Abstract 2560: Genomic biomarkers of survival in patients (pts) with metastatic castrate-sensitive prostate cancer (mCSPC) undergoing androgen deprivation therapy (ADT) intensification (ADTi)

Abstract Background: ADTi with androgen receptor pathway inhibitors (ARPI) with or without docetaxel improves survival outcomes in pts with mCSPC. Even with ADTi, 20% of these pts progress within a year and experience poor overall survival (OS). Identifying baseline genomic biomarkers predicting poor survival outcomes in pts receiving ADTi remains an unmet need. Methods: In this IRB-approved retrospective study, pts with a new diagnosis of mCSPC who underwent comprehensive genomic profiling of primary prostate tissue or metastatic site or cell-free DNA and treated with ADTi (ADT with ARPI or docetaxel) were included. Genomic alterations with an incidence > 5% were included in the analysis. Study endpoints: progression-free survival (PFS) was defined from the start of therapy for mCSPC to progression (per PCWG-2) or death from any cause. OS was defined from the start of therapy for mCSPC to the date of death from any cause or censored at the last follow-up. A multivariable analysis using the Cox proportional hazards model was used, adjusting for age at mCSPC diagnosis, disease volume (high vs. low), Gleason score (≥ 8 vs. < 8), Log2PSA at baseline, and initial timing of metastasis (de novo vs. non de novo). A subgroup analysis by intensification treatment received (ARPI vs. docetaxel) was also performed. Missing baseline characteristics such as volume of disease, Gleason score, and Log2PSA were multiply imputed on 50 chained equations using “mice” package in R. All the analyses were done using R version 4.3.1. Results: A total of 289 pts were included in the study. The baseline characteristics of the cohort will be presented in the meeting. The alterations included in the analysis were TP53 (31.8%), TMPRSS2 (30.4%), PTEN (17%), APC (10.4%), SPOP (9%), RB1 (6.2%), BRCA2 (5.2%), and CDK12 (5.2%). In the multivariable analysis, TP53 (HR 1.87, 95% CI 1.29-2.72, p = 0.001), RB1 (HR 2.56, 95% CI 1.45-4.53, p = 0.001), PTEN (HR 1.77, 95% CI 1.15-2.72, p = 0.009), and BRCA2 (HR 2.68, 95% CI 1.47-4.89, p = 0.002) were associated with significantly shorter PFS while TP53 (HR 1.78, 95% CI 1.1-2.88, p = 0.019), RB1 (HR 4.78, 95% CI 2.53-9.02, p < 0.001), and PTEN (HR 2.37, 95% CI 1.37-4.1, p = 0.003) were associated with significantly worse OS. Results of the subgroup analysis by intensification treatment (ARPI vs. docetaxel) will also be presented in the meeting. Conclusions: In this real-world study, we identified genomic biomarkers that could be associated with shorter PFS and OS in pts with mCSPC treated with ADTi. Upon external validation, these results may aid in developing a clinical-genomic risk stratification model, patient counseling, and treatment selection. Citation Format: Arshit Narang, Georges Gebrael, Chadi Hage Chehade, Nicolas Sayegh, Yeonjung Jo, Beverly Chigarira, Nishita Tripathi, Ayana Srivastava, Clara Tandar, Benjamin L. Maughan, Umang Swami, Neeraj Agarwal. Genomic biomarkers of survival in patients (pts) with metastatic castrate-sensitive prostate cancer (mCSPC) undergoing androgen deprivation therapy (ADT) intensification (ADTi) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2560.