Vical Inc. is quitting development of VCL-HB01, its Vaxfectin-formulated plasmid DNA vaccine against herpes simplex virus type 2 (HSV-2), after the candidate missed what company President and CEO Vijay Samant called a "very rigorous" primary endpoint of annualized recurrence rate in a phase II trial. Company shares (NASDAQ:VICL) fell about 26.4 percent to $1.20 by Monday's market close, marking the second big drop this year after a phase III cytomegalovirus vaccine the company had partnered with Astellas Pharma Inc. missed its endpoints in January.