Apalutamide Linked With Faster Time to PSA90 Than Abiraterone Acetate

In metastatic castration-sensitive prostate cancer, patients on apalutamide were 53% more likely to achieve PSA90, with faster response, versus abiraterone.

Significantly more patients with metastatic castration-sensitive prostate cancer (mCSPC) achieved prostate-specific antigen (PSA) response of 90% or greater with apalutamide compared with abiraterone acetate, according to a study published in Urologic Oncology: Seminars and Original Investigations. Furthermore, according to Benjamin H. Lowentritt, MD, and colleagues, this response was attained earlier than with apalutamide.

“PSA response of 90% or greater reduction in PSA (PSA90) is an important early response indicator of radiographic progression-free survival and overall survival in patients with mCSPC),” the study team wrote. “This study compared PSA90 responses by 6 months between patients with mCSPC at first use of apalutamide or abiraterone acetate, both androgen-receptor signaling inhibitors.”

Patients with mCSPC were categorized into treatment cohorts based on their first filled prescription for apalutamide (n=364) or abiraterone acetate (n=147) on or after September 17, 2019. The study team followed patients from the index date until the earliest of index treatment discontinuation, end of clinical activity, treatment switch, or end of data availability.

Patients on Apalutamide 53% More Likely to Reach PSA90 Versus Those on Abiraterone

To ensure similarity in distribution of baseline characteristics between cohorts, researchers used inverse probability of treatment weighting. PSA90 was defined as the earliest attainment of  a 90% or greater reduction in PSA relative to baseline (most recent value within 13 weeks pre-index). Weighted Kaplan-Meier analysis and Cox proportional hazards models were used to compare time to PSA90 between cohorts.

“Our study used real world evidence gathered from 77 community urology practices to evaluate responses for patients receiving treatment for mCSPC,” Dr. Lowentritt says. “Specifically, we looked at the proportion of men receiving either abiraterone acetate with prednisone or apalutamide that had at least a 90% reduction in PSA. The key takeaway was that within 6 months, patients started on apalutamide were 53% more likely to achieve a PSA90 than those initiated on abiraterone. Men receiving apalutamide had both a higher likelihood to reach a PSA90 ever and achieved this outcome more rapidly than patients on abiraterone.”

For patients who have difficulty swallowing, apalutamide has several options of administration, adds Dr. Lowentritt. “Both the 60 mg and 240 mg tablets can be crushed and mixed with applesauce, and the 240 mg tablet may also be administered in orange juice, water, or through a feeding tube,” he says. “These alternate dosing methods are unique among the modern androgen-receptor targeted agents.”