Pfizer and Astellas Pharma have shared positive top-line results from a late-stage study of their androgen receptor signalling inhibitor Xtandi (enzalutamide) in a subset of prostate cancer patients.
The phase 3 EMBARK study has been evaluating the drug both in combination with leuprolide and as a monotherapy in men with non-metastatic hormone-sensitive prostate cancer (nmHSPC) with biochemical recurrence (BCR) at high risk for metastasis.
The trial met its key secondary endpoint among the combination cohort, with Xtandi plus leuprolide demonstrating a statistically significant and clinically meaningful improvement in overall survival compared to placebo plus leuprolide.
There was also a favourable trend towards improved overall survival for patients treated with Xtandi monotherapy versus placebo plus leuprolide, but this did not reach statistical significance, and the safety results were consistent with the demonstrated safety profile of the drug.
Prostate cancer is the most common cancer in males in the UK, where around 55,100 cases of the disease are diagnosed every year.
nmHSPC, also known as non-metastatic castration-sensitive prostate cancer or (nmCSPC), means there is no detectable evidence of the cancer spreading to distant parts of the body and the disease still responds to testosterone-lowering treatments.
However, up to 40% of patients who have undergone definitive prostate cancer treatment will experience BCR within ten years, and around 90% of those with high-risk BCR will develop metastatic disease.
Already approved for multiple prostate cancer indications, including nmHSPC with high-risk BCR, Xtandi is designed to block the action of testosterone and other male hormones known as androgens, which prostate cancer needs to survive and grow.
Johanna Bendell, oncology chief development officer at Pfizer, said: “Xtandi is the only androgen receptor inhibitor-based regimen to demonstrate a survival benefit in mHSPC and nmHSPC with high-risk BCR, as well as castration-resistant prostate cancer, highlighting its significant patient impact in advanced prostate cancer.
“These positive results add to the robust clinical support for the use of Xtandi and broaden clinical confidence, offering men with high-risk BCR evidence that they might live longer when they start Xtandi early.”
Detailed overall survival results from EMBARK will be presented at a future medical meeting, the partners outlined.