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BIIB091

Phase 2

Relapsing Forms of Multiple Sclerosis | Small molecule | Neurology |Biogen Inc.|Last Updated: Feb 20, 2026

Success Probability

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Market & Valuation

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Trial Design

RandomizedDouble-BlindACTIVE_CONTROLLEDDMC
Total Trials1
Total Enrollment127

FDA Designations

No designations recorded

Clinical trial landscape

BIIB091 · 6 trials · 3 indications

Phase 2 1Phase 1 5
NCT05798520A Study to Learn About the Safety of BIIB091 and Its Effect on Brain Inflammation When Taken Alone or With Diroximel Fumarate (DRF) in Adults With Relapsing Forms of Multiple Sclerosis (MS)Relapsing Forms of Multiple Sclerosis
COMPLETED127 Analytics
PHASE2COMPLETED
A Study to Learn About the Safety of BIIB091 and Its Effect on Brain Inflammation When Taken Alone or With Diroximel Fumarate (DRF) in Adults With Relapsing Forms of Multiple Sclerosis (MS)
Relapsing Forms of Multiple SclerosisUnlock trial analytics

Study Endpoints

Primary Endpoints

Part 1: Number of Participants With Adverse Events (AEs)
Day 1 up to Week 50

An AE is any untoward medical occurrence in a participant or clinical investigation participant administered a pharmaceutical product and that does not necessarily have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease temporally associated with the use of a medicinal (investigational) product or auxiliary medicinal product, whether or not related to the medicinal (investigational) product or auxiliary medicinal product.

Part 1: Number of Participants With Serious Adverse Events (SAEs)
From signing the informed consent form (ICF) to Week 50

SAE is any untoward medical occurrence that at any dose results in death, in the view of the investigator, places the participant at immediate risk of death (a life-threatening event), requires inpatient hospitalization or prolongation of existing hospitalization, results in persistent or significant disability/incapacity, results in a congenital anomaly/birth defect or is a medically important event.

