Abstract 2605: A natural history study of men with high-risk genetics for prostate cancer (PCa) using multiparametric MRI (mpMRI)

Introduction: The understanding of molecular genetics in PCa provides insight into disease progression and treatment. Less is known about PCa development in men with known high-risk germline pathogenic/likely pathogenic variants in PCa related genes, particularly DNA damage repair (DDR). mpMRI can localize and detect PCa lesions in this population. We are conducting a multicenter natural history study of male participants (prts) with documented germline variant(s) in BRCA1, BRCA2, MLH1, MSH2, MSH6, PMS2, EPCAM, HOXB13, ATM, NBN, TP53, CHEK2, PALB2, RAD51D, BRIP1, or FANCA who do not have a PCa diagnosis using mpMRI (NCT03805919). Methods: Up to 500 men, 30-75 years old (y/o) will undergo mpMRI evaluation at baseline and every 2 years (yrs). Prts are followed at 12-mo intervals to determine PSA, PCa diagnosis, and/or disease/survival status until death. Indication for prostate biopsy includes PSA >2.0 for 30 - 49 y/o; >2.5 ng/mL for 50 - 75 y/o and/or PIRADS 3+ MRI lesion or clinical discretion. Tissue obtained will undergo full transcriptome analysis. Results: 100 prts have enrolled. Median age is 47 y/o. Median on-study PSA is 0.87 (0.16-10.05 ng/mL). Median PSA density is 0.029. Gene mutations are BRCA2 (40%), BRCA1 (33%), MSH2 (9%), and CHEK2 (4%). Mutations in ATM, HOXB13, MLH1, MSH6, PMS2, and EPCAM are ≤3%. No significant AEs have been observed. Of 96 prts, 25 (26%), had indication for biopsy [PIRADS 4 lesion: 16 (64%), PIRADS 3 lesion: 4 (16%), elevated PSA: 6 (24%), or clinical indication 1: (4%)]. 22 prostate biopsies were performed and 6 prts were diagnosed with PCa. One prt was upstaged on radical prostatectomy (RP). Conclusions: We found mpMRI-based PCa screening in men with high-risk gene mutations, especially DDR genes, is feasible and can be used to identify clinically significant PCa and monitor for disease progression. Future guidelines should consider age, mutation specificity and mpMRI. Accrual and correlative studies (biomarkers, PBMCs) are on-going. Citation Format: Fatima Karzai, Anna Couvillon, Yolanda McKinney, Katherine Lee-Wisdom, Peter L. Choyke, Veda N. Giri, Todd M. Morgan, Heather H. Cheng, Maria J. Merino, Peter A. Pinto, Baris Turkbey, William L. Dahut. A natural history study of men with high-risk genetics for prostate cancer (PCa) using multiparametric MRI (mpMRI) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2605.