Novel Ways to Reduce Protein Aggregation

(Alan D. Snow, ProteoTech, Inc.)

Case study: Small molecule inhibitors of protein aggregation

  • Research started at the University of Washington; current spin-off company ProteoTech with exclusive world-wide license from the university
  • $33 million has been raised so far, of which 1/3 comes from non-dilutive NIH (NIA) grants and private foundation funding
  • Targeting all stages of amyloid diseases – goal to create “disease-modifying” agents capable of preventing and reversing amyloid deposits
  • Current pipeline:
    • Exebryl-1 (beta-amyloid and tau, AD) – phase I clinical trial
    • PeptiClere (beta-amyloid, AD) – late preclinical development
    • Synuclere (alpha-synuclein, PD) – late preclinical development
    • Systebryl (AA amyloid, systemic amyloidosis) – phase I clinical trial
    • Inhibitor of islet amyloid polypeptide deposits (type 2 diabetes) – preclinical development

The patent portfolio is a key factor for starting and maintaining a small company.

  • ProteoTech has 177 total patents (125 issued U.S. and international patents)
  • Very important to protect the technology from the beginning
  • Patent various aspects of the technology: composition of matter, new chemical entities, methods of use, screening platforms, etc.

Preclinical development starting from natural products

  • Screened plant-derived compounds (from the Uncaria tomentosa plant) and used assay-guided fractionation to identify compounds with potent anti-abeta activity
  • The best candidate compound was too large to be a drug so a synthetic analog program was devised to create a small molecule library from the identified pharmacophore template.
  • The small molecule analogs were tested in vitro and in vivo; several were found to have specificity as inhibitors of different types of amyloid proteins.

Alzheimer’s disease: Exebryl-1 binds to abeta, prevents aggregation, disrupts existing aggregates and leads to abeta degradation by microglia.

  • Small molecule that adheres to Lipinski’s Rule of Five
  • Proposed mechanism of action: small planar structure acts as a wedge that disrupts aggregated abeta fibrils, leading to fragments that are cleared out of the brain by microglia
  • Aged hAPP transgenic mice were used to demonstrate efficacy in decreasing plaque number and reducing soluble and insoluble abeta levels (with a 90 day treatment). Spatial learning and memory were also improved.

Other small molecule drugs targeting amyloid diseases:

  • Systemic amyloidosis: Systebryl reduces AA amyloid deposits in the kidney, liver and spleen of mouse models.
  • Parkinson’s disease: Synuclere inhibits alpha-synuclein aggregation and reduces in-vivo deposits. Motor function is also improved
    • Funded by the Michael J. Fox Foundation (LEAPS program)
    • Synuclere is specific for alpha-synuclein and has little effect on abeta aggregation.
    • Low BBB penetration (~3-5%) – an active metabolite may be the active agent

Small molecule program consists of:

  • Cyclical process of in vitro screening (aggregation assays), cell culture screening, “druggability” screening and synthetic analogs re-design.
    • Ruled out “red flag” compounds (e.g. CYP inhibition, plasma protein binding)
    • Also screened for binding to other molecules which may cause undesirable side effects – receptors, transporters, channels in the brain (e.g. dopamine and norepinephrine transporters were found to bind some of the tested compounds)
    • Both negative and positive results can be informative in the refinement process.
  • Top 10 lead compounds go on to in vivo screening in mouse models.

Formulation is an important aspect to consider in preclinical development

  • Synuclere had a significantly better PK profile when administered subcutaneously versus intraperitoneal injection.
    • Currently working on subcutaneous dosing via Hydrogel formulation for early clinical studies
    • Also working on second generation drug with better bioavailability

For early stage companies with limited funds, offering stock for services from contract research organizations may be beneficial.

Academic Models of Drug Discovery: Services and Utilizing CROs >