In the vast majority of patients with advanced cancer, their muscles will gradually waste away for reasons that have never been well understood. Now, researchers reporting in the August 20 issue of Cell, a Cell Press Publication, have found some new clues and a way to reverse that process in mice. What's more, animals with cancer that received the experimental treatment lived significantly longer, even as their tumors continued to grow.
"This is the first demonstration that muscle mass plays a key role in cancer survival," said H.Q. Han of Amgen Research.
While it has long been recognized that this muscle wasting condition, known as cachexia, affects advanced cancer patients' quality of life, Han explained, its importance for survival had primarily been a matter of speculation. Nearly 30 percent of cancer-related deaths have been attributed to cachexia, but that was based on correlative evidence only. That is, there has seemed to be a connection in cancer patients between weight loss and mortality.
Still, cachexia had typically been considered a "multi-factorial" process with many causes. "That would make it hard to target," Han said. Indeed, few therapeutic options are available and efforts to treat this aspect of the disease haven't been top of mind. Given the new results, that could change.
The researchers suspected that a pathway known as ActRIIB might be involved. ActRIIB is what's known as an activin type 2 receptor. There was evidence to suggest that tumors secrete activin, such that circulating levels of the protein rise in those with cancer. Activin is closely related to another protein, called myostatin, which is known to be important in muscle. Animals lacking myostatin or taking treatments that block it grow bigger muscles. There was some evidence to suggest that activin blockers might have a similar effect.
Based on that hunch, the researchers treated mice with cancer and associated cachexia wi
|Contact: Cathleen Genova|