A Study of LY4213663 in Healthy Participants and Participants With Rheumatoid Arthritis

June 19, 2026 updated by: Eli Lilly and Company

A Phase 1, Multicenter, Randomized, Placebo-Controlled, Investigator- and Participant-Blinded, Single- and Multiple-Ascending Dose Study to Evaluate Safety, Tolerability, and Pharmacokinetics of LY4213663 in Healthy Participants, and Two Open-Label, Multiple-Dose Evaluations of LY4213663 in Patients With Rheumatoid Arthritis.

The purpose of this study is to evaluate how well LY4213663 is tolerated and what side effects may occur in healthy participants and participants with rheumatoid arthritis (RA). The study drug will be administered either subcutaneously (SC) (under the skin) or intravenously (IV) (into a vein in the arm).

Blood tests will be performed to investigate how the body processes the study drug and how the study drug affects the body. The study will last approximately 33 weeks excluding screening.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

141

Phase

  • Phase 1

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

  • Name: Trial questions or participation questions: 1-877-CTLILLY (1-877-285-4559) or
  • Phone Number: 1-317-615-4559
  • Email: LillyTrials@Lilly.com

Study Contact Backup

Study Locations

  • Germany
      • Berlin, Germany, 10117
        • Not yet recruiting
        • Universitätsklinikum Charité
        • Principal Investigator:
          • Stanislav Ignatenko
        • Contact:
          • Phone Number: +49 30 450 539 200
  • United States
    • Alabama
      • Anniston, Alabama, United States, 36207
        • Recruiting
        • Pinnacle Research Group, LLC
        • Contact:
          • Phone Number: 256-236-0055, ext 101
        • Principal Investigator:
          • Vishala Chindalore
    • Arizona
      • Phoenix, Arizona, United States, 85053
        • Recruiting
        • Arizona Research Center
        • Contact:
          • Phone Number: 602-773-3020
        • Principal Investigator:
          • Louise Taber
    • Florida
      • Clearwater, Florida, United States, 33765
        • Recruiting
        • Clinical Research of West Florida, Inc. (Clearwater)
        • Principal Investigator:
          • Robert Levin
        • Contact:
          • Phone Number: 727-466-0078
      • Cooper City, Florida, United States, 33024
        • Recruiting
        • GNP Research at Mark Jaffe, MD
        • Contact:
          • Phone Number: 754-248-3589
        • Principal Investigator:
          • Mark Jaffe
      • Daytona Beach, Florida, United States, 32117
        • Recruiting
        • Fortrea Clinical Research Unit
        • Contact:
          • Phone Number: 866-429-3700
        • Principal Investigator:
          • Sharrell Cooper
      • Hialeah, Florida, United States, 33012
        • Recruiting
        • AGA Clinical Trials
        • Contact:
          • Phone Number: 704-526-6864
        • Principal Investigator:
          • WILSON CUEVA
      • Miami, Florida, United States, 33417
        • Recruiting
        • Advanced Pharma Cr, Llc
        • Principal Investigator:
          • Simon Abelson
        • Contact:
          • Phone Number: 305-220-2727, Ext 802
      • Miami Lakes, Florida, United States, 33016
        • Recruiting
        • Floridian Clinical Research
        • Contact:
          • Phone Number: 305-330-9977
        • Principal Investigator:
          • Christopher Mesa
    • Nevada
      • Las Vegas, Nevada, United States, 89121
        • Recruiting
        • Oasis Clinical Research
        • Principal Investigator:
          • Stephen Tam
        • Contact:
          • Phone Number: 702-832-1369

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Have a body mass index (BMI) of 18.0 to 32.0 kilogram per square meter (kg/m²), inclusive

Part C and D Only:

  • Have a body weight at least 50 kilograms and BMI within the range 18.0 to 40.0 kg/m² (inclusive) at screening
  • Have a diagnosis of adult-onset RA for at least 3 months prior to screening

Exclusion Criteria:

Healthy Participants for SAD Part A and MAD Part B Only:

  • Have a history or presence of cardiovascular, respiratory, hepatic, ophthalmological, renal, gastrointestinal, endocrine, hematological, neurological, or psychiatric disorders capable of significantly altering the absorption, metabolism, or elimination of drugs

Participants with RA for Parts C and D Only:

  • Have Class 4 RA according to American College of Rheumatology (ACR) revised criteria
  • Have a 12-lead electrocardiogram (ECG) abnormality at screening
  • Have a current or recent acute active infection

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: LY4213663 (Part A)
Single-ascending dose (SAD) of LY4213663 administered subcutaneously (SC) and intravenously (IV) in healthy participants
Drug: LY4213663
Administered SC
Drug: LY4213663
Administered IV
Placebo Comparator: Placebo (Part A)
SAD placebo administered SC and IV
Drug: Placebo
Administered SC
Drug: Placebo
Administered IV
Experimental: LY4213663 (Part B)
Multiple-ascending doses (MAD) of LY4213663 administered SC and IV in healthy participants
Drug: LY4213663
Administered SC
Drug: LY4213663
Administered IV
Placebo Comparator: Placebo (Part B)
MAD placebo administered SC and IV
Drug: Placebo
Administered SC
Drug: Placebo
Administered IV
Experimental: LY4213663 (Parts C and D)
Multiple doses of LY4213663 administered SC and IV in participants with RA
Drug: LY4213663
Administered SC
Drug: LY4213663
Administered IV

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Number of Participants with One or More Serious Adverse Event(s) (SAEs) Considered by the Investigator to be Related to Study Drug Administration
Time Frame: Baseline up to Week 33
A summary of SAEs regardless of causality, will be reported in the Reported Adverse Events module
Baseline up to Week 33

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Pharmacokinetics (PK): Maximum Concentration (Cmax) of LY4213663
Time Frame: Baseline up to Week 33
PK: Cmax of LY4213663
Baseline up to Week 33
PK: Area Under the Concentration Versus Time Curve (AUC) of LY4213663
Time Frame: Baseline up to Week 33
PK: AUC of LY4213663
Baseline up to Week 33

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Eli Lilly and Company

Investigators

  • Study Director: Call 1-877-CTLILLY (1-877-285-4559) or 1-317-615-4559 Mon - Fri 8 AM - 8 PM Eastern time (UTC/GMT - 5 hours, EST), Eli Lilly and Company

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

December 2, 2025

Primary Completion (Estimated)

March 1, 2028

Study Completion (Estimated)

March 1, 2028

Study Registration Dates

First Submitted

November 21, 2025

First Submitted That Met QC Criteria

November 21, 2025

First Posted (Actual)

December 2, 2025

Study Record Updates

Last Update Posted (Actual)

June 23, 2026

Last Update Submitted That Met QC Criteria

June 19, 2026

Last Verified

June 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 27749
  • 2025-523980-39-00 (Ctis)
  • J6T-MC-KYAA (Other Identifier: Eli Lilly and Company)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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