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88 Background: The VISION (NCT03511664) and PSMAfore (NCT04689828) clinical trials have demonstrated the effectiveness of 177 Lu-PSMA-617 in patients with mCRPC who have previously received androgen receptor pathway inhibitors (ARPIs) with or without taxane-based chemotherapy. Sipuleucel-T is used for treatment of mCRPC in routine clinical practice, particularly among community urologists; however, to date, there are no data available to understand the effectiveness of 177 Lu-PSMA-617 in patients previously treated with sipuleucel-T. Methods: This was a retrospective, observational study of adult patients with a diagnosis of mCRPC who received 177 Lu-PSMA-617 between March 23, 2022, and June 27, 2025, and had a history of treatment with sipuleucel-T. Data were obtained from the PRECISION data platform, a harmonized dataset of patients with advanced prostate cancer in the US that integrates electronic health records and claims data from community, academic, urology, and medical oncology settings. The index date was the date of 177 Lu-PSMA-617 initiation. Patient characteristics and prostate-specific antigen (PSA) response rates were evaluated descriptively. Progression-free survival (PFS), defined as the time from 177 Lu-PSMA-617 initiation to disease progression or death, was analyzed using Kaplan–Meier curves. Results: A total of 290 patients met the inclusion criteria, of whom 72% were White and 12% were Black. At index, 32% of patients were treated in urology and 68% in oncology settings. The median age was 74 years, the median baseline PSA was 35.3 ng/mL (interquartile range [IQR] 10.0–99.2 ng/mL), and 57% of patients had a Gleason score of ≥8. In addition to sipuleucel-T, prior to 177 Lu-PSMA-617, 97% of patients had received ≥1 ARPI and 79% had received ≥1 taxane. The median follow-up for this cohort was 9.4 months (IQR 5.3–17.5 months). Among 144 patients with available PSA values both before and during 177 Lu-PSMA-617 treatment (representing 50% of the cohort), PSA response rates were as follows: a ≥50% reduction in PSA from baseline (PSA50) was observed in 60%, PSA80 in 42%, and PSA90 in 33% of patients. Overall, the median PFS was 15.2 months (95% confidence interval [CI] 11.6–19.4 months). Conclusions: In this real-world analysis of patients who received 177 Lu-PSMA-617 after sipuleucel-T treatment, the median PFS was similar to that observed in clinical trials, suggesting that 177 Lu-PSMA-617 can be sequenced after sipuleucel-T treatment in appropriate patients.

81 Background: In the PSMAfore clinical trial, 177 Lu-PSMA-617 achieved a PSA50 (defined as a ≥50% reduction in prostate-specific antigen [PSA] from baseline) response rate in 58%, a median radiographic progression-free survival (PFS) of 12 months, and a median overall survival (OS) of 25 months among taxane-naïve patients with mCRPC who had received one prior androgen receptor pathway inhibitor (ARPI). The aim of the present study was to evaluate the real-world effectiveness of 177 Lu-PSMA-617 in taxane-naïve patients with mCRPC who had received one or more prior ARPIs. Methods: This retrospective, observational study included taxane-naïve adults with mCRPC initiating 177 Lu-PSMA-617 between March 23, 2022, and June 27, 2025, after ≥1 prior ARPI. All data for the study were extracted from the PRECISION data platform, a harmonized dataset of patients with advanced prostate cancer in the US treated in a variety of clinical settings. The index date was the date of 177 Lu-PSMA-617 initiation. Patient characteristics and PSA response rates were evaluated descriptively. PFS, defined as the time from 177 Lu-PSMA-617 initiation to progression or death, was estimated using Kaplan–Meier methodology. Results: A total of 500 patients were included. The median age was 75 years, 75% of patients were White and 8% Black, and 18% were treated in urology centers while 82% were treated in oncology