Barely a week after the Patent Trials and Appeals Board (PTAB) rejected his petition challenging two patents for multiple sclerosis drug Ampyra (dalfampridine) through an inter partes review (IPR), hedge fund manager Kyle Bass reportedly filed a new petition against the drug's developer, Acorda Therapeutics Inc., of Ardsley, N.Y., requesting IPR on four patents protecting the drug, including two patents that had been part of the original petition.