The researchers in these 2 companion studies explore the efficacy of dupilumab, an anti–interleukin-4 receptor monoclonal antibody that blocks the interleukin 4 and interleukin 13 signaling.Patients ≥12 years old with uncontrolled asthma were included.In the first study, 1902 patients were randomly assigned 2:2:1:1 to receive 200 mg or 300 mg subcutaneously of dupilumab every 2 weeks or a matching placebo for 52 weeks. In the second study, 210 patients with oral corticosteroid (OCS)–dependent asthma were randomly assigned to receive 300 mg of dupilumab every 2 weeks or a matching placebo for 28 weeks. After OCS reduction in a down titration schedule from week 4 to 20, subjects continued with a stable dose for 4 weeks.In the first study, there was a 47% reduction in the exacerbation rate compared with the placebo in both treatment groups. At week 12, both dupilumab groups had a significantly greater increase in the forced expiratory volume in 1 second (FEV1) compared with the placebo groups. The improvement in FEV1 was greater in patients with a peripheral eosinophil count >150 cells per mm3. In subjects who were on active treatment, a reduction in the fraction exhaled nitric oxide was noted. In the second study, there was a 70.1% reduction in the OCS dose in the active group compared with a 41.9% reduction in the placebo group (P < .001). Also, 80% (vs 50%) had a 50% dose reduction in the OCS, 69% (vs 33%) had a dose reduction to <5 mg per day, and 48% (vs 25%) were able to discontinue the OCS. The active group had a 59% lower rate of severe exacerbation and a 220 mL greater increase in FEV1 compared with the placebo group.This soon-to-be-approved biologic for uncontrolled asthma had excellent results in reducing exacerbations and decreasing the OCS dose.This is another important adjunct to the treatment of severe uncontrolled asthma. This drug also improves atopic dermatitis and nasal polyps and decreases the fraction exhaled nitric oxide with a paucity of side effects. It is effective in the population with an eosinophil count of ≥150 cells per mm3.