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Objectives We evaluated 18F-DCFPyL test–retest repeatability of uptake in normal organs. Methods Twenty-two prostate cancer (PC) patients underwent two 18F-DCFPyL PET scans within 7 days within a prospective clinical trial (NCT03793543). In both PET scans, uptake in normal organs (kidneys, spleen, liver, and salivary and lacrimal glands) was quantified. Repeatability was determined by using within-subject coefficient of variation (wCOV), with lower values indicating improved repeatability. Results For SUVmean, repeatability was high for kidneys, spleen, liver, and parotid glands (wCOV, range: 9.0%–14.3%) and lower for lacrimal (23.9%) and submandibular glands (12.4%). For SUVmax, however, the lacrimal (14.4%) and submandibular glands (6.9%) achieved higher repeatability, while for large organs (kidneys, liver, spleen, and parotid glands), repeatability was low (range: 14.1%–45.2%). Conclusion We found acceptable repeatability of uptake on 18F-DCFPyL PET for normal organs, in particular for SUVmean in the liver or parotid glands. This may have implications for both PSMA-targeted imaging and treatment, as patient selection for radioligand therapy and standardized frameworks for scan interpretation (PROMISE, E-PSMA) rely on uptake in those reference organs.

Copy number for AR-V7 and ARv567es stratified by PSA response AR, androgen receptor; IQ, interquartile; PSA50, 50% reduction from baseline in prostate-specific antigen; SD, standard deviation.

Supplementary Tables

Supplementary Table from A Phase Ib/II Study of Sabizabulin, a Novel Oral Cytoskeleton Disruptor, in Men with Metastatic Castration-resistant Prostate Cancer with Progression on an Androgen Receptor–targeting Agent

S2 provides details on the methods used to determine and validate SOD2 germline genotypes.

Appendix

MSH2/6 immunostains in a formalin fixed and paraffin embedded primary prostate tumor with single copy MSH2 loss by sequencing. Standard tissue section of tumor with apparent single copy somatic gene inactivation of MSH2 (MSH2 c. 1728del), showing loss of both MSH2 and MSH6 immunostaining, with intact staining in stromal cells and lymphocytes for both markers. All photomicrographs are reduced from 200x.

Purpose: Inactivation of mismatch repair (MMR) genes may predict sensitivity to immunotherapy in metastatic prostate cancers. We studied primary prostate tumors with MMR defects.Experimental Design: A total of 1,133 primary prostatic adenocarcinomas and 43 prostatic small cell carcinomas (NEPC) were screened by MSH2 immunohistochemistry with confirmation by next-generation sequencing (NGS). Microsatellite instability (MSI) was assessed by PCR and NGS (mSINGS).Results: Of primary adenocarcinomas and NEPC, 1.2% (14/1,176) had MSH2 loss. Overall, 8% (7/91) of adenocarcinomas with primary Gleason pattern 5 (Gleason score 9–10) had MSH2 loss compared with 0.4% (5/1,042) of tumors with any other scores (P < 0.05). Five percent (2/43) of NEPC had MSH2 loss. MSH2 was generally homogenously lost, suggesting it was an early/clonal event. NGS confirmed MSH2 loss-of-function alterations in all (12/12) samples, with biallelic inactivation in 83% (10/12) and hypermutation in 83% (10/12). Overall, 61% (8/13) and 58% (7/12) of patients had definite MSI by PCR and mSINGS, respectively. Three patients (25%) had germline mutations in MSH2. Tumors with MSH2 loss had a higher density of infiltrating CD8+ lymphocytes compared with grade-matched controls without MSH2 loss (390 vs. 76 cells/mm2; P = 0.008), and CD8+ density was correlated with mutation burden among cases with MSH2 loss (r = 0.72, P = 0.005). T-cell receptor sequencing on a subset revealed a trend toward higher clonality in cases versus controls.Conclusions: Loss of MSH2 protein is correlated with MSH2 inactivation, hypermutation, and higher tumor-infiltrating lymphocyte density, and appears most common among very high-grade primary tumors, for which routine screening may be warranted if validated in additional cohorts. Clin Cancer Res; 23(22); 6863–74. ©2017 AACR.

Purpose:Sabizabulin, an oral cytoskeleton disruptor, was tested in a phase Ib/II clinical study in men with metastatic castration-resistant prostate cancer (mCRPC).Patients and Methods:The phase Ib portion utilized a 3+3 design with escalating daily oral doses of 4.5–81 mg and increasing schedule in 39 patients with mCRPC treated with one or more androgen receptor–targeting agents. Prior taxane chemotherapy was allowed. The phase II portion tested a daily dose of 63 mg in 41 patients with no prior chemotherapy. Efficacy was assessed using PCWG3 and RECIST 1.1 criteria.Results:The MTD was not defined in the phase Ib and the recommended phase II dose was set at 63 mg/day. The most common adverse events (>10% frequency) at the 63 mg oral daily dosing (combined phase Ib/II data) were predominantly grade 1–2 events. Grade ≥3 events included diarrhea (7.4%), fatigue (5.6%), and alanine aminotransferase/aspartate aminotransferase elevations (5.6% and 3.7%, respectively). Neurotoxicity and neutropenia were not observed. Preliminary efficacy data in patients treated with ≥1 continuous cycle of 63 mg or higher included objective response rate in 6 of 29 (20.7%) patients with measurable disease (1 complete, 5 partial) and 14 of 48 (29.2%) patients had PSA declines. The Kaplan–Meier median radiographic progression-free survival was estimated to be 11.4 months (n = 55). Durable responses lasting >2.75 years were observed.Conclusions:This clinical trial demonstrated that chronic oral daily dosing of sabizabulin has a favorable safety profile with preliminary antitumor activity. These data support the ongoing phase III VERACITY trial of sabizabulin in men with mCRPC.

Supplementary Data from A Phase Ib/II Study of Sabizabulin, a Novel Oral Cytoskeleton Disruptor, in Men with Metastatic Castration-resistant Prostate Cancer with Progression on an Androgen Receptor–targeting Agent

Assay sensitivity in 22RV1 prostate cancer cells spiked-in healthy donor blood run through the GEDI device. AR-FL (blue) and AR-V7 (red) mRNA expression (#copies per sample) was determined by ddPCR in varying amounts of 22RV1 cells in the presence of healthy donor blood run through the GEDI device. The assay, reliably and reproducibly detects both transcripts in single spiked-in cells. The table below the graph shows the raw data (copy number) for each transcript per condition. Healthy donor blood PBMCs alone were used as a control. AR, androgen receptor; ddPCR, droplet digital polymerase chain reaction; FL, full length; GEDI, geometrically enhanced differential immunocapture; PBMC, peripheral blood mononuclear cell.

