| Summary: | Introduction: The efficacy and tolerability of Enzalutamide and
Abiraterone Acetate have been reported in elderly patients with metastatic
castration resistant prostate cancer (mCRPC). However, there is no randomized
study directly comparing antitumor effects between these 2 agents in geriatric
patients. We aimed to evaluate the efficacy of Enzalutamide (ENZA) and
Abiraterone Acetate (AA) as a first-line treatment of mCRPC in elderly
patients.
Materials and methods: The geriatric patients (≥75 years of
age) with a diagnosis of mCRPC and treated with first-line ENZA or AA were
included. The impacts of clinical parameters and treatment modalities on overall
survival (mOS) were analyzed retrospectively and Cox regression analysis was
performed.
Results: One hundred thirty-four mCRPC patients (77 in AA, 57 in ENZA),
with a median age of 81 (75–93) were analyzed. The patient and disease
characteristics were similar between arms. While there were more grade 1–2
toxicities in AA arm (45.5% vs 17.5%, P = 0.001), the discontinuation
due to toxicity was similar between groups (8.5% vs 5.9%, P = 0.81).
The mOS was 18.0 months (95% CI, 15.2–20.7) in AA, and 20.0 months (95% CI,
4.4–35.5) in ENZA arm (P = 0.47). In multivariate analysis, high Gleason
score (≥8) (HR: 2.0 (95% CI, 1.1–3.4), P = 0.009) and high
initial PSA values (≥100 ng/mL) (HR: 2.6 (95% CI, 1.5–4.8), P =
0.001) were poor prognostic factors. The choice of AA vs ENZA was insignificant
as a predictor of OS (HR: 0.87 (95% CI, 0.48–1.56), P = 0.65).
Conclusion: In the first-line treatment of mCRPC in elderly (≥75) patients,
AA and ENZA showed similar results in terms of mPFS and mOS. The
clinical impacts of second-generation androgen receptor pathway inhibitors in the
elderly population should be tested in prospective randomized studies.
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