Pfizer's Epogen biosim scores solid backing from FDA staff ahead of panel review

After picking up Hospira and its biosimilar programs for $16 billion, Pfizer is nearing an FDA ruling on its version of Amgen’s blockbuster anemia medicine Epogen—and so far, it's looking good. Agency reviewers found the Pfizer product nearly identical to the Amgen drug, exactly what a biosimilar is supposed to be.

In a review document posted by the agency ahead of an advisory committee meeting Thursday, FDA reviewers called the Pfizer candidate “highly similar” to Amgen’s Epogen and Johnson & Johnson's Procrit, the same drug marketed for different uses under a licensing deal with the California biotech.

That similarity stands despite “minor differences in clinically inactive components,” the reviewers wrote.  There are “no clinically meaningful differences” between the two products “in terms of the safety, purity, and potency,” the documents state.

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If approved, Retacrit would be Pfizer's second biosimilar to win U.S. approval, after Inflectra, a copycat to J&J's immunology med Remicade. And it would be the second biosimilar threat to Amgen, which faces Sandoz' Zarxio, a copycat biologic to the Big Biotech's Neupogen.

The sales stakes are blockbuster-level, with Epogen and Procrit both bringing in $1 billion-plus in worldwide sales for their makers last year, despite a recent slide for Epogen as some patients switched to Amgen's longer-acting Aranesp.

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Skeptical agency staff can pose some pointed questions to its expert panels, but in this case, the official queries simply ask whether the Oncologic Drugs Advisory Committee thinks Pfizer’s biosimilar meets legal biosimilarity standards. The New York drug giant hopes to win an approval in each of Epogen’s four indications.

The approval isn't a sure thing: Retacrit has been turned away by the agency before. In the third quarter of 2015, after completing its Hospira acquisition, Pfizer said the FDA had issued a complete response letter on its application. At the time, CEO Ian Read said the company was “working closely” with the FDA to address its concerns, adding that the drugmaker was “confident that the additional evidence we provide will support approval.”

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And even if Pfizer’s biosimilar makes it past FDA gatekeepers this time, it will still have to fight a legal battle with Amgen to launch its product. Amgen has sued to block the launch on grounds Hospira provided marketing notice too soon, according to Bloomberg BNA.

Amgen is fighting a high-profile case at the Supreme Court over that very notification issue. Facing off against Novartis’ Sandoz, Amgen is disputing a case that centers on whether biosim developers have to participate in the "patent dance" under the Biologics Price Competition and Innovation Act, and exactly when biosim developers can provide official marketing notice.

For its part, Sandoz, which won the first U.S. biosimilar approval in Zarxio, is preparing to submit its own application for a biosim version of Epogen.