Modified monitoring of abiraterone acetate-induced hepatotoxicity in prostate cancer patients

Introduction Abiraterone is a standard treatment for prostate cancer and is a preferred treatment option at the Veterans Affairs North Texas Health Care System (VANTXHCS) due to its formulation, cost, and overall tolerability. In the combined data of five randomized controlled trials, grade 3 and 4 liver enzyme increases were reported in 6% of patients, most commonly within the first three months of initiating abiraterone. Therefore, the prescribing information recommends measuring serum transaminases and bilirubin levels (liver function tests, LFTs) every two weeks for the first three months of treatment and monthly thereafter. VANTXHCS utilizes a modified monitoring approach in which LFTs are evaluated two weeks after initiating abiraterone and less frequently thereafter. The purpose of this study is to assess if the modified monitoring approach leads to an increase in incidence and/or severity of abiraterone-induced hepatotoxicity. Methods A retrospective analysis was conducted within the VANTXHCS electronic record system to include adult patients diagnosed with prostate cancer who initiated abiraterone between January 1, 2014 and December 31, 2022. Patients were excluded if they were enrolled in clinical trials or were receiving care from an outside provider due to lack of accessible laboratory data. The primary outcome was to assess the incidence and severity of LFT elevations up to six months after initiation. Select secondary outcomes include time to LFT elevation, management of LFT elevation, and incidence and severity of LFT elevation up to 12 months after initiation. Results A total of 274 patients were included in the analysis, of which 72 (26.3%) experienced any grade LFT elevations during the 6-month period. Of those with LFT elevations, grade 1 elevations occurred in 48 (17.5%) patients, grade 2 in 20 (7.3%) patients, grade 3 in 3 (1.1%) patients, and grade 4 in 1 (0.4%) patient. The median time to detecting LFT elevations was 8 (4–16) weeks. The median time to resolution was 4 (3–7) weeks. Seventy-five percent of the patients with LFT elevations within 6 months of therapy were monitored without any interruptions in abiraterone therapy. Conclusion The current findings suggest that the modified monitoring approach to abiraterone does not result in an increase in incidence and/or severity of hepatotoxicity compared to the previously published clinical trial data. The modified monitoring approach may have a beneficial impact on healthcare resources.