The phase 3 trial assessed Xtandi plus androgen deprivation therapy (ADT) against placebo plus ADT in men with non-metastatic castration-resistant prostate cancer (nmCRPC). The OS was a major secondary endpoint of the trial.
Xtandi is an androgen receptor inhibitor designed to treat patients with castration-resistant prostate cancer (CRPC) and metastatic castration-sensitive prostate cancer (mCSPC).
The CRPC indicates the subset of men whose prostate cancer progresses on ADT despite castrate levels of testosterone, while non-metastatic CRPC is a condition that there will be no clinically detectable evidence of cancer spreading to other parts of the body.
The study showed a statistically significant improvement in OS in patients with nmCRPC, who have been treated Xtandi plus ADT.
In 2018, both firms reported that the PROSPER study achieved its primary endpoint of metastasis-free survival (MFS).
The phase 3 randomised, double-blind, placebo-controlled and multi-national study recruited around 1,400 patients with nmCRPC at sites in the US, Canada, Europe, South America and the Asia-Pacific region.
PROSPER trial recruited patients with prostate cancer that had progressed, based on an increasing PSA level despite ADT, but who had no symptoms and no prior or present evidence of metastatic disease.
The trial assessed enzalutamide at a dose of 160mg taken orally once daily plus ADT, against placebo plus ADT. Its primary endpoint metastasis-free survival (MFS) was measured as the time from patients entering the study until their cancer was radiographically identified as having metastasized, or until death, within 112 days of treatment discontinuation.
Major secondary endpoints comprised of overall survival, time to PSA progression and time to the first use of antineoplastic therapy.
In December 2019, Pfizer and Astellas Pharma have secured approval for a new indication for Xtandi from the US Food and Drug Administration (FDA) to include its use in metastatic castration-sensitive prostate cancer (mCSPC).
Pfizer Oncology has a portfolio of 22 approved innovative cancer medicines and biosimilars across more than 30 indications.