Regulatory Decision Summary for Enspryng

The efficacy and safety of Enspryng were evaluated in two Phase 3 clinical trials in patients with neuromyelitis optica spectrum disorder (NMOSD). The two studies had similar designs. Enrollment of AQP4-IgG seronegative patients was capped at 30%. The dosing regimen was 120 mg SC at Weeks 0, 2, 4 and Q4W thereafter.

In both studies, the primary efficacy endpoint was time to first relapse, based on a protocol defined relapse (PDR). Enspryng decreased risk of experiencing a relapse compared to placebo in a statistically significant manner when administered either in combination with immunosuppressing therapy or as monotherapy. A clinically relevant risk reduction was observed in the AQP4-IgG seropositive subgroups but not in the AQP4-IgG seronegative subgroups. In both clinical trials the efficacy of Enspryng treatment in the target population was demonstrated.

Enspryng was authorised for use in adolescent patients aged 12 or older based on clinical pharmacology data and extrapolation of efficacy and safety from adult NMOSD patients.

After adjustment for exposure, there was similar incidence of adverse events in patients treated with satralizumab or placebo. When used as monotherapy, there was a higher exposure-adjusted incidence of serious and severe adverse events in patients treated with satralizumab compared to placebo. The most common adverse events experienced by patients in clinical trials were infections (e.g., nasopharyngitis, upper respiratory tract infection, urinary tract infection) and headaches. The most common drug-related reactions were injection site reactions and clinical laboratory adverse events such as neutropenia. Based on its mechanism of action, Enspryng is known to cause decreased fibrinogen; however, no bleeding events were seen in clinical trials.

Overall, based on the clinical data provided in this submission, the benefit/risk profile of Enspryng supports authorization in the target patient population as described in the Product Monograph.

For more information on Health Canadas decision, please view the Summary Basis of Decision.