Zarxio hits market but not such a great bargain

The 15 percent discount is the same price gap set when Zarxio was launched in Europe in 2009, although the discount in Europe has since widened to an average of around 20 to 30 percent.

Insurers hope biosimilars will eventually cost the public 40 percent to 50 percent less than the original brands.

Neupogen is a $1.2 billion-a-year medicine for Amgen that boosts white blood cell counts to fight infections in cancer patients. The majority of its sales are generated in the United States.

An even bigger prize lies in the development of copies of multibillion-dollar antibody drugs for the treatment of diseases like cancer and rheumatoid arthritis, where Sandoz and rivals are also working to bring products to market.

Express Scripts, the largest manager of drug benefit plans for U.S. employers and insurers, has estimated the United States could save $250 billion between 2014 and 2024 if 11 of the likeliest biosimilars reach the market.