driven genotyping study to demonstrate that genetics are associated with QOL in patients with cancer, especially when treatment does not cause profound symptoms. Clinical trial information: NCT00309985 . [Table: see text]

5081 Background: To date there is no prospective survival data beyond 5 years for patients treated with ADT with or without docetaxel (D) when analyzed by well-defined baseline prognostic risk groups and treatment arms. In this updated analysis of the CHAARTED trial, we report the 8-year survival rate based on disease volume and metachronous vs. de novo metastatic disease status with ADT without or with docetaxel. Methods: An updated survival sweep was conducted in February 2022. Patients were prospectively identified by the state of metastatic disease as metachronous (prior local therapy) vs. de novo and low volume (LV) vs. high volume (HV; visceral and/or ≥4 bone metastases with one lesion beyond the vertebral bodies or pelvis) disease. Overall survival (OS) was defined as time from randomization to death or date last known alive and calculated using the Kaplan-Meier method. Results: Of the 790 patients randomized (last patient enrolled December 2012), 238 patients were still alive with a median follow up of 9.7 years for patients still alive. Median OS in the overall population was 60.4 and 47.2 mos in the ADT+ D and ADT arms respectively (Table; HR: 0.77; 95% CI: 0.65, 0.92; p=0.004). ADT+ D was associated with significantly higher 8-yr OS rate (28.5%) compared to ADT arm (15.4%; HR: 0.67; 95% CI: 0.53, 0.84; p=0.0005) in the de novo HV group (n=421). Notably, the 8-yr OS rates were almost doubled for patients with HV disease with early docetaxel (16% vs.30.2%, p

74 Background: Understanding the lethal nature of high risk prostate cancer, there is a need for the development of multimodal therapies. Prior studies have confirmed a survival benefit with the addition of docetaxel to androgen deprivation therapy (ADT) in men with metastatic hormone-sensitive prostate cancer (HSPC). We conducted a Phase II trial enrolling men with very high risk localized, locally advanced or oligometastatic prostate cancer (PC) to examine resistance and response to neoadjuvant chemohormonal therapy. This analysis aims to identify the preoperative predictors of biochemical recurrence (BCR). Methods: UW17009 is an IRB-approved open-label, single-arm trial that recruited 26 men with newly diagnosed advanced PC. Patients received ADT and docetaxel for 3 months followed by prostatectomy. The primary endpoint was pathologic complete response rate. A secondary clinical objective was the rate of PSA recurrence 12 months after surgery. The pre-trial PSAs, age, cancer grade, stage, percent tumor involvement of the initial biopsy, metastatic disease on conventional and 18F-DCFPyL PSMA (DCFPyL) PET/CT and MRI imaging, completion of chemohormonal therapy and PSA nadirs following chemohormonal therapy were assessed in relationship to biochemical recurrence. One way ANOVA was used to evaluate differences among continuous values: age, PSA at diagnosis, percent tumor involvement, and PSA nadir after chemo ADT. Fisher’s exact tests were used to evaluate the differences among categorical variables: stage at diagnosis, positive bone scan, and positive PSMA PET. Results: 26 patients were enrolled and underwent neoadjuvant treatment, radical prostatectomy (RP) and lymph node dissection. The median age was 62 (IQR 58-66), mean PSA at diagnosis was 32.8 ng/dl and 88.4% had Gleason 9 cancer. At study initiation, 12/26 patients had metastatic disease detected by DCFPyL-based PSMA PET. Final pathology demonstrated 81%(21/26) had ≥ pT3 and 73%(19/26) patients had negative margins. Positive lymph nodes were found in 10/26(38.5%) patients on final pathology. At week 6 after surgery, 91%(24/26) had undetectable PSA. At a mean follow up of 12.1 months(5.2-21.4), the biochemical recurrence rate is 58%(15/26). Features associated with BCR include stage, % tumor involvement, and positive PSMA PET scan. All patients with positive margins and 9/10 patients with positive nodes at final pathology developed BCR at a mean follow up of 12 months. Conclusions: In this neoadjuvant cohort, stage T2c, elevated PSA, positive pre-operative PSMA PET/CT, and PSA nadir > 1 following chemohormonal therapy predict biochemical recurrence. Clinically, and in the short term, neoadjuvant chemohormonal therapy prior to definitive surgery for very high risk localized and/or oligometastatic PC generates local tumor control with a high rate of negative surgical margins.

