The unexpected finding of cartilage damage in a preclinical toxicity study of Karo Bio AB's eprotirome may make it hard for other companies working on thyroid hormone receptor beta agonists to find partners, unless further data reveal it is a compound rather than a class problem.

Earlier this month, Karo Bio said a 12-month toxicology study in dogs showed all animals receiving the highest dose of eprotirome had cartilage damage, as well as some dogs given lower doses of the compound. Control animals showed no damage.