Citations

PURPOSE The continuous development of new imaging approaches, molecular phenotyping, genetic subtypes, prognosis assessments, and effective therapies across a range of disease states has created a need to redefine terminology and best practices for clinical trial conduct in patients with advanced prostate cancer. Methods We convened an international expert committee of diverse working groups, the Prostate Cancer Working Group 4 (PCWG4), between 2016 and 2025. Our objective was to formulate updated criteria based on emerging evidence and clinical trial data in a biomarker context to provide guidance for clinical trial design, eligibility, and end point assessments for patients with advanced prostate cancer. RESULTS PCWG4 redefines terminology around the disease state and previous therapies in a patient-centric context and terminology focused on androgen pathway modulation. We consider imaging, with a particular focus on positron emission tomography (PET)–defined disease. New recommendations are provided for disease state terminology, defining eligibility criteria, response and delay/prevent end points, intervals for reassessments including imaging, and patient-reported outcome determination. We provide recommendations in a biomarker-based context of use for the intended indication, reflective of patient benefit for specific interventions. We emphasize the need for development of validated PET imaging and molecular and phenotypic criteria as well as trial designs to appropriately risk stratify patients, predict and assess benefit, and measure post-treatment outcomes reliably in a trial framework. CONCLUSION PCWG4 updates recommendations on patient and tumor characterization, therapy development, and imaging criteria and extends guidance into earlier androgen pathway modulator–naïve/sensitive disease states to reflect an evolving, heterogeneous, and diverse patient population to optimize treatment benefits for all patients.

Indications for and implications of germline genetic testing (GGT) in patients with prostate cancer have expanded over the past decade, particularly related to precision therapies and management. GGT has become the standard of care for many cancers such as breast, ovarian, colorectal, pancreatic, and metastatic prostate cancer, and it is imperative that patients be offered timely and equitable access to testing as it can inform patient-physician shared decision making for management of the current cancer as well as anticipatory guidance for disease progression. Additionally, GGT guides screening for and prevention of secondary malignancies for the patient and cascade testing for at-risk family members. Here, we present data supporting the notion that clinicians should offer all patients with prostate cancer the opportunity to undergo comprehensive GGT for pathogenic germline variants known to be associated with familial cancer and/or known to have implications for treatment and management.

AbstractCurrent US clinical practice guidelines for advanced prostate cancer management contain recommendations based on high‐level evidence from randomized controlled trials; however, these guidelines do not address the nuanced clinical questions that are unanswered by prospective trials but nonetheless encountered in day‐to‐day practice. To address these practical questions, the 2024 US Prostate Cancer Conference (USPCC 2024) was created to generate US‐focused expert clinical decision‐making guidance for circumstances in which level 1 evidence is lacking. At the second annual USPCC meeting (USPCC 2024), a multidisciplinary panel of experts convened to discuss ongoing clinical challenges related to 5 topic areas: biochemical recurrence; metastatic, castration‐sensitive prostate cancer; poly [ADP‐ribose] polymerase inhibitors; prostate‐specific membrane antigen radioligand therapy; and metastatic, castration‐resistant prostate cancer. Through a modified Delphi process, 34 consensus recommendations were developed and are intended to provide clinicians who manage prostate cancer with guidance related to the implementation of novel treatments and technologies. In this report, the authors review the areas of consensus identified by the USPCC 2024 experts and evaluate ongoing unmet needs regarding translational application of the current clinical evidence.