36 Background: Interest has arisen in the use of prostate specific membrane antigen (PSMA) PET/CT imaging to detect prostate cancer at metastatic sites using different tracers. Here, we examined the ability of 18F-DCFPyL (DCFPyL) PSMA-based PET imaging to detect nodal disease in comparison to conventional imaging in a cohort of men with locally advanced or oligometastatic prostate cancer (PC). Methods: UW17009 is an IRB-approved open-label, single-arm trial that enrolled 26 patients with newly diagnosed advanced PC. Patients received androgen deprivation therapy and docetaxel for 3 months followed by radical prostatectomy (RP) and pelvic lymph node dissection (PLND). Exploratory interventions include PSMA PET/CT and MRI imaging as a method for determining treatment response and heterogeneity in primary PC and metastatic lesions performed before and after chemohormonal therapy. Prior to randomization, patients received DCFPyL PET/CT and PET/MR imaging as well as CTs and Bone Scans. A mean dose of 7.86 mCi DCFPyL was administered. Whole-body PET/CT images were acquired starting at approximately 60 minutes after radiotracer injection followed by dedicated pelvic PET/MR and whole-body PET/MR. PET imaging findings were compared to conventional dedicated CT imaging and were correlated to the results of final pathologic examination of each pelvic nodal dissection. Results: 26 patients underwent conventional and exploratory imaging with subsequent neoadjuvant treatment, RP and PLND. The mean diagnostic PSA was 32.1 ng/dl and 88.5% had Gleason 9 PCa. Using conventional imaging, pelvic nodal disease was identified in 6/26 patients. Pelvic lymph node uptake was identified in 12/26 patients using DCFPyL-based PSMA PET. Initial correlation of the pathologic specimens with pretreatment PSMA PET imaging revealed pelvic nodal metastatic PC in 10/12(83%) patients. On a per-lymph node packet basis (6 per patient), there were 156 evaluable regions, including 65 from patients with positive nodes. PSMA detected 14 packets that were positive for PC and 102 packets that were negative on imaging and final pathology. PC was missed in 5 packets. The mean tumor size in the missed nodes was 2.3 mm(range 1-4 mm). Calculated sensitivity was 73.7%(95% CI [48.8, 90.8]), 85.7 % specificity(95% CI[78.1, 91.4]), and 95.3 % negative predictive value(95% CI[90.5, 97.7]). Conclusions: In comparison to conventional imaging, in this cohort, DCFPyL PSMA-based PET imaging identified nodal positive disease at twice the rate and when evaluating on a per-packet basis, there was high negative predictive value. Ongoing analysis of post-chemohormonal therapy PET imaging may provide more information regarding tumor response in this cohort.

34 Background: Management of BCR PCa requires accurate assessment of location and extent of recurrent disease. FACBC has been shown to be a sensitive modality for detection and localization of recurrent disease but treatment guidelines are based on the findings of conventional (conv) imaging, including computed tomography, magnetic resonance imaging, or bone scintigraphy, and little is known about how prior treatment impacts FACBC findings and concordance with conv scans. Methods: This single-center retrospective study included 137 patients (pts) who had FACBC for BCR at the University of Wisconsin-Madison from 10/2017-10/2019. Clinical, pathological, imaging, and treatment data were collected by chart review. Pts were classified by type of primary treatment for localized PCa, either radical prostatectomy (RP) or radiation therapy (RT). Findings of conv scans performed within 4 weeks prior or any time after FACBC were collected. Results: 105 pts had RP and 32 pts had RT as their primary PCa treatment. Gleason score and PSA at diagnosis were similar between groups. Median PSA at time of FACBC was higher in the RT compared to RP group (3.3 vs 0.7 ng/dL) and median time from initial diagnosis to FACBC was longer (70 vs 55 months). Frequency of (+) FACBC findings was higher in the RT group (66% vs 47%); only 3% of pts in the RT group had a (-) FACBC compared to 29% in the RP group. The rate of (+) lesions in the prostate/prostate bed was higher in the RT group (41% vs 22%), while the rate of (+) lesions in pelvic nodes and distant sites was similar between groups. Of 69 pts who also had conv imaging, 61% had concordant conv imaging findings. In the RT group, conv and FACBC findings were similar in 47% of pts and not similar in 28%. In the RP group, conv and FACBC findings were similar in 26% of pts and not similar in 17%. Management after FACBC is listed in table. Median time from FACBC to first (+) conv scans was 6 (range: 0-18) and 5 (range: 0-17) months for RT and RP groups, respectively. Conclusions: In this large retrospective cohort, pts treated with initial RT had a longer median time from diagnosis to FACBC and higher median PSA at the time of FACBC compared to the RP group. RT patients had a higher rate of (+) FACBC findings but were more likely to continue on observation. The median time from FACBC to first (+) conv scan was 5-6 months, supporting the role of FACBC in earlier detection of recurrent disease in both groups of patients. Further analysis of concordance between FACBC and conv imaging is in process. [Table: see text]

