Toyo Biotechnology
Headquarters: Tokyo, Japan
Founded: 2022 (University of Tokyo spin-out)
Focus: Targeted protein degradation for neurodegenerative disease proteins
Website: https://www.toyo-biotech.com
Overview
flowchart TD
institutions_toyo_biotechnolog["Toyo Biotechnology"]
institutions_toyo_biotechnolog["Headquarters"]
institutions_toyo_biotechnolog -->|"related to"| institutions_toyo_biotechnolog
style institutions_toyo_biotechnolog fill:#81c784,stroke:#333,color:#000
institutions_toyo_biotechnolog["Tokyo"]
institutions_toyo_biotechnolog -->|"related to"| institutions_toyo_biotechnolog
style institutions_toyo_biotechnolog fill:#81c784,stroke:#333,color:#000
institutions_toyo_biotechnolog["Japan"]
institutions_toyo_biotechnolog -->|"related to"| institutions_toyo_biotechnolog
style institutions_toyo_biotechnolog fill:#81c784,stroke:#333,color:#000
institutions_toyo_biotechnolog["Founded"]
institutions_toyo_biotechnolog -->|"related to"| institutions_toyo_biotechnolog
style institutions_toyo_biotechnolog fill:#81c784,stroke:#333,color:#000
style institutions_toyo_biotechnolog fill:#4fc3f7,stroke:#333,color:#000
...Toyo Biotechnology
Headquarters: Tokyo, Japan
Founded: 2022 (University of Tokyo spin-out)
Focus: Targeted protein degradation for neurodegenerative disease proteins
Website: https://www.toyo-biotech.com
Overview
Mermaid diagram (expand to render)
Toyo Biotechnology is a University of Tokyo spin-out company developing targeted protein degradation (TPD) technologies for the treatment of Alzheimer's disease, Parkinson's disease, and related neurodegenerative conditions. The company leverages a novel TPD platform that combines small molecule degraders with brain-penetrant delivery systems, enabling the elimination of disease-driving proteins that are currently considered "undruggable" by conventional approaches["@toyobio2024"].
Targeted protein degradation represents a paradigm shift in drug discovery — instead of simply inhibiting a protein's function, TPD compounds recruit the cell's own protein disposal machinery (the ubiquitin-proteasome system) to selectively destroy the target protein. This approach is particularly valuable for neurodegenerative diseases because many of the key pathogenic proteins — including tau, alpha-synuclein, huntingtin, and TDP-43 — have been difficult to drug with traditional small molecule inhibitors due to their complex structures and lack of well-defined active sites["@protac_neuron"].
Scientific Foundation
Targeted Protein Degradation (TPD) Mechanisms
TPD technologies work by engaging two key mechanisms:
PROTACs (Proteolysis-Targeting Chimeras)
PROTACs are bifunctional molecules with two key domains: a ligand that binds to the target protein of interest (POI) and a ligand that recruits an E3 ubiquitin ligase. When a PROTAC simultaneously binds to both the target and the ligase, it brings them into proximity, leading to ubiquitination of the target protein and its subsequent degradation by the proteasome[@htt_degrader].
Key advantages of PROTACs:
- Substoichiometric activity (one PROTAC molecule can lead to degradation of many target molecules)
- Catalytic mode of action enables sustained target knockdown with low drug exposure
- Can target proteins previously considered "undruggable"
Molecular Glue Degraders
Molecular glue degraders are monovalent molecules that promote protein-protein interactions between the target protein and a substrate receptor (typically an E3 ligase complex)[@btb_domain]. Unlike PROTACs, molecular glues do not require high-affinity binding to the target — they work by stabilizing interactions that lead to target ubiquitination and degradation. Several molecular glue degraders have received regulatory approval for cancer, validating the therapeutic approach.
Challenges for CNS TPD
Despite the promise of TPD for neurodegeneration, significant challenges have limited progress:
Brain penetration: Most PROTAC molecules are large and polar, making blood-brain barrier (BBB) penetration difficult
E3 ligase expression: The brain has a distinct repertoire of E3 ligases compared to peripheral tissues; selecting the right ligase for CNS applications is critical
Target accessibility: Some disease proteins are localized in compartments (endosomes, lysosomes, mitochondria) that may be inaccessible to degrader molecules
Selectivity: Ensuring that only the disease-relevant protein is degraded, not related family membersToyo Biotechnology has developed proprietary chemistry to address the brain penetration challenge, creating a library of CNS-penetrant PROTAC and molecular glue scaffolds.
Pipeline
TB-301 (Lead Program)
Target: Tau protein (all isoforms including 3R and 4R tau)
Stage: Lead optimization
Indication: Alzheimer's disease, frontotemporal dementia, progressive supranuclear palsy
TB-301 recruits the CRBN E3 ligase to target tau for proteasomal degradation. The compound has demonstrated:
- Reduction of pathological tau in iPSC-derived neurons from frontotemporal dementia patients
- Dose-dependent decrease in tau across brain regions in transgenic mouse models
- Good brain penetration and favorable pharmacokinetics
- Selectivity for tau over related microtubule-associated proteins (MAP2, MAP4)
TB-302 (Secondary Program)
Target: Alpha-synuclein
Stage: Preclinical (hit-to-lead)
Indication: Parkinson's disease, Dementia with Lewy bodies
TB-302 targets alpha-synuclein using a brain-penetrant molecular glue approach. The compound has shown reduction of alpha-synuclein aggregates in cellular models of Parkinson's disease[@alpha_syn_degrad].
Toyo Biotechnology's platform consists of:
CNS PROTAC library — synthetic routes enabling rapid synthesis of brain-penetrant bifunctional molecules
Molecular glue discovery — screening for compounds that promote protein-protein interactions leading to degradation
Blood-brain barrier models — in vitro BBB models and in vivo pharmacokinetics for brain penetration optimization
Targeted degradation biomarkers — measurement of target protein degradation in the brain (qPET imaging, CSF biomarkers)Research Collaboration
Toyo Biotechnology collaborates with:
- University of Tokyo's Graduate School of Pharmaceutical Sciences
- RIKEN Center for Brain Science for in vivo validation
- AMED for regulatory engagement and clinical trial preparation[@toyobio2024]
Connection to NeuroWiki Topics
Toyo Biotechnology's work intersects with key mechanisms and topics in NeuroWiki:
- [Tau aggregation pathway in Alzheimer's disease](/mechanisms/amyloid-cascade-pathway)
- [Alpha-synuclein propagation and toxicity](/experiments/alpha-synuclein-propagation-model-validation)
- [Ubiquitin-proteasome system dysfunction in Parkinson's disease](/mechanisms/pd-ubiquitin-proteasome-system-therapeutic-companies)
- [Targeted protein degradation (PROTACs) therapeutic landscape](/therapeutics/targeted-protein-degradation-protacs)
- [Huntington's disease mechanism and therapeutics](/mechanisms/huntingtons-biomarkers-and-precision-therapy)