Amgen has been boosted by the news that regulators in the USA have expanded approval on the biotech major's bone drug Prolia.

The US Food and Drug Administration has approved two new indications for Prolia (denosumab). First up, the treatment can now be used to increase bone mass in women at high risk for fracture receiving adjuvant aromatase inhibitor therapy (ART) for breast cancer.

That approval is based on data from a Phase III study of 252 postmenopausal women with breast cancer receiving ART. Bone mineral density (BMD) in patients given Prolia was higher at the lumbar spine at 12 months compared to placebo. After two years of treatment, differences in BMD were 7.6% at the lumbar spine, 4.7% at the total hip and 3.6% at the femoral neck.

The green light has also been given for Prolia as a treatment to increase bone mass in men at high risk for fracture receiving androgen-deprivation therapy (ADT) for non-metastatic prostate cancer. That was based on a study of 1,468 men which showed that BMD was significantly higher at the lumbar spine after two years versus placebo.

After three years of treatment with Prolia, differences in bone mineral density were 7.9% at the lumbar spine, 5.7% at the total hip and 4.9% at the femoral neck. Also the incidence of new vertebral fractures was 62% lower for Prolia-treated men.

Prolia was originally approved in the USA in 2010 to treat osteoporosis in post-menopausal women at increased risk of fractures. Denosumab is also approved (and marketed as Xgeva) for the prevention of skeletal-related events in adults with bone metastases from solid tumours.