Enzalutamide Granted FDA Approval for Treatment of Patients With mCSPC

Enzalutamide (Xtandi) is now approved by the FDA for the treatment of metastatic castration-sensitive prostate cancer (mCSPC), making it the first oral agent to be approved for 3 different types of advanced prostate cancer, according to a press release from Pfizer.¹

The approval was prompted by results from the phase III ARCHES trial (NCT02677896). In this study, treatment with enzalutamide plus androgen deprivation therapy (ADT) demonstrated a 61% decrease in the risk of radiographic progression or death compared with placebo plus ADT (HR, 0.39, 95% CI, 0.30-0.50;P<0.0001). Data on the median radiographic progression-free survival (rPFS) had not yet been reached at the time of data cutoff for the enzalutamide group.¹In patients treated with placebo plus ADT, the median rPFS was 19 months.²

Adverse events (AEs) occurred more frequently with enzalutamide plus ADT compared to placebo plus ADT. The most common AEs observed included hot flash (27% vs. 22%), asthenic conditions (24% vs. 20%), hypertension (8.0% vs. 5.6%), fractures (6.5% vs. 4.2%), and musculoskeletal pain (6.3% vs. 4.0%), respectively.

&ldquo;Men with metastatic castration-sensitive prostate cancer face complex treatment decisions and it is critical for physicians and patients to have as much information as possible when deciding on all of the options available,&rdquo; said Andrew Armstrong, MD, professor of medicine, Surgery, Pharmacology and Cancer Biology, Director of Research in the Duke Cancer Institute&rsquo;s Center for Prostate and Urologic Cancers and lead investigator of ARCHES. &ldquo;The research supporting the FDA approval and updated treatment guidelines provide physicians and patients with compelling evidence to consider enzalutamide as a treatment option for men with this disease.&rdquo;

ARCHES is a randomized, double-blind, placebo-controlled study to evaluate the efficacy and safety of enzalutamide/ADT in patients with mHSPC. Patients in the study received enzalutamide once daily and ADT, as per standard of care (SOC) or placebo once daily with ADT, as per SOC. The primary endpoint of the study is radiographic progression-free survival (rPFS). Secondary endpoints in this study included OS, time to first symptomatic skeletal event, time to castration-resistance, time to deterioration of quality of life, time to deterioration in urinary symptom, time to prostate-specific antigen (PSA) progression, PSA undetectable rate, time to initiation of a new antineoplastic therapy, objective response rate, and time to pain progression.

To enroll in the trial, individuals must have been diagnosed with histologically or cytologically confirmed prostate cancer without neuroendocrine differentiation, signet cell, or small cell histology. Patients were required to have metastatic, have an ECOG performance status of 0 or 1, and be able to maintain ADT throughout the study.

Individuals were excluded if they had prior pharmacotherapy, radiation therapy or surgery for metastatic prostate cancer, known brain metastases, clinically significant cardiovascular disease, and other conditions that may have interfered with the experimental treatment.

Enzalutamide, an androgen receptor inhibitor has prior approvals for the treatment of non-metastatic prostate cancer and metastatic castration-resistant prostate cancer. Experts state that the new approval for treatment of mHSPC can get patients the therapy they need much faster.

&ldquo;[Enzalutamide] has been established as a standard of care for men with castration-resistant prostate cancer and has been prescribed to more than 420,000 patients worldwide since it was first approved in 2012,&rdquo; said Andrew Krivoshik, MD, PhD, senior vice president and Oncology Therapeutic Area head at Astellas. &ldquo;This approval in metastatic castration-sensitive prostate cancer means physicians can now offer {enzalutamide] to men earlier in their advanced prostate cancer treatment journey.&rdquo;

References

1. XTANDI (enzalutamide) Approved by U.S. FDA for the Treatment of Metastatic Castration-Sensitive Prostate Cancer [press release]. New York, New York; Pfizer, Inc; December 16, 2019.https://bwnews.pr/2r2IRgO. Accessed December 16, 2019.
2. Armstrong AJ, Szmulewitz RZ, Petrylak DP, et al. ARCHES: A Randomized, Phase III Study of Androgen Deprivation Therapy With Enzalutamide or Placebo in Men With Metastatic Hormone-Sensitive Prostate Cancer.Journal of Clinical Oncol.37, 32; 2974-2986.