Part 2: Cumulative Number of New T1 Gadolinium-Enhancing (GdE) Lesions
Week 8 to Week 16
Area Under the Concentration-Time Curve From Time Zero to Time of the Last Measurable Concentration (AUClast) of BIIB091
Predose and at multiple timepoints postdose (up to Day 4)
AUC from Time Zero to Infinity (AUCinf) of BIIB091
Predose and at multiple timepoints postdose (up to Day 4)
Maximum Observed Concentration (Cmax) of BIIB091
Predose and at multiple timepoints postdose (up to Day 4)
Time to Reach Cmax (Tmax) of BIIB091
Predose and at multiple timepoints postdose (up to Day 4)
Elimination Half-Life (t½) of BIIB091
Predose and at multiple timepoints postdose (up to Day 4)
Time of Last Measurable Concentration (Tlast) of BIIB091
Predose and at multiple timepoints postdose (up to Day 4)
Concentration of BIIB091 at 12 hours Postdose (C12h)
At multiple timepoints postdose (up to 12 hours)
Apparent Clearance (CL/F) of BIIB091
Predose and at multiple timepoints postdose (up to Day 4)
Apparent Volume of Distribution During the Terminal Elimination (VZ/F) of BIIB091
Predose and at multiple timepoints postdose (up to Day 4)
Change From Baseline in QT Interval Corrected for Heart Rate (QTc) for BIIB091
Baseline (Day -1) up to Day 14
Change From Baseline in QT Interval Corrected for Heart Rate (QTc) for Metabolite 23 (M23)
Baseline (Day -1) up to Day 14
Amount of BIIB091 Excreted per Sampling Interval in Urine (Aeu)
Pre-dose and at multiple timepoints up to Day 10
Amount of BIIB091 Excreted per Sampling Interval in Feces (Aef)
Pre-dose and at multiple timepoints up to Day 10
Cumulative Amount of BIIB091 Excreted per Sampling Interval in Urine (Cum Aeu)
Pre-dose and at multiple timepoints up to Day 10
Cumulative Amount of BIIB091 Excreted per Sampling Interval in Feces (Cum Aef)
Pre-dose and at multiple timepoints up to Day 10
Percentage of BIIB091 Excreted per Sampling Interval in Urine (%Feu)
Pre-dose and at multiple timepoints up to Day 10
Percentage of BIIB091 Excreted per Sampling Interval in Feces (%Fef)
Pre-dose and at multiple timepoints up to Day 10
Cumulative Percentage of BIIB091 Excreted in Urine (Cum %Feu)
Pre-dose and at multiple timepoints up to Day 10
Cumulative Percentage of BIIB091 Excreted in Feces (Cum %Fef)
Pre-dose and at multiple timepoints up to Day 10
Maximum Observed Concentration (Cmax) of [14C]-BIIB091-Derived Materials in Plasma and Whole Blood
Pre-dose and at multiple timepoints up to Day 5
Time to Reach Maximum Observed Concentration (Tmax) of [14C]-BIIB091-Derived Materials in Plasma and Whole Blood
Pre-dose and at multiple timepoints up to Day 5
Area Under the Concentration-Time Curve From Time 0 to Time of the Last Measurable Concentration (AUClast) of [14C]-BIIB091-Derived Materials in Plasma and Whole Blood
Pre-dose and at multiple timepoints up to Day 5
Area Under the Concentration-Time Curve From Time 0 to Infinity (AUCinf) of [14C]-BIIB091-Derived Materials in Plasma and Whole Blood
Pre-dose and at multiple timepoints up to Day 5
Terminal Half-Life (t1/2) of [14C]-BIIB091-Derived Materials in Plasma and Whole Blood
Pre-dose and at multiple timepoints up to Day 5
Apparent Clearance (CL/F) of BIIB091 in Plasma
Pre-dose and at multiple timepoints up to Day 5
Apparent Volume of Distribution (Vz/F) of BIIB091 in Plasma
Pre-dose and at multiple timepoints up to Day 5
Quantitative Profile of [14C]-BIIB091 Metabolites in Plasma
Pre-dose and at multiple timepoints up to Day 4
Quantitative Profile of [14C]-BIIB091 Metabolites in Urine
Pre-dose and at multiple timepoints up to Day 10
Quantitative Profile of [14C]-BIIB091 Metabolites in Feces
Pre-dose and at multiple timepoints up to Day 10
Parts 1 and 1B: Time Prior to the First Measurable Concentration (Tlag) of BIIB091
Part 1: Up to Day 4; Part 1B: Up to Day 5
Parts 1, 1B and 3: Time of Maximum Observed Concentration (Tmax) of BIIB091
Part 1: Up to Day 4; Part 1B: Up to Day 5; Part 3: Up to Day 14
Parts 1, 1B and 3: Maximum Observed Concentration (Cmax) of BIIB091
Part 1: Up to Day 4; Part 1B: Up to Day 5; Part 3: Up to Day 14
Parts 1 and 1B: Plasma Concentration at 12 Hours (C12h) of BIIB091
Parts 1 and 1B: 12 hours post-dose (Day 1)
Parts 1 and 1B: Plasma Concentration at 24 Hours (C24h) of BIIB091
Parts 1 and 1B: 24 hours post-dose (Day 2)
Parts 1 and 1B: Area Under the Curve from Time 0 to 12 Hours Post-Dose [AUC(0-12h)] of BIIB091
Parts 1 and 1B: Up to 12 hours post-dose (Day 1)
Parts 1 and 1B: Area Under the Curve from Time 0 to 24 Hours Post-Dose [AUC(0-24h)] of BIIB091
Parts 1 and 1B: Up to 24 hours post-dose (Day 2)
Parts 1 and 1B: Area Under the Curve from Time 0 to the Time of Last Measurable Concentration [AUC(0-last)] of BIIB091
Part 1: Up to Day 4; Part 1B: Up to Day 5
Parts 1, 1B and 3: Area Under the Curve from Time 0 Extrapolated to Infinity [AUC(0-inf)] of BIIB091
Part 1: Post-dose at multiple time points up to Day 4; Part 1B: Post-dose at multiple time points up to Day 5; Part 3: Post-dose at multiple time points up to Day 14
Parts 1 and 1B: Area Under the Curve from Time of the Last Measurable Concentration to Infinity as a Percentage of the Area Under the Curve Extrapolated to Infinity (AUC%extrap) of BIIB091
Part 1: Up to Day 4; Part 1B: Up to Day 5
Parts 1, 1B and 3: Terminal Elimination Half-Life (T1/2) of BIIB091
Part 1: Up to Day 4; Part 1B: Up to Day 5; Part 3: Up to Day 14
Parts 1, 1B and 3: First Order Rate Constant Associated with the Terminal (Log-Linear) Portion of the Curve (Lambda-z) of BIIB091
Part 1: Up to Day 4; Part 1B: Up to Day 5; Part 3: Up to Day 14
Parts 1 and 1B: Total Body Clearance of BIIB091 Calculated After a Single Extravascular Administration Where Fraction of Dose Bioavailable (F) is Unknown (CL/F)
Part 1: Up to Day 4; Part 1B: Up to Day 5
Parts 1 and 1B: Apparent Volume of Distribution of BIIB091 Based on the Terminal Phase Calculated Using AUC(0-inf) After a Single Extravascular Administration Where F is Unknown (Vd/F)
Part 1: Up to Day 4; Part 1B: Up to Day 5
Part 2: Relative Bioavailability of BIIB091 Based on Cmax (Frel Cmax) of BIIB091 Dosed With and Without Proton Pump Inhibitor (PPI)
Part 2: Up to Day 5
Part 2: Relative Bioavailability of BIIB091 Based on AUC(0-last) [Frel AUC(0-last)] of BIIB091 Dosed With and Without PPI
Part 2: Up to Day 5
Part 2: Relative Bioavailability of BIIB091 Based on AUC(0-inf) [Frel AUC(0-inf)] of BIIB091 Dosed With and Without PPI
Part 2: Up to Day 5
Part 2: Frel Cmax of BIIB091 Dosed With and Without Cytochrome P450 (CYP) 3A4 Inhibitor
Part 2: Up to Day 5
Part 2: Frel AUC(0-last) of BIIB091 Dosed With and Without CYP3A4 Inhibitor
Part 2: Up to Day 5
Part 2: Frel AUC(0-inf) of BIIB091 Dosed With and Without CYP3A4 Inhibitor
Part 2: Up to Day 5
Part 3: Concentration at the End of the Dosing Interval (Ctrough) of BIIB091
Part 3: Up to Day 14
Part 3: Area Under Curve Observed at the End of the Dosing Interval (AUCtau) of BIIB091
Part 3: Up to Day 14
Part 3: Plasma Concentration Observed at the End of the Dosing Interval (Ctau) of BIIB091
Part 3: Up to Day 14
Part 3: Minimum Observed Concentration (Cmin) of BIIB091
Part 3: Up to Day 14
Part 3: Average Concentration (Cave) of BIIB091
Part 3: Up to Day 14
Part 3: Peak to Trough Fluctuation
Part 3: Up to Day 14

