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LY3871801

Phase 2

Rheumatoid Arthritis | Small molecule | Immunology |Eli Lilly and Company|Last Updated: May 22, 2026

Success Probability

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Market & Valuation

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Trial Design

RandomizedDouble-BlindPLACEBO_CONTROLLEDDMC
Total Trials1
Total Enrollment164

FDA Designations

No designations recorded

Clinical trial landscape

LY3871801 · 5 trials · 2 indications

Phase 2 1Phase 1 4
NCT05848258An Adaptive Phase 2a/2b Study of LY3871801 in Adult Participants With Rheumatoid ArthritisRheumatoid Arthritis
COMPLETED164 Analytics
PHASE2COMPLETED
An Adaptive Phase 2a/2b Study of LY3871801 in Adult Participants With Rheumatoid Arthritis
Rheumatoid ArthritisUnlock trial analytics

Study Endpoints

Primary Endpoints

Phase 2a: Change from Baseline in Disease Activity Score - high-sensitivity C-reactive protein (DAS28-hsCRP)
Baseline, Week 12
Phase 2b: Percentage of Participants Achieving American College of Rheumatology (ACR)50
Baseline to Week 12
Urinary Excretion of LY3871801 Radioactivity Over Time Expressed as a Percentage of the Total Radioactive Dose Administered
Predose up to Day 7 post dose
Fecal Excretion of LY3871801 Radioactivity Over Time Expressed as a Percentage of the Total Radioactive Dose Administered
Predose up to Day 7 post dose
Number of Participants with One or More Treatment Emergent Adverse Events (TEAEs) and Serious Adverse Event(s) (SAEs) Considered by the Investigator to be Related to Study Drug Administration
Predose up to 24 days post dose

A summary of TEAEs, SAEs and other non-serious adverse events (AEs), regardless of causality, will be reported in the Reported Adverse Events module

Part 1: Pharmacokinetics (PK): Maximum Concentration (Cmax) of Methotrexate
Predose up to 48 hours postdose

Part 1: PK: Cmax of Methotrexate

Part 1: PK: Area Under the Plasma Concentration Versus Time Curve From Zero to Infinity (AUC[0-∞]) of Methotrexate
Predose up to 48 hours postdose

Part 1: PK: AUC\[0-∞\] of Methotrexate

Part 2: PK: Cmax of Midazolam
Predose up to 24 hours postdose
Part 2: PK: AUC[0-∞] of Midazolam
Predose up to 24 hours postdose

Part 2: PK: AUC\[0-∞\] of Midazolam

Part 2: PK: Cmax of S-warfarin
Predose up to 96 hours postdose
Part 2: PK: AUC[0-∞] of S-warfarin
Predose up to 96 hours postdose

Part 2: PK: AUC\[0-∞\] of S-warfarin

Part 2: PK: Cmax of Dextromethorphan
Predose up to 72 hours postdose
Part 2: PK: AUC[0-∞] of Dextromethorphan
Predose up to 72 hours postdose

Part 2: PK: AUC\[0-∞\] of Dextromethorphan

Part 2: PK: Cmax of Repaglinide
Predose up to 24 hours postdose
Part 2: PK: AUC[0-∞] of Repaglinide
Predose up to 24 hours postdose

Part 2: PK: AUC\[0-∞\] of Repaglinide

Pharmacokinetics (PK): Maximum Concentration (Cmax) of LY3871801
Predose through Day 4

PK: Cmax of LY3871801

PK: Area Under the Plasma Concentration Versus Time Curve From Zero to Infinity (AUC[0-∞]) of LY3871801
Predose through Day 4

PK: AUC\[0-∞\] of LY3871801

Secondary Endpoints

Phase 2a: Percentage of Participants Achieving ACR20/50/70
Baseline to Week 12
Phase 2b: Change from Baseline in DAS28-hsCRP
Baseline, Week 12
Phase 2b: Percentage of Participants Achieving ACR20/70
Week 12
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Study Design & Arms

