JU INSIGHT: Pathological Effects of Apalutamide in Lower-risk Prostate Cancer: Phase II Clinical Trial Results

By: Michael T. Schweizer, MD; Lawrence True, MD; Roman Gulati, MS; Yibai Zhao, PhD; William Ellis, MD; George Schade, MD; Bruce Montgomery, MD; Sonia Goyal, MPH; Katie Nega, MPH, ARNP; Alexander K. Hakansson, BS; Yang Liu, PhD; Elai Davicioni, PhD; Kenneth Pienta, MD; Peter S. Nelson, MD; Daniel Lin, MD; Jonathan Wright, MD | Posted on: 16 Feb 2023

Schweizer MT, True L, Gulati R, et al. Pathological effects of apalutamide in lower-risk prostate cancer: results from a phase II clinical trial. J Urol. 2023;209(2):354-363.

Study Need and Importance

Active surveillance (AS) is a strategy aimed at mitigating the overtreatment of lower-risk prostate cancer. AS has been shown to be safe, and this approach allows many patients to avoid surgery or radiation therapy; however, conversion to local treatment still occurs in approximately 20%-50% of patients. As such, medical approaches to decrease attrition from AS are appealing. To that end, we conducted a clinical trial to assess the pathological effects of 3 months of apalutamide in men followed on AS.

Figure. Positive biopsy-free survival with 95% confidence limits (shaded gray areas).

What We Found

Twenty-three patients enrolled and 22 had repeat biopsy after 90 days of apalutamide. Overall, 59% of study subjects had no residual cancer on post-treatment biopsy, with a median time to first positive biopsy of 364 days (see Figure). The impact of apalutamide on quality of life was minimal and transient. Decipher, a genomic risk classifier, revealed that those with higher baseline genomic risk were more likely to have a negative biopsy post-treatment.

Limitations

This study was designed to evaluate for preliminary evidence that apalutamide was effective in men enrolled in AS. While we acknowledge that a negative biopsy is not a validated proxy for long-term outcomes, this was felt to be a reasonable endpoint given that the majority of AS programs only recommend local therapy following pathological reclassification. We also acknowledge that the small sample size of this study was a limitation.

Interpretation for Patient Care

Short course apalutamide was associated with a high negative biopsy rate in men enrolled in AS. Notably, the observed pathological effects were similar to those reported in a separate study testing long course (ie, 12 months) of enzalutamide in a similar patient population. Importantly, the impact on quality of life was minimal and transient. Based on these results, follow-up studies appear justified.