Copy number for AR-FL, AR-V7 and ARv567es for the evaluable population at baseline AR, androgen receptor; FL, full length.

Supplementary Figure from A Phase Ib/II Study of Sabizabulin, a Novel Oral Cytoskeleton Disruptor, in Men with Metastatic Castration-resistant Prostate Cancer with Progression on an Androgen Receptor–targeting Agent

ddPCR primer and probe sequences AR, androgen receptor; FL, full length.

Purpose: MuscadinePlus (MPX), a commercial preparation of pulverized muscadine grape skin, was evaluated as a therapeutic option for men with biochemically recurrent (BCR) prostate cancer wishing to defer androgen deprivation therapy.Experimental Design: This was a 12-month, multicenter, placebo-controlled, two-dose, double-blinded trial of MPX in 125 men with BCR prostate cancer, powered to detect a PSA doubling time (PSADT) difference of 6 months (low dose) and 12 months (high dose) relative to placebo. Participants were stratified (baseline PSADT, Gleason score) and randomly assigned 1:2:2 to receive placebo, 500 mg MPX (low), or 4,000 mg MPX (high) daily. Correlates included superoxide dismutase-2 (SOD2) genotype, lipid peroxidation, and polyphenol pharmacokinetics.Results: The evaluable population included 112 patients, all treated for at least 6 months and 62% treated for 12 months. No significant difference was found in PSADT change between control and treatment arms (P = 0.81): control 0.9 months (n = 20; range, 6.7–83.1), low dose 1.5 months (n = 52; range, 10.3–87.2), high dose 0.9 months (n = 40; range, 27.3–88.1). One high-dose patient experienced objective response. No drug-related CTCAE grade 3–4 adverse events were seen. In a preplanned exploratory analysis, PSADT pre-to-post increase was significant in the 27 (26%) genotyped patients with SOD2 Alanine/Alanine genotype (rs4880 T>C polymorphism) on MPX (pooled treatment arms; 6.4 months, P = 0.02), but not in control (1.8 months, P = 0.25).Conclusions: Compared with placebo, MPX did not significantly prolong PSADT in BCR patients over two different doses. Exploratory analysis revealed a patient population with potential benefit that would require further study. Clin Cancer Res; 24(2); 306–15. ©2017 AACR.

Visual representation of AR-FL and AR splice variant expression per patient at baseline Data are shown as positive (green for AR-FL; red for AR-V7; blue for ARv567es) or negative (white boxes) for each transcript. AR, androgen receptor; FL, full length

AR-FL and AR-V expression in healthy donor blood run through the GEDI device. The mRNA expression levels of AR-FL (blue), AR-v7 (red) and AR-v567es (green) were analyzed in healthy donor blood from 10 volunteers. As previously described, 1 mL of healthy donor peripheral blood was processed through the GEDI microfluidic device. The table below the graph shows the raw data (copy number) for each transcript per sample. AR, androgen receptor; ddPCR, droplet digital polymerase chain reaction; FL, full length; GEDI, geometrically enhanced differential immunocapture; mRNA, messenger ribonucleic acid.

S3 provides detailed descriptions of methods used in pharmacokinetic assays.

S1 describes the process employed in manufacturing MPX and summarizes the chemical constituents of the MPX batch used in this study.

Purpose: Galeterone is a selective, multitargeted agent that inhibits CYP17, antagonizes the androgen receptor (AR), and reduces AR expression in prostate cancer cells by causing an increase in AR protein degradation. These open-label phase I and II studies [Androgen Receptor Modulation Optimized for Response-1 (ARMOR1) and ARMOR2 part 1] evaluated the efficacy and safety of galeterone in patients with treatment-naive nonmetastatic or metastatic castration-resistant prostate cancer (CRPC) and established a dose for further study.Experimental Design: In ARMOR1, 49 patients received increasing doses (650–2,600 mg) of galeterone in capsule formulation; 28 patients in ARMOR2 part 1 received increasing doses (1,700–3,400 mg) of galeterone in tablet formulation for 12 weeks. Patients were evaluated biweekly for safety and efficacy, and pharmacokinetic parameters were assessed.Results: In ARMOR1, across all doses, 49.0% (24/49) achieved a ≥30% decline in prostate-specific antigen (PSA; PSA30) and 22.4% (11/49) demonstrated a ≥50% PSA decline (PSA50). In ARMOR2 part 1, across all doses, PSA30 was 64.0% (16/25) and PSA50 was 48.0% (12/25). In the 2,550-mg dose cohort, PSA30 was 72.7% (8/11) and PSA50 was 54.5% (6/11). Galeterone was well tolerated; the most common adverse events were fatigue, increased liver enzymes, gastrointestinal events, and pruritus. Most were mild or moderate in severity and required no action and there were no apparent mineralocorticoid excess (AME) events.Conclusions: The efficacy and safety from ARMOR1 and ARMOR2 part 1 and the pharmacokinetic results support the galeterone tablet dose of 2,550 mg/d for further study. Galeterone was well tolerated and demonstrated pharmacodynamic changes consistent with its selective, multifunctional AR signaling inhibition. Clin Cancer Res; 22(6); 1356–63. ©2015 AACR.

Purpose: Sabizabulin, an oral cytoskeleton disruptor, was tested in a phase Ib/II clinical study in men with metastatic castration-resistant prostate cancer (mCRPC). Patients and Methods: The phase Ib portion utilized a 3+3 design with escalating daily oral doses of 4.5–81 mg and increasing schedule in 39 patients with mCRPC treated with one or more androgen receptor–targeting agents. Prior taxane chemotherapy was allowed. The phase II portion tested a daily dose of 63 mg in 41 patients with no prior chemotherapy. Efficacy was assessed using PCWG3 and RECIST 1.1 criteria. Results: The MTD was not defined in the phase Ib and the recommended phase II dose was set at 63 mg/day. The most common adverse events (>10% frequency) at the 63 mg oral daily dosing (combined phase Ib/II data) were predominantly grade 1–2 events. Grade ≥3 events included diarrhea (7.4%), fatigue (5.6%), and alanine aminotransferase/aspartate aminotransferase elevations (5.6% and 3.7%, respectively). Neurotoxicity and neutropenia were not observed. Preliminary efficacy data in patients treated with ≥1 continuous cycle of 63 mg or higher included objective response rate in 6 of 29 (20.7%) patients with measurable disease (1 complete, 5 partial) and 14 of 48 (29.2%) patients had PSA declines. The Kaplan–Meier median radiographic progression-free survival was estimated to be 11.4 months (n = 55). Durable responses lasting >2.75 years were observed. Conclusions: This clinical trial demonstrated that chronic oral daily dosing of sabizabulin has a favorable safety profile with preliminary antitumor activity. These data support the ongoing phase III VERACITY trial of sabizabulin in men with mCRPC.