centers. The most common site of metastasis was bone (77%), followed by lymph node (21%), visceral (12%), and unknown (5%). Overall, 51% had received 1 previous ARPI while 49% had received ≥2. The median baseline PSA was 26.7 ng/mL (interquartile range [IQR] 10−105 ng/mL) and the median time from mCRPC diagnosis to 177 Lu-PSMA-617 initiation was 23.6 months. The median number of 177 Lu-PSMA-617 cycles received was 4 (IQR 2−6). Among 219 patients with available PSA measurements both before and during 177 Lu-PSMA-617 treatment (representing 44% of the cohort), PSA response rates were as follows: PSA50 in 137 (63%), PSA80 in 86 (39%), and PSA90 in 56 (26%) patients. Overall, the median PFS was 13.5 months (95% confidence interval 11.7–14.7 months). Conclusions: The effectiveness of 177 Lu-PSMA-617 as a standard-of-care treatment in real-world, taxane-naïve patients with mCRPC who had received prior treatment with ≥1 ARPI is consistent with results from the PSMAfore trial, confirming the applicability of those findings to the real-world population now eligible for 177 Lu-PSMA-617. Further research on sequencing 177 Lu-PSMA-617 after one or more prior ARPIs in taxane-naïve patients with mCRPC is needed to guide optimal treatment sequencing in clinical practice.

79 Background: In March 2025, the indication for 177 Lu-PSMA-617 was expanded to include prostate-specific membrane antigen (PSMA)-positive patients with mCRPC treated with ≥1 androgen receptor pathway inhibitor (ARPI) and considered appropriate to delay taxane-based chemotherapy. With 177 Lu-PSMA-617 moving earlier in the treatment journey, it is important to understand the clinical activity of other systemic therapies after 177 Lu-PSMA-617. The aim of this study was to evaluate the clinical outcomes among patients with mCRPC receiving a systemic therapy after 177 Lu-PSMA-617 treatment. Methods: This retrospective, observational study used real-world data from the PRECISION data platform, a proprietary dataset developed by Novartis representative of patients with advanced prostate cancer in the US from diverse clinical settings. Patients with mCRPC treated with 177 Lu-PSMA-617 who received a systemic therapy ≥14 days after treatment with 177 Lu-PSMA-617 between March 23, 2022, and June 27, 2025, were included. Systemic therapies included ARPIs (abiraterone, enzalutamide, darolutamide, apalutamide); chemotherapy (cabazitaxel, docetaxel, carboplatin, cisplatin, etoposide, mitoxantrone); immunotherapy (pembrolizumab, sipuleucel-T); poly (ADP-ribose) polymerase (PARP) inhibitors (niraparib, olaparib, talazoparib, rucaparib); and radium-223. Patient characteristics and prostate-specific antigen (PSA) response were evaluated descriptively. Progression-free survival (PFS) from subsequent therapy initiation was estimated using Kaplan–Meier methodology. Results: A total of 442 patients receiving any subsequent systemic therapy after 177 Lu-PSMA-617 were included. Overall, 95% of patients received ≥1 ARPI and 76% ≥1 taxane pre- 177 Lu-PSMA-617. The median age was 73 years. Most patients received a taxane (n = 188), an ARPI (n = 176), or a PARP inhibitor (n = 33) as their subsequent therapy. The median time to subsequent therapy initiation was 70 days (interquartile range 38−137 days) from the last 177 Lu-PSMA-617 administration. Among 299 patients receiving a systemic therapy after 177 Lu-PSMA-617 with PSA values available both pre-index and during subsequent treatment, 48% achieved a ≥50% reduction in PSA from baseline (PSA50), 31% a PSA80, and 18% a PSA90. The median PFS from the initiation of subsequent therapy was 8.6 months in the entire cohort; this was 10.7 months with a subsequent ARPI, 7.2 months with a subsequent taxane, and 7.1 months with a subsequent PARP inhibitor. Conclusions: In this real-world analysis, meaningful clinical responses were observed in a subset of patients who received subsequent systemic therapies after 177 Lu-PSMA-617.

