Drug That 'Stops Prostate Cancer From Spreading To The Bones'
A new antibody drug can hold back the spread of prostate cancer to the bones, research has shown.
Denosumab acts on a bone signalling protein believed to play a role in metastasis, the migration of cancer cells.
A trial involving 1,432 men from 30 countries found that the drug increased bone metastasis-free survival by around four months. Time to first metastasis was extended and symptoms delayed.
Treatment-resistant prostate cancer almost always spreads to the bone, leading to pain, fractures and early death. Previous studies have indicated that prostate cancer metastasis involves interactions between tumours and the natural process by which bone is broken down and rebuilt.
A signalling protein called RANKL, which activates bone-resorption cells called osteoclasts, is believed to set the stage for tumour spread. Denosumab, a laboratory synthesised antibody, targets RANKL. The drug is already approved in the US and UK for the prevention of fractures due to osteoporosis.
Trial leader Dr Matthew Smith, from Massachusetts General Hospital in the US, said: "Prostate cancer patients who develop bone metastasis usually have poor outcomes, so preventing the development of metastasis has been a major unmet clinical need.
"The first demonstration of a treatment that can meet that goal is a significant accomplishment that should lead to better treatment strategies."
The study is published in an online edition of The Lancet medical journal.
All the men taking part had tumours which had stopped responding to hormone therapy, but were still metastasis-free. Patients were randomly assigned to receive injections of denosumab or a dummy placebo drug every four weeks. Over a period of two years they received bone scans and X-ray examinations.
Despite delaying metastasis there was no evidence that denosumab improved survival, with both groups living less than four years on average. However, the authors pointed out that treatment with denosumab was stopped when first metastasis was diagnosed, making it hard to judge the drug's survival impact.