Objectives PET-based radiomic metrics are increasingly utilized as predictive image biomarkers. However, the repeatability of radiomic features on PET has not been assessed in a test–retest setting. The prostate-specific membrane antigen-targeted compound 18F-DCFPyL is a high-affinity, high-contrast PET agent that we utilized in a test-retest cohort of men with metastatic prostate cancer (PC). Methods Data of 21 patients enrolled in a prospective clinical trial with histologically proven PC underwent two 18F-DCFPyL PET scans within 7 days, using identical acquisition and reconstruction parameters. Sites of disease were segmented and a set of 29 different radiomic parameters were assessed on both scans. We determined repeatability of quantification by using Pearson's correlations, within-subject coefficient of variation (wCOV), and Bland–Altman analysis. Results In total, 230 lesions (177 bone, 38 lymph nodes, 15 others) were assessed on both scans. For all investigated radiomic features, a broad range of inter-scan correlation was found (r, 0.07–0.95), with acceptable reproducibility for entropy and homogeneity (wCOV, 16.0% and 12.7%, respectively). On Bland–Altman analysis, no systematic increase or decrease between the scans was observed for either parameter (±1.96 SD: 1.07/−1.30, 0.23/−0.18, respectively). The remaining 27 tested radiomic metrics, however, achieved unacceptable high wCOV (≥21.7%). Conclusion Many common radiomic features derived from a test–retest PET study had poor repeatability. Only Entropy and homogeneity achieved good repeatability, supporting the notion that those image biomarkers may be incorporated in future clinical trials. Those radiomic features based on high frequency aspects of images appear to lack the repeatability on PET to justify further study.

Background AR-V7-positive metastatic prostate cancer is a lethal phenotype with few treatment options and poor survival. Methods The two-cohort nonrandomized Phase 2 study of combined immune checkpoint blockade for AR-V7-expressing metastatic castration-resistant prostate cancer (STARVE-PC) evaluated nivolumab (3 mg/kg) plus ipilimumab (1 mg/kg), without (Cohort 1) or with (Cohort 2) the anti-androgen enzalutamide. Co-primary endpoints were safety and prostate-specific antigen (PSA) response rate. Secondary endpoints included time-to-PSA-progression-free survival (PSA-PFS), time-to-clinical/radiographic-PFS, objective response rate (ORR), PFS lasting greater than 24 weeks, and overall survival (OS). Results Thirty patients were treated with ipilimumab plus nivolumab (N = 15, Cohort 1, previously reported), or ipilimumab plus nivolumab and enzalutamide (N = 15, Cohort 2) in patients previously progressing on enzalutamide monotherapy. PSA response rate was 2/15 (13%) in cohort 1 and 0/15 in cohort 2, ORR was 2/8 (25%) in Cohort 1 and 0/9 in Cohort 2 in those with measureable disease, median PSA-PFS was 3.0 (95% confidence interval [CI]: 2.1-NR) in cohort 1 and 2.7 (95% CI: 2.1-5.9) months in cohort 2, and median PFS was 3.7 (95% CI: 2.8-7.5) in cohort 1 and 2.9 (95% CI: 1.3-5.8) months in cohort 2. Three of 15 patients in cohort 1 (20%, 95% CI: 7.1%-45.2%) and 4/15 patients (26.7%, 95% CI: 10.5%-52.4%) in cohort 2 achieved a durable PFS lasting greater than 24 weeks. Median OS was 8.2 (95% CI: 5.5-10.4) in cohort 1 and 14.2 (95% CI: 8.5-NA) months in cohort 2. Efficacy results were not statistically different between cohorts. Grade-3/4 adverse events occurred in 7/15 cohort 1 patients (46%) and 8/15 cohort 2 patients (53%). Combined cohort (N = 30) baseline alkaline phosphatase and cytokine analysis suggested improved OS for patients with lower alkaline phosphatase (hazards ratio [HR], 0.30; 95% CI: 0.11-0.82), lower circulating interleukin-7 (IL-7) (HR, 0.24; 95% Cl: 0.06-0.93) and IL-6 (HR, 0.13; 95% Cl: 0.03-0.52) levels, and higher circulating IL-17 (HR, 4.53; 95% CI: 1.47-13.93) levels. There was a trend towards improved outcomes in men with low sPD-L1 serum levels. Conclusion Nivolumab plus ipilimumab demonstrated only modest activity in patients with AR-V7-expressing prostate cancer, and was not sufficient to justify further exploration in unselected patients. Stratification by baseline alkaline phosphatase and cytokines (IL-6, -7, and -17) may be prognostic for outcomes to immunotherapy.

