Brand-new FDA guidelines have created a long-awaited shortcut for bringing biosimilars—cheaper versions of biologically derived pharmaceuticals—to the U.S. market. But the pathway won’t be nearly as straightforward as the one for generic versions of less complex, chemically based drugs that was created under the Hatch-Waxman Act in 1984.

Unlike the Hatch-Waxman route, the biosimilar guidelines issued in February call for drug makers to be in regular contact with the FDA during virtually every step of the development process, explains Morrison & Foerster attorney Cary Miller. Many decisions will be made on a case-by-case basis. “I think the approval process will evolve as companies develop their products,” she says.

“The uncertainties associated with the new process could spur companies to forgo it in favor of the traditional licensing process,” adds Stephanie Hsieh, former Of Counsel at Morrison & Foerster. Some have also raised concerns about the amount of confidential information an applicant might have to disclose through the new process.

Despite the difficulties, it appears that many companies will press on with biosimilars efforts. One research firm has estimated that U.S. sales of biosimilars could reach $8 billion by 2020.