Blood-brain barrier (BBB) modulation and transport technologies represent a critical frontier in Alzheimer's disease therapeutics. The BBB — while essential for protecting the brain from pathogens and toxins — blocks approximately 98% of small molecule drugs and nearly all large molecule therapeutics, severely limiting treatment options for CNS disorders. This category page catalogs companies developing technologies to overcome this fundamental challenge.
The key approaches include:
Denali Therapeutics has developed a proprietary Transport Vehicle (TV) platform that enables delivery of large therapeutic molecules across the BBB via receptor-mediated transcytosis[@denali_tv]:
| Attribute | Details |
|-----------|---------|
| Focus | LRP1-based brain delivery platform |
| Platform | Transport Vehicle (TV) technology |
| Mechanism | LRP1-mediated transcytosis across BBB |
| Stage | Multiple clinical programs |
Blood-brain barrier (BBB) modulation and transport technologies represent a critical frontier in Alzheimer's disease therapeutics. The BBB — while essential for protecting the brain from pathogens and toxins — blocks approximately 98% of small molecule drugs and nearly all large molecule therapeutics, severely limiting treatment options for CNS disorders. This category page catalogs companies developing technologies to overcome this fundamental challenge.
The key approaches include:
Denali Therapeutics has developed a proprietary Transport Vehicle (TV) platform that enables delivery of large therapeutic molecules across the BBB via receptor-mediated transcytosis[@denali_tv]:
| Attribute | Details |
|-----------|---------|
| Focus | LRP1-based brain delivery platform |
| Platform | Transport Vehicle (TV) technology |
| Mechanism | LRP1-mediated transcytosis across BBB |
| Stage | Multiple clinical programs |
Scientific Rationale: The Transport Vehicle platform exploits the LRP1 (Low-Density Lipoprotein Receptor-related Protein 1) pathway, which is naturally expressed on brain endothelial cells and mediates uptake of various ligands. By engineering therapeutics to engage LRP1, Denali achieves 10-30x higher brain exposure compared to conventional delivery methods.
Clinical Applications:
Alnylam is pioneering RNA interference (RNAi) therapeutics with a focus on brain delivery through transferrin receptor (TfR)-targeting[@alnylam_tfr]:
| Attribute | Details |
|-----------|---------|
| Focus | siRNA delivery to brain via TfR |
| Platform | GALNAc-conjugated siRNA with TfR targeting + TRiM™ |
| Indication | CNS diseases including AD |
| Stage | Phase 1 (ALN-APP) |
Innovation: Alnylam's TfR-targeted approach enables siRNA delivery across the BBB. The company's TRiM™ (Targeted RNAi Molecule) platform was developed specifically for tissue-specific delivery including the CNS[@alnylam_tfr].
Key Programs:
The following companies are developing additional BBB modulation approaches:
Angiex is developing therapies targeting Notch1 and VEGF signaling to normalize BBB function:
| Attribute | Details |
|-----------|---------|
| Focus | BBB normalization through VEGF/Notch modulation |
| Approach | Restore barrier integrity |
| Stage | Preclinical |
Rationale: VEGF (Vascular Endothelial Growth Factor) plays a critical role in maintaining BBB integrity. Dysregulation of VEGF signaling contributes to barrier breakdown in Alzheimer's disease. Angiex's approach aims to normalize signaling rather than bypass the barrier.
Phranch is developing engineered BBB shuttle proteins:
| Attribute | Details |
|-----------|---------|
| Focus | Engineered protein scaffolds for BBB crossing |
| Mechanism | Receptor-mediated transcytosis |
| Stage | Discovery |
Excivia is developing next-generation transport technologies:
| Attribute | Details |
|-----------|---------|
| Focus | Novel BBB-crossing platforms |
| Approach | Multiple mechanisms |
| Stage | Discovery |
RMT exploits natural transport pathways used by essential molecules[@pardone2018]:
| Target Receptor | Natural Ligand | Therapeutic Application |
|---------------|----------------|------------------------|
| Transferrin receptor (TfR) | Transferrin | Antibodies, siRNAs |
| LDL receptor (LDLR) | Apolipoproteins | Lipidated therapeutics |
| LRP1 | ApoE, clusterin | Large proteins, enzymes |
| Insulin receptor | Insulin | Peptide therapeutics |
Companies Active in RMT: Denali, Alnylam, Roche, Lundbeck, AbbVie
Adsorptive transcytosis uses cationized molecules to bind negatively charged membrane lipids:
| Approach | Description | Companies |
|----------|------------|-----------|
| Cationized proteins | Positively charged protein domains | Research |
| Cell-penetrating peptides | CPPs for intracellular delivery | Research |
| Poly-arginine conjugates | Arginine-rich sequences | Research |
The ABC transporter family (P-glycoprotein, BCRP, MRPs) limits drug penetration into the brain[@abbott2022]:
| Target | Function | Inhibition Strategy |
|--------|----------|--------------------|
| P-glycoprotein (ABCB1) | Major efflux pump | Verapamil, tariquidar |
| BCRP (ABCG2) | Breast cancer resistance protein | Ko143 |
| MRP1-5 (ABCC1-5) | Multidrug resistance | Various inhibitors |
Clinical Challenge: Systemic efflux pump inhibitors have dose-limiting toxicity. Current approaches focus on localized delivery or substrate engineering.
Rather than bypassing the barrier, BBB normalization aims to restore integrity:
| Target | Approach | Companies |
|--------|----------|---------|
| Tight junction proteins | Claudin-5, occludin stabilization | Angiex, research |
| Pericyte function | PDGF-BB agonists | Research |
| VEGF signaling | Normalization | Angiex |
| Astrocyte endfeet | AQP4 polarization | Research |
Nanoparticle delivery systems offer multiple advantages[@joshi2020]:
| Nanocarrier Type | Advantages | Applications |
|-----------------|------------|--------------|
| Liposomes | Flexible surface modification | Protein delivery |
| Polymeric nanoparticles | Controlled release | Small molecules |
| Dendrimers | Multiple functional groups | siRNA delivery |
| Solid lipid nanoparticles | Biocompatible | Peptides |
| Exosomes | Endogenous origin | Multiple |
Companies: NanoCarrier, Medesis, research programs
Trojan horse approaches use endogenous peptides as delivery vehicles:
| Trojan Horse | Target | Cargo | Companies |
|-------------|--------|-------|----------|
| Angiopep-2 | LRP1 | Chemotherapeutics | Angiex |
| Apamin | Unknown | Peptides | Research |
| Tat peptide | Cell entry | Various | Research |
| Syn-B polymer | LRP1 | Proteins | Research |
| Company | Technology | Therapeutic | Phase | Indication |
|---------|------------|-------------|-------|------------|
| Denali | TV platform | DNL310 | Phase 2/3 | Hunter syndrome |
| Alnylam | TRiM™ + TfR | ALN-APP | Phase 1 | Alzheimer's disease |
| Roche | Brain Shuttle | RG6182 | Phase 1 | Parkinson's disease |
| Lundbeck | Bispecific | - | Discovery | CNS diseases |
| AbbVie | BRAIN platform | - | Discovery | AD/PD |