285 Background: Due to its high prevalence and often indolent natural history, prostate cancer(PC) active surveillance(AS) is an ideal setting for chemoprevention. Studies assessing pomegranate and its extracts have shown promising anti-proliferative and pro-apoptotic effects in cell lines and animal models and a single-arm clinical trial of pomegranate fruit extract(PFE) reported an increase in PSA doubling time(PSADT) during AS. The primary objective of this trial was to assess the effect of PFE supplementation on plasma levels of Insulin-like Growth Factor-1(IGF-1). Secondary objectives addressed PSA doubling time(PSADT), tumor volume on end-of-study(EOS) biopsy and plasma and prostate tissue biomarkers. Methods: Men with organ-confined favorable-risk PC on AS were randomly assigned to receive PFE 1,000 mg(n=15) or placebo(n=15) once daily for twelve months. Prostate biopsies were performed at study entry and upon completion of the one-year intervention. Tissue biomarkers were assessed by immunohistochemistry(IHC) with automated quantitation. Results: PFE was well-tolerated with no significant toxicities. One patient withdrew before study initiation and 29 completed the one-year intervention. No differences in plasma IGF-1 levels(p=0.5), PSADT, or tissue biomarkers of apoptosis or proliferation were observed. A significant increase in urolithin A(a urinary metabolite of pomegranate) was observed in the PFE arm. IHC analyses of both tumor (Table) and normal-appearing tissue adjacent to tumor showed reductions from baseline in IGF-1, 8-OHdG(DNA damage marker), and androgen receptor expression associated with PFE treatment. A trend towards a reduction in the maximum percent of biopsy core tumor involvement was observed(p=0.06) in PFE. Conclusions: PFE administration for 12-months was not associated with a decrease in plasma IGF-1 levels nor an increase in PSADT. However, exploratory analyses suggest that PFE may contain bioactive compounds capable of altering biomarkers in PC and normal-appearing adjacent tissue providing a rationale for further investigation of PFE in the active surveillance population.

334 Background: Previous studies have shown that addition of docetaxel to androgen deprivation therapy (ADT) significantly improves progression-free survival (PFS) and overall survival (OS) in men with metastatic hormone-sensitive PC. Removal of the primary may also improve outcomes by reducing tumor self-seeding. We are conducting a phase II trial in men with PC to examine the feasibility of NAC, response using PSMA PET/MRI imaging and molecular mechanisms of resistance. Methods: This is an open-label, single-arm trial. Thirty patients with newly diagnosed very high risk localized, locally advanced or oligometastatic PC will receive ADT/docetaxel for three cycles before prostatectomy. The primary endpoint is rate of complete pathologic response. Key secondary objectives include PSA recurrence at month 12 after surgery. Exploratory objectives include tumor response and response heterogeneity in primary and metastatic tumors before and after treatment assessed by PSMA PET/MRI and evaluation of gene expression signatures in cancer cells, prostate stroma, bone marrow microenvironment and circulating tumor cells. Results: To date, 26 of 30 patients have enrolled and completed treatment. Mean age was 61 and mean PSA at time of diagnosis was 32.1 ng/dl. All patients had multi-focal prostate cancer with 23/26 patients with Gleason Grade Group 5. Metastatic disease by conventional imaging was identified in 6/26 patients (5 in lymph nodes [LN] and bone, 1 in LN only). Treatment was overall well tolerated. All patients had multi-focal primary prostate cancer detected on PSMA PET/MRI. All patients had a decline in PSMA PET SUVmax in at least one intraprostatic lesion. Two patients had an increase in SUVmax in at least one intraprostatic lesion that correlated with a resistant tumor focus on histopathology. Conclusions: NAC prior to surgery generates high rates of local tumor control with a heterogeneous response between foci. Primary resistance, identified by increasing PSMA PET SUVmax, is uncommon, however incomplete responses were observed in nearly all patients, suggesting that more cycles of treatment would improve response. PSMA PET/MRI can be used to monitor response and resistance in PC. Clinical trial information: NCT03358563.

