Seizures and Neuropsychiatric Toxicity in Patients with Non-Metastatic CRPC Treated with New Antiandrogens: Systematic Review and Meta-Analysis

INTRODUCTION

Recently, enzalutamide, apalutamide, and darolutamide have shown benefits in metastasis-free survival in non-metastatic castration-resistant prostate cancer (nmCRPC) patients compared to placebo. Previous evidence about the safety profile of these new androgens is limited. This meta-analysis studies seizure and neuropsychiatric effects of new anti-androgens compared to placebo in nmCRPC patients.

METHODS

PubMed and Cochrane databases were systematically reviewed until 1 March 2020 by 2 independent researchers using a pre-specified search strategy. Placebo-compared randomized controlled trials (RCTs) of nmCRPC patients treated with new anti-androgens providing data on neuropsychiatric events and seizures were included. Variables were seizure, headache, mental impairment, and dizziness. Pooled risk ratios (RR) were calculated using the Mantel-Hansel random effects model and Review Manager v5.3 software.

RESULTS

After systematic review, 3 eligible RCTs were selected that included 4,104 patients; 2,687 comprised the treatment group and 1,417 the control group. No significant increase in RR for seizures was registered with the new anti-androgens compared to placebo (RR 1.96; 95% confidence interval [CI] 0.40-9.61). However, 2 trials excluded patients with risk factors or a history of seizures. There was also no significant increase RR for grade ≥3 seizures (RR 2.50; 95% CI 0.12-52.02). RR for suffering dizziness (any grade) was 1.57 (95% CI 1.07-2.32) with the new anti-androgens, but no significant differences were found in the other study regarding neuropsychiatric events or grade ≥3 events.

CONCLUSIONS

New anti-androgens (i.e., enzalutamide, apalutamide, and darolutamide) are acceptably safe in terms of seizures and neuropsychiatric toxicity compared to placebo in patients with nmCRPC.

Prostate cancer biomarkers: an update

Many aspects of prostate cancer diagnosis and treatment could be greatly advanced with new, effective biomarkers. Prostate-specific antigen (PSA) has multiple weaknesses as a biomarker, such as not distinguishing well between cancer and benign prostatic hyperplasia or between indolent and aggressive cancers, thus leading to overtreatment, especially unnecessary biopsies. PSA also often fails to indicate accurately which patients are responding to a given treatment. Yet PSA is the only prostate cancer biomarker routinely used by urologists. Here, we provide updated information on the most relevant of the other biomarkers currently in use or in development for prostate cancer. Recent research shows improvement over using PSA alone by comparing total PSA (tPSA) or free PSA (fPSA) with new, related markers, such as prostate cancer antigen (PCA) 3, the individual molecular forms of PSA (proPSA, benign PSA, and intact PSA), and kallikreins other than PSA. Promising results have also been seen with the use of the fusion gene TMPRSS2:ERG and with various forms of the urokinase plasminogen activation receptor. Initially, there were high hopes for early PCA, but those data were not reproducible and thus research on early PCA has been abandoned. Much work remains to be done before any of these biomarkers are fully validated and accepted. Currently, the only markers discussed in this paper with Food and Drug Administration-approved tests are PCA 3 and an isoform of proPSA, [-2]proPSA. Assays are in development for most of the other biomarkers described in this paper. While the biomarker validation process can be long and filled with obstacles, the rewards will be great-in terms of both patient care and costs to the health care system.