U.S. consumer groups and two large labor unions urged the U.S. Federal Trade Commission on Thursday to block Novo Holdings, the controlling shareholder of Novo Nordisk, from acquiring contract drug manufacturer Catalent,

Five U.S. consumer groups and two big labor unions are pushing for the Federal Trade Commission to block Novo Nordisk Foundation's planned $16.5 billion acquisition of Catalent (NYSE:CTLT), arguing that a deal would hurt competition in weigh-loss drugs.

Consumer groups and labor unions urged the U.S. FTC to block Novo Holdings' $16.5 billion acquisition of Catalent, warning it may stifle competition in weight loss drugs and gene therapies. Concerns include limited manufacturing options for GLP-1 rivals.

Senator Elizabeth Warren told the Federal Trade Commission that the acquisition of contract manufacturer Catalent could increase Novo’s dominance over the hot GLP-1 market, reducing competition and increasing prices.

The coalition said in a letter sent to the FTC Thursday that the deal could reduce access to GLP-1s, and harm competition in development of cell and gene therapies.