4574 Background: Mutations of COMPASS-related proteins KMT2D, KMT2C, and KDM6A are observed in 66% of advanced urothelial carcinomas (UC). In vivo, the administration of tazemetostat, an enzymatic EZH2 inhibitor (EZH2i), reduced tumor burden and enhanced the immune response in animal models of UC. We hypothesized that tazemetostat might improve response to immunotherapy in advanced UC. Methods: ETCTN 10183 (NCT03854474) is a multicenter pilot study evaluating the safety and efficacy of tazemetostat 800 mg BID+ pembrolizumab 200 mg given every three weeks for up to two years in patients (pts) with platinum-refractory (Arm A) or cisplatin/chemo-ineligible advanced UC (Arm B). The primary objective was to identify the recommended phase two dose (RP2D) of tazemetostat in combination with pembrolizumab. Secondary objectives included safety, response rate, and progression-free survival. Translational objectives included determining tumor mutational burden in COMPASS-related genes, tumor subtyping, TCR clonality, T cell infiltration, and PDL-1 expression. Results: There were no dose-limiting toxicities in the safety lead-in phase (n=6 pts), and the RP2D for tazemetostat was established at 800 mg BID. Baseline characteristics for Arm A N=12, Arm B N=13: 72% males; 96% white, 4% Black; 88% ECOG PS 0-1; 88% had bladder primary, 20% Stage III, 72% stage IV; 80% had visceral or bone metastases. The median number of cycles was 5 in Arm A (range 1-35) and 4 in Arm B (range 2-12). Treatment related G3/4 adverse events (AEs) were observed in 8 patients, most common were anemia and lymphopenia (n=2 each). Treatment related G1/2 AEs included nausea (n=6); skin and subcutaneous tissue disorders (n=3); anemia, lymphopenia, and thrombocytopenia (n=2 each). Among evaluable patients (n=10 in each arm), partial response rate was: Arm A 30%, Arm B 20%; stable disease: Arm A 30%, Arm B 30%; and progressive disease: Arm A 30%, Arm B 20%. 8 pts were on study treatment for ≥ 9 cycles (5 in Arm A, 3 in Arm B). All pts are off protocol treatment. Median progression-free survival was 3.06 (95% CI: 1.38-7.75) months for Arm A and 3.02 (95%CI: 2.4-5.65) for Arm B. Conclusions: Tazemetostat 800 mg BID and pembrolizumab combination is feasible and well-tolerated in patients with advanced UC. In this pilot study, improvement in efficacy relative to historical controls of pembrolizumab alone appears to be modest. Response in tumors with COMPASS-related mutations and EZH2 activity will be evaluated. Clinical trial information: NCT03854474 .

TPS5125 Background: B7-H3 is a member of the B7 superfamily, which includes PD-L1 (B7-H1) and PD-L2 (B7-DC). Enoblituzumab is a humanized Fc-optimized B7-H3–targeting antibody that induces antibody-dependent cellular cytotoxicity (ADCC). A recent investigator-initiated trial demonstrated that enoblituzumab therapy, used in the neoadjuvant prostate cancer setting, is feasible, safe, may enhance short-term clinical outcomes, and appears to stimulate intratumoral immune activation including CD8+ T cell infiltration and peripheral expansion of tumor-infiltrating T-cell clones that correlated with undetectable PSA at 1-year post-prostatectomy. To assess the impact of enoblituzumab on recurrence-free survival following prostatectomy, a phase 2, randomized, neoadjuvant clinical trial in high-risk localized prostate cancer patients has been started. We hypothesize that targeting B7-H3 with enoblituzumab will delay or prevent recurrence following prostatectomy compared to standard of care (SOC) . Methods: The HEAT trial is an investigator-initiated, multi-center, randomized, phase 2 study that is presently enrolling (NCT06014255). Eligible patients will undergo a pre-treatment prostate biopsy and conventional imaging (CT and bone scan) as well as PSMA-PET. Patients who have clinical stage cT1c-T3b, cN0 cM0 disease by conventional imaging (N1 by PSMA allowed with up to 3 LNs each ≤1 cm) will be eligible as long as concurrent hormonal or radiation therapy is not given. Prostate biopsy, within 3 months of enrollment, needs to show at least 3 positive cores containing at least 1 core with at least 50% disease involvement with Gleason ≥4+3=7 disease (with at least 1 additional high-risk feature such as PSA>20 ng/ml or cT3) or a Gleason sum ≥8. Patients will receive enoblituzumab at a dose of 15mg/kg IV biweekly for 6 doses (12 weeks) on the treatment arm, followed by prostatectomy, or will be scheduled for prostatectomy directly within 4-8 weeks on the SOC arm. 219 patients will be randomized (2:1) to treatment versus SOC. Pre-treatment, on-treatment, and post-treatment biomarkers of response and resistance will be collected. Patients will be followed according to standard institutional practices, but will require PSA evaluations every 3 (±1) months during year 1 and every 6 (±2) months during years 2-5. In both arms, salvage or adjuvant therapy will occur after biochemical or radiographic progression. The primary endpoint is recurrence-free survival (RFS) defined as any metastasis events, local pelvic visceral or lymph node recurrence, detectable prostate-specific antigen (PSA), or start of subsequent local or systemic therapy (including salvage or adjuvant therapy), or death for any cause, whichever occurs first. Secondary endpoints include additional clinical and immunologic correlates. Clinical trial information: NCT06014255 .

