On July 20, 2018, FDA approved Pfizer’s biosimilar of Amgen’s Neupogen® (filgrastim). Pfizer’s product, Nivestym™, is the second biosimilar of Neupogen to be approved after Sandoz’s Zarxio®, the first approved biosimilar in the United States. Pfizer’s Nivestym gained approval for all eligible Neupogen indications.

Neupogen reduces the risk of infections in cancer patients undergoing chemotherapy. Chemotherapeutic drugs can lead to neutropenia, a deficiency in certain immune cells produced by the bone marrow called neutrophils. Neupogen is a recombinant form of the human granulocyte-colony stimulating factor (“G-CSF”) protein that stimulates bone marrow to produce neutrophils.

Two days prior to the approval of Nivestym, Amgen sued the Pfizer subsidiary Hospira under the Biologics Price Competition and Innovation ACT (BPCIA). The BPCIA provides for pre-litigation exchange of information between the innovator company that developed the reference biologic and the biosimilar applicant, referred to as the “patent dance.” The patent dance streamlines litigation through a process of selecting which patents will be litigated in district court based on the biosimilar applicant’s regulatory application and manufacturing information and the parties’ respective patent infringement and validity contentions.

Not all biosimilar applicants initiate the patent dance, however. In the case of the first biosimilar, Zarxio, Sandoz did not provide Amgen with its regulatory information, ultimately leading to the Supreme Court’s Sandoz v. Amgen decision holding that the requirement that a biosimilar applicant provide its application to the manufacturer is not enforceable by injunction under federal law. On remand from the Supreme Court, the Federal Circuit held that the BPCIA’s requirement also is not enforceable under state law.

In the case of Nivestym, Pfizer chose a different strategy. It engaged in the patent dance. Pfizer provided Amgen with a copy of its regulatory application and manufacturing information. Based on that disclosure, Amgen identified six patents as potentially infringed. After negotiation between the parties, it was agreed that only one patent, US Patent No. 9,643,997 (“the ’997 Patent”), would be the subject of an action for patent infringement. The ’997 Patent is directed to methods of purifying a protein in a non-mammalian expression system using a refold solution.

Amgen’s ’997 Patent is not specific to Neupogen. Amgen is also asserting the patent in a lawsuit against Mylan under the BPCIA in connection with Mylan’s Neulasta® (pegfilgrastim) biosimilar. The Amgen v. Mylan lawsuit was filed in September 2017, and the parties are currently briefing claim construction. Mylan’s Neulasta biosimilar was approved in June of this year and launched in July. The ’997 Patent is also the subject of a BPCIA lawsuit filed by Amgen in March 2018 against Adello Biologics in connection with its proposed biosimilar version of Neupogen. Adello’s regulatory application was accepted for review by FDA in September 2017 but has not been approved. As both of these lawsuits are ahead of Amgen’s recent lawsuit against Pfizer’s Hospira, they are likely to preview issues that may arise.