Senator Edward Kennedy was diagnosed with brain cancer in 2008 and died 15 months later, close to the median survival time for the disease. Now, researchers at two California-based biotechnology companies, ImmunoCellular Therapeutics Ltd. and Tocagen Inc., along with the MD Anderson Cancer Center in Houston, are leading an effort to create drugs and treatments to fight the form of cancer that killed Kennedy, known as glioblastoma multiforme.