Niraparib Before Surgery in Treating Patients With High Risk Localized Prostate Cancer and DNA Damage Response Defects

Ability to understand and willingness to sign an informed consent form

Ability to adhere to the study visit schedule and other protocol requirements

Patients must have histologically or cytologically confirmed prostate cancer that is clinically localized as defined by negative cross-section imaging and/or bone scan, and classified as high or very high risk per National Comprehensive Cancer Network (NCCN) guideline

Eastern Cooperative Oncology Group (ECOG) performance status (PS) score of 0 or 1

Life expectancy \>= 10 years

Men who have selected radical prostatectomy as the primary treatment for their prostate cancer

Prostate cancer tumors with alterations in key DNA repair genes. This will include at least one alteration in a gene involved in DNA repair primarily through the homologous recombination pathway including BRCA1/2, ATM, CHEK1/2 FANCA, FANCD2, FANCL, GEN1, NBN, PALB2, RAD51, RAD51c, and BRIP1. Mutations will be selected that are known or likely pathogenic. Mean allele frequencies will be assessed to estimate mono versus biallelic loss of function. Patients with biallelic deletions or mutations will be prioritized for inclusion to make up at least 30% of the enrollment (i.e., 10 patients) to gauge response in this group over monoallelic loss. Final inclusion will be determined by the principal investigator

Must be able to swallow whole capsules

To avoid risk of drug exposure through the ejaculate, male subjects (even if they have undergone a successful vasectomy) must agree while on study therapy (including during dose interruptions) and for 3 months following the last dose of study drug to:

* Use a condom during sexual activity or practice complete sexual abstinence

* Not donate sperm

Absolute neutrophil count (ANC) \>= 1.5 x 10\^9/L (obtained =\< 14 days of the first study treatment)

Platelet count \>= 100 x 10\^9/L (obtained =\< 14 days of the first study treatment)

Hemoglobin \>= 9 g/dL (may have been transfused) (obtained =\< 14 days of the first study treatment)

Total bilirubin level =\< 1.5 x the upper limit of normal (ULN) range (obtained =\< 14 days of the first study treatment)

Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels =\< 2.5 x ULN or AST and ALT levels =\< 5 x ULN (for subjects with documented metastatic disease to the liver) (obtained =\< 14 days of the first study treatment)

International normalized ratio (INR) and activated partial thromboplastin time (aPTT) =\< 1.5 x ULN (for patients on anticoagulation they must be receiving a stable dose for at least 1 week prior to randomization) (obtained =\< 14 days of the first study treatment)

Creatinine clearance \> 30 mL/min by Cockcroft-Gault formula (or local institutional standard method) (obtained =\< 14 days of the first study treatment)

What this study is about