Real-world persistence and adherence to relugolix (REL) in US patients with nonmetastatic (nm) vs metastatic (m) prostate cancer (PC).
Authors: McKay Rana R. , Hong Agnes , Razo Juan Felipe , Flanders Scott C , Ferro Christine , Shapoval Mila , Li Benjamin , Freedland Stephen J. 
Published: February 2025

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Background:
REL is the only oral androgen deprivation therapy (ADT) for patients (pts) with PC, offering an alternative to long-acting injectable/implantable formulations. Intermittent ADT is often used in pts with biochemically recurrent nmPC, whereas continuous ADT is the backbone of treatment (Tx) for pts with mPC. Given potential differences associated with adherence to an oral ADT, we assessed Tx adherence and persistence stratified by presence of metastases in pts with PC treated with REL. We hypothesized REL adherence would be high in both cohorts while persistence would be shorter in pts with nmPC vs mPC.
Methods:
A retrospective cohort study was conducted using the Medicare fee-for-service claims database (Dec 2019–Dec 2023). Adult males with >1 claim for PC who filled ≥2 REL prescriptions and had continuous Medicare coverage ≥1 year before and ≥3 months (mo) following REL initiation (index), when claims for metastatic diagnosis could be identified, were included. Pts were categorized into nmPC vs mPC cohorts. Persistence on REL was measured from time of Tx initiation (first pharmacy claim) to discontinuation (earliest of: switch to a different ADT, Tx gap ≥60 days between REL claims, death, or end of follow-up). REL adherence was measured using proportion of days covered (PDC) for pts persistent through fixed time periods (6- and 12-mo). PDC was defined as the percentage of individual days that pts had access to REL (based on prescriptions filled and days supplied). “Adherent” was defined as PDC of ≥80%.
Results:
The study included 5274 pts initiating REL; mean (SD) age was 75 (±7) years; 32% had mPC. Follow-up was similar in pts with nmPC and mPC (Table). Persistence on REL was shorter for nmPC vs mPC (median, 7 vs 9 mo; log-rank
P
<0.001). Across both cohorts, the vast majority of pts had PDC ≥80% (nmPC, 95%; mPC, 94%). Of those persistent at 6 mo, 95% across both cohorts had PDC ≥80%. Of those persistent at 12 mo, 97% had PDC ≥80% (nmPC, 98%; mPC, 96%).
Conclusions:
In this real-world study, among pts with PC who persisted on REL,high treatment adherence was observed, regardless of disease state (nmPC and mPC). Pts with mPC persisted on REL therapy longer compared to those with nmPC (median 9 vs 7 mos). Further research is needed to understand what other characteristics are associated with persistence on REL.

Total(N=5274)
nmPC with REL(n=3603)
mPC with REL(n=1671)

Follow-up (mo), mean ± SD [median]
16 ± 9 [15]
16 ± 9 [14]
16 ± 9 [15]

Persistence on therapy (mo), mean ± SD [median]
10 ± 7 [7]
9 ± 7 [7]
11 ± 8 [9]

Overall PDC, mean ± SD [median]
96 ± 10 [99]
97 ± 10 [99]
96 ± 11 [98]

Overall PDC ≥80%, n (%)
4990 (95)
3424 (95)
1566 (94)

Pts with ≥6 mo of persistence, n
3870
2617
1253

PDC ≥80% at 6 mo, n (%)
3676 (95)
2486 (95)
1190 (95)

Pts with ≥12 mo of persistence, n
1830
1131
699

PDC ≥80% at 12 mo, n (%)
1775 (97)
1104 (98)
671 (96)