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.