CYT003, a TLR9 agonist, in persistent allergic asthma - a randomized placebo-controlled Phase 2b study.

Background: New treatment options are required for patients with asthma not sufficiently controlled with inhaled therapies. In a Phase 2a trial, CYT003, a Toll-like receptor-9 agonist immunomodulator, improved asthma control during inhaled glucocorticosteroid reduction in patients with allergic asthma. This double-blind Phase 2b study assessed the efficacy and safety of CYT003 in patients with persistent moderate-to-severe allergic asthma not sufficiently controlled on standard inhaled glucocorticosteroid therapy with/without long-acting beta-agonists (LABAs).

Methods: Overall, 365 patients received seven doses of subcutaneous CYT003 (0.3, 1, or 2 mg) or placebo as add-on therapy to conventional controller medication. Change from baseline in Asthma Control Questionnaire (ACQ) score was the primary outcome; secondary outcomes included change in forced expiratory volume, Mini Asthma Quality of Life Questionnaire, and safety.

Results: All groups, including placebo, showed a clinically important improvement in ACQ score; however, there was no significant difference between the CYT003 and placebo groups at week 12 (least-squares mean difference 0.3 mg: -0.027 [95% confidence interval -0.259 to 0.204]; 1 mg: 0.097 [-0.131 to 0.325]; 2 mg: 0.081 [-0.148 to 0.315]). No significant differences were seen in secondary outcomes. CYT003 was well tolerated; the most common treatment-emergent adverse events were injection site reactions. Due to lack of efficacy, the study was prematurely terminated at the end of the treatment phase with no further follow-up.

Conclusions: Toll-like receptor-9 agonism with CYT003 showed no additional benefit in patients with insufficiently controlled moderate-to-severe allergic asthma receiving standard inhaled glucocorticosteroid therapy with or without LABAs.