5020 Background: The HSD3B1(1245A > C) variant allele, whose frequency varies by race, encodes a missense sequence that stabilizes the rate-limiting enzyme responsible for extragonadal androgen synthesis, thus enhancing intratumoral dihydrotestosterone (DHT) synthesis. Multiple retrospective studies have found that men inheriting the HSD3B1(1245C) variant allele exhibit early resistance to ADT. We sought to validate these findings with prospective data from the Chemohormonal Therapy versus Androgen Ablation Randomized Trial for Extensive Disease in Prostate Cancer (CHAARTED). Methods: Men with newly metastatic PCa were randomized to receive either ADT plus docetaxel at a dose of 75 mg/m2 every 3 weeks for 6 cycles (arm A) or ADT alone (arm B). We determined germline HSD3B1 genotype in the subset of men with LV disease ( < 4 bone metastases, no visceral metastases). We analyzed freedom from castration-resistant prostate cancer (CRPC) and OS according to HSD3B1 genotype using Cox and Kaplan-Meier methods. Results: 197 patients with LV disease had blood samples available and were genotyped, including 97 in arm A and 100 in arm B. Docetaxel did not improve OS of LV men. Of the 197 men, 47% were homozygous wild-type (WT), 43% were heterozygous, and 10% were homozygous variant. When all 197 men were analyzed as one goup, the median time to CRPC was 39.7 mos. in homozygous WT men vs. 25.0 mos. in men with one or more copies of the variant allele (HR 1.27, 95% CI 0.89 to 1.82; p = 0.187). Although OS data are still maturing, at 52 months OS was 83% (95% CI 75% to 91%) in homozygous WT men vs. 64% (95% CI 55% to 74%) in men with one or more variant alleles. There was a suggestion that docetaxel delayed development of CRPC among men with at least 1 variant allele (20.3 vs. 40.7 mos.; HR 0.66, 95% CI 0.40 to 1.04; p = 0.08). Benefit for men with high-volume disease was not evident. Conclusions: Inheritance of the HSD3B1(1245C) allele that augments DHT synthesis may be associated with lower OS in men treated with ADT with or without docetaxel for LV newly metastatic PCa. Additional study is warranted in patients with LV disease. Clinical trial information: NCT00309985.

5046Background: Recent data has highlighted the high frequency with which metastatic prostate cancer can progress either radiographically or symptomatically without a rise in PSA, so called PSA-Cli...

Recent studies have suggested that matriptase, a transmembrane serine protease and its cognate inhibitor hepatocyte growth factor activator inhibitor-1 (HAI-1) are important in the progression of many cancers. Limited quantitative data are available on these proteins in prostate cancer. To validate the roles of matriptase and HAI-1 in prostate cancer and its progression, a prostate cancer tissue microarray was constructed. The tissue microarray includes 41 localized prostate cancers (Pca_local), 18 aggressive prostate cancers, 18 metastatic prostate cancers, 24 benign prostate hyperplasias, 18 high-grade intraepithelial neoplasias (HGPIN), and 41 benign prostate tissues. The cellular expression levels of matriptase and HAI-1 were quantified using automated quantitative analysis. We found that matriptase expression levels were significantly higher in Pca_local (P