Purpose: Positron emission tomography (PET) with small molecules targeting prostate-specific membrane antigen (PSMA) is being adopted as a clinical standard for prostate cancer (PCa) imaging. In this study, we evaluated changes in uptake on PSMA-targeted PET in men starting abiraterone or enzalutamide. Methods: This prospective, single-arm, two-center, exploratory clinical trial enrolled men with metastatic castration-resistant prostate cancer (CRPC) initiating abiraterone or enzalutamide. Each patient was imaged with 18F-DCFPyL at baseline and within 2-4 months after starting therapy. Patients were followed for up to 48 months from enrollment. A central review evaluated baseline and follow-up PET scans recording change in maximum standardized uptake value (SUVmax) at all disease sites and classifying the pattern of change. Two parameters: the delta percent SUVmax (DPSM) of all lesions and the delta absolute SUVmax (DASM) of all lesions were derived. Kaplan-Meier curves were used to estimate time to therapy change (TTTC) and overall survival (OS). Results: Sixteen evaluable patients were accrued to the study. Median TTTC was 9.6 months (95% confidence interval (CI), 6.9-14.2) and median OS was 28.6 months (95% CI 18.3-not available (N/A)). Patients with a mixed-but-predominantly-increased pattern of radiotracer uptake had shorter TTTC and OS. Men with low DPSM had median TTTC 12.2 months (95% CI 11.3-N/A) and median OS 37.2 months (95% CI 28.9-N/A), while those with high DPSM had median TTTC 6.5 months (95% CI 4.6-N/A, P = 0.0001) and median OS 17.8 months (95% CI 13.9-N/A, P = 0.02). Men with low DASM had median TTTC 12.2 months (95% CI 11.3-N/A) and median OS N/A (95% CI 37.2 months-N/A), while those with high DASM had median TTTC 6.9 months (95% CI 6.1-N/A, P = 0.003) and median OS 17.8 months (95% CI 13.9-N/A, P = 0.002). Conclusion: Findings on PSMA-targeted PET 2-4 months after initiation of abiraterone or enzalutamide are associated with TTTC and OS. Development of new lesions and/or increasing intensity of radiotracer uptake at sites of baseline disease are poor prognostic findings suggesting shorter TTTC and OS.

Background Cyclical, high-dose testosterone administration, termed bipolar androgen therapy (BAT), can induce clinical responses and restore sensitivity to androgen signalling inhibition in patients with previously treated castration-resistant prostate cancer (PCa) (CRPC). This trial evaluated whether BAT is a safe and effective first-line hormonal therapy for patients with CRPC. Patients and Methods In cohort C of this single-centre, open-label, phase II, multi-cohort trial (RE-sensitizing with Supraphysiologic Testosterone to Overcome REsistance study), 29 patients with CRPC received first-line hormonal therapy with 400 mg of testosterone cypionate intramuscularly every 28 days concurrent with a luteinising hormone-releasing hormone agonist/antagonist. The primary end-point of the study was the PSA50 response rate to BAT treatment. Results After treatment with BAT, four of 29 patients (14%; 95% confidence interval [CI]: 4–32%) experienced a PSA50 response. The median radiographic progression-free survival to BAT was 8.5 months (95% CI: 6.9–15.1) for patients with metastatic CRPC. After progression on BAT, 17 of 18 patients (94%; 95% CI: 73–100%) achieved a PSA50 response and 15 of 18 patients (83%; 95% CI: 59–96) achieved a PSA90 response on abiraterone or enzalutamide. Twelve of 15 patients (80%; 95% CI: 52–96) with metastatic CRPC remain on abiraterone or enzalutamide with a median duration of follow-up of 11.2 months. Conclusion As first-line hormonal treatment for CRPC, BAT was well tolerated and resulted in prolonged disease stabilisation. After progression on BAT, patients had favourable responses to second-generation androgen receptor–targeted therapy. Trial Registration ClinicalTrials.gov NCT02090114

Rationale: Bipolar androgen therapy (BAT) is an emerging treatment for metastatic castration resistant prostate cancer (mCRPC). 18F-DCFPyL is a small-molecule positron emission tomography (PET) radiotracer targeting prostate-specific membrane antigen (PSMA). We analyzed the utility of 18F-DCFPyL PET/CT in determining clinical response to BAT. Methods: Six men with mCRPC receiving BAT were imaged with 18F-DCFPyL PET/CT at baseline and after 3 months of treatment. Progression by PSMA-targeted PET/CT was defined as the appearance of any new 18F-DCFPyL-avid lesion. Results: Three of 6 (50%) patients had progression on 18F-DCFPyL PET/CT. All three had stable disease or better on contemporaneous conventional imaging. Radiographic progression on CT and/or bone scan was observed within 3 months of progression on 18F-DCFPyL PET/CT. For the 3 patients that did not have progression on 18F-DCFPyL PET/CT, radiographic progression was not observed for > 6 months. Conclusion: New radiotracer-avid lesions on 18F-DCFPyL PET/CT in men with mCRPC undergoing BAT can indicate early progression.

PURPOSE: Prostate specific membrane antigen targeted (18)F-DCFPyL positron emission tomography/computerized tomography may offer superior image quality and sensitivity for the detection of biochemically recurrent prostate cancer. We examined the association of Gleason sum, serum prostate specific antigen and prostate specific antigen doubling time with any detectable and pelvic confined disease in patients with biochemically recurrent prostate cancer. MATERIALS AND METHODS: Data from 108 patients with biochemically recurrent prostate cancer after radical prostatectomy who underwent prostate specific membrane antigen targeted (18)F-DCFPyL positron emission tomography/computerized tomography were analyzed. Data were collected on positive positron emission tomography findings as well as pelvic confined disease. Associations between Gleason sum, prostate specific antigen and prostate specific antigen doubling time were retrospectively explored. RESULTS: Serum prostate specific antigen was associated with positive prostate specific membrane antigen targeted imaging as continuous (OR 3.08, 95% CI 1.60–7.95, p=0.005) and categorical values (ie prostate specific antigen greater than 2.0 to 5.0 vs 0.5 ng/ml or less, OR 16.92, 95% CI 3.13–315.81, p=0.008). No relationship between Gleason sum or prostate specific antigen doubling time with overall positive imaging was observed. Patients with a prostate specific antigen greater than 2.0 to 5.0 ng/ml were significantly less likely to be diagnosed with pelvic confined disease compared with the 0.5 ng/ml or less subgroup (OR 0.21, 95% CI 0.06–0.69, p=0.013). A prostate specific antigen doubling time of 9 months or more (OR 4.20, 95% CI 1.57–11.89, p=0.005) or prostate specific antigen doubling time of 12 months or more (OR 3.03, 95% CI 1.12–8.76, p=0.033) was significantly associated with pelvic confined disease. No relationship between Gleason sum and pelvic confined disease was observed. CONCLUSIONS: Absolute prostate specific antigen was positively associated with the presence of findings on prostate specific membrane antigen targeted imaging and negatively associated with pelvic confined disease. Prostate specific antigen doubling time did not predict for overall disease detection, but long prostate specific antigen doubling times were associated with pelvic confined prostate cancer.

