Risk of seizure in patients with prostate cancer treated with enzalutamide in China: a noninterventional study

Enzalutamide, approved in China for the treatment of prostate cancer (PC), has been studied for risk of seizure, but there is limited real-world evidence on this risk in China. Cases of posterior reversible encephalopathy syndrome (PRES) among enzalutamide-treated patients have been reported.

To evaluate the risk of seizure and PRES in patients with PC treated with enzalutamide in China.

Observational cohort study.

Data were extracted from electronic medical records of patients with PC aged ⩾18 years treated at three clinical sites in China who started enzalutamide between March 1, 2020 and May 31, 2022. The primary objective was to estimate the proportion (%) of enzalutamide- or alternative antiandrogen-treated patients who experienced seizure. The index date was the date of the start of treatment. The follow-up period started from the index date and included both on- and off-treatment periods.

Demographic and clinical characteristics were generally similar between the enzalutamide (n = 385) and alternative antiandrogen (n = 365) groups. Risk factors for seizure were noted in 148 (38.4%) enzalutamide- and 130 (35.6%) alternative antiandrogen-treated patients. Median follow-up was 85 days for patients on enzalutamide and 196 days for those on alternative antiandrogens. During the on-treatment period, no patients on enzalutamide experienced seizure (95% confidence interval (CI): 0.00, 0.95), while one patient on an alternative antiandrogen experienced seizure (0.27%; 95% CI: 0.01, 1.48). The seizure incidence rates per 100 person-years for enzalutamide were 0.00 (95% CI: 0.00, 3.50) for the on-treatment period and 0.00 (95% CI: 0.00, 2.74) for the full follow-up period; for alternative antiandrogens, they were 0.58 (95% CI: 0.00, 2.14) during the on-treatment period and 0.43 (95% CI: 0.00, 1.61) during the full follow-up period. No cases of PRES were reported.

Among patients with PC in China, the risk of seizure was low in both the enzalutamide and alternative antiandrogen groups, despite the presence of risk factors for seizure in over one-third of patients.