78 Background: 177 Lu-PSMA-617 is currently under investigation in combination with an ARPI in those with metastatic hormone-sensitive prostate cancer (PSMAddition trial: NCT04720157). This observational study was performed to assess the effectiveness of 177 Lu-PSMA-617 in combination with an ARPI in patients with mCRPC in the real-world setting. Methods: This was a retrospective cohort study of adults with mCRPC in the PRECISION data platform, a comprehensive database of prostate cancer patients compiled from diverse clinical settings in the US. Patients who received 177 Lu-PSMA-617 during March 23, 2022–June 27, 2025 were identified, among whom two cohorts were selected for inclusion: those who had evidence of ARPI use (apalutamide, darolutamide, abiraterone, or enzalutamide) at any time during 177 Lu-PSMA-617 treatment (concomitant ARPI cohort), and those who had no other treatment for mCRPC during 177 Lu-PSMA-617 treatment (no concomitant therapy cohort). The index date was initiation of 177 Lu-PSMA-617. Patient characteristics and prostate-specific antigen (PSA) responses were evaluated descriptively. Progression-free survival (PFS), defined as the time from 177 Lu-PSMA-617 initiation to disease progression or death, was estimated using Kaplan–Meier analysis. Results: A total of 1,880 patients treated with 177 Lu-PSMA-617 were identified, 140 in the concomitant ARPI cohort and 1,740 in the no concomitant therapy cohort. The median age was 74 years. Demographic characteristics were balanced between the groups, except that median baseline PSA was lower in the concomitant ARPI cohort when compared with patients in the no concomitant therapy cohort (18 ng/mL vs. 32 ng/mL). Before 177 Lu-PSMA-617 initiation, 94.3% and 73.6% of patients in the concomitant ARPI and 80.9% and 56.7% in the no concomitant therapy cohort had received ≥1 prior ARPI and ≥1 prior taxane, respectively. PSA response rates were broadly comparable between cohorts. The median (95% confidence interval) PFS was 14.7 (11.7–21.3) months among patients in the concomitant ARPI cohort vs 12.5 (11.5–13.6) months in the no concomitant therapy cohort. Ongoing follow-up aims to evaluate the impact of combining ARPI with 177 Lu-PSMA-617 on long-term clinical outcomes, including overall survival. Conclusions: The results of this study demonstrate that 177 Lu-PSMA-617 delivers clinical benefits inpatients with mCRPC with or without ARPI; however, addition of an ARPI may potentially improve these benefits. Prospective randomized controlled studies are needed to confirm this.

77 Background: The incidence of metastatic hormone-sensitive prostate cancer (mHSPC) is increasing in the US, likely due to a decrease in screening practices. There has also been a rapid increase in recent years in the number of treatment options that can improve progression-free and overall survival (OS) for these patients. The objective of the current study was to evaluate the clinical outcomes among patients with mHSPC treated in contemporary US clinical practice (2020 to 2025). Methods: This retrospective, observational cohort study used data from PRECISION, a harmonized dataset on advanced prostate cancer in patients in the US treated in a range of clinical settings. Patients aged ≥18 years who were diagnosed with mHSPC during 01/01/2020–01/01/2024 and who initiated ≥1 therapy (index date = first-line [1L] treatment initiation) were included. The study period was from 01/01/2010 to 06/30/2025. Patient characteristics at mHSPC diagnosis and treatment utilization were evaluated descriptively. Castration resistance-free survival (CRFS; defined as the time to castration-resistant prostate cancer or death) and OS were evaluated from index using Kaplan–Meier analysis. Results: A total of 27,708 patients were included (median age, 72 years); 20,015 (72%) were treated in community urology, 4994 (18%) in community oncology, and 2669 (10%) in academic oncology centers at index. Almost half of patients (47%) initiated 1L treatment with androgen-deprivation therapy (ADT) monotherapy, 