Purpose: Metastasis-directed therapy (MDT) is increasingly used in castration-sensitive oligometastatic prostate cancer because it prolongs progression-free survival (PFS) and androgen deprivation free survival. Here we describe patterns of recurrence and identify modes of progression after MDT using SABR. Methods and Materials: Two hundred fifty-eight patients with castration-sensitive oligometastatic prostate cancer (≤5 lesions at staging) were retrospectively identified from a multi-institutional database. Descriptive patterns of recurrence and modes of progression were reported. Other outcomes including median time to prostate-specific antigen (PSA) recurrence, time to next intervention, distant metastasis–free survival, overall survival, and biochemical PFS (bPFS) were reported. Survival analysis was performed using the Kaplan-Meier method, and multivariable analysis was performed. Results: Median follow-up was 25.2 months, and 50.4% of patients received concurrent androgen deprivation. Median time to PSA recurrence was 15.7 months, time to next intervention was 28.6 months, distant metastasis–free survival was 19.1 months, and bPFS was 16.1 months. Two-year overall survival was 96.8%. On multivariable analysis, factors associated with bPFS included age (hazard ratio [HR], 1.03; P = .04), N1 disease at diagnosis (HR, 2.00; P = .02), M1 disease at diagnosis (HR, 0.44; P = .01), initial PSA at diagnosis (HR, 1.002; P = 3 lesions]) occurring in 23.1% of patients. Conclusions: After MDT, the majority of patients have long-term control or oligoprogression (class I or II). Recurrence tended to occur in osseous sites. These findings, if validated, have implications for future integration of MDT and clinical trial design.

BACKGROUND: Small cell neuroendocrine carcinoma (SCNC) of the prostate is an aggressive subtype with frequent TP53 mutation and RB1 inactivation, however the molecular phenotype remains an area of investigation. Here, we compared telomere lengths in prostatic SCNC and usual-type prostatic adenocarcinoma (AdCa). METHODS: We studied 32 cases of prostatic SCNC (including 11 cases with concurrent AdCa) and 347 cases of usual-type AdCa on tissue microarrays. Telomere lengths in tumor cells were qualitatively compared to that in normal cells using a telomere-specific fluorescence in situ hybridization assay. ERG, PTEN and TP53 status were assessed in a proportion of cases using genetically validated immunohistochemistry protocols. Clinical-pathologic and molecular characteristics of cases were compared between telomere groups using the chi-square test. RESULTS: A significantly higher proportion of prostatic SCNC cases (50%, 16/32) showed normal/long telomeres compared to AdCa cases (11%, 39/347; p

Background Metastasis directed therapy (MDT) for patients with oligometastatic disease is associated with improvements in progression free survival (PFS) and overall survival (OS) compared to systemic therapy alone. Additionally, within a prostate-cancer-specific cohort, MDT is able to forestall initiation of androgen deprivation therapy (ADT) in men with hormone-sensitive, oligometastatic prostate cancer (HSOPCa) compared to observation. While MDT appears to be safe and effective in HSOPCa, a large percentage of men will eventually have disease recurrence. Patterns of failure in HSOPCa demonstrate patients tend to have recurrence in the bone following MDT, raising the question of sub-clinically-apparent osseous disease. Radium-223 dichloride is a radiopharmaceutical with structural similarity to calcium, allowing it to be taken up by bone where it emits alpha particles, and therefore might have utility in the treatment of micrometastatic osseous disease. Therefore, the primary goal of the phase II RAVENS trial is to evaluate the efficacy of MDT + radium-223 dichloride in prolonging progression free survival in men with HSOPCa. Methods Patients with HSOPCa and 3 or less metastases with at least 1 bone metastasis will be randomized 1:1 to stereotactic ablative radiation (SABR, also known as stereotactic body radiation therapy (SBRT)) alone vs SABR + radium-223 dichloride with a minimization algorithm to balance assignment by institution, primary intervention, prior hormonal therapy, and PSA doubling time. SABR is delivered in one to five fractions and patients in the SABR + radium-223 dichloride arm will receive six infusions of radium-223 dichloride at four-week intervals. The primary end point is progression free survival. The secondary clinical endpoints include toxicity and quality of life assessments, local control at 12 months, locoregional progression, time to distant progression, time to new metastasis, and duration of response. Discussion The RAVENS trial will be the first described phase II, non-blinded, randomized study to compare SABR +/− radium-223 dichloride in patients with HSOPCa and 3 or less metastases with at least one bone metastasis. The primary hypothesis is that SABR + radium-223 dichloride will increase median progression-free survival from 10 months in the SABR arm to 20 months in the SABR + radium-223 dichloride arm. Trial registrations Clinicaltrials.gov. Identifier: NCT04037358. Date of Registration: July 30, 2019. Date of First Participant Enrolled: August 9, 2019. Date of Last Approved Amendment: October 16, 2019. Protocol Version: Version 5.

Background There is a discussion about the optimal timing to initiate or switch treatment in metastatic castration-resistant prostate cancer (mCRPC). This post hoc analysis of 3 large trials for men with mCRPC examined the influence of the type of progression at initiation of first-line chemotherapy, as well as the type of progression during treatment, on treatment outcomes. Methods Data from the phase III studies VENICE (n = 1224), TAX327 (n = 1006) and FIRSTANA (n = 1168) were used as independent data sets. Type of progression was defined as follows: prostate-specific antigen (PSA) only (group 1), radiological (±PSA) (group 2) or pain (±PSA, ± radiological) progression (group 3). The impact of baseline type of progression on overall survival (OS) was evaluated in multivariate Cox regression analysis with backward elimination, stratified for the Eastern Cooperative Oncology Group performance score and treatment arm. Results The median OS (arms combined) from treatment initiation in VENICE was 28.6, 26.3 and 16.9 months for G1, G2 and G3, respectively (hazard ratio: 1.14 [95% confidence interval {CI}: 0.92–1.41%] in G2 and 2.13 [95% CI: 1.75–2.59%] in G3 compared with G1). Multivariate analysis (arms combined) showed that pain progression at baseline was an independent predictor of poor OS. Similar findings were observed in the TAX327 and FIRSTANA data sets. During treatment, pain or radiological progression preceded PSA progression in ~55% of the patients. The retrospective characteristic of this study is a limitation. Conclusions The type of progression at baseline strongly predicts OS in men with mCRPC treated with first-line chemotherapy. During treatment, pain and/or radiological progression preceded PSA progression as the first progression event in ~55% of the patients. This finding has the prospect to be incorporated in clinical guidelines and to be practice changing because it implies the need for regular imaging and not to rely on PSA progression alone.

