Merck of Whitehouse Station, New Jersey, has halted development of its lead biogeneric product, MK-2578, a PEGylated erythropoietin-stimulating agent for treating anemia. The decision, announced on May 11, followed a request from regulatory authorities for a cardiovascular outcomes assessment, an expensive and time-consuming process, says Peter Kim, president of Merck Research Laboratories. MK-2578, in phase 2 trials, was Merck's most advanced biosimilar—similar to Amgen's blockbuster Aranesp (darbepoetin alfa). “Other biosimilars counterparts will have to face [similarly] strict regulatory hurdles,” says Swetha Shantikumar, research associate at Frost & Sullivan, Chennai, India. The difficulties may dissuade small and medium-sized companies from developing biosimilars, but large companies remain undeterred. Merck itself has two other biogeneric candidates, MK4214 a G-CSF (granulocyte colony stimulating factor) and MK6302 (a recombinant pegylated G-CSF), in development. Moreover, the news boosted share values for Affymax in Palo Alto, California, which is developing a competitor product to treat anemia. And Samsung, of Seoul, South Korea subsequently announced plans to invest about $1.72 billion in biosimilars, hoping to take advantage of biologics patent expiries expected by 2016. Merck's decision does not change the dynamics of the biosimilars market, says Shantikumar. “It is a definite reminder that it is strikingly different from the traditional generics market.”