Antigenics’s AG-707 vaccine has shown positive results in a Phase I study to treat herpes simplex virus-2 (HSV-2).

The vaccine triggered a cellular immune response, stimulating the CD4+ and CD8+ T-cell responses needed to treat genital herpes, a sexually transmitted infection.

In the four-arm Phase I trial, 35 HSV-2 seropositive patients were administered AG-707 with vaccine adjuvant QS-21, AG-707 alone, QS-21 alone, or placebo.

All patients who received AG-707 with QS-21 showed a statistically significant CD4+ T cell response to HSV-2 antigens and the majority (63%) demonstrated a CD8+ T cell response.

AG-707 is based on Antigenics’s heat shock protein platform technology. This study is the first to show that heat shock protein complexed to viral antigens induces an antigen-specific T-cell response in humans.

Antigenics said the investigational drug has the potential to manage outbreaks and disease transmission in patients with genital herpes.