Visterra’s Monoclonal Antibody in Development for the Treatment of Influenza A, VIS410, Demonstrated Significant Antiviral Activity and Reduced Duration of Respiratory Symptoms in Phase 2a Challenge Study

Cambridge, MA – October 5, 2015 – Visterra, Inc., a clinical-stage biotechnology company that uses its proprietary technology platform to identify unique disease targets and design novel therapeutics for infectious diseases, today announced that VIS410, a novel monoclonal antibody in development for the treatment of seasonal and pandemic influenza A, demonstrated a statistically significant viral response in its Phase 2a influenza viral challenge study and achieved its primary endpoint of reduction in viral shedding. The primary endpoint was achieved after a pre-specified interim analysis and therefore Visterra has stopped the comparative portion of the study. Subjects treated with VIS410 experienced a 92% reduction in viral shedding and resolved upper respiratory symptoms two days earlier than subjects in the placebo group. Based on these results, Visterra intends to advance VIS410 into further clinical trials in patients with influenza A.