In patients with prostate cancer (PC) receiving prostate-specific membrane antigen- (PSMA-) targeted radioligand therapy (RLT), higher baseline standardized uptake values (SUVs) are linked to improved outcome. Thus, readers deciding on RLT must have certainty on the repeatability of PSMA uptake metrics. As such, we aimed to evaluate the test-retest repeatability of lesion uptake in a large cohort of patients imaged withIn this prospective, IRB-approved trial (NCT03793543), 21 patients with history of histologically proven PC underwent twoIn total, 230 pairs of lesions (177 bone, 38 LN, and 15 other) were delineated, demonstrating a wide range of SUVIn this prospective test-retest setting, SUV parameters demonstrated high repeatability, in particular in LNs, while volumetric parameters demonstrated low repeatability. Further, the large number of lesions and wide distribution of SUVs included in this analysis allowed for the demonstration of a dependence of repeatability on SUV, with higher SUVs having more robust repeatability.

Background: Emerging data suggest that metastasis is a spectrum of disease burden rather than a binary state, and local therapies, such as radiation, might improve outcomes in oligometastasis. However, current definitions of oligometastasis are solely numerical. Objective: To characterize the somatic mutational landscape across the disease spectrum of metastatic castration-sensitive prostate cancer (mCSPC) to elucidate a biological definition of oligometastatic CSPC. Design, setting, and participants: This was a retrospective study of men with mCSPC who underwent clinical-grade sequencing of their tumors (269 primary tumor, 25 metastatic sites). Patients were classified as having biochemically recurrent (ie, micrometa-static), metachronous oligometastatic (5 lesions), or de novo metastatic (metastasis at diagnosis) disease. Outcome measurements and statistical analysis: We measured the frequency of driver mutations across metastatic classifications and the genomic associations with radiographic progression-free survival (rPFS) and time to castrate-resistant prostate cancer (CRPC). Results and limitations: The frequency of driver mutations in TP53 (p = 0.01), WNT (p = 0.08), and cell cycle (p = 0.04) genes increased across the mCSPC spectrum. TP53 mutation was associated with shorter rPFS (26.7 vs 48.6 mo; p = 0.002), and time to CRPC (95.6 vs 155.8 mo; p = 0.02) in men with oligometastasis, and identified men with polymetastasis with better rPFS (TP53 wild-type, 42.7 mo; TP53 mutated, 18.5 mo; p = 0.01). Mutations in TP53 (incidence rate ratio [IRR] 1.45; p = 0.004) and DNA double-strand break repair (IRR 1.61; p < 0.001) were associated with a higher number of metastases. Mutations in TP53 were also independently associated with shorter rPFS (hazard ratio [HR] 1.59; p = 0.03) and the development of CRPC (HR 1.71; p = 0.01) on multivariable analysis. This study was limited by its retrospective nature, sample size, and the use of commercially available sequencing platforms, resulting in a limited predefined set of genes examined. Conclusions: Somatic mutational profiles reveal a spectrum of metastatic biology that helps in redefining oligometastasis beyond a simple binary state of lesion enumeration. Patient summary: Oligometastatic prostate cancer is typically defined as less than three to five metastatic lesions and evidence suggests that using radiation or surgery to treat these sites improves clinical outcomes. As of now, treatment decisions for oligometastasis are solely defined according to the number of lesions. However, this study suggests that tumor mutational profiles can provide a biological definition of oligometastasis and complement currently used numerical definitions. (C) 2021 The Authors. Published by Elsevier B.V. on behalf of European Association of Urology.

Since 2004, eight therapeutic agents have received approval from the Food and Drug Administration for the treatment of men with advanced prostate cancer. Four are androgen-signaling–targeted inhibi...

Background Poly ADP-ribose polymerase (PARP) inhibitors, such as olaparib, are being explored as a treatment option for metastatic castration-resistant prostate cancer (mCRPC) in men harboring mutations in homologous recombination DNA-repair genes. Whether responses to PARP inhibitors differ according to the affected gene is currently unknown. Objective To determine whether responses to PARP inhibitors differ between men with BRCA1/2 and those with ATM mutations. Design, setting, and participants This was a multicenter retrospective review of 23 consecutive men with mCRPC and pathogenic germline and/or somatic BRCA1/2 or ATM mutations treated with olaparib at three academic sites in the USA. Outcome measurements and statistical analysis The proportion of patients achieving a ≥50% decline in prostate-specific antigen (PSA50 response) was compared using Fisher's exact test. Clinical and radiographic progression-free survival (PFS) and overall survival were estimated using Kaplan-Meier analyses and compared using the log-rank test. Results and limitations The study included two men with BRCA1 mutations, 15 with BRCA2 mutations, and six with ATM mutations. PSA50 responses to olaparib were achieved in 76% (13/17) of men with BRCA1/2 versus 0% (0/6) of men with ATM mutations (Fisher's exact test; p = 0.002). Patients with BRCA1/2 mutations had median PFS of 12.3 mo versus 2.4 mo for those with ATM mutations (hazard ratio 0.17, 95% confidence interval 0.05–0.57; p = 0.004). Limitations include the retrospective design and relatively small sample size. Conclusions Men with mCRPC harboring ATM mutations experienced inferior outcomes to PARP inhibitor therapy compared to those harboring BRCA1/2 mutations. Alternative therapies should be explored for patients with ATM mutations. Patient summary Mutations in BRCA1/2 and ATM genes are common in metastatic prostate cancer. In this study we compared outcomes for men with BRCA1/2 mutations to those for men with ATM mutations being treated with olaparib. We found that men with ATM mutations do not respond as well as men with BRCA1/2 mutations.