181 Background: To evaluate whether metformin (Met) a widely-used, nontoxic oral antidiabetic drug with putative anticancer properties leads to improvements in prostate cancer (PC) outcomes in the CHAARTED trial. Methods: In the CHAARTED database where metformin use at baseline was recorded prospectively, we identified patients with metastatic PC who underwent either ADT alone or ADT and docetaxel (D) chemotherapy. Cox proportional hazards models were used to determine the effect of Metformin on outcomes. Results: A total of 788 patients (median age, 63 y) had complete data after randomization. Comparison of ADT+D+Met (n = 39) to ADT+D (n = 357) and ADT+Met (n = 29) to ADT alone (n = 363) revealed similar clinicopathologic characteristics. Cause of death was PC in 13(81%) of ADT+D+Met, 72(85%) ADT+D, 9(82%) ADT+Met and 105(84%) ADT alone groups. See table for PC outcomes and overall survival by metformin use. Cox regression analysis for overall survival stratified by stratification factors at randomization demonstrates Met use was associated with a trend for worse overall survival (HR 1.47 95%CI: [0.95,2.26], p = 0.08) with adjustment for treatment arm and prior local therapy. In contrast, ADT+D use (HR 0.62; 95%CI: [0.47,0.81]) and prior local therapy with surgery or radiation (HR 0.56; 95% CI: [0.38, 0.82]) were associated with improved survival. Conclusions: In this study, baseline metformin did not improve PC outcomes. Partial support and drug supply by Sanofi. Clinical trial information: NCT00309985. [Table: see text]

137 Background: Prior work from SWOG 9346 revealed that PSA ≤ 0.2 ng/dL at 7 months (mo) is prognostic for longer OS with ADT alone. We sought to evaluate if this optimal decline remained predictive of better OS when D was added to ADT for initial mHSPC treatment. Methods: We performed a landmark survival analysis at 7 mo using the E3805 database (NCT00309985). Inclusion required at least 7 mo of followup and PSA levels at 7 mo from ADT initiation. Survival was defined from ADT start or randomization to death. SWOG 9346 PSA nadirs of ≤ 0.2, > 0.2-4 and > 4 were used as classifiers. Results: 719 patients were eligible for analysis: 358 treated with ADT plus D and 361 with ADT alone. Median follow-up was 23.1 mo. On multivariable analysis (MVA), achieving a PSA ≤ 0.2 at 7 mo was more likely if the patient received D and had lower volume disease, prior local therapy, and lower baseline PSAs (all p ≤ 0.01). Across all patients, median OS was significantly longer if PSA at 7 mo reached ≤ 0.2 compared to > 4 (p < 0.0001) (Table). On MVA, PSA ≤ 0.2 at 7 mo and low volume disease were prognostic of longer OS (all p < 0.01). On ADT, 28.8% achieved a PSA ≤ 0.2 at 7 mo vs. 45.3% on ADT+D. Patients on ADT alone who achieved a PSA nadir ≤ 0.2 had the best survival. These patients were more likely to have low volume disease (56.7%) compared to the ADT + D pts (46.3%). Conclusions: Achieving PSA ≤ 0.2 at 7 mo remains prognostic for longer OS with ADT for mHSPC, whether administered alone or with D. Adding D to ADT increased the likelihood of a lower PSA and improved survival. Partial support and drug supply by Sanofi. Clinical trial information: NCT00309985. [Table: see text]

136 Background: Patients with a low burden of metastatic disease and who relapse after localized therapy with curative intent have a longer overall survival. It is unclear whether these patients benefit from early docetaxel (D). Methods: Patients in GETUG-AFU15 (N = 385, median follow-up 84 mo) and CHAARTED (N = 790, median follow up 54 mo) were randomized to ADT alone or ADT + D and outcomes described using the same definition of high volume (HV) and low volume (LV) disease. (HV: visceral metastases and/or 4 or more bone metastases with at least one outside the axis) and whether the patients had prior local therapy or not. Results: Table 1 details across both studies that de novo HV group treated with ADT alone has the shortest overall survival and D has a consistent effect in improving OS. In contrast, in both studies patients with LV disease had a much longer OS with no evidence that D improved OS. Conclusions: There was no apparent survival benefit in CHAARTED and GETUG-15 studies with D for LV whether patients had prior local treatment or not. Across both studies, early D had a consistent effect and improved OS in HV pts especially those with no prior local therapy. Partial Support and drug supply by Sanofi. Clinical trial information: NCT00104715, NCT00309985. [Table: see text]

