A Study of Lebrikizumab in Adult Participants With Perennial Allergic Rhinitis (PREPARED-1)

Inclusion Criteria: * Physician-diagnosed perennial allergic rhinitis (PAR). * Has a positive skin prick test (SPT) with indoor allergens and/or positive serum antigen-specific immunoglobulin E (IgE) for indoor allergens ≥0.70 kU/L, utilizing a validated assay (central laboratory). * The participant must have clinical symptoms at study entry associated with positive perennial allergen as tested by the SPT or a positive serum antigen-specific IgE test. * A participant who has a known history of dermatographism or identified during the SPT may participate in this study with a positive serum antigen-specific IgE test. * Participants who have concomitant asthma must be stable in the 3 months prior to screening using permitted regular asthma treatment. Exclusion Criteria: * Have received a dose of lebrikizumab. * Is currently on AIT subcutaneous immunotherapy or sublingual immunotherapy. However, individuals who discontinued subcutaneous or sublingual immunotherapy for ≥3 years prior to randomization are eligible. * Have received treatment with any rescue medication during the run-in period. * Have received treatment with any biologic or systemic immunosuppressants, including Janus Kinase inhibitors (JAK) for inflammatory disease or autoimmune disease prior to the baseline visit: * Any current or prior use of biologics indicated for asthma or AD are prohibited. * B cell-depleting biologics, including rituximab, within 6 months. * Other biologics within 5 half-lives (if known) or 8 weeks, whichever is longer. * Systemic immunosuppressants, including JAK inhibitors, within 4 weeks prior to baseline. * Have a history of seasonal worsening of AR and if the seasonal worsening is expected during the 4-week run-in period, the first 16 weeks after randomization, or during the last 8 weeks of the maintenance period. * Anticipates significant changes in their daily environmental exposure. * Has a known history of recurrent acute or chronic sinusitis. * Female participant who is pregnant, breastfeeding or is planning to become pregnant or to breastfeed during the study.