Opexa Therapeutics has granted Merck Serono a licence option to its personalised T-cell therapy Tcelna™ (imilecleucel-T), which may be exercised prior to or on completion of the ongoing Phase IIb trial of the immunotherapy for secondary progressive multiple sclerosis (MS). Tcelna, formerly known as Tovaxin®, has had a chequered development history and failed to meet its primary end-points in a Phase IIb trial in relapsing-remitting MS in 2008. Merck Serono is a key player in the MS market but suffered a setback in 2011 when its oral MS therapy cladribine failed to win regulatory approval.