Modex's EBV Vaccine Enters Late-Stage Trials With Promising Results

Gary Nabel's Modex Therapeutics is developing a vaccine against Epstein-Barr virus (EBV), which causes mononucleosis and is linked to roughly 200,000 annual cancer cases. The bivalent vaccine targets EBV through both B cells and epithelial cells.

Nabel, the former NIH Vaccine Research Center director, claims that the prior GSK vaccine trial failed because it only blocked one entry point of the virus, leaving the other open. His new candidate strips down the GP350 protein to its active binding domain and adds the GH/GL/GP42 trimer to block epithelial cell entry.

In animal models, the bivalent vaccine induced high-titer neutralizing antibodies that prevented EBV from entering both B cells and epithelial cells, resulting in sterilizing immunity. Modex is currently enrolling patients for a Phase 1 trial with nearly 200 participants, positioning the company for a Phase 2 decision soon.

The Merck partnership followed a logic of complementarity, where Modex carries the program through Phase 1 and Merck takes over clinical development thereafter. This collaboration brings together expertise in vaccine manufacturing, adjuvant formulation, and regulatory muscle.