Tocagen Stock Tanks After Gene Therapy Drug for Brain Cancer Fails

Tocagen?s experimental gene therapy for brain cancer therapy has failed a late-stage test, sinking the biotech?s stock price below $1. San Diego?s Tocagen (NASDAQ: TOCA), has been testing its drug in recurrent high-grade glioma, the most common and deadly type of brain cancer in adults. The company said Thursday that the drug combination, Toca 511 [?]