Complement Depletion with Humanized Cobra Venom Factor in a Mouse Model of Age-Related Macular Degeneration

Abstract

The effect of complement depletion with humanized cobra venom factor (CVF) on retinal lesion development/neovascularization was determined in a mouse model of wet age-related macular degeneration (AMD). Mice were treated with the humanized CVF protein HC3-1496 prior to, and once daily for 28 days after laser coagulation surgery of the retina. CVF transgenic mice exhibiting permanently low levels of serum complement activity and PBS-treated mice served as positive and negative controls, respectively. Fluorescein isothiocyanate (FITC)-dextran funduscopy after laser surgery indicated the presence of lesions in all mice that underwent laser surgery. In HC3-1496-treated mice as well as CVF transgenic mice smaller lesions were seen after 8 days. Measurement of lesion sizes by histopathological examination of eyes after 28 days revealed a significant reduction of lesion area and volume in both HC3-1496-treated animals and CVF transgenic animals compared to PBS-treated control animals. Systemic complement depletion with a complement depletor, such as the humanized CVF protein HC3-1496, represents a promising therapeutic concept for patients with wet AMD.

Humanized cobra venom factor: Structure, activity, and therapeutic efficacy in preclinical disease models

“…injection of FITC-dextran on days 0 and 8 as well as histopathological examination of retinal lesions in formalin-fixed eyes on day 28. Similar results were obtained in CVF transgenic mice which constitutively express CVF and exhibit low serum C3 levels and low complement activity (Andrä et al, 2002;Fritzinger et al, 2010a). Supplementary Fig.…”

“…depletion, although depletion with CVF is more or less limited to no more than two to three weeks because of its immunogenicity (see Section 4.3, below); and hCVF has so far only been used for depletion of up to one month. Significantly, CVF transgenic mice, constitutively expressing CVF and living with low C3 levels and low serum complement activity exhibit a normal life span and no abnormal phenotype (Andrä et al, 2002;Fritzinger et al, 2010a). No tendency to develop infections was observed although the CVF transgenic mice were kept under normal animal housing condition.…”

“…Complement-depletion was accomplished by daily i.p. injection of HC3-1496 at a rather low dose (25 g/kg) prior to and daily after laser surgery for 28 days (Fritzinger et al, 2010a). Supplementary Fig.…”

Complement in Immune and Inflammatory Disorders: Therapeutic Interventions

“…Though not a classical “inhibitor”, the C3 homolog cobra venom factor (CVF) also targets C3 by forming long-lasting C3 convertases that rapidly deplete C3 stores (32). Therapeutic C3 depletion by CVF and its humanized form (HC3-1496, InCode) has shown efficacy in disease models including AMD (33) and transplantation (34). Of note, HC3-1497 does not act as a C5 convertase (in contrast to some forms of native CVF), thereby alleviating toxicity concerns due to direct generation of massive C5a levels (32).…”

Progress and Trends in Complement Therapeutics

“…Cobra venom factor (CVF) is the most prominent example of the first category; this snake protein isolated from certain cobra species shares high structural and sequence similarity with C3 and is able to form highly stable convertase complexes that rapidly activate and consume C3 and C5 in circulation (Vogel and Fritzinger 2010). CVF and a recombinant humanized form created by replacing small stretches of the C3 sequence with the stabilizing parts of CVF (HC3-1496, InCode BioPharmaceutics) have been evaluated in various disease models including myocardial I/R injury, CNV, arthritis, PNH, or transplant accommodation (Vogel and Fritzinger 2010; Fritzinger et al 2010; Chen Song et al 2011). …”