Practical implications of androgen receptor inhibitors for prostate cancer treatment

Antiandrogens have been used for the treatment of prostate cancer as a single agent or in combination with hormone deprivation therapy. New generation antiandrogens act like androgen receptor inhibitors (ARIs). Their binding complex blocks the pathways of cellular proliferation and differentiation of the prostate. Enzalutamide, apalutamide and darolutamide are the new ARIs that demonstrated acceptable tolerability and toxicity, both active in hormone-sensitive and castration-resistant prostate cancer (CRPC). There is no evidence of superiority of one drug over the other, therefore the therapeutic choice depends on the safety profile in relation to the individual patient, their comorbidities and clinical condition. ARIs have also shown promising results in association with new drugs that are active on patients with metastatic CRPC carrying the mutated breast cancer gene (BRCA). Before undergoing new antiandrogenic therapies, patients should be evaluated for cardiological and metabolic risk and possible drug interactions.

Comparison of Abiraterone Acetate and Docetaxel with Androgen Deprivation Therapy in High-risk and Metastatic Hormone-naïve Prostate Cancer: A Systematic Review and Network Meta-analysis

CONTEXT

Randomized clinical trials have recently examined the benefit of adding docetaxel or abiraterone to androgen deprivation therapy (ADT) in hormone-naïve advanced prostate cancer (PCa).

OBJECTIVE

To perform a systematic review and network meta-analysis of randomized clinical trials, indirectly evaluating overall survival (OS) for men treated with abiraterone acetate plus prednisone/prednisolone with ADT (Abi-ADT) versus docetaxel with ADT (Doce-ADT) in hormone-naïve high-risk and metastatic PCa.

EVIDENCE ACQUISITION

Medline, Embase, Web of Science, Scopus, and Clinicaltrials.gov databases were searched in August 2017. We pooled results using the inverse variance technique and random-effects models. The Bucher technique for indirect treatment comparison was used to compare Abi-ADT with Doce-ADT. A priori subgroup and sensitivity analyses were performed.

EVIDENCE SYNTHESIS

Overall, 6067 patients from five trials were included: 1181 (19.5%) patients who received Doce-ADT, 1557 (25.7%) patients who received Abi-ADT, and 3329 (54.9%) patients who received ADT-alone. There was a total of 1921 deaths: 391 in the Doce-ADT group, 353 in the Abi-ADT group, and 1177 in the ADT-only group. The pooled hazard ratio (HR) for OS was 0.75 (95% confidence interval [CI]: 0.63-0.91, I²=51%, 3 trials, 2951 patients) for Doce-ADT versus ADT-alone and 0.63 (95% CI: 0.55-0.72, I²=0%, 2 trials, 3116 patients) for Abi-ADT versus ADT-alone. The indirect comparison of Abi-ADT to Doce-ADT demonstrated no statistically significant difference in OS between these approaches (HR: 0.84, 95% CI: 0.67-1.06). Findings were similar in various a priori subset analyses, including patients with metastatic disease. Bayesian analyses demonstrated comparable results (HR: 0.83, 95% CI: 0.63-1.16). Despite the lack of statistical significance, Surface Under the Cumulative Ranking Analysis demonstrated an 89% probability that Abi-ADT was preferred.

CONCLUSIONS

We did not identify a significant difference in OS between Abi-ADT and Doce-ADT for men with hormone-naïve high-risk or metastatic PCa, although Bayesian analysis demonstrates a high likelihood that Abi-ADT was preferred.

PATIENT SUMMARY

We synthesized the evidence available from studies examining the administration of docetaxel or abiraterone in combination with hormonal therapy for patients with newly diagnosed, advanced prostate cancer. While these studies did not directly compare these agents, we used methodological techniques to indirectly compare them and found no significant difference in overall survival.