AstraZeneca and Merck announced further positive results from the Phase III PROfound trial of Lynparza (olaparib) in men with metastatic castration-resistant prostate cancer (mCRPC) who have a homologous recombination repair gene mutation (HRRm) and have progressed on prior treatment with new hormonal agent (NHA) treatments (e.g. enzalutamide and abiraterone).
Results from the trial showed a statistically significant and clinically meaningful improvement in the key secondary endpoint of overall survival (OS) with Lynparza versus enzalutamide or abiraterone in men with mCRPC selected for BRCA1/2 or ATM gene mutations, a subpopulation of HRR gene mutations.
The Phase III PROfound trial had met its primary endpoint in August 2019, showing significantly improved radiographic progression-free survival (rPFS) in men with mutations in BRCA1/2 or ATM genes, and had met a key secondary endpoint of rPFS in the overall HRRm population.
"Overall survival in metastatic castration-resistant prostate cancer has remained extremely challenging to achieve. We are thrilled by these results for Lynparza and we are working with regulatory authorities to bring this medicine to patients as soon as possible," José Baselga, Executive Vice President, Oncology R&D, said.
"Lynparza has demonstrated significant clinical benefit across key endpoints in PROfound, including overall survival for patients with BRCA or ATM mutations, and this reinforces its potential to change the treatment standard for patients with metastatic castration-resistant prostate cancer. These data further support MSD and AstraZeneca’s commitment to uncovering the ways in which Lynparza can help patients impacted by cancer," Roy Baynes, Senior Vice President and Head of Global Clinical Development, Chief Medical Officer, MSD Research Laboratories, said.
Lynparza was granted Priority Review in the US for patients with HRRm mCRPC in January 2020, with regulatory reviews ongoing in the EU and other jurisdictions. AstraZeneca and MSD are exploring additional trials in prostate cancer including the ongoing Phase III PROpel trial, with first data expected in 2021, testing Lynparza as a 1st-line medicine for patients with mCRPC in combination with abiraterone acetate versus abiraterone acetate alone.
Prostate cancer is the second-most common cancer in men, with an estimated 1.3 million new cases diagnosed worldwide in 2018, and is associated with a significant mortality rate. Development of prostate cancer is often driven by male sex hormones called androgens, including testosterone. 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. Approximately 10-20% of men with advanced prostate cancer will develop CRPC within five years, and at least 84% of these men will have metastases at the time of CRPC diagnosis. Of men with no metastases at CRPC diagnosis, 33% are likely to develop metastases within two years. Despite advances in treatment for men with mCRPC, five-year survival is low and extending survival remains a key goal for treating these men.
HRR mutations occur in approximately 20-30% of patients with mCRPC. HRR genes allow for accurate repair of damaged DNA in normal cells. HRR deficiency (HRD) means the DNA damage cannot be repaired, and can result in normal cell death. This is different in cancer cells, where a mutation in HRR pathways leads to abnormal cell growth and therefore cancer. HRD is a well-documented target for PARP inhibitors, such as Lynparza. PARP inhibitors block a rescue DNA damage repair mechanism by trapping PARP bound to DNA single-strand breaks which leads to replication fork stalling causing their collapse and the generation of DNA double-strand breaks, which in turn lead to cancer cell death.
Lynparza (olaparib) is a first-in-class PARP inhibitor and the first targeted treatment to block DNA damage response (DDR) in cells/tumours harbouring a deficiency in homologous recombination repair, such as mutations in BRCA1 and/or BRCA2. Inhibition of PARP with Lynparza leads to the trapping of PARP bound to DNA single-strand breaks, stalling of replication forks, their collapse and the generation of DNA double-strand breaks and cancer cell death. Lynparza is being tested in a range of PARP-dependent tumour types with defects and dependencies...
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