Nauseef, Jones T.

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.

PURPOSE Hot flashes are a common side effect reported by men receiving androgen-deprivation therapy (ADT) for the treatment of prostate cancer. We sought to determine whether oxybutynin could improve hot flash symptoms in men with prostate cancer. PATIENTS AND METHODS Patients with prostate cancer receiving a stable regimen of ADT with at least 28 hot flashes per week were randomly assigned to receive either oxybutynin 2.5 mg twice daily, oxybutynin 5 mg twice daily, or matching placebo for 6 weeks. The primary end point was the change in patient-reported hot flash scores since baseline at 6 weeks. Additional outcomes included incidence of adverse events (AEs), changes since baseline in Hot Flash–Related Daily Interference Scale (HFRDIS) scores, and patient-reported symptoms. RESULTS Eighty-eight patients were enrolled, with the 81 participants eligible for final analysis reporting an average of 10.1 (standard deviation [SD], 5.55) hot flashes per day and an average daily hot flash score of 18.2 (SD, 13.5) included in final analysis. On average, patients on the placebo arm, 2.5 mg oxybutynin arm, and 5 mg oxybutynin arm had reductions in hot flashes/day of 2.15, 4.77 ( P = .02), and 6.89 ( P < .001), respectively. Daily hot flash scores for placebo, 2.5 mg oxybutynin, and 5 mg oxybutynin reduced by an average of 4.85, 9.94 ( P = .07), and 13.95 ( P = .002) points, respectively. No treatment-related grade 3+ AEs occurred. HFRDIS total scores improved by 14.2 and 20.7 points in the 2.5 mg ( P = .042) and 5 mg ( P < .01) oxybutynin arms, respectively, compared with a 3.1-point improvement with placebo. CONCLUSION Oxybutynin is superior to a placebo for the management of ADT-associated hot flashes in men with prostate cancer.

PURPOSE Previous studies suggest that SPOP mutations result in increased sensitivity to androgen receptor pathway inhibitors (ARPIs) but are limited by lack of granular data. We hypothesize that SPOP mutations are associated with improved outcomes across the spectrum of advanced prostate cancer (PC). METHODS Using the real-world clinicogenomic Prostate Cancer Precision Medicine Multi-Institutional Collaborative Effort database, we analyzed outcomes based on SPOP mutation status. The primary end point was overall survival (OS) from the diagnosis of metastatic disease. Secondary end points included real-world progression-free survival (PFS) and PSA90 response. RESULTS Among 2,097 patients with metastatic PC, 5.5% (N = 115) had SPOP -mutated tumors. Compared with SPOP wild-type, patients with SPOP mutations were older at diagnosis (median 65 v 63 years; P = .001) and had higher (≥8) Gleason sum (68% v 54%; P = .02), higher incidence of lung metastasis (17% v 6%; P = .001), and increased frequency of intraductal features (13% v 5%; P < .001). SPOP mutations were associated with improved PSA90 response with first ARPI exposure in the castrate-resistant setting (60% v 40.6%; OR, 2.20 [95% CI, 1.15 to 4.19]; P = .02) but not in the castrate-sensitive setting (78.9% v 71.5%; OR, 1.49 [95% CI, 0.66 to 3.37]; P = .43). Median PFS with first ARPI did not differ in SPOP- mutated versus wild-type group in both the castrate-sensitive (24.2 v 19.2 months; hazard ratio [HR], 0.80 [95% CI, 0.49 to 1.32]; P = .39) and castrate-resistant settings (15.0 v 12.4 months; HR, 0.81 [95% CI, 0.58 to 1.12]; P = .20). In multivariable analysis, SPOP mutations were associated with improved OS (HR, 0.65, P = .02). CONCLUSION SPOP mutations were associated with longer OS despite the presence of aggressive clinical features. The distinct clinical and molecular features of SPOP -mutated PC support its consideration as a unique molecular subtype with prognostic implications.

