BTG plc said the U.S. Food and Drug Administration denied premarket approval for its Elevair Endobronchial Coil System.

Elevair uses a procedure in which metal coils are placed into the lungs of patients with severe emphysema. The treatment, branded outside the U.S. as the RePneu Coil System, is a product of BTG's California-based unit PneumRx Inc.

The regulator's anesthesiology and respiratory therapy devices panel voted against Elevair's approval in June, questioning its efficacy.

The London-based company said it is reviewing its options.

Emphysema, which affects an estimated 3.5 million adults in the U.S., causes breathlessness, labored breathing and eventual respiratory failure.

BTG develops and sells pharmaceutical products through three segments — interventional medicine, pharmaceuticals and licensing.