The formula used will be (Cmax-Cmin)/average concentration (Cavg) × 100.

Part 3: Accumulation Ratio Based on Cmax/Cmax Single Dose (AR Cmax)
Part 3: Up to Day 14
Part 3: Accumulation Ratio Based on AUCtau/AUCtau Single Dose (AR AUCtau)
Part 3: Up to Day 14
Part 3: Total Body Clearance Calculated Using AUCtau After Repeated Extravascular Administration Where F is Unknown (CL/Ftau)
Part 3: Up to Day 14
Part 3: Apparent Volume of Distribution Based on the Terminal Phase Calculated Using AUCtau After Extravascular Administration Where F is Unknown (Vd/Ftau)
Part 3: Up to Day 14
Number of Participants with Adverse Events (AEs) and Serious Adverse Events (SAEs)
Baseline up to Day 9 for SAD Cohorts; Baseline up to Day 24 for MAD Cohorts

An AE is any untoward medical occurrence in a patient or clinical investigation participant administered a pharmaceutical product and that does not necessarily have a causal relationship with this treatment. An SAE is any untoward medical occurrence that at any dose: results in death, in the view of the Investigator, places the participant at immediate risk of death (a life-threatening event), however, this does not include an event that, had it occurred in a more severe form, might have caused death; requires inpatient hospitalization or prolongation of existing hospitalization; results in persistent or significant disability/incapacity; results in a congenital anomaly/birth defect or is a medically important event.

Secondary Endpoints

Part 1: Cumulative Number of New T1 Gadolinium-Enhancing (GdE) Lesions
Week 8 to Week 16
Part 1: Cumulative Number of New or Enlarging T2 Hyperintense Lesions
Week 8 to Week 16
Part 1: Cumulative Volume of New or Enlarging T2 Hyperintense Lesions
Week 8 to Week 16
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Study Design & Arms

