Recently, the United States Court of Appeals for the Federal Circuit released a divided decision concerning the interpretation of two key provisions of the Biologics Price Competition and Innovation Act (BPCIA); legislation the court likened to a "riddle wrapped in a mystery inside an enigma". Much of the court's discussion centred on the interpretation of the word "shall" in different parts of the statute.

The decision, Amgen Inc. v Sandoz Inc. (2015-1499), involved a dispute between Sandoz and Amgen over the drug filgrastim, marketed since 1991 by Amgen under the name Neupogen. In May of 2014, Sandoz filed an abbreviated biologics licence application (aBLA) pursuant to the BPCIA for its filgrastim biosimilar, Zarxio. At issue was Sandoz' decision not to comply with a section of the BPCIA that states that a biosimilar applicant "shall" provide to the reference product sponsor (RPS, i.e. Amgen) a copy of its aBLA as well as its drug manufacturing information. Under Sandoz' interpretation of the law, despite the use of the word shall, the disclosure of information under the BPCIA should not be considered as mandatory given that the act specifically contemplates the consequences for non-disclosure: the BPCIA makes a failure to disclose information an "artificial act of infringement" entitling the RPS to bring an action "for a declaration of infringement, validity, or enforceability for any patent that claims the biological product or a use of the biological product". The majority of the court sided with Sandoz on this point noting that the remedy provisions in the BPCIA would be made superfluous if disclosure was meant to be mandatory – a finding that would run afoul of the fundamental canons of statutory interpretation.

On this point Judge Newman dissented, writing that the remedies present in the BPCIA should not be interpreted to diminish the disclosure requirements and that “[d]eparture from the statutory obligation, to achieve purposes that the legislation intended to curtail, should not be judicially ratified”. 

Also at issue in the decision was the interpretation of another section of the BPCIA, which states that a biosimilar applicant "shall" provide notice to the RPS of its licensed biosimilar no later than 180 days before it is meant to enter the market. Sandoz had provided Amgen notice prior to obtaining FDA approval and licence for Zarxio. The majority of the court agreed with Amgen and held that "shall" in this case should be interpreted as "must" and that Sandoz' notice was therefore ineffective as it was premature. The majority noted that requiring "that a product be licensed before notice of commercial marketing ensures the existence of a fully crystallized controversy regarding the need for injunctive relief" and affords the RPS precise knowledge of the product that will actually go to market. 

However, the majority's interpretation of the BPCIA requiring that a biosimilar be FDA licensed before notice can be given effectively extends the period of exclusivity for the RPS by 180 days, adding to the 12 years already provided for. On this point Justice Chen dissented stating that such an "extra-statutory exclusivity windfall" was not justified. Justice Chen further stated that "the majority's opinion creates an uncomfortable result in which language ... is interpreted in two different ways."

In March 2015, Zarxio was the first biosimilar to gain FDA approval. Despite the fractured nature of the decision, Amgen v Sandoz still answers several fundamental questions regarding aspects of the BPCIA and provides guidance on how the American biosimilar approval process may proceed in the future.