Fourteen years later, the BPCIA is designed to leverage what has long been recognized as the next logical step—flowing directly out of the Avonex comparability determination and hundreds of other comparability determinations that the FDA subsequently rendered—by establishing a new regulatory pathway for biosimilars. Thus, under the BPCIA, a biosimilar is a biological product demonstrated to be "highly similar" to a reference biologic from another company that the FDA previously licensed. By adopting this approach to biosimilarity, Congress could be considered to have codified the FDA's longstanding comparability standard. For many years, comparability has been
"[A] conclusion that products have highly similar quality attributes before and after manufacturing process changes and that no adverse impact on the safety or efficacy, including immunogenicity, of the drug product occurred. This conclusion can be based on an analysis of product quality attributes. In some cases, nonclinical or clinical data might contribute to the conclusion." 1Against this historical regulatory backdrop, the BPCIA establishes a biosimilar pathway that adds explicit, albeit waiveable, mandates to the BLA-licensure provisions of the PHS Act for the first time in their 66-year history. Most notably, the law establishes an express requirement that a biosimilar application include "a clinical study or studies (including the assessment of immunogenicity...)." This contrasts with the very broad, longstanding statutory regime, which was in place throughout the biotech revolution and that was aptly summed up in the Federal Court decision affirming the FDA's comparability determination for Avonex:
"Biogen and FDA acknowledge FDA's past insistence upon clinical trials of each drug being considered for approval, but they contend that no statute or regulation requires it and submit that the use of data on "comparable" drugs is within FDA's discretion.... Neither the PHSA itself nor FDA's regulations issued under the PHSA provide that the clinical study offered to demonstrate the safety, purity and potency of a new biological product shall have been conducted on that very product.... FDA conceded that it had never before approved a new biological drug on the basis of a clinical study of a "comparable" drug, but FDA demonstrated by reference to public documents that the principle of comparability was not unknown and that, in fact, it had been previously applied in other situations." 2
Under the BPCIA, the statutory regime that the FDA must apply to a "highly similar" biosimilar differs significantly from the very broad and straightforward provisions governing traditional BLAs, which make no reference to clinical trials or other studies, and simply require a demonstration of safety, purity, and potency to secure BLA approval for an originator biologic. Although Congress greatly amplified the detail of the requirements for what must be included in a biosimilar application, Congress nonetheless delegated scientific responsibility for implementing those requirements to the FDA. In doing so, Congress established what can be, on a product-by-product basis, a self-implementing pathway and one that, in all cases, defers to the expert scientific judgment of the FDA's career reviewers in the same review divisions having responsibility for the counterpart reference biologic BLA.