AGN-211745

To assess the safety, tolerability, pharmacokinetics, and dose-limiting toxicity of single intravitreal injection of Sirna-027, a small interfering RNA targeting vascular endothelial growth factor receptor-1, in patients with choroidal neovascularization (CNV) resulting from neovascular age-related macular degeneration (AMD). Secondary objectives included assessment of anatomic changes in retinal thickness, size of CNV, and changes in visual acuity.

Prospective, open-label, single-dose, dose-escalation phase 1 study.

Twenty-six eyes of 26 patients with a median age of 82 years and CNV resulting from AMD who had previous treatments with other therapies were treated at 2 academic retinal practices. Patients received a single dose of Sirna-027 (100, 200, 400, 800, 1200, or 1600 microg/eye). Blood was sampled for pharmacokinetic analysis at 1, 4, and 24 hours after injection and on day 7. Patients underwent ophthalmic examinations including visual acuity, fluorescein angiography, and optical coherence tomography at screening and days 7, 14, 28, and 84. The main outcome measures were adverse reactions and dose-limiting toxicities.

Intravitreal injection of a single dose of Sirna-027 from 100 to 1600 microg was well tolerated in patients with AMD, with no dose-limiting toxicity found. Adverse events were mild to moderate in severity. Adjusted mean foveal thickness decreased within 2 weeks after study treatment. The decrease was most pronounced in the 100- and 200-microg doses.

A single intravitreal dose of Sirna-027 up to 1600 microg/eye was well tolerated in patients with CNV resulting from neovascular AMD that had been refractory to other therapies. Stabilization or improvement in visual acuity and foveal thickness was observed. No dose-response or dose-limiting effects were noted.

Angiogenesis, the process by which new vessels are created from pre-existing vasculature, has become the subject of intense research in recent years. Increased rates of angiogenesis are associated with several disease states, including cancer, age-related macular degeneration (AMD), psoriasis, rheumatoid arthritis, and diabetic retinopathy. Vascular endothelial growth factor (VEGF) is an important modulator of angiogenesis, and has been implicated in the pathology of a number of conditions, including AMD, diabetic retinopathy, and cancer. AMD is a progressive disease of the macula and the third major cause of blindness worldwide. If not treated appropriately, AMD can progress to involve both eyes. Until recently, the treatment options for AMD have been limited, with photodynamic therapy (PDT) the mainstay of treatment. Although PDT is effective at slowing disease progression, it rarely results in improved vision. Several therapies have been or are now being developed for neovascular AMD, with the goal of inhibiting VEGF. These VEGF inhibitors include the RNA aptamer pegaptanib, partial and full-length antibodies ranibizumab and bevacizumab, the VEGF receptor decoy aflibercept, small interfering RNA-based therapies bevasiranib and AGN 211745, sirolimus, and tyrosine kinase inhibitors, including vatalanib, pazopanib, TG 100801, TG 101095, AG 013958, and AL 39324. At present, established therapies have met with great success in reducing the vision loss associated with neovascular AMD, whereas those still under investigation offer the potential for further advances. In AMD patients, these therapies slow the rate of vision loss and in some cases increase visual acuity. Although VEGF-inhibitor therapies are a milestone in the treatment of these disease states, several concerns need to be addressed before their impact can be fully realized.