Pfizer's Epogen Biosimilar Called "Highly Similar" to Reference Drug

Ahead of today's review of Retacrit, Pfizer’s proposed biosimilar of Amgen’s epoetin alfa (Epogen) by the FDA’s Oncologic Drugs Advisory Committee (ODAC), committee members expressed positive views of the drug’s similarity to the reference drug Epogen.

In a review document posted on the FDA website, agency reviewers called Pfizer’s product “highly similar” to Amgen’s Epogen (and Johnson & Johnson’s Procrit, which is the same drug but is marketed for different uses under a licensing arrangement with a California biotech), and wrote that despite minor differences in clinically inactive components, the similarity stood. They further state that there are no clinically meaningful differences between the biosimilar and reference products in terms of the safety, purity, and potency. Pfizer hopes to gain approvals for Retacrit in each of Epogen’s 4 indications:

• Anemia due to chemotherapy in patients with cancer
• Anemia due to chronic kidney disease
• Anemia due to zidovudine in HIV-infected patients
• To reduce the need for allogeneic red blood cell transfusions in patients at high risk for perioperative blood loss from elective, noncardiac, nonvascular surgery.

If approved, Retacrit will be Pfizer’s second biosimilar to be marketed in the United States. Inflectra, Pfizer’s biosimilar of infliximab (Remicade), was approved in November 2016. If approved, Retacrit would also be the second biosimilar approval to compete directly with an Amgen reference biologic product. Amgen is already facing competition from filgrastim-sndz (Zarxio), an approved biosimilar of filgrastim (Neupogen).

Retacrit’s approval, while likely, is not assured. Retacrit has faced prior regulatory denial: in 2015, the FDA issued a complete response letter to Pfizer following Pfizer’s acquisition of Hospira, which had developed the drug. And even if Retacrit is approved, a legal battle with Amgen looms over the marketing of Retacrit. Amgen is suing in federal court to block the launch of Retacrit, alleging that Hospira provided Amgen with notice of commercial launch too soon in the “patent dance” process laid out in the Biologics Price Competition and Innovation Act.

Epogen and Procrit are blockbuster drugs, with each earning over $1 billion in worldwide sales in 2016. Another Epogen biosimilar is likely to add to the competition with Amgen: Sandoz is also preparing to submit an application to the FDA for its Epogen biosimilar.

*Update: Pfizer announced in a press release that ODAC recommended approval of the company's epoetinalpha biosimilar across all the indications listed above. the recommendation will come into play when the FDA evaluates Pfizer's Biologics Licence Application for the proposed epoetin alfa biosimilar.