Based on early evidence of efficacy in an initial cohort of 25 patients refractory to Avastin (bevacizumab, Roche AG unit Genentech Inc.), Celldex Therapeutics Inc. added an expansion cohort of approximately 75 patients to its Phase II ReACT study of rindopepimut in EGFRvIII (v3)-positive glioblastoma (GBM), seeking a better bead on the compound's potential activity in a refractory patient population.