EMD Serono, the biopharmaceutical division of Merck KGaA, and Opexa Therapeutics, have amended their agreement for the development and commercialization of EMD’s investigational compound Tcelna (imilecleucel-T), which has received Fast Track Designation from the FDA.   A $3 million payment to Opexa will support the ongoing Phase IIb Abili-T trial in patients with secondary progressive MS (SPMS).   In February 2013, the companies entered an agreement, at which time Opexa received $5 million upfro...