SAT0146 Earth Explorer 2, A Phase IIB Exploratory Study Evaluating Efficacy and Safety of Mavrilimumab, A Fully Human Granulocyte-Macrophage Colony-Stimulating Factor Receptor-Alpha Monoclonal Antibody, and The Tumor Necrosis Factor Antagonist Golimumab in Rheumatoid Arthritis

Novel Therapeutic Targets in Axial Spondyloarthritis

Purpose of review

Axial spondyloarthritis remains an area of significant unmet clinical need with only two immune pathways currently targeted by licenced therapies compared to other immune-mediated inflammatory joint disorders such as rheumatoid arthritis where a multitude of therapeutic options are available. This review will look at emerging therapeutic targets in axial spondyloarthritis beyond the neutralisation of IL-17A and TNF by monoclonal antibodies.

Recent findings

Several promising targets are in various stages of pre-clinical and clinical development in axial spondyloarthritis. These include small molecule approaches to target transcription factors, epigenetic modification and intracellular modulation of cytokine signalling by kinase inhibition. GM-CSF has also emerged as a potential driver of inflammation.

Summary

A number of novel and promising therapeutic options are in various stages of development in axial spondyloarthritis. The Janus kinase inhibitors have shown great promise in other immune-mediated inflammatory disorders and will be an exciting addition to the axial spondyloarthritis field as the first oral disease-modifying agents. GM-CSF blockade also shows great promise since antibodies for neutralising this cytokine are safe in patients and have shown efficacy in other immune-mediated inflammatory diseases.

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 α. We undertook to determine the long‐term safety and efficacy of mavrilimumab in rheumatoid arthritis patients in 2 phase IIb studies (1071 and 1107) and in 1 open‐label extension study (ClinicalTrials.gov identifier: NCT01712399).

Methods

In study 1071, patients with an inadequate response to disease‐modifying antirheumatic drugs (DMARDs) received mavrilimumab (30, 100, or 150 mg) or placebo every other week plus methotrexate. In study 1107, patients with an inadequate response to anti–tumor necrosis factor agents and/or DMARDs received 100 mg mavrilimumab every other week or 50 mg golimumab every 4 weeks plus methotrexate. Patients entering the open‐label extension study received 100 mg mavrilimumab every other week plus methotrexate. Long‐term safety and efficacy of mavrilimumab were assessed.

Results

A total of 442 patients received mavrilimumab (14 of 245 patients from study 1071, 9 of 70 patients from study 1107, and 52 of 397 patients from the open‐label extension study discontinued mavrilimumab treatment throughout the studies). The cumulative safety exposure was 899 patient‐years; the median duration of mavrilimumab treatment was 2.5 years (range 0.1–3.3 years). The most common treatment‐emergent adverse events (AEs) were nasopharyngitis (n = 69; 7.68 per 100 patient‐years) and bronchitis (n = 51; 5.68 per 100 patient‐years). At weeks 74 and 104, 3.5% and 6.2% of patients, respectively, demonstrated reduction in forced expiratory volume in 1 second, while 2.9% and 3.4% of patients, respectively, demonstrated reduction in forced vital capacity (>20% reduction from baseline to <80% predicted). Most pulmonary changes were transient and only infrequently associated with AEs. Mavrilimumab at 100 mg every other week demonstrated sustained efficacy; at week 122, 65.0% of patients achieved a Disease Activity Score in 28 joints using the C‐reactive protein level (DAS28‐CRP) of <3.2, and 40.6% of patients achieved a DAS28‐CRP of <2.6.

Conclusion

Long‐term treatment with mavrilimumab maintained response and was well‐tolerated with no increased incidence of treatment‐emergent AEs. Safety data were comparable with those from both phase IIb qualifying studies.