Apotex’s application for a biosimilar version of Amgen’s chemotherapy Neulasta has been accepted by the FDA, one of several recent signs that regulatory movement on approving the therapies is gaining momentum.

The filing marks the third FDA biosimilar application that has been confirmed in the past five months. The agency’s efforts to implement the biosimilars pathway are clearly bearing fruit, Apotex said, adding that the biosimilar market as envisioned by the 2010 biosimilar pathway law is taking shape.

Neulasta (pegfilgrastim) is a long-acting formulation of Amgen’s blockbuster Neupogen (filgrastim), Apotex said, citing IMS Health data that found Neulasta generated $3.6 billion in 2013. The biosimilar version was developed jointly with Intas Pharmaceuticals, Apotex added.

The other biosimliar applications come from Sandoz, which in July confirmed it had filed against Amgen’s Neupogen, and from Celltrion, which in August said it had filed against Janssen’s Remicade (infliximab). Celltrion already markets that drug in dozens of countries under the brand name Remsima.

Growing momentum for approving biosimilars in the U.S. can be seen in the FDA’s recently announced Jan. 7, 2015, oncologic drugs advisory committee meeting to consider Sandoz’s Neupogen application, which the agency is scheduled to act on as soon as May.

At least for filgrastim itself, the meeting should help shine a light on how the FDA will deal with residual concerns on issues such as data requirements in applications, Kurt Karst, an attorney with Hyman Phelps & McNamara, said.

On the biosimilar legal front, Sandoz and Amgen remain locked in litigation over exactly how much of Sandoz’s planned manufacturing methods it has to disclose to the brand firm. Sandoz claims handing over such data is voluntary under the 2010 pathway law. But Amgen counters the manufacturing information is crucial to the process, and the FDA should require biosimilars makers to reveal the data so that brands may know which process patents to sue over.

Movement for biosimilars also is growing outside of the legal and regulatory pathways, said Karst. An increasing number of states, for example, are passing biosimilar substitution laws needed for patients to be switched from the brand therapy. The generics and brand industries also recently revealed compromise language over exactly how other states should write such laws, Karst said.

Despite progress, some experts remain cautious about exactly how much momentum U.S. biosimilars have. 

There’s still no sign of several promised FDA biosimilars guidances, including one on interchangeability, notes Brian Malkin, an attorney with McGuireWoods who leads the firm’s FDA regulatory teams. Malkin also said that some generics firms appear to still be on the biosimilar learning curve as they continue to adapt from ANDA processes to the far more stringent demands of a biosimilar application. — Bryan Koenig