44% initiated a 1L doublet regimen (36% ADT + androgen receptor pathway inhibitor [ARPI], 5% 1L ADT + radiotherapy, 2% 1L ADT + docetaxel), and 5% a 1L triplet regimen (ADT + radiotherapy + ARPI or docetaxel); the remaining patients received other regimens. The 5-year CRFS rate was 41%; this was significantly higher in patients with a 1L doublet (45%) or triplet (58%) regimen compared with patients with 1L ADT monotherapy (31%; p<0.001). Similarly, the 5-year OS rate was 59% overall and was significantly higher in patients with a 1L doublet (61%) or triplet (59%) regimen compared with patients with 1L ADT monotherapy (55%; p<0.001) (Table). Conclusions: Though both CRFS and OS rates appear to be increasing among real-world patients with mHSPC, >40% of patients in this study died within 5 years of initiating 1L treatment. Patients who received guideline-recommended combined systemic treatment regimens experienced improved CRFS and OS, confirming the importance of implementing therapies in practice that prolong survival. CRFS and OS rates from start of 1L therapy, by therapy type. CRFS rate (%) OS rate (%) 1 y 2 y 3 y 4 y 5 y 1 y 2 y 3 y 4 y 5 y Overall 68 58 51 46 41 93 84 76 67 59 ADT monotherapy 59 49 41 36 31 92 83 74 65 55 Doublet therapy 72 62 55 49 45 94 85 76 68 61 Triplet therapy 85 77 70 68 58 94 89 82 74 59

75 Background: Although the number of life-prolonging treatment options for pts with mHSPC has increased, initial real-world evidence has demonstrated slow uptake. This study utilized a large, contemporary, real-world dataset to evaluate the characteristics and treatment utilization among US pts with mHSPC in recent years. Methods: This retrospective, observational study used data from PRECISION, a harmonized dataset on pts with advanced prostate cancer. Adult men who were diagnosed with mHSPC during 01/01/2020–01/01/2024 (index date) and who initiated ≥1 therapy were included; the study period was 01/01/2010–06/30/2025. Pt characteristics were described at index. Treatment utilization was evaluated from index until progression to metastatic castration-resistant prostate cancer, death, or last follow-up. If an androgen receptor pathway inhibitor (ARPI), docetaxel, or radiotherapy was started within 4 months of index/androgen-deprivation therapy (ADT) start, it was considered a first-line (1L) combination; if it was started after >4 months, it was considered treatment intensification. All analyses were descriptive. Results: Among the 27,708 pts who met the inclusion criteria in PRECISION, 72%, 18%, and 10% were treated in community urology, community oncology, and academic oncology centers at index, respectively. Median age was 72 years; 62% were White; 43% were from the US South; 53% had synchronous and 54% had metachronous metastases (2% unknown). Median prostate-specific antigen level was 9 ng/mL (mean, 130 ng/mL). Prior to mHSPC diagnosis, 19% of pts had a prostatectomy and 17% had radiotherapy. Almost half of pts (47%) initiated 1L treatment with ADT monotherapy; 36% initiated 1L ADT + ARPI, 5% 1L ADT + radiotherapy, 2% 1L ADT + docetaxel, 5% 1L ADT + radiotherapy + ARPI or docetaxel, and 5% other regimens. From 2020 to 2023, 1L ADT monotherapy use decreased, while 1L combination use increased (Table). In addition, 19% of pts with 1L ADT monotherapy had evidence of subsequent treatment intensification, mainly the addition of an ARPI. Conclusions: In this study, use of 1L ADT monotherapy declined over time, accompanied by an increase in 1L combinations and treatment intensification. Nonetheless, approximately 1/3 of pts still did not receive a combination or intensification. Further research is needed to understand treatment trends in pts with mHSPC. Treatment patterns by index year. Pts, % 2020(n=5278) 2021(n=6203) 2022(n=7701) 2023(n=8526) 1L ADT monotherapy* 54 52 45 40 Subsequent treatment intensification* 18 19 20 18 1L ADT + ARPI* 29 33 38 42 1L ADT + radiotherapy 5 5 5 6 1L ADT + docetaxel* 3 2 2 1 1L ADT + radiotherapy + ARPI or docetaxel* 3 3 5 7 *p<0.001 for trend across years.

