Gonzalez, Diego Ospina

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.