Purpose
Polymorphisms in the alternative pathway of the complement system correlate with risk of AMD. Cleavage of C5 generates C5a and the membrane attack complex (MAC), key mediators of the terminal complement pathway and complement activation. We designed LFG316 to test whether inhibition of C5 cleavage may prevent AMD or slow the rate of progression.
Methods
LFG316, a fully-human antibody, was generated using phage-display technology. Antibodies were identified using the HuCAL GOLD library by selections on human and cynomolgus C5 protein. The selection criteria of the final candidate antibody was based on assessments of potency in hemolytic assays, affinity, expression and biophysical behaviour.
Results
LFG316 is an IgG1 antibody with modifications to the Fc region to attenuate immune effector activity. LFG316 binds to the human and cynomolgus C5 with affinities of 12.1 pM and 74.1 pM, respectively. In an alternative pathway hemolytic assay the antibody has an IC50 of 23.9 nM in 10% human serum and an IC50 of 37.3 nM in 10% cynomolgus monkey serum. LFG316 blocks the generation of C5a during the hemolysis reaction with an IC50 of 25.4 nM. These results indicate that LFG316 binds to C5 and prevents cleavage by the C5 convertase to C5a and C5b. LFG316 also blocks C5 cleavage due to complement classical pathway activation with an IC50 of 20.1 nM in the presence of 10% human serum.
Conclusions
LFG316 is a fully-human, high affinity antibody that prevents the cleavage of C5 via the complement classical or alternative pathways. Inhibition of C5 with LFG316 is currently being tested as a therapy for the treatment of geographic atrophy.
Keywords: 412 age-related macular degeneration •
555 immunomodulation/immunoregulation