In late March, a bipartisan group of US senators introduced a bill that would open the US market to generic versions of biologic drugs, which have until now been the all-but-exclusive province of brand-name makers.

Senator Charles Schumer, the bill's leading sponsor, bemoaned the price tags of biologic drugs, large proteins that are produced by a complicated process involving living cell cultures, rather than straightforward chemistry. Biologic treatments such as Genentech's cancer-fighting antibody Avastin can cost up to $100,000 a year. “It's past time we created a way for generic versions of these expensive drugs to come to market,” Schumer said a statement.

In Europe such medications are known as 'biosimilars', and a regulatory path opened in 2005 has already brought more than a dozen such drugs to market.

The US senators' bill, known as the Promoting Innovation and Access to Life-Saving Medicine Act, is virtually identical to a recently-introduced House bill whose lead author is Henry Waxman. But these pieces of legislation stand in contrast to a markedly more industry-friendly bill also introduced in the House in March by a bipartisan group of lawmakers led by Anna Eshoo with the backing of brand-name biologics makers.

The starkest point of difference is the period of market exclusivity granted to brand-name companies. Under the Waxman and Schumer bills, such companies would be guaranteed at most six years of competition-free market access, whereas Eshoo's version grants them at least 12 years.

Although both bills give the US Food and Drug Administration (FDA) broad discretion to make other key determinations—such as whether costly clinical trials will be required for a generic biologic to win market approval —Eshoo's bill goes further by obliging the agency to go through stringent public procedures when it waives such requirements.

Safety concerns about biologics are far from theoretical. For instance,, a biologic drug for anemia, provoked a near-total shutdown of red blood cell production in scores of patients in Canada and Europe after its manufacturing process was modified (N. Engl. J. Med. 346, 469–475; 2002).

The FDA walked a middle line in 2007 Congressional testimony when Janet Woodcock, then the agency's deputy commissioner said that human trials shouldn't be required just for the sake of requiring them. Still, she told lawmakers, given the current state of the science on biosimilars, “we cannot predict the immunogenicity answers without doing human trials.”