Merck KGaA's experimental medicine for biliary tract cancer received an orphan drug designation from the European Medicines Agency.

The EMA's orphan designation encourages the development of new treatments for life-threatening or chronic conditions that affect not more than five in 10,000 people in the EU. These drugs qualify for certain incentives in their developmental process.

Biliary tract cancer is a group of rare and aggressive gastrointestinal cancers that affect about 186,000 people annually worldwide, the German-based pharmaceutical giant said in a Dec. 20 press release.

The company's immunotherapy targets a protein called the transforming growth factor beta and the PD-L1 proteins on tumor cells. Merck said the drug, called M7824, is believed to curb tumor growth by potentially strengthening the immune system's ability to fight the cancer.

Merck said a trial evaluating the drug in Asian patients who had previously received chemotherapy showed that 20% of the 30 participants experienced a reduction in tumor size by a predefined amount and for a minimum amount of time.

In June, the company reported positive data from a trial demonstrating the safety profile of the medicine.

The EMA's designation follows the U.S. Food and Drug Administration's decision to grant orphan drug designation to M7824 to treat biliary tract cancer.