My endocrinologist is concerned that Forteo should only be used for 2 years. I have seen the clinical trial results seem to end at 2 years. Why is this an indication that Forteo use should be stopped after 2 years?
Hi JAS, welcome. Yes your endocrinologist is correct about the 2 year limit on Forteo. Since the clinical trial ended before 24 months, the FDA only approved it for this amount of time.
Here's a quote from Dr. Gonter here at our site:
"When Forteo was approved in November 2002, the FDA mandated that it carry a black-box warning because it was associated with an increased risk of osteosarcoma, or bone cancer, in rats. The particular strain of rats that were used in the studies are highly sensitive to developing cancer. Paired with the fact that the rats were exposed to more than twice the human dose for their entire lifespan indicates that developing osteosarcoma depends on the dose given and the duration of therapy. Given the limited dose of Forteo as well as length of administration (two years only), it is generally understood that this would significantly limit a patient's risk of developing osteosarcoma. Eli Lilly, the maker of Forteo, has also given physicians guidelines to identify patients that are at increased risk of developing osteosarcoma so that they are excluded as potential drug candidates. These patients include those that have had radiation to the bones, children, and those with Paget's disease."
To read more about this here's Dr. Gonters article on Forteo.