BACKGROUND: Isolated pulmonary involvement is uncommon in metastatic hormone-sensitive prostate cancer (mHSPC). To characterize outcomes and molecular alterations of this unique patient subset, we conducted a retrospective review of patients with hormone-naïve prostate cancer presenting with lung-only metastases. METHODS: This was a retrospective single-institution study. Medical records of 25 patients presenting with pulmonary-only metastases before receiving androgen deprivation therapy (ADT) were analyzed. Germline and/or somatic genomic results, where available (n = 16), were documented. Tumor tissue was analyzed using clinical-grade next-generation DNA sequencing assays. Clinical endpoints included complete prostate-specific antigen (PSA) response to ADT (

Background Pathogenic mutations in genes mediating homologous recombination (HR) DNA repair are present in 20–30% of men with metastatic castrate-resistant prostate cancer (mCRPC). Radium-223 is a bone-seeking α-emitter that induces double-strand DNA breaks, thereby killing cancer cells in the bone microenvironment. Objective To evaluate the potential impact of germline or somatic HR-deficiency (HRD) mutations on radium-223 efficacy in mCRPC with bone metastasis. Design, setting, and participants This is a retrospective single-institution study. Medical records of 190 mCRPC patients for whom germline and/or somatic DNA sequencing data were available were reviewed. Of these patients, 28 had received standard-of-care radium-223 at Johns Hopkins between February 2013 and February 2018. Outcome measurements and statistical analysis Alkaline phosphatase (ALP) responses and time-to-ALP-progression were the coprimary endpoints. Prostate-specific antigen (PSA) responses, overall survival (OS), and time to next systemic therapy were also evaluated. Results and limitations Of the 28 patients included, 10 men (35.7%) had a germline/somatic HRD mutation (three in BRCA2, and one each in ATM, ATR, CHEK2, FANCG, FANCI, FANCL, and PALB2) and 18 (64.3%) did not. Men with HRD mutations (HRD+) had numerically lower ages (66 vs 73yr, p=0.25), more soft-tissue metastases (50% vs 38%, p=0.43), and higher baseline ALP levels (130 vs 108 U/l, p=0.84). Compared with HRD(–) men, HRD(+) patients showed greater ALP responses (80% vs 39%, p=0.04), longer time to ALP progression (median10.4 vs 5.8mo, hazard ratio [HR] 6.4, p=0.005), and a trend toward longer OS (median 36.9 vs 19.0mo, HR 3.3, p=0.11). PSA responses (0% vs 0%, p>0.99) and time to next systemic therapy (HR 1.5, p=0.39) were similar between the two groups. Results are limited by the retrospective nature of the analysis and the small sample size. Conclusions In this exploratory study, bone-metastatic CRPC patients with inactivating HRD mutations demonstrated significantly improved ALP responses and time to ALP progression. These results should motivate prospective validation of the "synthetic lethality" hypothesis between HRD mutations and radium-223 activity. Patient summary In this report, we retrospectively examined outcomes to metastatic prostate cancer in patients with and without DNA repair mutations who received radium-223, a therapy that kills cancer cells by causing direct DNA damage. Our study suggested that patients who have inherited or acquired DNA repair gene mutations derived greater benefit from radium-223 when compared with patients without these mutations. We concluded that radium-223 might have an important role in this setting; however, prospective studies are needed to confirm whether DNA repair mutations truly make radium-223 work better or not.

Summary The makeup of the tumor immune microenvironment may be associated with tumor somatic genomic alterations and plays a key role in tumor progression and response to immunotherapy. We examined the association of tumor-infiltrating T-cell density with TP53 status in surgically treated primary prostate cancer using 3 independent tissue microarray sets, including one set of tumors from grade-matched patients of European American or African American ancestry (n = 391), a retrospective case-cohort of intermediate- and high-risk patients enriched for adverse outcomes (n = 267), and a set of tumors with primary Gleason pattern 5 (n = 77). The presence of TP53 missense mutation, indicated by p53 nuclear accumulation using a genetically validated assay, was significantly associated with increased CD3+ T-cell density (median, 341 versus 231 CD3+ T cells/mm2; P = .004) in the matched European American and African American ancestry patient sets. The same association was present in patients of both ancestries when analyzed separately, despite the fact that p53 nuclear accumulation was less frequent among African American compared with European American tumors (7% versus 3%, P = .2). The validation cohorts of intermediate/high-risk and primary Gleason pattern 5 patients corroborated the association of increased CD3+ T-cell density with presence of p53 nuclear accumulation. In a pooled analysis of all sets, adjusting for clinicopathological variables, CD3+ and CD8+, but not FOXP3+, T-cell densities remained significantly higher in tumors with p53 nuclear accumulation compared with those without. TP53 mutation is associated with higher tumor-infiltrating T-cell density, which may be relevant in future clinical trials of immunotherapy in prostate cancer.

Purpose Several studies have reported that among patients with localized prostate cancer, black men have a shorter overall survival (OS) time than white men, but few data exist for men with advanced prostate cancer. The primary goal of this analysis was to compare the OS in black and white men with metastatic castration-resistant prostate cancer (mCRPC) who were treated in phase III clinical trials with docetaxel plus prednisone (DP) or a DP-containing regimen. Methods Individual participant data from 8,820 men with mCRPC randomly assigned in nine phase III trials to DP or a DP-containing regimen were combined. Race was based on self-report. The primary end point was OS. The Cox proportional hazards regression model was used to assess the prognostic importance of race (black v white) adjusted for established risk factors common across the trials (age, prostate-specific antigen, performance status, alkaline phosphatase, hemoglobin, and sites of metastases). Results Of 8,820 men, 7,528 (85%) were white, 500 (6%) were black, 424 (5%) were Asian, and 368 (4%) were of unknown race. Black men were younger and had worse performance status, higher testosterone and prostate-specific antigen, and lower hemoglobin than white men. Despite these differences, the median OS was 21.0 months (95% CI, 19.4 to 22.5 months) versus 21.2 months (95% CI, 20.8 to 21.7 months) in black and white men, respectively. The pooled multivariable hazard ratio of 0.81 (95% CI, 0.72 to 0.91) demonstrates that overall, black men have a statistically significant decreased risk of death compared with white men ( P < .001). Conclusion When adjusted for known prognostic factors, we observed a statistically significant increased OS in black versus white men with mCRPC who were enrolled in these clinical trials. The mechanism for these differences is not known.

