The agency sent a warning letter to the drugmaker for omitting and minimizing the most serious risks, and selectively stating efficacy info, in letters that were sent to docs as part of a promotional campaign. The campaign began shortly after the FDA approved Tykerb as a treatment for certain patients with advanced breast cancer. (Here’s the evidence).

In its Nov. 21 letter (which you can read here), the FDA notes the promo letters “minimize the important risk of decreased left ventricular ejection fraction,” which measures of the amount of blood pumped out of one section of the heart. The Glaxo letter also failed “to present the most serious and important risk information,” including warnings about pregnancy, patients with liver impairment and diarrhea.

“We are particularly concerned that these materials, which were disseminated to healthcare professionals during the product’s launch and formed the basis of their first impressions of the drug, suggest to healthcare professionals that Tykerb is safer and more effective than has been demonstrated,” the FDA wrote the drugmaker.

The drugmaker “takes seriously the concerns outlined in the FDA letter, and we will work with the agency to address its concerns,” Glaxo spokeswoman Sarah Alspach wrote Reuters in an e-mail.