Researchers have created a molecule that blocks the activity of the muscle-limiting protein myostatin in mice. It can fully reverse the devastating muscle loss that often accompanies advanced cancer — and thereby increase the lifespan of animals with the disease. Instead of myostatin binding to its normal receptor and triggering muscle wastage, it is ‘mopped up’ by binding to the decoy molecule instead. Muscle wasting — called cachexia — is thought to account for about 30% of deaths in patients with cancer.
In another study of frailty and aging, a proportional hazards model controlling for age, sex, education and baseline frailty, each 1-unit increase in annual change in frailty was associated with an almost 5 times the risk of mortality. About 7% of persons older than 65 years are frail, and that the occurrence of frailty increases with age and may exceed 45% after age 85.
A single injection of the soluble receptor into normal mice boosted their muscle mass by 25% or more in a week or two. When it was given to mice implanted with colon cancer cells, their muscle mass returned to normal, even though their tumours continued to grow. Strikingly, all of the animals that did not receive the soluble receptor were dead 40 days after cancer cells were implanted, but more than half of the treated animals survived to this point.