OSMO is an open-label, single-arm study which investigated whether patients who had been receiving omalizumab, (a biologic targeting IgE in patients with allergic sensitisation) for an average of 2.5 years and continued to have uncontrolled severe asthma, gained better asthma control following a switch to mepolizumab, (a biologic targeting IL-5 for patients with severe eosinophilic asthma). In the study 145 patients, who were documented to have experienced at least two asthma exacerbations in the year prior to enrolment, were switched directly to mepolizumab without a wash-out period and followed for 32 weeks. In this study, mepolizumab data compared with baseline values prior to first dose, unless otherwise stated:
- Met the primary endpoint of asthma control with clinically significant improvements, as evaluated by the Asthma Control Questionnaire (ACQ-5), with a mean change from baseline of -1.45 at week 32
- Met all secondary endpoints and other key endpoints:
- Rate of exacerbations requiring oral steroids reduced by 64% vs prior 12 months (3.26 to 1.18)
- Rate of exacerbations requiring an ED visit or hospitalization reduced by 69% vs prior 12 months (0.63 to 0.19)
- Improvement in lung function (pre-bronchodilator FEV1) of 159 mL vs baseline
- Improvement in Quality of life as evaluated by the SGRQ (-19 units, compared with MCID -4.0) vs baseline
- Reduction in blood eosinophils of approximately 80% by Week 4 (vs baseline), which was sustained until Week 32
- Safety profile was consistent with the known profile of the treatment
