Background
The 6-month double-blind placebo-controlled REGAIN study (NCT01997229) and its open-label extension (OLE; NCT02301624) demonstrated the sustained effectiveness of the terminal complement inhibitor eculizumab in adult patients with anti-acetylcholine receptor antibody-positive refractory generalized myasthenia gravis (gMG).
Objective
To analyze response profiles in REGAIN and its OLE.
Approach
The analysis was conducted using Myasthenia Gravis–Activities of Daily Living (MG-ADL) and Quantitative Myasthenia Gravis (QMG) scores recorded during REGAIN and its OLE. Early/late responses were defined as improvement in MG-ADL score (≥3 points) or QMG score (≥5 points) occurring at ≤12/>12 weeks, respectively, after baseline (eculizumab initiation).
Results
The analysis included 98 patients. By Week 12 and OLE end, MG-ADL response had been achieved at some point by 67.3% and 84.7% of patients, respectively; QMG response by 56.1% and 71.4%, respectively. Response was observed over multiple consecutive assessments for the vast majority of patients. At Week 130, the least-squares mean (LSM) percentage changes from baseline in MG-ADL score were -61.9% and -47.5% in early and late MG-ADL responders, respectively; the LSM percentage changes from baseline in QMG score were -40.8% and -55.5% in early and late QMG responders, respectively (all p<0.0001). Significant baseline differences between early versus late QMG responders were seen for mean duration of MG (10.46 versus 5.46 years, respectively; p=0.0002) and mean QMG score (18.6 versus 15.1, respectively; p=0.0223).
Conclusion
The findings suggest that although most patients with refractory gMG will achieve clinical response (assessed by MG-ADL or QMG scores) by Week 12 of eculizumab treatment, responses can be observed with longer-term treatment.