Endocrine Abstracts

JOINT3669

Introduction: Abiraterone acetate (AA) is an approved treatment for advanced prostate cancer. As a CYP17A1 inhibitor, it suppresses adrenal androgen and cortisol biosynthesis, potentially leading to adrenal insufficiency (AI). In order to mitigate this risk, treatment regimens include prednisone (5 mg/day). Additionally, the accumulation of steroid precursors may, in some cases, result in mineralocorticoid excess syndrome (MES). However, real-world data on the incidence and management of endocrine adverse effects (EAE) associated with AA remain scarce.

Objectives: This study aimed to characterize the EAE associated with AA therapy, with a particular focus on MES, and to assess potential contributing factors to their development.

Materials and methods: We conducted a retrospective descriptive study of prostate cancer patients treated with AA, identified from the pharmacy dispensing registry at Hospital Clínic Barcelona (Spain) between January 1 and December 31, 2024. Clinical and biochemical parameters, medication use and cancer-related variables were analyzed.

Results: A total of 110 patients (mean age 74.9 years [range: 53–96], mean age at prostate cancer diagnosis 67 years [range: 49–94]) received AA during the study period. One confirmed case of MES (the only case referred to the Endocrinology Department) and nine probable but unconfirmed cases (characterized by new-onset or worsening hypertension, edema and three cases of hypokalemia) were identified, seven of which occurred within the first 12 weeks of treatment. No baseline or post-treatment aldosterone/renin measurements were available and cortisol was measured in only one case (3.2 μg/dl). No acute AI events were reported; however, two patients likely developed chronic AI after discontinuing AA due to disease progression (mean duration of AA and prednisone treatment: three months). Five deaths were recorded. No significant clinical or prognostic differences were observed between patients who developed probable ME and those who did not.

Conclusions: AA is an increasingly utilized agent in the management of prostate cancer, with potential EAE – including MES and AI – whose prevalence remains poorly characterized. Our findings contribute to the understanding of these adverse effects in a real-world setting. Recognizing and optimizing the preventive and therapeutic management of AA-associated EAE is essential to improving patient outcomes.