58 Background: Skeletal-related events (SREs) are a common cause of morbidity and mortality in metastatic castration-resistant prostate cancer (mCRPC). These complications are managed using bone-modifying agents (BMAs), radiation therapy, and surgery, and lead to diminished quality of life irrespective of their castration status. We sought to evaluate the mortality trends for patients with PC and SREs in patients of >65 years from 1999 to 2023 using the CDC WONDER (Wide-ranging Online Data for Epidemiologic Research) database. Methods: The database was searched from January 1, 1999, to December 31, 2023. Mortality trends were assessed by identifying prostate cancer international classification of diseases-10th revision code (ICD-10 code C61) as the underlying cause of death in individuals aged >65 years, and (SREs) as contributing causes using the following ICD-10 codes: S02, S12, S22, S32, S42, S52, S62, S82, S92, T02, T08, T10, T12, T14.2, Y93.2, E55, M80, M81, M84.4. Joinpoint 5.0 software was used to analyze mortality trends. Results: From 1999 to 2023, a total of 3,231 deaths were reported. Trend analysis revealed a decline in overall mortality from 1999 to 2014, with an annual percentage change (APC) of -1.60 (CI: -2.6, -0.5; p = 0.005), followed by a significant increase in mortality from 2015 to 2023, with an APC of 5.30 (p = 0.0001). When stratified by age, individuals aged 65-69 showed an insignificant decline in mortality over the entire study period. For those aged 70-74, mortality significantly decreased from 1999 to 2014 (APC: -3.02, CI: -5.0, -0.9; p = 0.008), but experienced an exponential increase from 2014 to 2023 (APC: 14.07, CI: 8.7, 19.6; p = 0.00005). In the 75-79 age group, mortality significantly decreased from 1999 to 2011 (APC: -5.6, CI: -9.5, -1.6; p = 0.0091), followed by a robust increase from 2011 to 2023 (APC: 7.06, CI: 2.7, 11.5; p = 0.002). For individuals aged >80 years, the trend showed an insignificant decline in mortality from 1999 to 2023 (APC: -0.260, CI: -0.8, 0.3; p = 0.380). Conclusions: Our study revealed significant trends in prostate cancer mortality attributable to SREs, contributing to a sharp increase from 2015 to 2023. Age-stratified analysis revealed that substantial mortality is reported in patients aged 70-79, with the most pronounced rise occurring after 2014. These findings emphasize the growing burden of SREs in older prostate cancer patients, underscoring the need for targeted interventions along with a focus on patient-reported outcomes to improve survival and quality of life.

