Adding Xtandi (enzalutamide) to hormone therapy reduces the risk of cancer spreading in patients with non-metastatic castration-resistant prostate cancer (CRPC), new Phase 3 trial data shows.
Additional results announced by Pfizer and Astellas Pharma, the drug developers, also show that the safety profile of Xtandi in this population is consistent with previous clinical trials.
“Many prostate cancer patients who initiate androgen deprivation therapy will experience disease progression illustrated by a rising PSA level, and currently, there are no FDA-approved treatment options for patients with non-metastatic CRPC until they develop confirmed radiographic metastatic disease,” Dr. Neal Shore, MD, director, Carolina Urologic Research Center, said in a press release.
Pfizer and Astellas initiated the multinational PROSPER trial (NCT02003924) to determine the effects of Xtandi in men with non-metastatic CRPC. The trial enrolled approximately 1,400 patients with prostate cancer that had progressed, based on rising PSA levels, despite androgen deprivation therapy (ADT) but with no symptoms or other evidence of metastasis.
Participants were randomly assigned Xtandi plus hormone therapy or a placebo plus hormone therapy. The study’s primary endpoint was metastasis-free survival, which is the amount of time passed until the cancer spread.
“We are delighted with the significant results seen in the PROSPER study, showing that Xtandi plus ADT delayed clinically detectable metastases compared to ADT alone in patients with non-metastatic CRPC whose only sign of underlying disease was a rapidly rising prostate-specific antigen (PSA) level,” said Mace Rothenberg, MD, chief development officer, Oncology, at Pfizer Global Product Development. “We look forward to discussing the data with regulatory authorities.”
“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,” he said. Based on the favorable PROSPER results, Pfizer and Astellas are now pursuing the label expansion to cover all CRPC patients.
“We want to thank the patients, family members and clinicians who participated in the PROSPER trial and helped advance the scientific understanding of the potential role for Xtandi in this prevalent disease,” said Steven Benner, MD, senior vice president and global therapeutic area head, Oncology Development, at Astellas.
“We look forward to further analyzing the detailed efficacy and safety results from PROSPER, and submitting them for presentation at an upcoming major medical meeting,” Benner added.
Additional studies on Xtandi are ongoing, including the ARCHES trial (NCT02677896) in metastatic hormone-sensitive prostate cancer, and the EMBARK trial (NCT02319837) in non-metastatic hormone-sensitive prostate cancer.