AstraZeneca and MSD's Lynparza (olaparib) in combination with abiraterone and prednisone or prednisolone has been approved in the US for the treatment of adult patients with deleterious or suspected deleterious BRCA-mutated (BRCAm) metastatic castration-resistant prostate cancer (mCRPC).
This approval was based on a subgroup analysis of the Phase III PROpel trial which showed that Lynparza plus abiraterone demonstrated highly clinically meaningful improvements in both radiographic progression-free survival (rPFS) (HR of 0.24, 95% CI, 0.12-0.45) and overall survival (OS) (HR of 0.30, 95% CI, 0.15-0.59) versus abiraterone alone in patients with BRCA mutations.1 Median rPFS and median OS were not reached for patients treated with Lynparza plus abiraterone versus a median of 8 months and 23 months, respectively, for those treated with abiraterone alone.
Prostate cancer is the second-most common cancer in men and despite an increase in the number of available therapies for patients with mCRPC, five-year survival remains low.2,3 Approximately 10% of patients with mCRPC have BRCA mutations, which is associated with poor prognosis and outcomes.4,5
Andrew Armstrong, MD, ScM, of the Duke Cancer Institute, Durham, North Carolina, US, and an investigator in the trial, said: "Preventing or delaying radiographic progression or death is an important clinical endpoint in assessing cancer treatment and is very important to patients, their caregivers and their families. The PROpel results showed the Lynparza combination demonstrated a notable clinically meaningful benefit that should rapidly be considered as the standard of care treatment for patients with BRCA-mutated metastatic castration-resistant prostate cancer."
Dave Fredrickson, Executive Vice President, Oncology Business Unit, AstraZeneca, said: "There is a critical unmet need for new first-line treatment options for patients with BRCA-mutated metastatic castration-resistant prostate cancer and this approval underscores the importance of BRCA testing at metastatic diagnosis. We look forward to bringing the benefit of this Lynparza combination to patients earlier in their treatment."
Eliav Barr, Senior Vice President, Head of Global Clinical Development and Chief Medical Officer, MSD Research Laboratories, said: "It is imperative that we create new ways to treat advanced cancers and help improve patient outcomes by building on the current standard of care. In PROpel, the Lynparza combination improved radiographic progression-free survival and overall survival for the subgroup of patients with BRCA-mutated metastatic castration-resistant prostate cancer. This approval reinforces the importance of routine testing for genetic mutations at metastatic diagnosis to help guide clinical decisions."
The safety and tolerability profile of Lynparza plus abiraterone in PROpel was in line with that observed in prior clinical trials and the known profiles of the individual medicines.
Lynparza in combination with abiraterone and prednisone or prednisolone is approved in the European Union (EU) and several other countries for the treatment of adult patients with mCRPC based on the PROpel trial.
Lynparza is already approved in the US based on results from the PROfound Phase III trial as monotherapy for patients with homologous recombination repair (HRR) gene-mutated mCRPC (BRCAm and other HRR gene mutations) who have progressed following prior treatment with enzalutamide or abiraterone; and in the EU, Japan, and China for patients with BRCAm mCRPC who have progressed following prior therapy that included a new hormonal agent.
Financial considerations
Following this approval for Lynparza in the US, AstraZeneca will receive a regulatory milestone payment from MSD, anticipated to be booked as Collaboration Revenue by the Company and confirmed in the second quarter 2023 results.
Notes
Prostate cancer
Prostate cancer is the second most commonly diagnosed cancer in men and the fifth leading cause of cancer death in men globally, with an incidence of 1.4 million and 375,000 deaths in 2020.2,3 In the US, it is estimated that there will be 288,300 new cases and 34,700 deaths in 2023.6 Overall survival for patients with mCRPC is approximately three years in clinical trial settings, and even shorter in the real-world.7 Approximately half of patients with mCRPC may receive only one line of active treatment, and those that go on to receive further treatment often have diminishing benefit of subsequent therapies.8-13
Metastatic castration-resistant prostate cancer
Metastatic prostate cancer is associated with a significant mortality rate.14 Development of prostate cancer is often driven by male sex hormones called androgens, including testosterone.15
In patients with mCRPC, their prostate cancer grows and spreads to other parts of the body despite the use of androgen-deprivation therapy to block the action of male sex hormones.16 Approximately 10-20% of men with advanced prostate cancer will develop castration-resistant prostate cancer (CRPC) within five years, and at least 84% of these men will have metastases at the time of CRPC diagnosis.17 Of patients with no metastases at CRPC diagnosis, 33% are likely to develop metastases within two years.17
Despite the advances in mCRPC treatment in the past decade with taxane and new hormonal agent (NHA) treatment, there is high unmet need in this population.16-19
PROpel
PROpel is a randomised, double-blind, multi-centre Phase III trial testing the efficacy, safety, and tolerability of Lynparza versus placebo when given in combination with abiraterone, as well as prednisone or prednisolone, in men with mCRPC who had not received prior chemotherapy or NHAs in the mCRPC setting.
The primary endpoint is rPFS and secondary endpoints include OS, time to secondary progression or death, and time to first subsequent therapy. In September 2021 at a planned interim analysis, the Independent Data Monitoring Committee concluded that the PROpel trial met the primary endpoint of rPFS.
