Japan's health ministry warned of side effects of Eli Lilly and Co.'s breast cancer drug Verzenio after three patients taking the drug died.

According to a blue letter from Japan's Pharmaceuticals and Medical Devices Agency, 14 serious cases of interstitial lung disease have been reported in patients taking Verzenio tablets since the therapy's launch in the Asian country in November 2018, including three deaths. An estimated 2,000 patients are using Verzenio in Japan, according to the agency.

The Japanese regulator issues blue letters to alert healthcare professionals of certain safety information about drugs and medical devices. The agency also decided that a warning section regarding the lung disease risk should be added to the package insert for the drug.

Verzenio is also approved in the U.S. for certain breast cancer indications.