rAAV.sFlt-1 has the potential to provide long-term treatment of retinal neovascular diseases following a single injection by driving expression of sFlt-1, a potent (Kd 10 pM), naturally-occurring VEGF inhibitor. Here we present the baseline data for subjects with exudative age-related macular degeneration (AMD) enrolled in an investigator-sponsored, single center, Phase 2a safety study of rAAV.sFlt-1 gene therapy. Of the 32 randomized subjects, 21 were randomized to the rAAV.sFlt-1 group and 11 to the ranibizumab control group. All subjects were treated with two initial intravitreal injections of ranibizumab and then followed monthly for the need for rescue ranibizumab injections based on pre-specified criteria for evidence of active exudative AMD. Subjects underwent a thorough ophthalmic examination at baseline, and clinical laboratory assessments included blood biochemistry, complete blood count, and T-cell response. Anti-AAV antibodies (both total and neutralizing), AAV capsid protein, and sFlt-1 protein levels were also measured. Baseline demographics were 100% Caucasian, 59% female, and average age 79+7 years. All subjects had active subfoveal choroidal neovascularization secondary to exudative AMD, and the average visual acuity was 59+15 EDTRS letters (Snellen equivalent 20/63). Subjects had received an average of 10 anti-VEGF injections prior to enrolment. Anti-AAV antibody results indicated that 25% of subjects serum contained neutralizing antibody titres 1/100-1/500 while 19% had titres 1/20-1/100. All subjects tested negative for presence of AAV capsid in fluids at baseline. sFlt-1 protein averaged 13.9+5.4 pg/ml in urine, 116+5.9 pg/ml in serum, and 229+12.7 pg/ml in saliva. One patient had IgM deficiency and 6/32 patients had lymphopenia or T cell deficiency and/or CD8 lymphopenia. No other immune defects that might pose a hazard to the use of the rAAV vector were identified. In conclusion, the study subjects had characteristics representative of a population with exudative AMD and are appropriate for enrollment in a safety study for rAAV.sFlt-1.