AllocationRANDOMIZED
MaskingDOUBLE
ModelPARALLEL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
LY3871801 Phase 2aEXPERIMENTALParticipants will receive LY3871801 administered orally.
Placebo Phase 2aPLACEBO_COMPARATORParticipants will receive placebo.
LY3871801 Dose 1 Phase 2bEXPERIMENTALParticipants will receive LY3871801 administered orally.
LY3871801 Dose 2 Phase 2bEXPERIMENTALParticipants will receive LY3871801 administered orally.
LY3871801 Dose 3 Phase 2bEXPERIMENTALParticipants will receive LY3871801 administered orally.
Placebo Phase 2bPLACEBO_COMPARATORParticipants will receive placebo.
[14C]-LY3871801EXPERIMENTALSingle dose of \[¹⁴C\]-LY3871801 administered orally
LY3871801 (Part A)EXPERIMENTALLY3871801 administered orally in Japanese and Non-Asian Participants.
Placebo (Part A)PLACEBO_COMPARATORPlacebo administered orally in Japanese and Non-Asian Participants.
LY3871801 (Part B)EXPERIMENTALLY3871801 administered orally in Chinese Participants.
Placebo (Part B)PLACEBO_COMPARATORPlacebo administered orally in Chinese Participants.
LY3871801 + Methotrexate (Part 1)EXPERIMENTALLY3871801 administered orally in combination with methotrexate given orally.
LY3871801 + Repaglinide + Drug Cocktail (Part 2)EXPERIMENTALLY3871801 administered orally in combination with repaglinide given orally and drug cocktail which includes warfarin, dextromethorphan and midazolam administered orally.
LY3871801 (Period 1)EXPERIMENTALLY3871801 solid dispersion suspension administered orally.
LY3871801 (Period 2)EXPERIMENTALLY3871801 crystalline freebase tablet administered orally.

Interventions

NameTypeDescription
LY3871801DRUGAdministered orally
PlaceboDRUGAdministered orally
[14C]-LY3871801DRUGAdministered orally
MethotrexateDRUGAdministered orally.
WarfarinDRUGAdministered orally.
DextromethorphanDRUGAdministered orally.
MidazolamDRUGAdministered orally.
RepaglinideDRUGAdministered orally.
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Eligibility Criteria

Age Range18 Years to N/A
SexALL
Healthy VolunteersNo
Study Sites54

Inclusion Criteria: * Have a diagnosis of adult-onset RA for at least 3 months prior to screening as defined by the 2010 ACR/European League Against Rheumatism (EULAR) classification criteria. * Have moderately-to-severely active RA at screening and baseline, defined by the presence of * ≥6 swol...

Countries:United StatesArgentinaCzechiaFranceGermanyHungaryIndiaMexicoPolandUnited KingdomSingapore
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Recent Changes (Last 90 Days)

MEDIUMJun 22, 2026NCT05848258TRIAL_REMOVED: changed
MEDIUMJun 22, 2026NCT05848258TRIAL_REMOVED: changed
MEDIUMJun 22, 2026NCT05848258TRIAL_REMOVED: changed

Frequently asked questions about LY3871801

What is LY3871801 used for?

LY3871801 is an investigational small molecule being studied for use in healthy participants and in rheumatoid arthritis. As of the latest data, it is in Phase 1 clinical development and has not been approved by regulatory authorities. All four completed trials enrolled healthy volunteers, with no active trials currently listed.

Who makes LY3871801?

LY3871801 is being developed by Eli Lilly and Company, a biopharmaceutical company traded on the NYSE under the ticker symbol LLY. The company has sponsored four Phase 1 clinical trials of this investigational small molecule, all of which have been completed.

What phase is LY3871801 in?

LY3871801 is in Phase 1 clinical development. All four clinical trials listed for this drug are Phase 1 studies and have been completed. The drug is investigational and has not been approved by the FDA or any other regulatory agency for any use.

What clinical trials is LY3871801 in?

LY3871801 has been studied in four completed Phase 1 trials: NCT05222399 in healthy participants in Singapore, NCT05602675 a drug interaction study in the US, NCT05960851 in healthy Asian and non-Asian participants in the US, and NCT06049108 a carbon-14 labelled study in healthy males in the US. No active trials are currently listed.

Is LY3871801 FDA approved?

LY3871801 is not FDA approved. It is an investigational drug currently in Phase 1 clinical development, with all completed trials conducted in healthy volunteers. The drug has not yet progressed to later-stage trials or received marketing authorization for any indication.