A post-hoc analysis to understand factors leading to initiation of a new rozanolixizumab cycle in the Phase 3 MycarinG and open-label extension (OLE) studies.

In the Phase 3 MycarinG study (NCT03971422), one 6-week cycle of rozanolixizumab significantly improved MG-ADL and QMG scores versus placebo. After MycarinG, patients could enroll in OLE studies (MG0004/NCT04124965 then MG0007/NCT04650854, or into MG0007 directly) to receive additional rozanolixizumab treatment.

Initiation of a new cycle of rozanolixizumab treatment was at the investigator’s discretion, with advisory protocol guidance to consider a new cycle when MG-ADL scores worsened by ≥2 points or QMG scores worsened by ≥3 points. MG-ADL and QMG score changes before the start of a new cycle were analyzed for patients receiving or waiting for a new cycle after initial rozanolixizumab treatment.

Overall, 145 patients were included in the analysis (patients with MG-ADL values: n=120; patients with QMG values: n=119). A new cycle of rozanolixizumab was initiated following a mean (SD) worsening in score of 3.1 (3.5) for MG-ADL and 4.1 (5.2) for QMG from the end of the first cycle to the start of the new cycle. In total, 76/145 (52.4%) and 66/145 (45.5%) patients received a new cycle of rozanolixizumab having met the definition of MG-ADL and QMG score worsening, respectively. Initiation of a new cycle of rozanolixizumab followed worsening on either scale in 34/145 (23.4%) patients, on both scales in 54/145 (37.2%) patients, and on neither scale in 32/145 (22.1%) patients.