A novel full-length recombinant human complement factor H (CFH; GEM103) for the treatment of age-related macular degeneration shows similar in vitro functional activity to native CFH

Robyn M Biggs, Elisavet Makou, Scott Lauder, Andrew P Herbert, Paul N Barlow, Suresh K Katti

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose/Aim: GEM103 is a recombinantly produced full-length version of the human complement factor H (CFH) under clinical investigation for treatment of age-related macular degeneration (AMD) in individuals carrying an AMD risk-associated genetic variant of CFH. This study aimed to investigate the complement pathway-related functions of GEM103 in comparison with those of native human CFH.

MATERIALS AND METHODS Key biological activities of GEM103 and human serum-derived CFH (sdCFH) were compared using four independent functional assays. Assays of C3b binding and C3 convertase decay-accelerating activity (DAA) were performed by surface plasmon resonance (SPR). Cofactor activity (CA) was measured using 8-anilinonaphthalene-1-sulfonic acid as a fluorescent probe of C3b integrity. The abilities of GEM103 and sdCFH to protect sheep erythrocytes from hemolysis by CFH-depleted normal human serum were assessed colorimetrically.

RESULTS In multiple SPR-based assays of C3b binding and DAA, the performance of GEM103 was consistently comparable to that of sdCFH across a range of matching concentrations. The EC50 ± SD in the fluorescence-based fluid-phase CA assay was 0.21 ± 0.06 µM for GEM103 compared to 0.20 ± 0.09 µM for sdCFH. In hemolysis assays, the EC50 value of 0.33 ± 0.16 µM for GEM103 versus 0.46 ± 0.06 µM for sdCFH were not significantly different (P = 0.81).

CONCLUSIONS GEM103, a recombinant CFH developed by Gemini Therapeutics, shows activity profiles comparable to sdCFH in all complement-related assays employed in this study, suggesting that GEM103 is equivalent to the native glycoprotein in terms of its in vitro functional activity. These results support further study of GEM103 as a potential therapy for AMD.
Original languageEnglish
Pages (from-to)1-8
Number of pages9
JournalCurrent Eye Research
Early online date3 Apr 2022
DOIs
Publication statusE-pub ahead of print - 3 Apr 2022

Keywords

  • age related macular degeneration
  • complement factor H
  • recombinant protein therapy
  • GEM103
  • alternative pathway

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