Pfizer and Astellas have reported positive top line results from a phase 3 trial of their androgen receptor signalling inhibitor, Xtandi (enzalutamide), in non-metastatic hormone-sensitive prostate cancer (nmHSPC) with high-risk biochemical recurrence (BCR).

The medicine is already a standard of care in the US for metastatic hormone-sensitive prostate cancer (mHSPC), metastatic castration-resistant prostate cancer (mCRPC) and non-metastatic castration-resistant prostate cancer (nmCRPC), and for one or more of these indications in more than 100 countries.

Compared with those indications, nmHSPC represents an earlier stage of disease, in which there is no detectable evidence of the cancer spreading to distant parts of the body, and it still responds to testosterone-lowering treatments.

However, some patients remain at a higher risk for BCR following primary treatment, which may result in metastases.

The EMBARK trial met its primary endpoint, demonstrating a statistically significant and clinically meaningful improvement in metastasis-free survival (MFS) for patients treated daily with Xtandi plus leuprolide versus placebo plus leuprolide.

Ahsan Arozullah, senior vice president and head of development therapeutic areas at Astellas, explained: “The EMBARK trial is the first study to demonstrate a statistically significant improvement in MFS using the combination of Xtandi plus leuprolide in men with this stage of disease.”

The study also met a key secondary endpoint of a statistically significant and clinically meaningful improvement in MFS for patients treated with Xtandi monotherapy versus placebo plus leuprolide.

Additional key secondary endpoints reached statistical significance, including time to prostate-specific antigen progression and time to first use of new antineoplastic therapy.

A positive trend in the key secondary endpoint of overall survival was also observed, but this data was not yet mature at the time of analysis, the companies said.

The companies said they will present detailed results from the study at a future medical meeting, as well as discuss the data with regulatory authorities to support a potential submission for Xtandi in this indication.

Chris Boshoff, chief development officer, oncology and rare disease, Pfizer Global Product Development, said: “As the only novel hormone therapy approved for three disease states of prostate cancer in the US, Xtandi has impacted hundreds of thousands of men.

“The top line findings from EMBARK are highly encouraging and we look forward to engaging with health authorities to potentially bring Xtandi to men with nmHSPC with high-risk BCR.”

https://www.pmlive.com/pharma_news/pfizer_and_astellas_xtandi_shows_promise_in_phase_3_prostate_cancer_study_1489946