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

5049 Background: Sabizabulin is a novel oral cytoskeleton disruptor being developed for use in metastatic castration resistant prostate cancer (mCRPC). A Phase 1b/2 clinical study was conducted to establish the maximum tolerated dose (MTD) and evaluate the preliminary efficacy in men with mCRPC resistant to androgen receptor targeting agents. Methods: The Phase 1b portion of the study in 39 men utilized escalating and expanding dose and duration. The Phase 2 portion studied 41 men with mCRPC at the recommended Phase 2 dose of 63 mg daily. Efficacy was assessed by bone/CT scans. A final analysis of the safety and efficacy data including the primary endpoint, the median progression-free survival was conducted. Results: Although the MTD was not reached in the Phase 1b, the recommended Phase 2 dose was set at 63 mg/day to maximize GI tolerability. The most common adverse events (> 10% frequency) at the 63 mg oral daily dosing (combined Phase 1b/2 data) were predominantly Grade 1-2. Grade ³3 events included diarrhea (7.4%), fatigue (5.6%) and ALT/AST elevations (5.6% and 3.7%, respectively). Neurotoxicity and neutropenia were not observed. Preliminary efficacy data in patients treated with ≥1 continuous cycle (21 days) of 63 mg or higher (n = 55) included an objective response rate of 6/29 (20.7%) in patients with measurable disease (1 complete, 5 partial). 14/48 (29.2%) of the patients had PSA declines. The Kaplan-Meier median radiographic progression-free survival was estimated to be 11.4 months (95% C.I. 29.63-65.79) (n = 55). Durable responses lasting > 2.75 years were observed with 14.5% (8/55) demonstrating a response greater than 12 months. Conclusions: This clinical trial demonstrated that chronic oral daily dosing of sabizabulin has a favorable safety profile with significant preliminary cytotoxic and cytostatic antitumor activity. These data support the ongoing Phase 3 VERACITY trial of sabizabulin in men with mCRPC who have progressed on an androgen receptor targeting agent. Clinical trial information: NCT03752099.

5012 Background: We sought to investigate whether enzalutamide (ENZA) treatment, without androgen deprivation therapy, increases freedom-from-PSA-progression (FFPP) when combined with salvage radiation therapy (SRT) in men with recurrent prostate cancer post-radical prostatectomy (RP). Methods: Men with biochemically recurrent prostate cancer after RP were enrolled into a randomized, double-blind, phase II, placebo-controlled, multicenter study of SRT + placebo vs SRT + ENZA. The randomization (1:1) was stratified by center, surgical margin status (R0 vs R1), PSA prior to salvage treatment (PSA ≥0.5 vs < 0.5 ng/mL), and pathologic Gleason sum (7 vs 8-10) using a minimization algorithm. Following randomization, patients received either placebo or ENZA 160 mg PO once daily for 6 months. Following 2 months of study drug therapy, external beam radiotherapy to 66.6-70.2 Gy was administered to the prostate bed (no pelvic nodes). The primary endpoint was FFPP. The trial design was powered for a HR 0.44 FFPP benefit with intended enrollment of 96 subjects and was closed as planned to enrollment on March 2020 short of that goal. Secondary endpoints were time to local recurrence (LR) within the radiation field, metastasis‐free survival (MFS), and safety as determined by frequency and severity of adverse events (AEs). Results: A total of 86 patients were randomized with a median follow-up of 34 (range 0-52) months. The median pre-SRT PSA was 0.3 (range 0.06-4.6) ng/mL, 56/86 (65%) had extra-prostatic disease (pT3), 39/86 (45%) had Gleason Grade Group 4 or higher and 43/96 (50%) had positive surgical margins. Trial arms were well balanced. FFPP was significantly improved with ENZA vs placebo, for example 2-year FFPP was 87.1% vs 68.1%, respectively, and overall with a HR 0.40 [95% confidence interval (CI), 0.17-0.92, p-value = 0.026]. Subgroup analyses demonstrate differential benefit (p-value of interaction = 0.031) of ENZA in men with pT3 (HR 0.19, 95%CI 0.05-0.67) vs pT2 disease (HR 1.29, 95%CI 0.34-4.81). There were insufficient secondary endpoint events for analysis. The most common adverse events were grade 1-2 fatigue (13% ENZA vs 9%) and urinary frequency (6 % ENZA vs 8%). Conclusions: SRT plus ENZA monotherapy for men with PSA recurrent high-risk prostate cancer following RP is safe and delays PSA progression relative to SRT alone. The impact of ENZA on distant metastasis or survival is unknown at this time. Additional molecular biomarker analyses are being pursued. Clinical trial information: NCT02203695.

PURPOSE: There were 3 recent U.S. Food and Drug Administration approvals for drugs to be used in nonmetastatic castration resistant prostate cancer, a state that arises from the unproven start of continuous androgen deprivation therapy (ADT) for biochemical recurrent prostate cancer (BCR), before metastatic disease is evident. This report examines the outcome of men with BCR who defer ADT until time of metastasis. MATERIALS AND METHODS: Retrospective review of men diagnosed with clinically localized prostate cancer who underwent radical prostatectomy at Johns Hopkins Hospital and Walter Reed National Military Medical Center and developed BCR with a prostate specific antigen doubling time of not more than 10 months (806 patients). The primary end points were metastasis-free survival and overall survival from time of local treatment among men who delayed ADT until time of metastasis. RESULTS: The median metastasis-free survival of men with BCR and a prostate specific antigen doubling time

Background: In the PROSELICA phase III trial (NCT01308580), cabazitaxel 20 mg/m2 (CABA20) was non-inferior to cabazitaxel 25 mg/m2 (CABA25) in mCRPC patients previously treated with docetaxel (DOC). The present post hoc analysis evaluates how the type of progression at randomization affected outcomes. Methods: Progression type at randomization was defined as follows: PSA progression only (PSA-p, no radiological progression (RADIO-p), no pain), RADIO-p (±PSA-p, no pain), or pain progression (PAIN-p, ±PSA-p, ±RADIO-p). Relationships between progression type and overall survival (OS), radiological progression-free survival (rPFS), and PSA response (confirmed PSA decrease ≥ 50%) were analyzed. Results: All randomized patients (n = 1200) had received prior DOC, and 25.7% had received prior abiraterone or enzalutamide. Progression type at randomization was evaluable in 1075 patients (PSA-p = 24.4%, RADIO-p = 20.8%, PAIN-p = 54.8%). Pain progression was associated with clinical and biological features of aggressive disease. Median OS from CABA initiation or date of mCRPC diagnosis, all arms combined, was shorter in the PAIN-p group than in the RADIO-p or the PSA-p groups (12.0 versus 16.8 and 18.4 months, respectively, p &lt, 0.001). In multivariate analysis, all arms combined, PAIN-p was an independent predictor of poor OS (HR = 1.44, p &lt, 0.001). PSA response, rPFS, and OS were numerically higher with CABA25 versus CABA20 in patients with PAIN-p. Conclusions: This post hoc analysis of the PROSELICA phase III study shows that pain progression at initiation of CABA in mCRPC patients previously treated with DOC is associated with a poor prognosis. Disease progression should be carefully monitored, even in the absence of PSA rise.