The Food and Drug Administration (FDA) approved Xtandi (enzalutamide) for the treatment of patients with non-metastatic castration-sensitive prostate cancer (nmCSPC) with a high risk of biochemical recurrence — meaning a recurrence that is determined by rising prostate-specific antigen (PSA) levels — according to Pfizer, the manufacturer of the drug.
Notably, this marks the first approval of an androgen receptor signaling inhibitor that is FDA approved for this patient population.
“Having had the privilege of taking care of patients with prostate cancer for nearly 40 years, I have been fortunate to have participated in many of the prostate cancer landscape changing trials; notably, we have not progressed our evidenced-based care for patients with biochemical recurrence (BCR), also known as nmCSPC, until the completion of the EMBARK trial,” said Dr. Neal Shore, chief medical officer of strategic innovation and pharmacy, GenesisCare USA, director, CPI, Carolina Urologic Research Center, and primary investigator for the EMBARK trial, said in the press release. “Previously, treatment options for these BCR patients, especially those who have a high likelihood of developing metastases were limited. The FDA approval of Xtandi for patients with nmCSPC with BCR at high risk of metastasis represents an important advancement whereby an androgen deprivation signaling inhibitor, Xtandi, has achieved standard of care discussion for patient-physician decision-making.”
The approval is based off findings from the randomized phase 3 EMBARK clinical trial, which included 713 patients with nmCSPC, who were randomly assigned to receive Xtandi plus leuprolide (355 patients) or leuporlide (358 patients). The main goal of the trial was to determine if either group of patients had a longer metastasis-free survival (time from treatment until metastatic disease). Findings showed that Xtandi plus leuprolide significantly reduces the risk of metastasis or death compared to placebo plus leuprolide.
Specifically, five-year metastases-free survival was 87.3% in the Xtandi arm, compared with 71.4% in leuprolide-only group and 80% in the monotherapy group, according to findings published in the New England Journal of Medicine.
Before the FDA approval, secondary findings from the EMBARK trial were presented at the 2023 European Society of Medical Oncology (ESMO) Congress, where the researchers wrote, “If approved, (this Xtandi) combination may represent a new standard of care for patients with high-risk (of biochemical recurrence.”
Patient-reported quality of life data was also presented at the ESMO Congress. Data showed no major differences between time to first and confirmed meaningful deterioration in quality of life, as measured with the Brief Pain Inventory Short Form worst pain and Functional Assessment of Cancer Therapy-Prostate scores.Additionally, sexual activity may be better preserved with single-agent Xtandi compared with leuprolide.
“For patients who were previously treated for prostate cancer and had achieved remission, only to later receive the distressing news of disease recurrence with a risk of metastasis, the emotional toll can be profound,” said Courtney Bugler, president and CEO of ZERO Prostate Cancer, in a press release issued by Pfizer. “This approval of Xtandi is a promising treatment option for the community, offering a ray of hope to patients and their caregivers during these challenging times.”
Regarding side effects, 46% of patients in the Xtandi plus leuprolide group, 50% in the single-arm Xtandi group and 43% in the placebo plus leuprolide group experienced moderate to severe (grade 3 or higher) side effects. Permanent discontinuation due to side effects occurred in 21%, 18% and 10% in the Xtandi combination, Xtandi alone and placebo/leuprolide groups, respectively.
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