The stock market shaved $4.50 off Chiron Corp. stock last week following the announcement that a preliminary review of CHIR's Phase II/III trial of its immunotherapeutic vaccine for HSV-2 infection did not reach statistical significance on its primary end point. However, the negative results do not necessarily affect the odds of success in a far more important Phase III preventive vaccine study, which is ongoing.

While CHIR (Emeryville, Calif.) did not give details of the treatment trial, the vaccine is a formulation of two antigens, glycoprotein B and D (gB and gD), and the company's MF59 adjuvant