Pfizer and Astellas Pharma announced they have amended the protocols for two Phase III clinical trials, ARCHES and EMBARK, to evaluate Xtandi (enzalutamide) in hormone-sensitive prostate cancer (HSPC). Both trials will wrap sooner than planned as a result.
ARCHES is evaluating the efficacy and safety of Xtandi plus androgen deprivation therapy (ADT) versus ADT alone in HSPC patients. The primary endpoint is radiographic progression-free survival (rPFS). The changes to the protocol involve revision of the planned analysis of the primary and secondary endpoints. Enrollment in the study was completed earlier this year and the companies now expect the trial to be completed in late 2018, which is way ahead of the original completion date of April 2020.
The EMBARK trial is evaluating Xtandi plus leuprolide, enzalutamide monotherapy, and leuprolide alone in HSPC. The primary endpoint is metastasis-free survival (MFS). Again, they are revising the analysis. Enrollment was completed earlier this year, and with the changes, the estimated primary completion date is mid-2020 compared to the original date of March 2021.
“We continually strive to design and implement clinical trials that bring innovations to people with the greatest need,” Steven Benner, Astellas’ senior vice president and global therapeutic area head, Oncology Development, said in a statement. “With the amendments to ARCHES and EMBARK, we will be able to evaluate the potential of Xtandi for men with hormone-sensitive prostate cancer sooner, including for those with non-metastatic disease in which there are no currently approved oral treatment options.”
Xtandi is an androgen receptor inhibitor approved for the treatment of patients with castration-resistant prostate cancer. The drug brought in $171 million in the last quarter.
Prostate cancer is the second most common cancer in men around the world. Each year in the U.S., more than 164,000 men are newly diagnosed with the disease.
The drug was approved for non-metastatic Castration-Resistant Prostate Cancer (CRPC) in July. Pfizer and Astellas filed the supplemental New Drug Application (sNDA) in March, a month after Phase III results showed efficacy for that indication. The combination of Xtandi plus ADT significantly cut the risk of developing metastases or death by 71 percent. The data also showed the combination treatment had a 93 percent reduction in relative risk of prostate-specific antigen (PSA) progression, compared to patients who received ADT alone. Median time for the primary endpoint of metastasis-free survival (MFS) was 36.6 months for men who received Xtandi compared to 14.7 months for patients receiving only ADT.
Benner noted at the time that Xtandi had become a standard of care for treating metastatic CRPC. It was approved under the FDA’s Priority Review Designation based on Phase III data. That approval made the drug the first and only oral medication approved by the FDA for both non-metastatic and metastatic CRPC.
At the same time, Jonathan Simons, head of the Prostate Cancer Foundation said, “With today’s approval, there is now a new option for men with non-metastatic CRPC, who are in between the failure of androgen deprivation therapy resulting in CRPC and the onset of metastatic disease. As a foundation that drives research aimed at improving patient outcomes, it is exciting to see approvals like this, which are vital to help address unmet patient needs.”