Mavrilimumab, a Fully Human Granulocyte-Macrophage Colony-Stimulating Factor Receptor α Monoclonal Antibody: Long-Term Safety and Efficacy in Patients With Rheumatoid Arthritis

Objective: Mavrilimumab, a human monoclonal antibody, targets granulocyte-macrophage colony-stimulating factor receptor alpha. We report mavrilimumab long-term safety and efficacy in rheumatoid arthritis patients in two phase IIb studies (1071, 1107) and open-label extension (OLE; NCT01712399). Methods: In 1071, patients with disease-modifying antirheumatic drug (DMARD)-inadequate responses received mavrilimumab 30, 100, 150 mg, or placebo every other week (eow), plus methotrexate. In 1107, patients with anti-tumor necrosis factor agent- and/or DMARD-inadequate responses received mavrilimumab 100 mg eow or golimumab 50 mg every 4 weeks, plus methotrexate. Patients entering the OLE received mavrilimumab 100 mg eow plus methotrexate. Mavrilimumab long-term safety and efficacy were assessed. Results: In total, 442 patients received mavrilimumab (14/245 patients from 1071, 9/70 from 1107, 52/397 from OLE discontinued mavrilimumab treatment throughout the studies). The cumulative safety exposure was 899 patient-years (PY); the median duration of mavrilimumab treatment was 2.5 (range 0.1–3.3) years. Most common treatment-emergent adverse events were nasopharyngitis (n=69, 7.68/100 PY), bronchitis (n=51, 5.68/100 PY). At Weeks 74/104: 3.5%/6.2% patients showed reduction in forced expiratory volume in 1 second; 2.9%/3.4% patients showed reduction in forced vital capacity, respectively (>20% reduction from baseline to <80% predicted). Most pulmonary changes were transient and only infrequently associated with adverse events. Mavrilimumab 100 mg eow demonstrated sustained efficacy; 65.0% and 40.6% patients achieved Disease Activity Score 28–C-reactive protein <3.2 and <2.6, respectively at Week 122. Conclusion: Mavrilimumab long-term treatment maintained response and was well-tolerated with no TEAE incidence increase. Safety data were comparable with both phase IIb qualifying studies.