** Shares of cancer therapy developer Mustang Bio MBIO.O rise 234% to over 5-month high of $3.97

** Stock set for its best day in over a year, if gains hold

** Co says it received 'orphan drug designation' from the FDA for its experimental cancer therapy, MB-101, to treat astrocytomas and glioblastoma

** The designation gives Mustang incentives like tax credits and seven years of market exclusivity if the product is approved

** Astrocytomas and glioblastoma are brain cancers that develop from star-shaped support cells in the brain, with glioblastoma being the most aggressive form

** MB-101 works by training the body's own immune cells to find and destroy brain cancer cells by targeting a specific protein, IL13Rα2, found on the surface of those tumors

** FDA grants orphan drug status to promote drug development for rare diseases affecting fewer than 200,000 people in the U.S.

** Including session's moves, stock down 55.4% YTD

(Reporting by Kamal Choudhury in Bengaluru)

((Kamal.Choudhury@thomsonreuters.com;))