5074 Background: PC commonly expresses PSMA and has dose-responsive radiosensitivity. 177Lu-based radioligands usually use an empiric dosing regimen. This 1st dose-escalation study of 177Lu-PSMA-617 employed a dose-dense fractionation schedule intended to allow delivery of higher total doses to overcome radioresistance due to repopulation. Here, we report mature results of the study. Methods: Progressive mCRPC following > 1 potent ARPI (e.g., abi/enza) and chemo (or unfit/refuse taxane) without limit of # prior therapies provided adequate organ function and ECOG PS 0-2. Treatment: single cycle of fractionated dose 177Lu-PSMA-617 on D1 and D15. In Ph I dose-escalation, patients (pts) received one cycle of 7.4 - 22 GBq followed by Simon 2-stage Ph II at 22.2 GBq. PSMA expression was not required for treatment, but pre- and post-treatment 68Ga-PSMA11 PET/CT and/or 177Lu-PSMA-617 SPECT done. Primary efficacy by PSA changes with 2ndary outcomes with CT/bone scans, PSMA PET, circulating tumor cell (CTC; CellSearch) counts, plasma DNA (PCF_SELECT), and survival. Results: Between 1/2017 – 2/2021, 50 pts treated with median PSA 164.3, 35 (70%) CALGB (Halabi) poor risk. 47 (94%) bone, 38 (76%) nodal, 12 (24%) lung, 5 (10%) liver mets (4 additional pts with PSMA PET+ liver mets not apparent on CT). 29 (58%) with prior >2 ARPI, 29 (58%) with >1 chemo, 14 (28%) with Ra-223, 2 (4%) with 177Lu-J591. 27 (54%) treated at 22 GBq. No dose-limiting toxicity during Ph I. 38 (76%) with any PSA decline, 27 (54%) with >50% PSA. Median rPFS 8.3 mo [5.6-16.7], and OS 15.7 mo [10.9-20.6]. Of 17 RECIST measurable, 6 (35.3%) responded, 7 (41.2%) stable, 4 (23.5%) progressed. Of 31 with paired CTC counts, 16 (52%) decreased, 5 (16%) were stable; 10 (32.3%) converted to favorable/undetectable. Plasma DNA with high allele-specific ploidy and ARcopy number gain associated with OS (univariate). Treatment emergent adverse events (TEAE): 32 (64%) dry mouth, 22 (44%) pain flare, 22 (44%) fatigue, 19 (38%) nausea, 15 (30%) anemia, 15 (28%) thrombocytopenia (plts), 9 (18%) neutropenia (ANC). All TEAEs restricted to grade (Gr) 1-2 except 6 (12%) with Gr 3 anemia, 2 (4%) Gr 3/4 plts, 1 (2%) Gr 3 ANC. TEAE incidence and Gr were not related to dose. On multivariable analysis, 177Lu dose administered (p=0.09), CALGB risk (p=0.04), prior chemo (p=0.009), associated with OS; dose (p=0.1), CALGB risk (p=0.2), and AR copy number (p=0.2) associated with PSA50 decline. Baseline PSMA imaging (by imaging score or SUVmax) was not associated with OS or response. Conclusions: A single-cycle of fractionated-dose 177Lu-PSMA-617 is safe. Despite no pre-selection for PSMA expression, most had PSA decline with favorable PFS and OS compared to historical controls and similar to PSMA-selected targeted radionuclide studies administering multiple cycles in a less dose-intense approach. Clinical trial information: NCT03042468 .

