Amsterdam Molecular Therapeutics (AMT) NV's bid to become the first Western biotechnology firm to gain a gene therapy approval suffered a second rebuff, as the European Medicines Agency's Committee for Medicinal Products for Human Use (CHMP) stood over its original negative opinion on a marketing authorization application for Glybera (alipogene tiparvovec), which is in development for the ultra-rare indication lipoprotein lipase deficiency.Shares in the company (AMSTERDAM:AMT) plunged 51 percent when the news was disclosed Friday, to close at €0.38 (US$0.43).