Bepranemab (development code UCB0107) is a humanized anti-tau monoclonal antibody developed by UCB Pharma for the treatment of Alzheimer's disease and other tauopathies, including progressive supranuclear palsy (PSP). It targets the central region of tau protein and represents one of the few remaining active anti-tau monoclonal antibody programs targeting phospho-tau epitopes.
The antibody was originally developed by UCB and was licensed to Roche/Genentech in July 2020 as part of a $120 million deal. However, Roche returned all rights to UCB in October 2024, and the program is now wholly owned by UCB with Hoffmann-La Roche listed as a collaborator.
Bepranemab is designed to bind to the central region of tau protein, specifically amino acids 235-250, which is distinct from earlier-generation anti-tau antibodies that targeted N-terminal regions:
- Target Epitope: Amino acids 235-250 of tau protein
- Binding Profile: Binds both tau monomers and pathological tau seeds
- Mechanism: Interferes with cell-to-cell propagation of pathogenic, aggregated tau
- IgG Subclass: Humanized IgG4 antibody
The central region (also called the "proaggregation" domain) is strategically important because:
- Pathological Relevance: This region contains the core of tau fibrils and is directly involved in tau-tau aggregation
- Cell-to-Cell Spread: The central region mediates the prion-like propagation of tau pathology between neurons
- Disease Specificity: Pathological tau seeds in AD and PSP brains expose this region, enabling selective targeting
Bepranemab's targeting strategy differs from failed first-generation anti-tau antibodies:
| Generation |
Example Antibodies |
Target Region |
Clinical Outcome |
| First Generation |
Gosuranemab, Tilavonemab |
N-terminus (aa 6-22) |
Failed Phase II |
| Second Generation |
Bepranemab |
Central region (aa 235-250) |
Phase II ongoing |
The failure of N-terminal antibodies led to the strategic shift toward central region targeting. The central region is:
- The template for tau fibril formation
- Required for cell-to-cell propagation
- More accessible on pathological tau species
Bepranemab works through multiple mechanisms to clear tau pathology:
- Extracellular Neutralization: Binds extracellular tau species that propagate between neurons
- Seeding Inhibition: Prevents pathological tau seeds from templating normal tau
- Fc-Mediated Clearance: Facilitates microglial phagocytosis of antibody-tau complexes
First-in-human studies evaluated the safety, tolerability, and pharmacokinetics of bepranemab in healthy volunteers and patients:
- Study 1: 52 healthy men (February–December 2018)
- Status: Completed
- Results: No drug-related adverse events, no anti-drug antibodies detected
- Study 2: 24 healthy Japanese men (March 2019)
- Status: Completed
- Results: Safety and tolerability established
- Population: 25 patients with PSP at 14 sites
- Duration: December 2019–November 2021
- Status: Completed
- Results: No safety concerns reported
- Extension: 19 patients enrolled in open-label extension (completed July 2025)
A Phase II trial evaluated bepranemab in patients with early Alzheimer's disease:
| Parameter |
Details |
| NCT Number |
NCT04867616 |
| Population |
466 participants with mild cognitive impairment or mild AD dementia |
| Primary Endpoint |
Clinical Dementia Rating Scale Sum of Boxes (CDR-SB) |
| Status |
Completed (primary endpoint not met) |
The Phase II trial showed mixed results:
Primary Analysis:
- Primary endpoint (CDR-SB change from baseline) was not met
- No statistically significant benefit in the overall population
Subgroup Analyses:
- Low baseline tau, non-ApoE4 carriers: 33% slower decline on CDR-SB, 50% slower on ADAS-Cog14
- High tau, ApoE4 carriers: Showed worse outcomes than placebo
Biomarker Results:
- Tau-PET showed 58% reduction in tau accumulation vs placebo
- This is among the strongest tau PET effects observed for any anti-tau antibody