5 Background: Penile cancer (PC) is often diagnosed late, which leads to advanced disease. Studies have reported that less than 18% of individuals with metastatic PC receive any kind of palliative therapy. Place of Death (PoD) is a crucial determinant of patient and caregiver preferences and the cost of caregiving at the end of life (EOL). We aimed to evaluate the trends in PoD for patients with PC in the U.S. from 2003 to 2023 based on the CDC WONDER (Wide-ranging Online Data for Epidemiologic Research) database. Methods: We analyzed data from January 01, 2003, to December 31, 2023. The data for deaths due to PC were pooled using the International Classification of Diseases-10th Revision code as C60 for malignant neoplasm of the penis. The inclusion criteria included patients aged > 25 years. PoD is defined as deaths at home and hospice (H&H) versus medical facilities. Average annual percentage change (AAPC) was calculated using the Joinpoint Regression Program, version 5.0.2. Results: The analysis demonstrated a total of n = 6,074 deaths from PC. A total of 52.1% of deaths, n = 3,167, were reported at H&H. The trend analysis demonstrates an exponential rise in H&H utilization from 34.4% in 2003 to 57.5% in 2023, AAPC [5.4284, CI (4.7-6.10, p < 0.000001]. A significant increase in the utilization of H&H is notable in both African Americans (AA), AAPC [2.8514, CI (1.0-4.7), p = 0.004], and the White population, AAPC [5.3497, CI (4.6-6.0); p < 0.000001]. However, a racial disparity is also noted, with 45.4% in AA, while the White population is at 52.5% deaths in H&H-based care. PC mortality in medical facilities has a 29.7% decline from 2003 to 2023. On age stratification, there was a significant increase in utilizing H&H as PoD for the 45-64 years cohort AAPC [4.29, CI (3.2, 5.2), p < 0.000001], similarly, with the older age group 65+ cohorts AAPC [6.26, CI (5.4, 7.0), p < 0.000001]. In contrast, the younger cohort deduced no significant trend AAPC [2.92, CI (-1.5, 7.6), p = 0.14]. Conclusions: This is the first study to our knowledge providing valuable insights into the evolving PoD preferences among PC patients in the U.S.The age-related trends underscore the importance of tailoring end-of-life care strategies to specific age cohorts. The findings emphasize the importance of policies promoting and supporting H&H care for PC patients. Targeted efforts are warranted to address notable disparities in PoD preferences among racial and age groups.

369 Background: MRI-guided transurethral ultrasound ablation (TULSA) uses MRI to target, monitor, and control thermal ablation of prostate tissue with high intensity directional ultrasound, demonstrating favorable histologic control and preservation of genitourinary function in single-arm studies [1,2]. CAPTAIN (NCT05027477) is a post-market, multi-center randomized controlled trial (RCT) of TULSA vs RARP for intermediate-risk prostate cancer, and is the first such study to meet its enrolment target. Here we compare baseline patient characteristics, treatment parameters, and periprocedural outcomes. Methods: CAPTAIN enrolled men with treatment-naïve, organ-confined, Grade Group 2 or 3 prostate cancer at 23 centers including academic and private clinics in the USA (20), Canada (2), and Finland (1). Patients were randomized 2:1 to TULSA or RARP, without crossover. Endpoints include pad-free urinary continence (EPIC) and erections sufficient for penetration (IIEF Q2) at 1 year, salvage treatment at 3 years, and survival to 10 years. Periprocedural metrics include length of stay, blood loss, catheter time, and 30-day patient diary (EQ-5D-5L, NRS pain score). Results: 211 patients were treated from Jan 2022 to Aug 2025 (70% TULSA, 30% RARP), surpassing the enrolment target of 201. Arms had similar baseline characteristics: median (IQR) age for TULSA vs. RARP was 63 (58–68) vs 65 (60–69) years (p=0.12), PSA was 6.5 (4.9–9.6) vs 7.2 (5.6–9.7) ng/mL (p=0.63), Grade Group 2/3 proportions were 76%/24% vs 77%/23% (p=0.88). RARP involved bilateral, unilateral, or no nerve sparing in 89%, 5.7%, and 5.7% of cases. TULSA ablation plans included whole-gland (68%) and ≥hemi-ablation (32%). Median (IQR) blood loss was lower during TULSA vs RARP: 0 (0–0) vs 100 (100–200) mL (p<0.001). Hospital stay was shorter for TULSA: 0.29 (0.27–0.32) vs 1.24 (1.12–1.36) days (p<0.001). Catheter duration was longer post-TULSA: 13 (11–15) vs 8 (8–10) days (p<0.001). Patients reported lower NRS pain scores after TULSA to post-operative day 6, and less decline in overall health on the EQ-5D-5L 0-100 visual analog scale over 30 days (p<0.05). Fewer patients reported extreme inability on EQ-5D-5L after TULSA vs RARP over the first month for mobility (0% vs 15%), self-care (1% vs 18%), and usual activities (18% vs 38%) (all p<0.05). Conclusions: CAPTAIN is the first multicenter RCT comparing ablation to radical prostate cancer treatment to meet its enrollment target. Early perioperative results from CAPTAIN demonstrate that TULSA had no blood loss or overnight hospitalization, reduced post-procedural pain, and faster return to baseline activities and overall health. Data collection to 1 and 3 years post-treatment continues to readout of the primary safety and oncological outcomes. [1] Klotz et al 2021, JUrol 205(3):769-779. [2] Eggener et al 2024, UrolOnc 42:S83. Clinical trial information: NCT05027477 .

