The purpose of this study is to evaluate the amount of mirikizumab (test) that gets into the blood stream and how long it takes the body to get rid of it, when given via autoinjector, an injection under the skin, compared to mirikizumab (reference) solution given via autoinjector.

Screening is required within 35 days prior to enrollment. For each participant, the total duration for of the clinical trial will be about 15 weeks, including screening.

Inclusion Criteria:

Type of participant and disease characteristics

1. Overtly healthy males and females as determined by medical evaluation including:

   • Medical history,
   • Physical examination,
   • Clinical laboratory tests,
   • Electrocardiogram (ECG),
   • Vital signs

   Note: participants may have chronic, stable medical conditions that, in the investigator's opinion, will not place the participant at increased risk by participating in the study, and will not interfere with interpretation of the data.

2. Have clinical laboratory test results:

   • Within normal reference range for the population, or
   • Within normal reference range for the investigative site, or
   • Results with acceptable deviations that are judged to be not clinically significant by the investigator.

   Weight

3. Have a body mass index (BMI) within the range of 18.0 to 34.0 kilograms per milligram squared (km/m^2), inclusive.

   Exclusion Criteria:

   Participants are excluded from the study if any of the following criteria apply:

   Medical conditions

4. Have significant allergies to humanized monoclonal antibodies or known allergies to citrate-free mirikizumab, related compounds or any components of the formulation.

5. Have significant previous or current history of comorbidities capable of significantly altering the absorption, metabolism, or elimination of drugs; of constituting a risk when taking the investigational product; or of interfering with the interpretation of data.

6. Have clinically significant multiple or severe drug allergies, or intolerance to topical corticosteroids, or severe post-treatment hypersensitivity reactions.

7. Have a diagnosis or history of malignant disease within 5 years prior to baseline.

   Prior/concomitant therapy

8. Intend to use over-the-counter or prescription medication, including herbal medications and traditional medications, within 7 days prior to dosing.

9. Have received treatment with biologic agents, such as monoclonal antibodies, including marketed drugs, within 3 months or 5 half-lives, whichever is longer, prior to dosing.

10. Have ever received anti-interleukin (IL)-12p40 antibodies or anti-IL-23p19 antibodies, for any indication, including investigational use.

11. Have received any live vaccine (that is, live attenuated) within less than 4 weeks or inactivated vaccine within less than 2 weeks before randomization.

    Prior/concurrent clinical study experience

12. Are currently enrolled in a clinical study involving an investigational product or any other type of medical research judged not to be scientifically or medically compatible with this study.

13. Have participated in a clinical study involving an investigational product within the last 30 days or 5 half-lives, whichever is longer, prior to screening. If the clinical trial involved treatment with biologic agents, such as monoclonal antibodies, including marketed drugs, at least 3 months or 5 half-lives, whichever is longer, should have elapsed prior to dosing.

14. Have previously completed or withdrawn from this study or any other study investigating mirikizumab, and have previously received mirikizumab.

    Diagnostic assessments

15. Have a current infection with hepatitis C virus.

16. Have a current infection with hepatitis B virus.

17. Have a current or recent acute, active infection.

18. Have had any of the following types of infection within 3 months prior to screening or develops any of these infections before the randomization:

    1. Serious: Requiring hospitalization, or intravenous (IV) or equivalent oral antibiotic treatment, or both.
    2. Opportunistic: As defined in Winthrop et al. 2015. Note: Herpes zoster is considered active and ongoing until all vesicles are dry and crusted over.
    3. Chronic: Duration of symptoms, signs, and/or treatment of 6 weeks or longer.
    4. Recurring: Including, but not limited to, herpes simplex, herpes zoster, recurring cellulitis, chronic osteomyelitis.

19. Show evidence of active or latent tuberculosis (TB).

    Other exclusion criteria

20. Have alcohol intake that exceeds recommended average weekly alcohol consumption limits per local regulation, or an amount deemed significant by the investigator.

21. Smoke more than 10 cigarettes per day, or equivalent, or are unable to abide by investigative site smoking restrictions.

22. In the opinion of the investigator or sponsor, are unsuitable for inclusion in the study.

All participants who were exposed to study intervention (Safety Population).

Baseline up to Day 74

All participants who were exposed to study intervention (Safety Population). Participants were analyzed according to the intervention they actually received.