Prognostic factors of long-term response to androgen receptor signaling inhibitors used as first-line treatment for mCRPC

Aim: Androgen receptor signaling inhibitors (ARSI) demonstrated to be efficacious as first-line therapy for mCRPC. The present real-world study aimed to identify the characteristics of the long-term responders (LTR) patients to first-line ARSI. Methods: We retrospectively reviewed a consecutive series of 622 mCRPC patients treated with one ARSI as first line. Patients received standard doses of abiraterone (1000 mg daily plus prednisone 10 mg daily) or enzalutamide (160 mg daily) until progression. Patients with an ARSI exposure ≥ 36 months were considered as LTR. Results: We identified 99 LTR patients who were compared to 523 no-LTR patients. At the multivariable analysis, LTR patients showed younger age (p < 0.0001), longer time to mCRPC (p < 0.0001), higher baseline levels of hemoglobin (p = 0.007), lower baseline PSA levels (p = 0.03), longer PSA doubling time (p = 0.03), low number of bone metastases (p = 0.01), and receivedenzalutamide (p = 0.01). The median overall survival (OS) of LTR was 78.2 months (95% CI 72.3–84.1 months) vs 27.7 months of no-LTR (95% CI 25.9–29.6 months). Conclusions: Several clinical and biological factors allow to identify those patients with higher probability of becoming LTR to ARSI in first-line mCRPC setting.