FDA reviewers back Novartis biosim of Amgen's blockbuster Neupogen

Those looking for a window into the FDA's thoughts on biosimilars got their first direct peek Monday. The agency released briefing documents for an upcoming panel meeting on Novartis' ($NVS) biosimilar of Amgen's ($AMGN) Neupogen. The takeaway? The FDA seems to be softpedaling on whether the biosim is "interchangeable" with Neupogen itself, allowing approval to be based on biosimilarity instead.

As the agency gears up for a Wednesday advisory committee meeting on Sandoz's Zarzio, the first biosimilar to come up for FDA approval, its staff review focuses on the drug's biosimilarity "and not the higher bar of interchangeability or substitutability," ISI Group analyst Mark Schoenebaum wrote in a note to investors. And to that point, the regulators said Sandoz's data met "the requirement for a demonstration of 'no clinically meaningful differences' … in terms of safety, purity and potency."

It's a good sign for copycat drugmakers looking to cash in on the biosimilars gold rush. As Bernstein analyst Ronny Gal wrote in a note to clients, trials to demonstrate the interchangeability of biosimilars with Neupogen and similar meds are already underway. Regulators could have taken this opportunity to grab some early feedback from its expert panelists. Instead, they let Sandoz off the hook. "The absence of any mention of interchangeability is interesting," Gal wrote. "We suspect FDA just decided this may be too much…"

Of course, the document raises other questions and issues that may come to light Wednesday as panel members cast their votes on whether the FDA should green-light Zarzio for each of Neupogen's 5 indications, Schoenebaum notes. For one, Sandoz used EU-approved Neupogen in some clinical studies and had to justify the relevance of that data to the U.S.-licensed drug.

But "what's not being addressed is interesting as well," Gal points out. The briefing contains no discussion of labeling, reporting requirements or switching, all hot topics that biosimilars makers and branded drugmakers have been squabbling about for years now.

Novartis CEO Joe Jimenez

Whether the FDA's advisers vote in favor of approving Zarzio, though, it'll still be a year or more before Sandoz' treatment--and others like it--take hold in the marketplace, Novartis chief Joe Jimenez has predicted. As he told Reuters in August, doctors, patients and payers will need some time to figure out how to respond to the new therapies once they hit the market. But come 2020, "you're going to see a big impact," he said.

- check out the FDA's briefing document

Special Report: Top 10 generics makers by 2012 revenue - Novartis (Sandoz)