Background and Importance Systemic involvement of prostate cancer(PC) typically occurs at the bone level (65–85%). Patients with metastatic hormone-sensitive prostate cancer(mHSPC) have survival rates ranging from 1–6 years, depending on high-risk prognostic factors such as:

• Elevated levels of prostate-specific antigen(PSA>20) at diagnosis.

• High Gleason score(8–10).

• Increased volume of metastatic disease.

• Poor functional status.

• Bone symptoms or the presence of visceral metastases.

Apalutamide, abiraterone, and enzalutamide are orally administered treatments financed for use in combination with androgen deprivation therapy. They have demonstrated improvement in overall survival (OS), particularly in high-risk progression populations, and a favourable safety profile.

Aim and Objectives Study to asses the efficacy profile, safety and clinical follow-up of patients with mHSPC undergoing Apalutamide treatment.

Material and Methods A retrospective observational study was conducted on patients with mHSPC who initiated Apalutamide treatment in 9 public hospitals in Valencian Community, Spain. These patients had a minimum clinical follow-up of 6 months as of March 2023. Clinical records, PSA evolution, and toxicity reported by healthcare professionals or the patients themselves were reviewed. A comprehensive descriptive statistical analysis was conducted, both overall and by disease volume.

Results A total of 172 patients(73±8 years) were included, with high disease volume(n=80;46.5%) and low disease volume(n=92;53.5%). 41.3% had received prior local treatment. The median pre-treatment PSA level was 22.2 (3.4–97.9) ng/mL, 69.8% had metastases at diagnosis with predominantly bone metastasis (61.6%), and a median time from diagnosis to the initiation of apalutamide was 4 (2–51) months.

At 3 months, 69.7% of patients achieved >90% reduction in baseline PSA, and an 87.7% reduction >50% in PSA in real-world conditions. After 12 months of treatment, 80% of patients continued with apalutamide, with discontinuation due to toxicity in 4.2% and progression or death in 13.1% of patients.

Conclusion and Relevance We did not observe significant response differences between low and high volume groups. Apalutamide in real-world treatment of men with mHSPC demonstrates a favourable safety profile like data published in clinical trials.

References and/or Acknowledgements 1. Cornford, Philip & Bergh, Roderick & Briers, et al. EAU-EANM-ESTRO-ESUR-SIOG Guidelineson Prostate Cancer. Part II-2020 Update: Treatment of Relapsing and Metastatic Prostate Cancer. European Urology. 2020;79.10.1016/j.eururo.2020.09.046.

Conflict of Interest No conflict of interest.