(103) Evaluation of PARPi utilization for treatment of prostate cancer at St. Luke’s Cancer Institute

Poster Abstract:

Background:
Talazoparib, rucaparib, niraparib, and olaparib are oral poly-ADP ribose polymerase (PARP) enzyme inhibitors, which have varying indications for the treatment of prostate cancer. Olaparib and rucaparib, hold indications for the treatment of metastatic, castration resistant, Breast Cancer Gene (BRCA) mutated prostate cancer (mCRPC) and were approved for this indication in May 2020. Niraparib in combination with abiraterone was approved for BRCA mutated mCRPC in August 2023. Olaparib has garnered an additional indication for homologous recombination repair (HRR) muted mCRPC in May 2023.1 Talazoparib in combination with enzalutamide was approved June 2023 for the treatment of HRR mutated mCRPC.

The broader category of HHR gene mutations (somatic or germline), including BRCA mutations, are estimated to be present in up to 33% of patients with prostate cancer and represent the opportunity for additional targeted therapy options for patients with these genetic alterations. Current guidelines recommend somatic tumor testing for alterations in homologous recombination DNA repair genes such as BRCA1, BRCA2, ATM, PALB2, FANCA, RAD51D, CHECK2, and CDK12 in patients with mCRPC and indicate that testing can be considered in patients with regional or castration-sensitive metastatic prostate cancer (CSPC). Despite HRR gene testing recommendations in the regional or metastatic castration-sensitive prostate cancer populations, targeted therapies such as PARPi must be utilized off-label. Given the recent expanded therapy approvals as well as evolving somatic tumor testing recommendations, the objective of this analysis will be to evaluate the utilization of PARPi in prostate cancer.

Objectives:
The primary outcome will be percentage of PARPi prescriptions that are being utilized for on label and off label indications in prostate cancer. Key secondary outcomes will be type of sample used for NGS test, stage/hormone sensitivity status of prostate cancer (at initiation of olaparib prescription), and percentage of each type of gene mutation detected by NGS test.

Methods:
This analysis is a retrospective medication use evaluation. Epic reports with Slicer Dicer will be used to gather patients for review. Patients will be included if they have had/or currently have an active prescription for talazoparib, rucaparib, olaparib, or niraparib starting May 1st 2020 – December 31st 2023 and a diagnosis of prostate cancer. Data will be analyzed using descriptive statistics.

Results:
Preliminary results suggest that oncology providers expanding somatic genetic testing in prostate cancer, and that the amount of PARPi prescriptions for off label use may be increased. Results will be presented.

Discussion/

Conclusions:
Will be presented.

References (must also be included in final poster): 1. Olaparib (Lynparza®) [package insert]. Wilmington (DE): AstraZeneca; September 2023.
2. Rucaparib (Rubraca®) [package insert]. Boulder (CO): Clovis Oncology, Inc.; June 2022.
3. Niraparib and abiraterone acetate (Akeega®) [package insert]. Titusville (NJ): Janssen Biotech, Inc.; August 2023.
4. Talazoparib (Talzenna®) [package insert]. New York (NY): Pfizer, Inc.; June 2023.
5. Scott RJ, Mehta A, Macedo GS, Borisov PS, Kanesvaran R, El Metnawy W. Genetic testing for homologous recombination repair (HRR) in metastatic castration-resistant prostate cancer (mCRPC): challenges and solutions. Oncotarget. 2021 Aug 3;12(16):1600-1614.
6. National Comprehensive Cancer Network (NCCN). NCCN Clinical Practice Guidelines in Oncology. Prostate Cancer. 4.2023. Sept. 7, 2023; National Comprehensive Cancer Network. https://www.nccn.org/professionals/physician_gls/pdf/prostate.pdf.