HSV 2 Formulation 4

HSV 2 Formulation 4 is an investigational therapeutic vaccine candidate developed by Sanofi Pasteur for the treatment of recurrent genital herpes caused by herpes simplex virus type 2 (HSV-2). It was one of several formulations evaluated in a Phase 1/2 clinical trial (NCT04222443) designed to assess safety and efficacy in reducing viral shedding and recurrence frequency. The trial investigated combinations of two primary vaccine components: HSV529, a replication-defective HSV-2 vaccine (strain 186 with deletions in the UL5 and UL29 genes), and G103, a subunit vaccine containing three recombinant HSV-2 proteins (truncated UL19 and gD2, and full-length UL25), with or without the GLA-SE adjuvant. Although the specific composition of Formulation 4 was not publicly detailed, the entire HSV-2 vaccine program was discontinued by Sanofi in April 2022 for business reasons, leading to the early termination of the clinical trial.