AllocationRANDOMIZED
MaskingQUADRUPLE
ModelSEQUENTIAL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
Part 1: BIIB091 High Dose + Matching Placebo for DRFEXPERIMENTALParticipants will receive BIIB091 high dose and matching placebo for DRF, orally, for up to 48 weeks.
Part 1: BIIB091 Low Dose + Matching Placebo for DRFEXPERIMENTALParticipants will receive BIIB091 low dose and matching placebo for DRF, orally, for up to 48 weeks.
Part 1: DRF + Matching Placebo for BIIB091ACTIVE_COMPARATORParticipants will receive DRF standard dose and matching placebo for BIIB091, orally, for up to 48 weeks.
Part 2: BIIB091 + DRF Standard DoseEXPERIMENTALParticipants will receive selected dose of BIIB091 (based on Part 1 data) and DRF standard dose, orally, for up to 48 weeks.
Part 2: BIIB091 + DRF Low DoseEXPERIMENTALParticipants will receive selected dose of BIIB091 (based on Part 1 data) and DRF low dose, orally, for up to 48 weeks.
Part 2: DRF + Matching Placebo for BIIB091ACTIVE_COMPARATORParticipants will receive DRF standard dose and matching placebo for BIIB091, orally, for up to 48 weeks.
BIIB091 IREXPERIMENTALParticipants will receive BIIB091 IR tablets on Day 1 of its respective period, with food.
BIIB091 GR-slowEXPERIMENTALParticipants will receive BIIB091 GR-slow tablets on Day 1 of its respective period, with food.
BIIB091 GR-fastEXPERIMENTALParticipants will receive BIIB091 GR-fast tablets on Day 1 of its respective period, with food.
BIIB091 ER-slowEXPERIMENTALParticipants will receive BIIB091 ER-slow tablets on Day 1 of its respective period, with food.
BIIB091 ER-fastEXPERIMENTALParticipants will receive BIIB091 ER-fast tablets on Day 1 of its respective period, with food.
BIIB091 ER-slow FastedEXPERIMENTALParticipants will receive BIIB091 ER-slow tablets on Day 1 of its respective period, without food.
BIIB091, BIIB091-matched placebo, Moxifloxacin-matched placeboEXPERIMENTALParticipants will receive BIIB091, BIIB091-matched placebo, and moxifloxacin-matched placebo orally during the inpatient period (Days -1 to 13).
Moxifloxacin, Moxifloxacin-matched placebo, BIIB091-matched placeboACTIVE_COMPARATORParticipants will receive moxifloxacin, moxifloxacin-matched placebo, and BIIB091-matched placebo orally during the inpatient period (Days -1 to 13).
[14C]-BIIB091EXPERIMENTALParticipants will receive a single oral dose of \[14C\]-BIIB091 on Day 1.
Part 1EXPERIMENTALParticipants will receive single oral dose of BIIB091 on Day 1 of each study period, in fasted state, for up to 5 periods. There will be a minimum 7-day washout between Day 1 of each study period.
Part 1BEXPERIMENTALParticipants will be randomized to receive single oral or 2 oral doses for divided daily doses of BIIB091 on Day 1 of Period 1, in fasted state or single oral dose of BIIB091 on Day 1 of Period 1, in fed state. Participants will receive single oral dose of BIIB091 on Day 1 of Period 2, in fasted state. Participants will receive single or two divided oral dose(s) of BIIB091 on Day 1 of Periods 3 and 4, in fasted or fed state. There will be a minimum 7-day washout between Day 1 of each study period.
Part 2EXPERIMENTALParticipants will receive single oral dose of BIIB091 on Day (D) 1 of Period (P) 1 in fasted/fed state; then itraconazole 100 milligram (mg) capsules (cap), orally, twice daily (BID) for 1 day (D -4) of P2, in fed state; then itraconazole 100 mg cap, orally, once daily (QD) for 2 days (D -3, -2) of P2, in fed state; then itraconazole 100 mg cap, orally, QD for 1 day (D -1) of P2, in fasted/fed state; then combination of itraconazole 100 mg cap, orally and BIIB091, orally on 5th day (D 1) of P2, in fasted/fed state; then itraconazole 100 mg cap, orally on 6th day (D 2) of P2, in fed state; then rabeprazole 20 mg tablets (tab), orally, BID for 3 days (D -3, -2, and -1) of P3 in fed state; then combination of rabeprazole 20 mg tab, orally and BIIB091, orally, on 4th day (D 1) of P3 in fasted/fed state. Minimum 7-day washout between dose of BIIB091 in P1 and 1st dose of itraconazole in P2; minimum 10-day washout between final dose of itraconazole in P2 and 1st dose of rabeprazole in P3.
Part 3EXPERIMENTALParticipants will receive BIIB091, orally, QD or BID for at least 7 days in fasted or fed state.
Single Ascending Dose (SAD): Cohort 1AEXPERIMENTALParticipants will receive dose level 1 of BIIB091 or placebo, orally, while fasting on Day 1.
(SAD): Cohort 2AEXPERIMENTALParticipants will receive dose level 2 of BIIB091 or placebo, orally, while fasting on Day 1.
(SAD): Cohort 3AEXPERIMENTALParticipants will receive dose level 3 of BIIB091 or placebo, orally, while fasting on Day 1, then again following a 7 day washout and high-fat meal.
(SAD): Cohort 4AEXPERIMENTALParticipants will receive dose level 4 of BIIB091 or placebo, orally, while fasting on Day 1.
(SAD): Cohort 5AEXPERIMENTALParticipants will receive dose level 5 of BIIB091 or placebo, orally, while fasting on Day 1.
Multiple Ascending Dose (MAD): Cohort 1BEXPERIMENTALParticipants will receive dose level 1 of BIIB091 or placebo, orally, twice daily (BID) for 13 days, and a single dose on Day 14.
(MAD): Cohort 2BEXPERIMENTALParticipants will receive dose level 2 of BIIB091 or placebo, orally, BID for 13 days, and a single dose on Day 14.
(MAD): Cohort 3BEXPERIMENTALParticipants will receive dose level 3 of BIIB091 or placebo, orally, BID for 13 days, and a single dose on Day 14.

