Irisin, a new hormone that might be the basis for new therapy for diabetes
(March 5, 2012))
A reader recently asked about a hormone I had never heard of:
"Have you heard of a proposed new drug based on the hormone Irisin? Apparently irisin causes a gene to be switched on that turns "bad" white body fat into "good" brown fat. It is flagged up as a possible treatment for diabetes because of its potential for weight loss but also because it seems to improve control of glucose levels. The hormone's discoverer Bruce Spiegelman, head of the team at the Dana-Farber Cancer Institute in Boston has already set up a company called Ember Therapeutics to develop brown fat related treatments and hopes to start clinical trials in two years.
"Do you think this could provide a new branch of diabetes treatments?"
My reply to the reader was brief ("It's way too early to speculate whether this will lead to new therapy for any condition."), but I decided to have another look at irisin.
There were several apparent red flags in the reader's question which piqued my curiosity:
1) A new hormone I had never heard of. Sure, hormones are discovered every now and then, and some of them turn out to have theoretical if not practical significance (for example, leptin). But announcing a hormone by press release is an interesting tactic.
2) The cute name (irisin). According to one news story, it's named after the Greek messenger goddess Iris. A goddess named Iris -- I hadn't heard of her, which was my goof: Wikipedia (that fountain of all knowledge) says she's "the personification of the rainbow and messenger of the gods. She is also known as one of the goddesses of the sea and the sky. Iris links the gods to humanity. She travels with the speed of wind from one end of the world to the other, and into the depths of the sea and the underworld." Fascinating.
Wikipedia also has a (very sketchy) summary of irisin, which quotes Dr. Spiegelman's research as the sole source of the information.
3) Naming the hormone's discoverer, and indicating he's set up a company to develop a "treatment." This is a standard tactic that researchers (or their financial backers) use when they're out to make a buck off a scientific idea. Ember Therapeutics does exist, http://www.embertx.com/ as does Dr. Spiegelman: he's a PhD researcher at Harvard (and has 93 publications at PubMed). And unsurprisingly, Ember Therapeutics is backed by a venture capital company.
4) I was curious to find out how many publications about the "new hormone" exist. The publicity recently is about an article in Nature from January 2012: "A PGC1-α-dependent myokine that drives brown-fat-like development of white fat and thermogenesis." It's a mouse study. The editors at Nature enthuse that "Irisin counters diabetes and obesity... It is a very powerful activator of a thermogenic program... These data identify irisin as a possible novel therapeutic for metabolic disorders." Sounds like the editor has bought into the breathless hype of the press release!
BTW, this Nature study is the only research article about irisin that is listed in PubMed (there are two other articles, one a commentary on the Nature article, and one a commentary that's not yet published). Perhaps someday there will be independent research to confirm - or refute - the theory that irisin does more than being a messenger from the gods.
5) The comment that Ember Therapeutics wants to "start clinical trials in two years." Of course they do. The only way that they can make money is to have a product approved for sale, and that will take a dozen years or more. Further preclinical studies may find that their new hormone has unforeseen effects, or is ineffective in some species, or may uncover other roadblocks that delay or torpedo the possible start of human trials. And identifying a new hormone doesn't mean that a new drug can be commercialized based on the hormone itself. For example, a while back, some unusual proteins were found in lizard venom (exendin-3 and exendin-4), but the actual drug that was developed based on those proteins (exenatide/Byetta) took years to get synthesized then started in human trials.
To expand on my brief answer to the reader:
"After looking over the available information, I really can't understand why Dr Spiegelman and Ember Therapeutics and their financial backers are making a big publicity splash at this time. It's way too early to get anyone's hopes up that this putative hormone will make any difference in diabetes or any other condition. Come back in a few years, and ask again."