Background: Management strategies for metastatic castration-resistant prostate cancer (mCRPC) have rapidly shifted in recent years. As novel imaging and therapeutic approaches have made their way to the clinic, providers are encountering increasingly challenging clinical scenarios, with limited guidance from the current literature. Materials and Methods: The US Prostate Cancer Conference (USPCC) is a multidisciplinary meeting of prostate cancer experts intended to address the many challenges of prostate cancer management. At the first annual USPCC meeting, areas of controversy and consensus were identified during a 2-day meeting that included expert presentations, full-panel discussions, and postdiscussion responses to questions developed by the USPCC cochairs and session moderators. Results: This narrative review covers the USPCC expert discussion and perspectives relevant to mCRPC, including neuroendocrine/aggressive-variant prostate cancer (NEPC/AVPC). Areas of broad agreement identified among USPCC experts include the benefits of poly (ADP-ribose) polymerase (PARP) inhibitors for patients with BRCA1/2 mutations, the use of radioligand therapy in patients with prostate-specific membrane antigen (PSMA)–positive mCRPC, and the need for clinical trials that address real-world clinical questions, including the performance of novel therapies when compared with modern standard-of-care treatment. Ongoing areas of controversy and uncertainty included the appropriateness of PARP inhibitors in patients with non-BRCA1/2 mutations, the optimal definition of PSMA positivity, and systemic therapies for patients with NEPC/AVPC after progression on platinum-based therapies. Conclusions: The first annual USPCC meeting identified several areas of controversy in the management of mCRPC, highlighting the urgent need for clinical trials designed to facilitate treatment selection and sequencing in this heterogeneous disease state.

Purpose: Castration-sensitive prostate cancer (CSPC) is a complex and heterogeneous condition encompassing a range of clinical presentations. As new approaches have expanded management options, clinicians are left with myriad questions and controversies regarding the optimal individualized management of CSPC. Materials and Methods: The US Prostate Cancer Conference (USPCC) multidisciplinary panel was assembled to address the challenges of prostate cancer management. The first annual USPCC meeting included experts in urology, medical oncology, radiation oncology, and nuclear medicine. USPCC co-chairs and session moderators identified key areas of controversy and uncertainty in prostate cancer management and organized the sessions with multidisciplinary presentations and discussion. Throughout the meeting, experts responded to questions prepared by chairs and moderators to identify areas of agreement and controversy. Results: The USPCC panel discussion and question responses for CSPC-related topics are presented. Key advances in CSPC management endorsed by USPCC experts included the development and clinical utilization of gene expression classifiers and artificial intelligence (AI) models for risk stratification and treatment selection in specific patient populations, the use of advanced imaging modalities in patients with clinically localized unfavorable intermediate or high-risk disease and those with biochemical recurrence, recommendations of doublet or triplet therapy for metastatic CSPC (mCSPC), and consideration of prostate and/or metastasis-directed radiation therapy in select patients with mCSPC. Conclusions: CSPC is a diverse disease with many therapeutic options and the potential for adverse outcomes associated with either undertreatment or overtreatment. Future studies are needed to validate and clinically integrate novel technologies, including genomics, AI, and advanced imaging, to optimize outcomes among patients with CSPC.

5074 Background: Analysis of phase 3 studies of patients (pts) with mHSPC in the era of ADT, including in combination with docetaxel and/or androgen receptor axis targeted therapies have established PSA-7mo as a key prognostic marker. Our objective was to evaluate the association between PSA-3mo, PSA 7-mo and OS measured in the phase 3 S1216 trial in mHSPC comparing ADT + orteronel (treatment arm) vs ADT + bicalutamide (control arm) [NCT01809691]. Methods: Pts enrolled in the S1216 trial with available PSA-3mo & PSA-7mo were included in this analysis. PSA responses were defined as complete response (CR) if PSA ≤ 0.2 ng/mL, partial response (PR) for PSA >0.2 and ≤ 4ng/mL, and no response (NR) as PSA >4 ng/mL at month 3 or 7. Landmark OS was measured and Cox regression model applied adjusting for stratification (performance status, extent of disease, early vs late start of treatment, treatment arm). Results: 1251 pts were alive and evaluable for PSA-3mo and 1231 pts were evaluable at 7 mo, out of a total of 1279 pts. The median age was 67 (range: 43-92), 10% of patients were black, 96% had a Zubrod performance status of 0-1. Median PSA at baseline was 29 ng/ml (range: 2-6710). Of pts on treatment vs.control arm, PSA-3mo CR, PR, and NR occurred in 52% vs 35%; 31% vs 42%, and 17% vs 23%, respectively. Of pts on treatment vs control arm, PSA-7mo CR, PR, and NR occurred in 61% vs 46%, 20% vs 26%, and 19% vs 29%, respectively. CR or PR at either timepoint led to significantly better outcomes than those with NR. No interaction between treatment arm and PSA response was observed in terms of OS. Conclusions: PSA-3mo and PSA-7mo are strong prognostic markers for pts with mHSPC. More pts on ADT with orteronel achieved CR at 3 and 7 mo. In addition to its use in counseling patients in the clinic, PSA-3mo and PSA-7mo may be used as parameters for designing future trials in pts with mHSPC, utilizing the next generation of intensification or de-intensification treatment regimens. Clinical trial information: NCT01809691 . [Table: see text]