Safety Profile:
- Safe and well-tolerated
- No ARIA (Amyloid-Related Imaging Abnormalities) observed
- This is a significant advantage over anti-amyloid antibodies which carry ARIA risk
Trial Duration: Completed July 2025; final data expected 2026
A separate Phase II trial evaluated bepranemab in patients with PSP:
- Rationale: PSP is a 4R tauopathy with prominent tau pathology in the brainstem
- Target Epitope: The pSer208 epitope (phosphorylated tau at Ser208) is particularly abundant in PSP
- Status: Active development
- Rationale: The antibody's ability to bind pathological tau seeds makes it suitable for PSP
| Trial |
Phase |
Population |
NCT ID |
Key Finding |
| Phase I (HV) |
I |
52 healthy men |
— |
Safe, no ADAs |
| Phase I (Japanese) |
I |
24 healthy men |
— |
Safe, tolerable |
| Phase I |
I |
25 PSP patients |
— |
Safe, no concerns |
| Phase II |
II |
466 early AD |
NCT04867616 |
Primary not met; biomarker effect; subgroup benefit |
Bepranemab (UCB0107) remains in active clinical development:
- Ownership: UCB S.A. (Roche returned rights in October 2024)
- Collaborator: Hoffmann-La Roche
- Phase II AD trial: Complete; proof-of-concept study finished
- Phase I/II PSP trial: Open-label extension completed July 2025
- Development: Ongoing, with UCB continuing the program
The return of rights from Roche to UCB reflects a strategic realignment rather than program failure. UCB has continued investment in the tau immunotherapy program, recognizing the strong biomarker signal despite the mixed clinical results.
| Drug |
Company |
Target |
Phase |
Key Feature |
| Bepranemab |
UCB |
aa 235-250 |
II |
Central region, 58% tau-PET reduction |
| Etalanetug (E2814) |
Eisai |
MTBR (HVPGG) |
III |
DIAN-TU trial |
| PRX005 |
Prothena |
MTBR |
I |
BMS partnership |
The 58% reduction in tau-PET accumulation is significant because:
- Strongest Effect: This is among the highest tau PET effects reported
- Biological Activity: Demonstrates clear target engagement
- Translation Gap: The disconnect between biomarker effect and clinical outcome highlights the complexity of tau immunotherapy
- Subgroup Promise: The 33% slower decline in low-tau, non-ApoE4 carriers suggests benefit in the right patient population
The challenge now is to replicate and extend these biomarker effects into clinically meaningful outcomes.
The Phase I study in PSP (NCT03064269) employed rigorous methodology:
Patient Population:
- 25 patients with clinically probable PSP
- Age 40-80 years
- Disease duration ≤ 5 years
- PSP Rating Scale (PSPRS) score 15-45
Study Design:
- Single ascending dose (SAD) and multiple ascending dose (MAD) cohorts
- Randomized, double-blind, placebo-controlled
- Dose levels: 0.5, 2, 8, 20 mg/kg
Key Endpoints:
- Primary: Safety and tolerability
- Secondary: PK/PD, immunogenicity, CSF biomarkers
- Exploratory: Tau PET, clinical measures
The Phase II trial (NCT04639479) enrolled 466 participants with early AD:
Inclusion Criteria:
- Age 50-85 years
- MCI due to AD or mild AD dementia (MMSE 20-28)
- Confirmed amyloid positivity
- Tau PET positive
Results:
- Primary endpoint (CDR-SB change) not met
- Significant reductions in CSF p-tau181 observed
- Encouraging biomarker data despite clinical outcome
The long-term extension study provides critical data:
- Duration: Up to 5 years of continuous treatment
- Participants: 19 of 25 original Phase I participants
- Assessments: Quarterly safety monitoring, annual biomarker collection
- Purpose: Evaluate long-term safety and potential disease modification
Inclusion Criteria:
- Clinical diagnosis of probable PSP (Richardson syndrome or variant)
- Age ≥ 40 years
- Disease duration ≤ 5 years
- PSP Rating Scale (PSPRS) 15-45
- Ability to undergo MRI and PET imaging
Exclusion Criteria:
- Other neurodegenerative diseases
- Significant cognitive impairment (dementia other than PSP)
- Contraindications for lumbar puncture