514 Background: Poly(ADP-ribose) polymerase 1 (PARP1) senses single strand DNA damage and catalyzes repair mechanisms. PARP inhibitor (PARPi) suppresses PARP1 activity and promotes cell death in BRCA1 or BRCA2 mutated cancers that are homologous recombination repair deficient (HRD) via a phenomenon known as “synthetic lethality”. Utility of PARPi in HRD-negative (HRDn) cancers remain uncertain, although in a preclinical study overexpression—but not endogenous levels—of BRCA2 in mouse hybridoma cells led to HRD and increased sensitivity to DNA crosslinking agents, suggesting potential sensitization to PARPi. In renal cell carcinoma (RCC), HRD mutations are rare and the role of PARPi remains investigational. In this study, PARP1 and BRCA1/2 expression and overall survival (OS) in high risk of recurrence localized clear cell-type renal carcinoma (hrr-ccRCC) were explored. Methods: Batch-corrected bulk mRNA profile (RNA Seq V2 RSEM) and clinical data of HRDn stages II grade 4-only (n = 4) and III (n = 100) ccRCC from The Cancer Genome Atlas Pan-Cancer project were reviewed. Gene expression was classified “high” if mRNA level is higher than median, otherwise it was classified “low”. Survival analyses were Log-rank Kaplan-Meier. Group comparisons were two-tailed Mann-Whitney test. Results: In HRDn hrr-ccRCC (n = 104), BRCA1 and BRCA2 were upregulated by median fold change (mFC) of 1.6 and 3.7, respectively, whereas PARP1 was downregulated by mFC 0.8 compared to normal control (n = 72, all p < 0.0001). BRCA1 and BRCA2 levels were positively correlated (R 2 = 0.71). Median duration of follow-up for OS was 36.5 months (IQR 20.9-60.0). High BRCA2 (n = 54) was associated with superior OS compared to low BRCA2 (n = 50) with hazard ratio (HR) for death at 0.34 (95% CI 0.19-0.63, p = 0.0008). When high BRCA2 group was further stratified by PARP1 level, those with concomitant low PARP1 (n = 16) trended towards a superior OS compared to those with high PARP1 (n = 38) with HR 0.19 (95% CI 0.06-0.60, p = 0.067). Similarly, high BRCA1 (n = 53) was associated with superior OS compared to low BRCA1 (n = 51) with HR 0.53 (95% CI 0.29-0.96, p = 0.04). However, no differential OS was seen when high BRCA1 group was stratified by PARP1 level. No differential OS was seen when low BRCA1 or low BRCA2 groups were stratified by PARP1 level. Conclusions: In this retrospective analysis of HRDn hrr-ccRCC, high BRCA2 was associated with superior OS which was more pronounced with concomitant low PARP1 . High BRCA1 was also associated with superior OS, but PARP1 levels had no influence. The findings of this study may imply a potential therapeutic value of PARP1 suppression with PARPi by mimicking low PARP1 expression in treating HRDn hrr-ccRCC with BRCA2 overexpression. Further investigation is warranted.