Pfizer and Astellas report positive Phase III data from prostate cancer trial

Pfizer and Astellas Pharma have reported positive results from a Phase III clinical trial (PROSPER) of Xtandi (enzalutamide) in combination with androgen deprivation therapy (ADT) to treat patients with non-metastatic (M0) castration-resistant prostate cancer (CRPC).

Enzalutamide is an androgen receptor inhibitor being developed to block various steps in the receptor’s signalling pathway within the tumour cell.

The trial has met the primary endpoint with a statistically significant improvement in metastasis-free survival (MFS).

Conducted at trial sites across the US, Canada, Europe, South America and Asia Pacific, the PROSPER trial compared the Xtandi (160mg once daily) and ADT combination with ADT alone in 1,400 subjects.

The Phase III trial recruited patients with cancer progression even after ADT and without any symptoms, previous or present evidence of metastatic disease.

A preliminary safety analysis of the PROSPER trial is reported to have indicated a consistent profile of Xtandi compared to prior clinical trials.

Pfizer Global Product Development Oncology chief development officer Mace Rothenberg said: “Xtandi is already established as a standard of care for men with metastatic CRPC based on the results of prior studies, such as AFFIRM and PREVAIL, which demonstrated that Xtandi delayed disease progression and improved overall survival in men with clinically detectable metastatic disease.”

Xtandi is being further studied in ongoing ARCHES trial for metastatic hormone-sensitive prostate cancer and EMBARK trial for the treatment of non-metastatic hormone-sensitive prostate cancer.

In previous trials for metastatic CRPC, the drug candidate showed a statistically significant overall survival benefit.