237 Background: Recent advances in proteomic and chromatin immunoprecipitation tools have been crucial in studying cancer epigenetics but the ability to measure directly the enzyme activities of dysregulated histone-modifiers is lacking. We utilize a novel approach to identify altered histone-modifying enzymes in the progression from hormone sensitive (HS) to castrate-resistant prostate cancer (CRPC) progression. Methods: We developed, validated and utilized a high-throughput peptide microarray assay to identify altered histone lysine (de)acetylation activity in tumor lysates. Functional assays, novel HS and CRPC human tumor arrays and xenografts were utilized to confirm these findings. Results: This microarray-based activity assay revealed up-regulated histone acetyltransferase (HAT) activity against specific histone H3 sites in a castrate-resistant CR cell line compared to its hormone-sensitive (HS) isogenic counterpart. NAD+-dependent deacetylation assays revealed down-regulated Sirtuin activity in validated CR lines. Levels of acetyltransferases GCN5, PCAF, CBP and p300 were unchanged between matched HS and CR cell lines. However, auto-acetylation of p300 at K1499, a modification known to enhance HAT activity and a target of deacetylation by SIRT2, was highly elevated in CR cells. Among all 7 Sirtuins, only SIRT2 and SIRT3 protein levels were reduced in CR lines. Interrogation of HS and matched CR xenograft lines reveals that H3K18 hyperacetylation, increased p300 activity, and decreased SIRT2 expression are associated with progression to CR in 8/12 (66%). Tissue microarray analysis revealed that hyperacetylation of H3K18 is a feature of CRPC. Inhibition of p300 results in lower H3K18ac levels and increased expression of androgen receptor. Conclusions: This novel microarray approach provides a method to identify commonly dysregulated chromatin enzymes during progression providing a personalized therapeutic strategy to direct available drugs to target enzymes. Reduced SIRT2 expression and increased p300 activity lead to a concerted mechanism of hyperacetylation at specific histone lysine sites (H3K9, H3K14, and H3K18)

5004Background: Androgen deprivation therapy plus docetaxel (ADT+D) for metastatic hormone sensitive prostate cancer (mHSPC) improves overall survival over ADT. However, docetaxel’s adverse event p...

1540Background: Inherited genetic factors are among the variables influencing PCa outcome and response to treatment. We conducted a GWAS to identify germline genetic polymorphisms associated with t...

286 Background: Docetaxel concurrent with androgen deprivation (ADT) for metastatic hormone sensitive prostate cancer (mHSPC) improves overall survival over ADT alone. However, docetaxel as a cytotoxic has an adverse event profile that can diminish QOL. Methods: Patients were randomized to ADT plus 6 cycles of docetaxel every 3 weeks (Arm A, N = 397) or ADT alone (Arm B, N = 393). Validated QOL instruments for PrCa and docetaxel including Functional Assessment of Cancer Therapy (FACT)–Prostate were administered at baseline and 3, 6, 9 and 12 months (mos.) after randomization. Paired t-tests were used to examine QOL changes over time. A mixed effect model compared QOL between arms at each time point (Table). Results: 790 patients were randomized and QOL completed for Arm A and B (91% and 88%, baseline; 87% and 80%, 3 mos.; and 70% and 67%, 12 mos.). Patients in Arm A (ADT + docetaxel) reported -2.7 [Standard Error (SE) 0.9] decline in FACT-P at 3 mos. (p = 0.003), but did not differ significantly from baseline at 12 mos. (-0.7, SE 1.1). In contrast, patients in Arm B (ADT alone), did not differ significantly at 3 mos. [-1.1 (SE: 1.0)], but reported a significant decline [-4.2 (SE: 1.1); p = 0.0001] from baseline to 12 mos. FACT-P scores differed significantly between Arm A and B at 3 mos. (p = 0.02) and 12 mos. (0.04), with Arm A lower at 3 mos. and higher at 12 mos. Conclusions: Docetaxel is associated with decreased QOL on treatment (at 3 mos.) not seen with ADT alone. However, 12 mos. QOL was better for the patients who had docetaxel versus ADT alone, returning to baseline. This suggests that docetaxel + ADT does not confer long-term negative impact on QOL for mHSPC. Clinical trial information: NCT00309985. [Table: see text]