The FDA has placed Regeneron's ($REGN) trial for an experimental pain medicine on hold, signaling that the entire drug class it belongs to could be in big trouble. The hold was announced after a patient in a different study involving a similar drug developed avascular necrosis, or bone tissue death triggered by a lack of blood supply.
REGN475/SAR164877 is an nerve growth inhibitor much like Pfizer's tanezumab, which was put on hold last summer after patients in a trial required joint replacements. A spokesman for Pfizer told Bloomberg the FDA is examining all anti-nerve growth drugs now in development.
"The FDA believes this additional case provides evidence to suggest" bone problems for the entire class, Regeneron said in a filing. The drug is partnered with Sanofi-Aventis.