This is a parallel-group, Phase 2, randomized, double-blind, placebo-controlled, 2-arm study for the treatment of asthma. The purpose of this study is to assess the efficacy, safety, and tolerability of add-on therapy with SC lunsekimig compared with placebo in male and female participants (aged 18 to 80 years, inclusive) with asthma, who are not currently eligible for biologic treatments. Study details include: * The study duration will be approximately 64 weeks for participants not transitioning into the LTS study and approximately 60 weeks for participants transitioning into the LTS study. * The investigational treatment duration will be up to approximately 52 weeks. * The number of visits will be 18.