Efficacy of rozanolixizumab in muscle-specific kinase antibody-positive generalized myasthenia gravis: The Phase 3 randomized MycarinG study

Topic:

Clinical Trials

Poster Number: 146

Author(s):

Ali Habib, MD, University Of California Irvine, Henry J. Kaminski, Department of Neurology & Rehabilitation Medicine, George Washington University, Washington DC, USA, Artur Drużdż, Department of Neurology, Municipal Hospital Poznań, Poznań, Poland, Julian Grosskreutz, Precision Neurology, Department of Neurology, University of Lübeck, Lübeck, Germany, Renato Mantegazza, MD, Fondazione IRCCS Istituto Neurologico Carlo Besta, Sabrina Sacconi, MD, Centre Hospitalier Universitaire de Nice, Nice, France, Kimiaki Utsugisawa, MD, PhD, Hanamaki General Hospital, John Vissing, MD, DMSci, Copenhagen Neuromuscular Center, Rigshospitalet, University of Copenhagen, Tuan Vu, MD, University of South Florida, Marion Boehnlein, UCB Pharma, Monheim, Germany, Bernhard Greve, UCB Pharma, Monheim, Germany, Franz Woltering, UCB Pharma, Monheim, Germany, Vera Bril, MD, Ellen & Martin Prosserman Centre for Neuromuscular Diseases, University Health Network

Background
Muscle-specific kinase antibody-positive (MuSK Ab+) generalized myasthenia gravis (gMG) is often more severe and harder to treat than acetylcholine receptor antibody-positive (AChR Ab+) gMG
Objectives
This study was conducted to analyze the efficacy of rozanolixizumab, a neonatal Fc receptor inhibitor, in a subgroup of patients with MuSK Ab+ gMG.
Methods
The Phase 3, double-blind MycarinG study (MG0003/NCT03971422) randomized 200 patients (≥18 years with MGFA Class II–IVa gMG, AChR Ab+ or MuSK Ab+) to weekly rozanolixizumab 7mg/kg, 10mg/kg or placebo for 6 weeks. The primary endpoint was change from baseline (CFB) at Day 43 in Myasthenia Gravis Activities of Daily Living (MG-ADL) score; other efficacy endpoints were Myasthenia Gravis Composite (MGC) and Quantitative Myasthenia Gravis (QMG) scores. Efficacy was tested statistically in the overall population and described in prespecified antibody subgroups.
Results
Patients (N=200 [21 historical MuSK Ab+]) were randomized to rozanolixizumab 7mg/kg (n=66 [5]), 10mg/kg (n=67 [8]), or placebo (n=67 [8]). Day 43 least squares mean CFBs in MG-ADL for the overall population were −3.37 for 7mg/kg and −3.40 for 10mg/kg vs −0.78 for placebo (both dose groups statistically significant vs placebo, p<0.001); MGC and QMG CFBs for both rozanolixizumab groups were also statistically significantly different vs placebo CFB (p<0.001). Autoantibody subgroup Day 43 CFBs for 7mg/kg, 10mg/kg and placebo were as follows: MG-ADL: −7.28, −4.16, 2.28 (MuSK) vs −3.03, −3.36, −1.10 (AChR); MGC: −14.14, −8.56, 1.40 (MuSK) vs −4.45, −6.70, −1.83 (AChR); and QMG: −10.79, −7.01, −3.87 (MuSK) vs −6.14, −7.77, −3.09 (AChR). Conclusion Rozanolixizumab improved myasthenia gravis-specific outcomes in MuSK Ab+ gMG, consistent with results in AChR Ab+ gMG and the overall population. Funding: UCB Pharma. These data were previously presented at the MGFA Scientific Session at AANEM, 21–24 September 2022.