HRR Testing & PARPi Underutilized in Patients With Metastatic Prostate Cancer

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Only half of patients with metastatic castration-resistant prostate cancer were tested for HRR mutations, and PARP inhibitors were underused.

A recent study of real-world patients with metastatic castration-resistant prostate cancer showed that testing for homologous recombination repair (HRR) mutations testing was low, and poly (ADP-ribose) polymerase inhibitors (PARPi) were underutilized.¹

“HRR mutations have prognostic value in metastatic castration-resistant prostate cancer,” Anupama Vasudevan, PhD, MPH, and colleagues wrote. “Treatment with [PARPi] has shown better outcomes among patients with HRR mutations.”

Dr. Vasudevan and colleagues previously investigated the use of PARPi among patients with confirmed HRR mutations. They found that PARPi was underutilized, and the rate of PARPi use varied by which type of HRR mutation patients had.²

“Patients with BRCA and ATM mutations were more likely to receive PARPi than those with other HRR mutations,” the researchers reported in their previous study.² “This real-world study shows an opportunity to increase rates of PARPi treatment…across all HRR gene mutations.”

For their recent study, which they presented at the 2024 ASCO Genitourinary Cancers Symposium, Dr. Vasudevan and colleagues continued investigating PARPi utilization, paying particular attention to how many patients were tested for HRR mutations to begin with.¹

HRR Mutation Testing Low

The researchers conducted a retrospective observational analysis using the IntegraConnect PrecisionQ deidentified database, which includes data from more than 2 million patients across 500 facilities, predominantly community oncology sites. Dr. Vasudevan and colleagues pulled a random sample of 480 adult patients with metastatic castration-resistant prostate cancer.

The mean age was 76.9 (8.3) years, with 78.3% of patients identifying as White, 7.9% as African American, 1% as Asian, and 12.7% as Other. Medicare/Medicaid was the predominant payer type (69.2%). Patients received treatment between 2020 and 2023.

HRR testing was conducted in 235 patients, less than half of the total sample (48.9%). Among patients who received testing, 59 (25.1%) had HRR mutations.

PARPi Underutilization

The subgroup of patients with HRR mutations had an average age of 77.1 (7.2) years. Findings indicated that 88.1% of these patients were White, 6.8% were African American, and 5.1% had race listed as Other.

Testing also revealed BRCA and ATM mutations in 22 (37.2%) and 15 (25.4%) patients in this subgroup, respectively. Almost all patients (n=50, 90%) received prior novel hormone agents, but only about two-thirds (n=36, 67.9%) received PARPi.

The researchers concluded that HRR testing and PARPi were underutilized in real-world clinics.

“This highlights the lack of testing among those receiving care in a real-world setting. The underutilization of PARPi in these patients is a missed potential opportunity for improving their outcomes,” Dr. Vasudevan and colleagues reported.