Development of a therapeutic anti-HtrA1 antibody and the identification of DKK3 as a pharmacodynamic biomarker in geographic atrophy

Proc Natl Acad Sci U S A. 2020 May 5;117(18):9952-9963. doi: 10.1073/pnas.1917608117. Epub 2020 Apr 28.


Genetic polymorphisms in the region of the trimeric serine hydrolase high-temperature requirement 1 (HTRA1) are associated with increased risk of age-related macular degeneration (AMD) and disease progression, but the precise biological function of HtrA1 in the eye and its contribution to disease etiologies remain undefined. In this study, we have developed an HtrA1-blocking Fab fragment to test the therapeutic hypothesis that HtrA1 protease activity is involved in the progression of AMD. Next, we generated an activity-based small-molecule probe (ABP) to track target engagement in vivo. In addition, we used N-terminomic proteomic profiling in preclinical models to elucidate the in vivo repertoire of HtrA1-specific substrates, and identified substrates that can serve as robust pharmacodynamic biomarkers of HtrA1 activity. One of these HtrA1 substrates, Dickkopf-related protein 3 (DKK3), was successfully used as a biomarker to demonstrate the inhibition of HtrA1 activity in patients with AMD who were treated with the HtrA1-blocking Fab fragment. This pharmacodynamic biomarker provides important information on HtrA1 activity and pharmacological inhibition within the ocular compartment.

Keywords: age-related macular degeneration (AMD); biomarker; proteomics.

MeSH terms

  • Adaptor Proteins, Signal Transducing / genetics*
  • Adaptor Proteins, Signal Transducing / isolation & purification
  • Aged
  • Animals
  • Antibodies, Anti-Idiotypic / genetics
  • Antibodies, Anti-Idiotypic / immunology
  • Antibodies, Anti-Idiotypic / pharmacology*
  • Biomarkers / blood
  • Disease Progression
  • Female
  • Genetic Predisposition to Disease
  • Genotype
  • Geographic Atrophy / blood
  • Geographic Atrophy / drug therapy*
  • Geographic Atrophy / genetics
  • Geographic Atrophy / immunology
  • High-Temperature Requirement A Serine Peptidase 1 / antagonists & inhibitors
  • High-Temperature Requirement A Serine Peptidase 1 / genetics*
  • Humans
  • Immunoglobulin Fab Fragments / immunology
  • Immunoglobulin Fab Fragments / pharmacology
  • Macular Degeneration / blood
  • Macular Degeneration / drug therapy*
  • Macular Degeneration / genetics
  • Macular Degeneration / immunology
  • Male
  • Polymorphism, Single Nucleotide / genetics
  • Proteome / genetics
  • Proteome / immunology
  • Rats
  • Retina / drug effects
  • Retina / immunology
  • Retina / pathology
  • Small Molecule Libraries / pharmacology


  • Adaptor Proteins, Signal Transducing
  • Antibodies, Anti-Idiotypic
  • Biomarkers
  • DKK3 protein, human
  • Immunoglobulin Fab Fragments
  • Proteome
  • Small Molecule Libraries
  • High-Temperature Requirement A Serine Peptidase 1
  • HtrA1 protein, human