On May 19, 2020, the Food and Drug Administration approved olaparib for adult patients with deleterious or suspected deleterious germline or somatic homologous recombination repair (HRR) gene-mutated metastatic castration-resistant prostate cancer (mCRPC), who have progressed following prior treatment with enzalutamide or abiraterone.

Today, the FDA also approved FoundationOne CDx (Foundation Medicine, Inc.) for selection of patients with mCRPC carrying HRR gene alterations and BRACAnalysis CDx test (Myriad Genetic Laboratories, Inc.) for selection of patients with mCRPC carrying germline BRCA1/2 alterations as companion diagnostic devices for treatment with olaparib. 

Efficacy was investigated in PROfound (NCT02987543), an open-label, multicenter trial randomising (2:1) 256 patients to olaparib 300 mg twice daily and 131 patients to investigator’s choice of enzalutamide or abiraterone acetate.

All patients received a GnRH analog or had prior bilateral orchiectomy.

Patients were divided into two cohorts based on their HRR gene mutation status.

Patients with mutations in either BRCA1, BRCA2, or ATM were randomised in Cohort A (N=245); patients with mutations among 12 other genes involved in the HRR pathway were randomised in Cohort B (N=142); those with co-mutations (Cohort A gene and a Cohort B gene) were assigned to Cohort A.

The major efficacy outcome of the trial was radiological progression-free survival (rPFS) (Cohort A).

Additional efficacy outcomes included confirmed objective response rate (ORR) (Cohort A) in patients with measurable disease, rPFS (combined Cohorts A B), and overall survival (OS) (Cohort A).

A statistically significant improvement was demonstrated for olaparib compared to investigator’s choice in Cohort A for rPFS with a median of 7.4 months vs 3.6 months (HR 0.34; 95% CI: 0.25, 0.47; p<0.0001), for OS with a median of 19.1 months vs. 14.7 months (HR 0.69; 95% CI: 0.50, 0.97, p=0.0175) and for ORR 33% vs 2% (p<0.0001).

A statistically significant improvement for olaparib compared to investigator’s choice was also demonstrated for rPFS in Cohort A B, with a median of 5.8 months vs. 3.5 months (HR 0.49; 95% CI: 0.38, 0.63; p<0.0001).

The most common adverse reactions in PROfound for olaparib (≥10% of patients) were anemia, nausea, fatigue (including asthenia), decreased appetite, diarrhoea, vomiting, thrombocytopenia, cough and dyspnea.

Venous thromboembolic events, including pulmonary embolism, occurred in 7% of patients randomised to the olaparib arm compared to 3.1% of those receiving enzalutamide or abiraterone.

The recommended olaparib dose is 300 mg taken orally twice daily, with or without food.

Source: The Food and Drug Administration (FDA)

Watch our interview with Prof Maha Hussain on the PROfound trial here.