Swiss drugmaker Roche has dropped out of a high-profile project to develop an antibiotic for treating “superbug” infections, the company said on Sunday.

Roche had agreed in 2013 to pay privately held partner Polyphor up to 500 million Swiss francs ($485.3 million) for rights to the product, marking a rare foray by a major pharmaceuticals company into the battle against superbug infections in hospitals.

“Roche has decided to discontinue its involvement in the clinical development of the investigational antibiotic RG7929/POL7080 for the treatment of patients with severe Pseudomonas aeruginosa infections and will return the asset to Polyphor,” a company spokesman said by email when asked about a report to this effect by the NZZ am Sonntag newspaper.