LBA12004 Background: Hot flashes are among the most common adverse events impacting quality of life reported by patients receiving androgen deprivation therapy (ADT) for the treatment of prostate cancer. Oxybutynin is an effective therapy for reducing frequency and severity of hot flashes in women. Pilot information supports that this drug may also benefit men with hot flashes related to ADT. Methods: Patients with prostate cancer receiving a stable regimen of ADT with at least 28 hot flashes per week were randomized to receive either oral oxybutynin 2.5 mg twice a day, oxybutynin 5 mg twice a day, or matching placebo doses for 6 weeks. The primary endpoint was the change in patient-reported hot flash scores (determined by multiplying the number of hot flashes by the mean hot flash severity [grade 0: none, 1: mild, 2: moderate, 3: severe, and 4: very severe]) from baseline to 6 weeks, as measured by a daily hot flash diary. A total of 87 patients provided 76% power to reject the null hypothesis of no between-arm mean difference in hot flash score reduction from baseline to 6 weeks, when comparing each oxybutynin arm to the combined placebo arms. This was based on a two-sided contrast estimated from a generalized linear mixed model, α= 0.10, intraclass correlation of 0.50, population standardized mean difference of 0.50, and 10% missing data rate. Results: 88 patients were accrued between 10/28/21 and 12/02/23. Six patients cancelled before starting treatment and one was ineligible, leaving 81 analyzed patients with a median age of 68. Baseline characteristics were balanced between arms with patients reporting an average of 10.15 (SD = 5.55) hot flashes per day and an average daily hot flash score of 18.23 (SD = 13.48) at enrollment. On average, patients on the placebo arm, low dose oxybutynin arm, and high dose oxybutynin arm had reductions of 2.15, 4.77, and 6.89 hot flashes/day, respectively. Compared to placebo arm patients, high dose oxybutynin arm patients had a greater reduction in hot flashes/day (p < 0.001), as did low dose oxybutynin arm patients (p = 0.02). Daily hot flash scores for the same three protocol arms reduced by an average of 4.85, 9.94, and 13.95 points, respectively. Compared to placebo arm patients, high dose oxybutynin arm patients had a greater reduction in daily hot flash scores (p = 0.002), as did low dose oxybutynin arm patients (p = 0.07). No treatment-related grade 3+ adverse events occurred. The most commonly reported oxybutynin-related grade 2 adverse event was dry mouth. Conclusions: Oxybutynin is superior to a placebo for the management of hot flashes in men associated with androgen deprivation therapy and appears to be well tolerated. Support: UG1CA189823; https://acknowledgments.alliancefound.org . Clinical trial information: NCT04600336 .

Abstract Background: We have previously reported that 177Lu-PSMA-617 given as a single-cycle, dose-intense regimen for patients (pts) with pretreated mCRPC is efficacious even without selection by PSMA (ESMO 2021). Quantitative analyses of pre-treatment PSMA PET may allow for better patient selection and prediction of toxicities. Analyses of sequential PET images may also provide insights that may be associated with longer term outcomes. Our previous analysis of 13 patients demonstrated association of PSMA PET signal with overall survival (OS) and PSA responses, as well as trends with adverse events (Nauseef GU ASCO 2022). Here we present long-term follow up data and expanded imaging correlatives from our completed phase I/II study. MethodsEntry criteria: progressive mCRPC after at least one prior potent AR pathway inhibitor and prior chemotherapy (excepting men ineligible for or refusing of chemotherapy) with allowance for prior radionuclides (incl. Ra223 and PSMA-TRTs). Treatment was fractionated-dose (D1 and D15) 177Lu-PSMA-617 (7.4-22.2 GBq). TRAQinform IQ (AIQ Solutions) was used to identify, track, and quantify regions of interest suspicious of cancer (lesion-ROI) on PSMA PET/CT images and quantify uptake in normal organs outside of lesion-ROI. Measurements included SUVmean across all lesion-ROI, volume of lesion-ROI, and SUVtotal (sum of SUV in all lesion-ROI), as well as changes after treatment, including in PSMA-expressing healthy tissues. Associations with survival were tested via Cox proportional hazard models in univariate analyses and associations with adverse events (AEs) and PSA responses were via assessed via Wilcoxon rank sum tests. Results32 pts (of 50 total in the study between 1/2017-2/2021) had pre- and post-treatment imaging suitable TRAQinform IQ analysis and associated survival analyses. Baseline characteristics were similar to the entire study cohort. PSA response of 50% was observed in 21/32 (66%) of which 16 were confirmed. No imaging variable predicted PSA30 or PSA50, although an association was observed in pretreatment SUVmean and lesion-ROI volume reduction. No imaging variable was significantly associated with OS (e.g., pretx SUVmean HR 0.9, p=0.10, pretx Volume HR 1.00, p=0.052). Pretx SUVmean was associated with mPFS (HR 0.85, 95% CI 0.74, 0.98, p=0.023). Among select AEs, anemia was associated with non-lesion-ROI skeleton SUVtotal in pre- (p=0.027) and post-tx (p=0.007). Higher pre-treatment salivary gland uptake (SUVmean) was associated with more xerostomia (p=0.11). Fatigue was associated with a variety of variables including salivary SUVs (mean, max, and total) and post-tx bowel SUVmax (p=0.030). ConclusionsPre-treatment and pre- to post-treatment 68Ga-PSMA11-PET data analyzed may be associated with outcome. While a strength of this study is the prospective nature of patient enrollment and fixed imaging timepoints, our associations are limited by small sample size. Expansion of this analysis to larger datasets may improve our ability to predict treatment response and toxicity by body-wide PSMA detection. Citation Format: Jones Trevor Nauseef, Charlene Thomas, Michael Sun, Nicole Jacobs, Andrés Ricaurte Fajardo, Sam Ruder, Escarleth Fernandez, Zachary Davidson, Amie Patel, A. Oliver Sartor, Shankar Vallabhajosula, Ana Molina, Cora N. Sternberg, David M. Nanus, Sandra Huicochea Castellanos, Joseph Osborne, Neil H. Bander, Timothy Perk, Scott Tagawa. Quantitative assessment of PSMA imaging before and after 177Lu-PSMA-617 treatment in a Ph I/II trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT225.