506 Background: Despite response to systemic therapy, few metastatic urothelial carcinoma (mUC) patients (pts) achieve durable responses. Mutations in the COMPASS-related proteins KMT2D, KMT2C, and KDM6A are found in 66% of UC patients suggesting histone regulation may be an acquired mechanism of tumor viability. We previously found regression of UC in mice when treated with EZH2 inhibitor, tazemetostat. In vivo administration of tazemtostat enhanced the immune response with direct regulation of cytokines and antigen recognition machinery (MHCI and MHCII). We hypothesized that restoration of epigenetic imbalance, combined with immunotherapy, may improve outcomes in mUC pts. Methods: ETCTN 10183 (NCT03854474) is a pilot study evaluating the efficacy of tazemetostat 800 mg BID + pembrolizumab 200 mg every 3 weeks for cisplatin-refractory (Cohort A) or cisplatin/chemo-ineligible advanced UC (Cohort B) pts, with N=12 pts in each cohort. The primary objective is to identify the recommended phase two dose (RP2D) of tazemetostat in combination with pembrolizumab. Secondary objectives include RECIST-based response rate, safety, and progression-free survival. The maximum planned treatment duration is 2 years. Translational objectives include defining total and COMPASS-related genes tumor mutational burden, tumor subtyping, TCR clonality, T cell infiltration, and PDL-1 expression. Results: In the safety lead-in phase, 6 mUC pts were treated. There were no dose-limiting toxicities (DLTs). The RP2D for tazemetostat was established at 800 mg BID. Here we report results of fully accrued cohort A (N=12); 67% males, 33% females, 83% white, 8.3% Black, and 25% Hispanic/Latino ethnicity. The primary sites of UC were: bladder (n=9, 75%), renal pelvis (n=2, 17%), and ureter (n=1, 8.3%). The median (interquartile range, IQR) time since primary diagnosis was 1.1 years (0.7, 1.9); 11/12 patients had non-nodal metastatic disease; 10/12 had 1 or more visceral/bone metastasis. Median number of treatment cycles was 5 (IQR: 3-11; range 1-35). Median duration on protocol treatment was 12 weeks (IQR: 7-30; range 3-107 weeks). Three pts had treatment related grade 3/4 AEs: grade 4 sepsis (n=1), grade 3 lymphopenia (n=2); anemia, increased alkaline-phosphatase, and HSV oral infection (n=1 each). Best response was partial response (PR) in 3 pts (25%) and 3 (25%) had stable disease. Median PFS was 3.1 months (95%CI: 2.3-NA), and median overall survival was 8.0 months (95% CI: 4.7 – NA). Conclusions: The RP2D dose for tazemetostat is 800 mg + 200 mg Pembrolizumab q 3 weeks. The combination was feasible, well tolerated, and resulted in durable responses in poor-risk chemo-refractory UC patients. Clinical trial information: 03854474 .

AbstractBackgroundE3805 (CHAARTED) is a phase 3 trial demonstrating improved survival for men with metastatic hormone‐sensitive prostate cancer (mHSPC) randomized to treatment with docetaxel (D) and androgen‐deprivation therapy (ADT) versus ADT alone. We assessed the association of baseline body mass index (BMI) and metformin exposure with quality of life (QOL) and prostate cancer outcomes including survival in patients enrolled in the CHAARTED study.MethodsWe performed a posthoc exploratory analysis of the CHAARTED trial of men with mHSPC randomized to treatment with ADT with or without D between 2006 and 2012. Cox proportional hazards models and Kruskal–Wallis test were used to evaluate the association between BMI with QOL and prostate cancer outcomes and between metformin exposure and survival.ResultsIn 788 of 790 enrolled patients with prospectively recorded baseline BMI and metformin exposure status, lower BMI was not associated with survival, but was associated with high volume disease (p < 0.0001) and poorer baseline QOL on functional assessment of cancer therapy–prostate (p = 0.008). Only 68 patients had prevalent metformin exposure at baseline in the CHAARTED trial. Four groups were identified: ADT + D + metformin (n = 39); ADT + D (n = 357); ADT + metformin (n = 29); and ADT alone (n = 363). Baseline clinicopathologic characteristics were similar between groups. In this small exploratory multivariable analysis, metformin exposure was not associated with survival (hazard ratio: 1.15; 95% confidence interval: 0.81–1.63, p = 0.44).ConclusionsThere was no link between baseline BMI and survival, but lower baseline BMI was associated with features of greater cancer burden and poorer QOL.