Merck has announced that it is discontinuing development of new hepatitis C virus (HCV) medications, opting to focus on its approved treatment, Zepatier (grazoprevir/elbasvir).

The company had been researching two different combination treatments. One combined the NS3/4A protease inhibitor grazoprevir, which is already approved as a component of Zepatier, with two experimental direct-acting antivirals, the NS5A inhibitor ruzasvir and the NS5B polymerase inhibitor uprifosbuvir. Another combination included only the two experimental medications.

According to a Merck press release, the pharmaceutical company made the decision to drop out of the hep C development race after reviewing efficacy data from Phase II trials of the two combination treatments while also analyzing the increasingly crowded HCV treatment marketplace.

Eliav Barr, MD, senior vice president of global clinical development, infectious diseases and vaccines at Merck Research Laboratories, said in a press release, “We will continue to study Zepatier to understand even more about its role in treating chronic hepatitis C infection and will continue to work with others to help bring Zepatier to appropriate patients with chronic hepatitis C genotype 1 or 4 infection, the genotypes which make up the majority of patients with chronic hepatitis C infection.”

To read a press release about the discontinued program, click here.