Prevalence and Causes of Discontinuation of Androgen Receptor Inhibitors in Advanced Prostate Cancer Patients and Analysis of Physician Management to Increase Duration of Therapy.

Objective: To investigate the prevalence and cause of early discontinuation (DC) of androgen receptor inhibitor (ARi) in advanced prostate cancer (PCa) patients. Additionally, to study the effect of changing ARi vs dose reduction on duration of treatment (DOT).

Materials And Methods: A retrospective cohort study of 333 patients with advanced PCa who started ARi between 2016 and 2020 was performed. ARi medication, treatment duration, reason for DC, stage of PCa, prostate specific antigen, Gleason score, and prior PCa treatments were collected. The cohort was divided into 2 subgroups, patients that stayed on one medication (Group A) vs patients who changed ARi medication (Group B). Student's t test, chi-square test, and Kaplan-Meier survival analysis were performed.

Results: At 1 year 28.8% of patient's had discontinued ARi. Reasons for DC were side effects (34.4%), death (34.4%), and cancer progression (18.8%). DOT was 13 months for enzalutamide, 13.7 months for abiraterone, 7.6 months for darolutamide, and 12.1 months for apalutamide. Average DOT for patients with a dose change was 13.4 months, similar to those without dose change at 13.9 months (P = .630). DOT was 12.7 months in Group A vs 19.8 months in Group B (P = .001).

Conclusion: In our study population DC of ARi is higher than reported in the published trials. Providing patients with an alternative ARi is associated with an increase in DOT while dose reduction is not. It is important for clinicians to understand the causes of early DC to develop strategies to maximize duration of therapy for management of advanced PCa patients.