5038 Background: Platinum-based chemotherapy has shown palliative and radiographic benefit in small unselected studies of metastatic castration-resistant prostate cancer (mCRPC). Alterations in DNA damage repair genes (DDRmut), which occur in ~25% of patients with mCRPC, may sensitize to platinum-based chemotherapy, and may aid in the selection of patients for this therapy. We sought to evaluate the efficacy of platinum-based chemotherapy in DDRmut mCRPC. Methods: We performed a retrospective review of patients with prostate cancer who underwent tumor genomic profiling and received platinum-based chemotherapy. Deleterious alterations in a panel including BRCA2, BRCA1, ATM, FANCA, CDK12 or PALB2 were classified as DDRmut. Absence of deleterious alterations in those genes was classified as DDRwt. MSI-H cases were excluded from analysis. Electronic charts, PSA values, and scans were reviewed to assess for outcomes. Results: From October 2013 to July 2018, 109 patients with mCRPC received platinum-based chemotherapy. 64/109 had prior taxane progression and were PARP inhibitor (PARPi) naïve at the time of platinum-based chemotherapy. DDRmut was found in 16/64 (25%) of patients ( BRCA2, n = 6; ATM, n = 2; CDK12, n = 4; FANCA, n = 4; PALB2, n = 1). Visceral metastasis occurred in 4/16 (25%) of DDRmut patients and in 22/48 (46%) of DDRwt patients. PSA50 responses were more common among DDRmut (8/15 evaluable = 53%, 95% CI, 30-75%) than among DDRwt patients (5/42 evaluable = 12%, 95% CI, 5-25%). Time on platinum-based chemotherapy tended to be longer in the DDRmut group (median 3.1 vs 1.8 months; HR 0.73, 95% CI 0.42-1.26). Of 8 DDRmut patients ( BRCA2, n = 6; BRCA1, n = 1; ATM, n = 2) who received platinum-based chemotherapy after progression on a PARPi, 3/7 evaluable patients (43%) had RECIST response or stable disease, and 2/7 evaluable patients (29%) had a PSA50 response. Of 4 patients with ATM deleterious mutations, none had a radiographic or PSA50 response to platinum-based chemotherapy. Conclusions: Platinum-based chemotherapy showed activity in DDRmut mCRPC patients before and after PARPi treatment.