Cut-price copies of an expensive Roche biotech drug for blood cancer have taken 80 percent of the British market since launching last year, saving the healthcare system 80 million pounds ($113 million) a year, experts said on Wednesday.

The rapid adoption of two so-called biosimilar forms of rituximab from Celltrion and Novartis has been accompanied by discounts of 50-60 percent as the National Health Service (NHS) has used tenders to bring down costs.

The situation contrasts sharply with the United States, where regulators have lagged Europe in approving biosimilars while a complex system of rebates offered to insurers by original-brand drugmakers has created barriers to use.

The U.S. logjam prompted Food and Drug Administration (FDA) Commissioner Scott Gottlieb to complain of "rebating mischief" and a "rigged payment scheme" in a speech here on March 7.

Biological drugs such as Rituxan, a $7 billion-a-year seller, are complex molecules made inside living cells.

Copies of some biotech medicines have been on sale in Europe for more than a decade, but it is only now that patents are starting to expire on big-selling antibody treatments for cancer and other serious diseases, with the pace expected to accelerate.

(Source: https://www.reuters.com/article/us-pharmaceuticals-biosimilars/britains-use-of-copycat-biotech-drugs-takes-off-while-u-s-lags-idUSKBN1GX2LE)