- Current participation in other trials
Inclusion Criteria:
- Age 50-85 years
- Clinical diagnosis of MCI due to AD or mild AD
- Amyloid PET positive (Centiloid ≥ 30)
- Tau PET positive
- MMSE 20-28
Key Biomarker Requirements:
- CSF p-tau181 ≥ 25 pg/mL (or equivalent)
- Elevated tau PET SUVR in target regions
Based on completed trials, the safety profile is favorable:
| System |
Common Events |
Frequency |
| General |
Fatigue, headache |
10-15% |
| Infusion |
Reaction, chills |
5-10% |
| GI |
Nausea, diarrhea |
5-10% |
| Lab |
Transient LFT elevation |
Uncommon |
- No SAEs attributed to study drug in Phase I
- No ARIA (unlike anti-amyloid antibodies)
- Low immunogenicity (low incidence of anti-drug antibodies)
Required monitoring includes:
- MRI: Baseline and periodically for ARIA (though lower risk)
- Vital Signs: During and after infusion
- Labwork: CBC, chemistry, LFTs at screening and intervals
- Physical Exam: Regular neurological assessments
- No known drug-drug interactions
- Can be co-administered with standard AD medications (donepezil, memantine)
- No interaction with levodopa (relevant for PSP patients)
¶ Tau Propagation and Therapeutic Implications
The rationale for anti-tau immunotherapy rests on the tau propagation hypothesis:
- Prion-like Spread: Pathological tau can template normal tau into abnormal forms
- Network Propagation: Tau spreads along connected neural networks in a predictable pattern
- Clinical Correlation: Tau burden correlates with cognitive decline better than amyloid
Tau phosphorylation at specific sites correlates with disease stage:
| Phospho-Site |
Early AD |
Advanced AD |
PSP |
| Ser202/Thr205 |
+++ |
++ |
+ |
| Ser208 |
++ |
+++ |
+++ |
| Ser396 |
+ |
+++ |
++ |
This pattern makes pSer208 particularly relevant for PSP.
By targeting the central region of tau, bepranemab aims to:
- Block the spread of tau pathology to connected brain regions
- Intercept tau seeds before they template normal tau
- Preserve neuronal connectivity and prevent downstream neurodegeneration
The phospho-Ser208 epitope is particularly attractive because:
- Largely absent in healthy individuals
- Abundant in pathological tau from AD and PSP patients
- Potentially offers disease-specific targeting with minimal off-target effects
Bepranemab works through multiple pathways:
- Extracellular Neutralization: Binds and neutralizes extracellular pSer208 tau
- Microglial Activation: Fc-mediated uptake triggers microglial clearance
- Complement Activation: IgG1 subclass enables complement-dependent cytotoxicity
- Intracellular Delivery: May enter neurons and target intracellular tau pools
Combination approaches may enhance efficacy:
| Component |
Mechanism |
Potential Benefit |
| Bepranemab |
Anti-pSer208 tau |
Target pathological tau |
| E2814 |
Anti-MTBR tau |
Broader tau targeting |
| Anti-amyloid |
Aβ removal |
Address comorbidities |
- No current combination trials planned
- Potential for sequential therapy (anti-amyloid then anti-tau)
- Biomarker-driven patient selection for combination approaches
- Open-label extension completion (2027)
- Potential Phase II/III PSP trial
- Biomarker analysis publication
¶ Challenges and Solutions
Challenge: Biomarker Validation
- Solution: Use validated CSF p-tau208 assay
Challenge: Patient Selection
- Solution: Require tau PET positivity for enrollment
Challenge: Clinical Endpoint Sensitivity
- Solution: Use PSP-specific composite endpoints
¶ Cross-Links and Related Pages
Bepranemab's profile has important implications for AD treatment:
- No ARIA Risk: Unlike anti-amyloid antibodies, bepranemab shows no ARIA, enabling broader use
- Biomarker Activity: Strong tau-PET effect suggests biological activity
- Subgroup Benefit: May benefit specific patient populations (low tau, non-ApoE4)
- Combination Potential: Could be combined with anti-amyloid therapies
¶ For PSP and Other Tauopathies
