01O Response to rozanolixizumab across treatment cycles in patients with generalised myasthenia gravis: a post hoc analysis

In the Phase 3 MycarinG (NCT03971422) study, one cycle (six once-weekly subcutaneous infusions) of rozanolixizumab 7mg/kg or 10mg/kg significantly improved myasthenia Gravis (MG)-specific outcomes versus placebo. After MycarinG, patients could enrol in open-label extensions (OLEs) MG0004 (NCT04124965) then MG0007 (NCT04650854), or MG0007 directly. We evaluate response to rozanolixizumab over multiple treatment cycles in patients with generalised MG based on Cycle 1 response. MG0004 was a ≤52-week OLE of chronic, once-weekly rozanolixizumab 7mg/kg or 10mg/kg. In MG0007, after one six-week cycle (rozanolixizumab 7mg/kg or 10mg/kg), subsequent cycles were administered upon symptom worsening. Data were pooled across MycarinG, MG0004 (first 6 weeks) and MG0007 (interim analysis; data cut-off: 08 July 2022) for patients with ≥2 symptom-driven cycles. MG-Activities of Daily Living (MG-ADL) and Quantitative MG (QMG) response rate (≥2.0- and ≥3.0-point improvement from baseline, respectively) at Day 43 in each cycle was analysed. Post hoc analyses of response rates were conducted based on Cycle 1 response. Overall, 127 patients had ≥2 symptom-driven cycles. In Cycle 1, 74.0% (94/127) and 68.5% (87/127) of patients were MG-ADL and QMG responders, respectively, at Day 43. Among MG-ADL Cycle 1 responders, MG-ADL response rates remained high over subsequent cycles (Cycle 2: 78.7% [74/94]; Cycle 3: 77.1% [54/70]; Cycle 4: 78.0% [46/59]). Similar patterns were observed for QMG response among QMG Cycle 1 responders (Cycle 2: 67.4% [58/86]; Cycle 3: 76.2% [48/63]; Cycle 4: 69.2% [36/52]). Of 33 (26.0%) MG-ADL non-responders at Cycle 1, 63.6% (21/33) were responders at Cycle 2. Of 40 (31.5%) QMG non-responders at Cycle 1, 51.3% (20/39) were responders at Cycle 2. Patients receiving rozanolixizumab demonstrated a high response rate over multiple cycles irrespective of initial response. Initial non-responders may benefit from additional rozanolixizumab treatment cycles.