Rationale: IL-4 and IL-13 share many biological functions important in the development of allergic airway inflammation and are implicated in the pathogenesis of asthma. AMG 317 is a fully human monoclonal antibody to IL-4Rα that blocks both IL-4 and IL-13 pathways.

Objectives: To evaluate efficacy and safety of AMG 317 in patients with moderate to severe asthma.

Methods: In this phase 2, randomized, double-blind, placebo-controlled study, patients received weekly subcutaneous injections of placebo or AMG 317 (75–300 mg) for 12 weeks, followed by a 4-week follow-up period. The primary endpoint was change from baseline at Week 12 in Asthma Control Questionnaire (ACQ) symptom score.

Measurements and Main Results: Mean ACQ change (SE) was −0.49 (0.09) in placebo (n = 74), and −0.43 (0.11), −0.58 (0.12), and −0.70 (0.09) in the AMG 317 75 mg (n = 73), 150 mg (n = 73), and 300 mg (n = 74) groups, respectively (treatment effect P = 0.25). No statistically significant differences were observed in the secondary endpoints. Numerical decreases in number of and time to exacerbations were noted in patients receiving AMG 317 150 mg and 300 mg. Preplanned analyses by tertile of baseline ACQ revealed that patients with higher baseline ACQ scores (≥2.86) were more likely to respond to AMG 317. Serious adverse events were reported in three patients, each noted as not related to study drug.

Conclusions: AMG 317 did not demonstrate clinical efficacy across the overall group of patients. Clinically significant improvements were observed in several outcome measures in patients with higher baseline ACQ scores. AMG 317 was safe and well tolerated in this study population.

Clinical trial registered with www.clinicaltrials.gov (NCT 00436670).