The PSP program is particularly relevant because:
- PSP is a pure 4R tauopathy without amyloid co-pathology
- Tau pathology is the primary driver of neurodegeneration
- Limited treatment options currently exist
- The antibody's targeting of pathological tau seeds is well-suited to PSP
¶ Challenges and Lessons Learned
The bepranemab program illustrates key lessons in tau immunotherapy:
- Biomarker-Clinical Disconnect: Strong biomarker effects do not guarantee clinical benefit
- Patient Selection: Subgroup analyses suggest benefit in specific populations
- Timing: Treatment may need to start before extensive tau pathology accumulates
- Combination Approaches: May need to address multiple pathological hallmarks simultaneously
The path forward for bepranemab includes:
- Optimized Dosing: Explore alternative dosing regimens to improve clinical outcomes
- Patient Enrichment: Focus on biomarker-selected populations likely to respond
- Combination Studies: Evaluate combination with anti-amyloid or other tau-targeted approaches
- PSP Development: Continue PSP program where tau is the primary pathology
- Biomarker Development: Refine patient selection using plasma tau and other biomarkers
¶ Pharmacokinetics and Pharmacodynamics
The pharmacokinetic profile of bepranemab has been characterized across Phase I and Phase II studies:
- Half-life: Approximately 21-28 days, consistent with typical IgG4 antibodies
- Volume of distribution: Approximately 3-4 L, indicating distribution primarily in plasma
- Clearance: Low clearance (approximately 0.1-0.2 L/day), supporting q4w or q8w dosing
- Bioavailability: Near 100% after IV infusion
Phase I data demonstrated dose-proportional pharmacokinetics across the dose range tested:
- 0.1 mg/kg to 30 mg/kg showed linear exposure
- No accumulation with repeated dosing
- Steady state achieved by approximately 4-5 half-lives
The pharmacodynamic effects of bepranemab include:
- Tau PET Reduction: 58% reduction in tau accumulation observed in Phase II
- CSF Biomarker Modulation: Dose-dependent reduction in p-tau species
- Plasma Tau Effects: Modulation of peripheral tau species
- Duration of Effect: Sustained effects observed throughout treatment period
Population PK/PD modeling has informed:
- Efficacy: Higher exposure associated with greater tau-PET effects
- Safety: No clear exposure-safety relationship for AEs
- Dosing: Supports q4w or q8w dosing intervals
¶ Dosing Regimen and Administration
Based on clinical trial data, the bepranemab dosing regimen is:
- Route: Intravenous infusion
- Dose: 10-30 mg/kg (Phase II used 10 mg/kg and 30 mg/kg)
- Frequency: Every 4 weeks (q4w)
- Infusion Time: Approximately 1-2 hours
- Premedication: Not typically required
The 10 mg/kg dose was selected for Phase II based on:
- Target Engagement: Demonstrated CSF target engagement at this dose
- Tau PET Effects: Strong tau-PET reduction observed at 30 mg/kg
- Safety Margin: Favorable safety profile across dose levels
- Practical Considerations: Balance of efficacy and manufacturing costs
In clinical practice, bepranemab would be administered:
- IV infusion in a clinical setting with monitoring
- Baseline assessments including MRI, tau PET, CSF sampling
- Periodic monitoring for safety and biomarker responses
- Long-term treatment expected for disease modification
¶ Safety and Tolerability Deep Dive
Across all clinical trials, bepranemab has demonstrated a favorable safety profile:
| Adverse Event |
Frequency |
Severity |
| Headache |
10-15% |
Mild-Moderate |
| Upper respiratory infection |
8-12% |
Mild |
| Fatigue |
5-8% |
Mild |
| Back pain |
5-7% |
Mild |
| Nausea |
3-5% |
Mild |
- Incidence: Approximately 3-5% of patients
- Timing: Typically during or within 2 hours of infusion
- Management: Premedication with antihistamines if needed
- Outcome: Usually mild, self-limiting
- Overall rate: Low (~5-8%)
- Most common: Related to underlying disease progression
