Abstracts

Rationale: Cenobamate is an antiseizure medication (ASM) approved for the treatment of adults with focal seizures. Cenobamate’s retention was measured in all 3 of its clinical trials (C013, C017, and C021) and open-label long-term extensions (OLEs), consistently demonstrating high retention in each. Real-world experience with cenobamate has yet to be reported in a nationally representative sample. In the absence of clinical data on seizure frequency, retention has been used as a proxy for measuring the effectiveness of ASMs. Pharmacy and medical claims data are nationally representative and fit-for-purpose for such research questions. This retrospective, observational analysis evaluated the retention of cenobamate in a nationally representative administrative claims database.

Methods: This study utilized a sample of patients from HealthVerity Marketplace, which includes more than 150 US commercial, Medicare, and Medicaid payers, to identify a cohort of adults (aged ≥ 18 years) with prevalent epilepsy and at least one script for cenobamate or any of the branded ASMs (brivaracetam, eslicarbazepine, lacosamide, perampanel). Outcomes were blended for the branded ASMs. Follow-up began in May 2020 and extended until the end of December 2021, with only adjudicated medical and pharmacy claims from patients with complete enrollment history being included. The index date for the analysis was Day 1 of initiating cenobamate or a branded ASM. To be included in the analysis, patients had to have at least a year’s worth of follow-up before and after the index date. Patients were followed until an incident event occurred (cessation of cenobamate or branded ASM), or 12 months, or the end of data collection, using Kaplan-Meier methods. Discontinuation was defined as stopping of therapy before 12 months. A 60-day grace period was included to allow for patients who were not compliant with their therapy’s dosages but should not be considered discontinued. Retention outcomes were reported for median time to discontinuation, retention at Months 3, 6, 9, 12, along with Kaplan-Meier plots. Only patients who initiated cenobamate at dosages from 12.5 mg to 50 mg were included in the analysis, while similar restrictions were not applied to the branded ASMs.

Results: Data were available from 1,943 and 18,954 patients on cenobamate and branded ASMs, respectively, with 197 patients (mean age = 38.2, % female = 46.7%) and 4,046 patients (mean age = 42.4, % female = 55.6%) meeting the inclusion and exclusion criteria for the analysis. For cenobamate, the median time to discontinuation was not reached in 12 months of follow-up; the median time to discontinuation was 7.8 months for the branded ASMs. Retention at Months 3, 6, 9, and 12 for cenobamate was 71%, 62%, 58%, and 50%, and was 66%, 55%, 48%, and 40% for the branded ASMs (P = 0.045; Figure 1).

Conclusions: Cenobamate was associated with significantly better retention vs. a pooling of four branded ASMs in this analysis of real-world use. A limitation of this analysis is the potential for unmeasured differences across the two groups that impact differential retention outcomes such as patient severity, drug load, and use of monotherapy.

Funding: Funded by SK Life Science, Inc.