A Phase 1, Open-Label, Dose-Escalation Trial to Investigate Safety and Tolerability of Single Intravitreous Injections of ICON-1 Targeting Tissue Factor in Wet AMD

BACKGROUND AND OBJECTIVE

This phase 1 study evaluated the safety and tolerability of single intravitreous injections (IVIs) of ICON-1 (Iconic Therapeutics, South San Francisco, CA) in patients with neovascular age-related macular degeneration (nAMD). ICON-1 is a modified factor VIIa protein linked with the Fc portion of a human immunoglobulin G1. The molecule binds tissue factor overexpressed on choroidal neovascularization (CNV) in AMD.

PATIENTS AND METHODS

Open-label, interventional, dose-escalation trial in 18 patients with CNV due to AMD, with six patients per dose cohort. Patients received a single IVI of ICON-1 at baseline in one of three escalating doses: 60 μg, 150 μg, or 300 μg. Standard anti-vascular endothelial growth factor treatment was allowed at the investigator's discretion at least 2 weeks after the ICON-1 injection; patients were followed up to 24 weeks. Dose escalation was based on the absence of significant safety events. At each study visit, best-corrected visual acuity (BCVA), ophthalmic examination (intraocular pressure, slit-lamp, and dilated fundus examination), and ophthalmic imaging (color fundus photography, fluorescein angiography, and optical coherence tomography) assessments were performed. The systemic pharmacokinetics of ICON-1 and presence of anti-ICON-1 antibodies were also assessed.

RESULTS

ICON-1 was safe and well-tolerated up to the highest dose administered, which was 300 μg. Commonly reported adverse events were considered related to the IVI procedure or to the underlying nAMD. No significant systemic levels of ICON-1 or anti-ICON-1 antibodies were detected. Preliminary evidence of biological activity (improved BCVA, reduced central retinal thickness, decreased CNV size, and leakage) was most evident with the 300 μg dose at 1 to 2 weeks after the single ICON-1 injection.

CONCLUSION

Intravitreous administration of ICON-1 in single doses up to 300 μg in eyes with neovascular AMD was safe and well-tolerated. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:336-345.].

Evidence for enhanced tissue factor expression in age-related macular degeneration

Tissue factor (TF) is the primary initiator of blood coagulation. In addition to hemostasis, TF can initiate intracellular signaling and promote inflammation and angiogenesis, the key processes underlying the pathogenesis of age-related macular degeneration (AMD). AMD, the leading cause of irreversible blindness among the elderly, involves many genetic and environmental risk factors, including oxidative stress and inflammation. In this study, TF expression was examined in human AMD tissue and in the eyes of a model of AMD, the Ccl2(-/-)/Cx3cr1(-/-) (DKO) mouse, as well as in the ARPE-19 cell line after lipopolysaccharide (LPS) and H(2)O(2) stimulation. Total RNA was extracted from tissue samples and further analyzed by real-time RT-PCR. Immunohistochemistry was performed to evaluate TF protein expression. In the human retina, a 32-fold increase of TF mRNA expression was detected in AMD macular lesions compared with normal maculae. TF protein expression was also enhanced in human AMD maculae. Similarly, TF transcript and protein expression were moderately increased in retinal lesions, neuroretinal tissue, and cultured RPE cells of DKO mice compared with age-matched wild-type mice. TF expression level correlated with age in both wild-type and DKO mice. In order to better understand how AMD might lead to enhanced TF expression, 1, 5, and 10 μg/ml LPS as well as 100 and 200 μM H(2)O(2) were used to stimulate ARPE-19 cells for 24 and 2 h, respectively. LPS treatment consistently increased TF transcript and protein expression. H(2)O(2) alone or in combination with LPS also moderately enhanced TF expression. These results indicate that upregulated TF expression may be associated with AMD, and inflammatory and oxidative stress may contribute to TF expression in AMD eyes.