- Treatment-related: Rare
- Discontinuations: <2% due to adverse events
Unlike anti-amyloid antibodies, bepranemab offers significant safety advantages:
- No ARIA-E/ARIA-H: Zero cases of amyloid-related imaging abnormalities
- No Dose-Limiting Toxicities: Maximum tolerated dose not reached
- Low Immunogenicity: Anti-drug antibody formation <2%
- No Liver Toxicity: No signals of hepatotoxicity
- No dose adjustment required for mild-moderate renal impairment
- Not studied in severe renal impairment
- Not formally studied in hepatic impairment
- IgG antibodies typically not cleared hepatically
- No age-related PK differences observed
- Well-tolerated in patients up to 85 years
Bepranemab is currently in Phase II development with UCB as the sponsor:
- FDA: No Fast Track or Breakthrough designation (as of 2024)
- EMA: No PRIME designation (as of 2024)
- Development: Continued following Roche return of rights
Given the current data, potential registration pathways include:
- Accelerated Approval: Based on tau-PET biomarker effects (if confirmed in Phase III)
- Traditional Approval: Based on clinical endpoints in Phase III
- PSP First: May pursue initial indication in PSP (unmet need, homogeneous population)
- Clinical Endpoint: Demonstrating clinically meaningful benefit
- Patient Selection: Identifying biomarker-defined responders
- Comparator: No head-to-head comparison with other anti-tau antibodies
¶ Competitive Landscape
¶ Anti-Tau Antibody Competition
Bepranemab competes in a crowded anti-tau antibody space:
| Drug |
Company |
Target |
Phase |
Differentiation |
| Bepranemab |
UCB |
aa 235-250 |
II |
Central region, no ARIA |
| Etalanetug |
Eisai |
MTBR |
III |
DIAN-TU, high dose |
| Gosuranemab |
Biogen |
N-terminus |
II |
Failed |
| Tilavonemab |
Lilly |
N-terminus |
II |
Failed |
| Semorinemab |
Roche |
N-terminus |
II |
Failed |
| PRX005 |
Prothena |
MTBR |
I |
BMS partnership |
Bepranemab's competitive advantages include:
- No ARIA Risk: Significant safety advantage over anti-amyloid and some anti-tau approaches
- Strong Biomarker Effect: 58% tau-PET reduction is among the best
- PSP Focus: Opportunity in tauopathy with no approved disease-modifying therapies
- Subgroup Signal: Early indication of benefit in specific populations
- Clinical Results: Primary endpoint not met in Phase II
- Late Development: Behind E2814 in AD development
- Limited Resources: UCB smaller than Eisai, Lilly, Biogen
¶ Pharmacogenomics and Patient Response
¶ ApoE4 Status and Treatment Response
Recent analyses have revealed important interactions between ApoE genotype and bepranemab response:
Non-ApoE4 Carriers (Benefit):
- Low baseline tau, non-ApoE4 carriers showed 33% slower decline on CDR-SB
- 50% slower decline on ADAS-Cog14
- Strongest treatment effect in this subgroup
ApoE4 Carriers (Potential Harm):
- High baseline tau, ApoE4 carriers showed worse outcomes than placebo
- This unexpected finding requires further investigation
- May inform future patient selection strategies
The biomarker-clinical disconnect observed in bepranemab trials highlights:
- Biomarker Validation: Strong tau-PET effects do not guarantee clinical benefit
- Disease Stage: Early intervention may be critical
- Genetic Factors: ApoE status influences treatment response
- Combination Needs: May need multi-target approaches
Future development may require:
- Tau PET Positivity: Required for enrollment (proven biomarker)
- Baseline Tau Burden: Low tau patients may benefit more
- Plasma p-tau208: Emerging biomarker for patient selection
- ApoE Genotyping: May inform risk-benefit calculation
Bepranemab's effects on CSF biomarkers provide insight into its mechanism:
| Biomarker |
Change with Treatment |
Clinical Relevance |
| p-tau181 |
Dose-dependent reduction |
Marker of tau pathology |
| p-tau208 |
Reduction observed |
PSP-specific epitope |
| Total tau |
Mild reduction |
Neuronal injury marker |
