Multicenter Real-World Study: 432 Patients with Apalutamide in Metastatic Hormone-Sensitive Prostate Cancer

<b>Background:</b> The management of metastatic hormone-sensitive prostate cancer (mHSPC) has evolved significantly in recent years due to the introduction of androgen receptor-targeted agents (ARTAs). When used alongside androgen deprivation therapy (ADT), these treatments have shown improved oncological results and enhanced survival rates for patients with this condition. <b>Objectives:</b> The objective of this study was to describe the decline in prostate-specific antigen (PSA), the oncological outcomes, and the toxicity profile of mHSPC patients treated with apalutamide. <b>Materials and Methods:</b> Clinical data obtained from seven national hospitals were utilized between March 2021 and July 2024. PSA responses were collected at 3, 6, 12, 18, and 24 months, along with adverse effects reported by patients, dose reductions, or drug discontinuations. The association between PSA decline and progression-free survival (PFS) was evaluated with respect to metastasis volume, location, and timing of diagnosis. <b>Results:</b> A total of 432 patients were included, of whom 40% were de novo cases, and the greater part were classified as M1b. After one year, a reduction of more than 90% in PSA levels was observed in 88.2% of cases, with undetectable levels (≤0.2 ng/mL) achieved in 81.7% of them. The drug was discontinued in 76 patients (15.6%), with adverse effects reported in 7.8% (grade 3) and 1.9% (grade 4). Regarding PSA levels <0.02 ng/mL, promising results were observed, with ultralow PSA (UL2) achieved in 43% of cases at 6 months. <b>Conclusions:</b> This study revealed strong oncological outcomes, with rapid and profound PSA declines and drug safety consistent with emerging evidence. The distinctive finding of this study underscores the importance of a rapid and profound response (UL PSA) as a predictor of better oncological outcomes.