The US Food and Drug Administration (FDA) is to deny approval for Arena’s obesity drug lorcaserin without further data, following potential safety risks and its apparently “minimal” weight-loss effect.

The regulator had addressed a letter to the pharmaceutical firm to request more positive data to confirm lorcaserin’s long-term efficacy and to dismiss concerns following breast tumour growth on female rats given the drug.

The move follows a continually hard line taken by the FDA on weight loss drugs, with Abbott Laboratories pulling appetite suppressant Meridia from the shelves in early October at the its request.

Shareholders and investors in Arena have said they will continue to push for approval, with initial results from a one-year weight-loss trial involving type 2 diabetes patients expected in the coming weeks.