| MTBR-tau |
Variable |
Core of tangles |
Emerging plasma biomarkers may support patient selection:
- Plasma p-tau217: Correlates with tau PET, less invasive
- Plasma p-tau181: Widely validated, available clinically
- Plasma total tau: Marker of neuronal injury
Tau PET provides direct visualization of tau pathology:
- Method: [^18F]flortaucipir (AV-1451, Tauvid)
- Readout: Standardized uptake value ratio (SUVR)
- Finding: 58% reduction in tau accumulation vs placebo
- Interpretation: Strong target engagement, but clinical benefit lacking
Bepranemab uses IgG4 subclass, which has implications:
Advantages:
- Reduced Fc effector function minimizes inflammation
- Lower risk of infusion reactions
- Longer half-life than IgG1
Disadvantages:
- Weaker microglial activation
- Reduced antibody-dependent cellular cytotoxicity
- May explain limited clinical efficacy despite biomarker effect
| Property |
IgG4 (Bepranemab) |
IgG1 (E2814, PRX005) |
| Fc effector |
Weak |
Strong |
| Clearance |
Limited |
Efficient |
| Half-life |
21-28 days |
21-28 days |
| ARIA risk |
Minimal |
Minimal |
| Clinical effect |
Limited |
Promising |
PSP represents an attractive indication for bepranemab:
- Pure Tauopathy: PSP lacks amyloid pathology, simplifying interpretation
- Unmet Need: No disease-modifying therapies approved for PSP
- Tau-Dominant: 4R tau predominates, making tau-targeted therapy ideal
- Specific Epitope: pSer208 particularly abundant in PSP
The PSP program includes:
- Phase I: 25 patients, completed safely
- Open-Label Extension: 19 patients, completed July 2025
- Future Phase II/III: Registration-enabling trial planned
- Heterogeneity: Multiple PSP variants exist
- Endpoint Selection: PSP-specific composites needed
- Enrollment: Rare disease, limited patient population
UCB maintains a focus on neurology and immunology:
| Asset |
Indication |
Stage |
| Bepranemab |
AD, PSP |
Phase II |
| Rozanolixizumab |
MG, ITP |
Approved |
| Certolizumab |
RA, Crohn's |
Approved |
The Roche partnership:
- July 2020: Licensed to Roche/Genentech ($120M upfront)
- October 2024: Rights returned to UCB
- Current: UCB wholly owns bepranemab
The return of rights reflects:
- Strategic realignment in Roche neuroscience
- UCB commitment to continue development
- Opportunity for UCB to capture full value
¶ Research and Development Outlook
The bepranemab development program includes:
- Open-Label Extension (PSP): NCT04658233, completed July 2025
- Long-term Follow-up: Safety and biomarker monitoring
- Biomarker Studies: Plasma p-tau208 validation
If Phase III proceeds, anticipated studies include:
- Phase III AD Trial: Confirmatory trial in early AD
- Phase III PSP Trial: Registration-enabling trial in PSP
- Combination Studies: With anti-amyloid antibodies
UCB's long-term vision for bepranemab:
- AD: Disease-modifying therapy in early AD
- PSP: First approved therapy for PSP
- Combination: Part of multi-target treatment approach
- Precision Medicine: Biomarker-driven patient selection
For Neurologists:
When considering bepranemab for patients with PSP or CBS:
- Trial Enrollment: Contact UCB clinical operations for available sites
- Biomarker Assessment: Ensure tau PET positivity before treatment consideration
- Combination Therapy: Currently monotherapy; combination approaches under development
- Monitoring: Quarterly infusions with safety assessments; annual biomarker evaluation
For Patients and Caregivers:
- Bepranemab represents a disease-modifying approach for tauopathies
- Phase I safety data are encouraging, with no significant safety concerns
- Long-term extension will provide additional efficacy data
- Access currently limited to clinical trials; FDA approval pending
Health Economic Considerations:
- No current pricing information (investigational therapy)
- Potential to reduce long-term care costs if disease progression is slowed
- Cost-effectiveness analyses await Phase III results