Does race predict adherence to relugolix among patients with prostate cancer? A Veterans Health Administration data analysis.

Abstract

e17102 Background : Relugolix, a gonadotropin-releasing hormone (GnRH) receptor antagonist, is the only oral androgen deprivation therapy (ADT) approved for advanced prostate cancer (PC), which distinguishes it from injectable GnRH receptor agonists or antagonists. In the US, patients (pts) from minority populations have shown lower adherence to oral medications vs White pts in other disease areas. Given the potential for racial disparities, we assessed treatment (tx) adherence to relugolix and tx modifications between Black and White pts with PC. Methods : Veterans Health Administration data (2006–2023) were analyzed between Black and non-Hispanic White adult males with PC who initiated relugolix tx. Adherence to relugolix (defined as medication possession ratio [MPR] ≥80%) was assessed every 3 months for up to 1 year after tx initiation among those who were continuously prescribed relugolix tx during each period. MPR was defined as the ratio of the total dispensed dose in a given period to the standard recommended dose, capped at 100%. Multivariable generalized linear modeling compared adherence between races. Discontinuation of relugolix, switching to another ADT, and initiating an add-on PC tx were assessed using the Kaplan–Meier method and Cox regression. Results : We identified 141 Black and 313 White pts with PC who initiated relugolix. During year 1 of tx, both groups had >90% adherence to relugolix with no significant differences (Table). During follow-up (median 10.7 and 12.6 months for Black and White pts, respectively), 27% Black and 21% White pts discontinued relugolix (HR 1.61; 95% CI 1.04, 2.49; P =0.034); 9% Black and 4% White pts switched to another ADT (HR 2.65; 95% CI 1.06, 6.66; P =0.038); and 11% Black and 10.5% White pts had add-on PC tx (HR 1.50; 95% CI 0.78, 2.91; P =0.226). Conclusions: Adherence to relugolix was very high during the first year of tx in both Black and White pts, with no differences by race. Black pts were more likely than White pts to discontinue relugolix as well as switch to another ADT. While our findings align with prior clinical trial and real-world evidence suggesting adherence to relugolix is high, further study is needed to elucidate reasons for racial differences in discontinuation and switching to other ADTs. Adherence to relugolix by race. Black pts White pts MPR ratio (Black vs. White) ‡ 95% CI P -value Follow-up (months) n † Median MPR (%) n Median MPR (%) 3 128 98.6 301 100.0 0.98 0.94, 1.01 0.209 6 106 95.1 238 98.6 0.98 0.93, 1.03 0.462 9 77 87.6 175 97.1 1.00 0.93, 1.08 0.931 12 52 94.4 142 92.3 1.09 0.99, 1.21 0.078 † Number of pts who were continuously prescribed relugolix tx during each time period. ‡ MPR was defined as the ratio of the total dispensed dose in a given period to the standard recommended dose. Individual MPRs were capped at 100%. Adjusted generalized linear models were used to calculate MPR ratio of Black vs. White pts, 95% CI and p-value.