Interferon alfa-2a is ineffective for patients with choroidal neovascularization secondary to age-related macular degeneration. Results of a prospective randomized placebo-controlled clinical trial. Pharmacological Therapy for Macular Degeneration Study Group.
Interferon alfa-2a has been shown to be effective as an antiangiogenic agent for several systemic human angiogenic disorders and has shown antiangiogenic activity in the laboratory.
                To evaluate the safety and efficacy of interferon alfa-2a for the treatment of choroidal neovascularization secondary to age-related macular degeneration.
                A randomized, placebo-controlled, parallel, multicenter double-blind trial was performed at 45 ophthalmic centers worldwide. Four hundred eighty-one patients were randomly assigned to 4 treatment groups: placebo or interferon alfa-2a (Roferon-A), 1.5, 3.0, or 6.0 million international units (MIU). Visual acuity testing, clinical examination, fluorescein angiography, and indocyanine green angiography were evaluated, with the primary end point being a comparison of the number of patients who experienced a loss of 3 lines or more of vision at 1 year.
                At 52 weeks, 40 (38%; 95% confidence interval, 29%-48%) of 105 placebo-treated patients had lost at least 3 lines of vision (with 12% unavailable for follow-up), compared with 142 (50%; 95% confidence interval, 44%-55%) of 286 in the 3 active treatment groups combined. The difference in proportions was not statistically significant. However, a pairwise comparison of these proportions for the placebo group vs the group that received interferon alfa-2a, 6 MIU (with 26% unavailable for follow-up), showed a statistically significant difference in favor of the placebo group (P = .02) and a nearly significant difference for the placebo vs the 1.5-MIU group (P = .05) (with 16% unavailable for follow-up), again favoring the placebo group. The 3-MIU group (with 22% unavailable for follow-up) did not show a statistically significant difference in pairwise comparison (P = .48), suggesting that a dose-response relationship was not evident.
                Interferon alfa-2a provides no benefit as a treatment for choroidal neovascularization secondary to age-related macular degeneration and may be associated with a poorer visual outcome when given at a dose of 6 MIU. However, the absence of a clear dose-response relationship raises the possibility that the observed differences result from chance.
At present there is not enough evidence to recommend the use of interferon alfa-2a for the treatment of age-related macular degeneration.