Abstract
Purpose :
Inflammation has an important role in retinal diseases such as diabetic eye disease and age-related macular degeneration. Currently approved treatments that target only VEGF do not completely address the underlying immune component of these diseases. Elevated intraocular levels of Interleukin-6 (IL-6) have been implicated in diabetic eye disease and are also linked to anti-VEGF treatment resistance in AMD. Similarly, both IL-6 and VEGF are implicated in vision loss in patients with uveitic macular edema. We designed a novel anti-IL-6 anti-VEGF bispecific protein, OG2072, and its biopolymer conjugate, KSI-501, as a next-generation therapeutic candidate for these diseases.
Methods :
OG2072 was engineered as a trap antibody fusion protein to bind and inhibit both IL-6 and VEGF with the capability of being conjugated to a high molecular weight phosphorylcholine-based biopolymer to optimize potency, stability, ocular durability and tissue bioavailability. Binding affinity to IL-6 and VEGF-A were determined by surface plasmon resonance (SPR) or Kinetic Exclusion Assay (KinExA). These molecules were also tested for their ability to (1) competitively block IL-6 and VEGF from binding to their respective receptors and (2) to inhibit VEGF and inflammatory activities.
Results :
OG2072/KSI-501 are novel trap antibody fusion molecules that bind with picomolar affinity to both VEGF-A and IL-6 at 37 degrees. Binding of each target occurs independently of the other, indicating that IL-6 and VEGF-A interact with OG2072/KSI-501 simultaneously. Functional assays indicate that OG2072 effectively inhibits VEGF-A and IL-6 interactions with their respective receptors. Furthermore, cell-based assays showed that the dual inhibitor effectively inhibited LPS mediated endothelial cell tubule formation and VEGF-A/IL-6 co-stimulated endothelial cell proliferation significantly better than either mono-therapy targeting IL-6 or VEGF alone.
Conclusions :
We have engineered a novel and highly potent bispecific molecule targeting VEGF and IL-6 using a trap antibody fusion approach; it demonstrated high binding affinity, bioactivity and synergistic inhibition in vitro. KSI-501 is being developed as a promising and differentiated new therapeutic candidate to address retinal vascular and inflammatory diseases.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.