Interventions

NameTypeDescription
BIIB091DRUGAdministered as specified in the treatment arm.
DRFDRUGAdministered as specified in the treatment arm.
PlaceboDRUGAdministered as specified in the treatment arm.
MoxifloxacinDRUGAdministered as specified in the treatment arm.
BIIB091-matched PlaceboDRUGAdministered as specified in the treatment arm.
Moxifloxacin-matched PlaceboDRUGAdministered as specified in the treatment arm.
[14C]-BIIB091DRUGAdministered as specified in the treatment arm.
RabeprazoleDRUGAdministered as specified in the treatment arm
ItraconazoleDRUGAdministered as specified in the treatment arm
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Eligibility Criteria

Age Range18 Years to 55 Years
SexALL
Healthy VolunteersNo
Study Sites77

Key Inclusion Criteria: 1. Diagnosis of RMS \[relapsing-remitting multiple sclerosis (RRMS) or active secondary progressive multiple sclerosis (SPMS)\] in accordance with the 2017 Revised McDonald criteria. 2. Time since MS symptom onset is \<20 years. 3. Must have expanded disability status scale ...

Countries:United StatesBulgariaCzechiaGermanyItalyPolandPuerto RicoRomaniaSpainSwitzerlandUnited Kingdom
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Frequently asked questions about BIIB091

What is BIIB091 used for?

BIIB091 is an investigational small molecule being studied for relapsing forms of multiple sclerosis (MS). It has also been evaluated in healthy volunteers for safety, tolerability, pharmacokinetics, and pharmacodynamics. The drug is not approved and remains in clinical development.

What does BIIB091 target?

BIIB091 is a Bruton's tyrosine kinase (BTK) inhibitor. BTK is an enzyme involved in B-cell and macrophage signaling, which are implicated in the inflammatory processes of multiple sclerosis. By inhibiting BTK, BIIB091 may reduce brain inflammation associated with the disease.

Who makes BIIB091?

BIIB091 is being developed by Biogen Inc., a biotechnology company traded on the NASDAQ under the ticker symbol BIIB. Biogen is conducting clinical trials to evaluate the safety and efficacy of BIIB091 in healthy volunteers and in patients with relapsing forms of multiple sclerosis.

What phase is BIIB091 in?

BIIB091 is in Phase 1 clinical development. While one trial listed under the drug is labeled Phase 2, the overall development stage is Phase 1, with all four studies completed. BIIB091 is investigational and has not been approved by regulatory authorities.

What clinical trials is BIIB091 in?

BIIB091 has completed four clinical trials. NCT03943056 and NCT06574828 evaluated safety and heart effects in healthy volunteers, while NCT06640933 studied how different forms are processed with and without food. NCT05798520, a Phase 2 study, assessed safety and brain inflammation in adults with relapsing MS when taken alone or with diroximel fumarate.

Is BIIB091 the same as diroximel fumarate?

No, BIIB091 is not the same as diroximel fumarate. BIIB091 is a Bruton's tyrosine kinase inhibitor, while diroximel fumarate is a separate medication. In clinical trials, BIIB091 has been studied alone and in combination with diroximel fumarate to assess its effects on brain inflammation in multiple sclerosis.