On August 5th, the U.S. Food and Drug Administration issued a "Guidance for Industry" entitled "Reference Product Exclusivity for Biological Products file under Section 351(a) of the PHS Act."  Before setting forth the first word of the Guidance, the Administration set forth the following caveat:

This draft guidance, when finalized, will represent the Food and Drug Administration's (FDA's or the Agency's) current thinking on this topic.  It does not create or confer any rights for or on any person and does not operate to bind FDA or the public.  You can use an alternative approach if the approach satisfies the requirements of the applicable statutes and regulations.  If you want to discuss an alternative approach, contact the FDA staff responsible for implementing this guidance.

The term of market exclusivity under the BPCIA (12 years; Sec. 351(k)(7), codified at 42 U.S.C. 55 262(k)) requires that the agency identify the date from which to calculate the term.  This Guidance, prefaced by the quote set forth above, provides some grounds for making that determination.  However, as with many of the FDA's Guidances on provisions of the law, the tentativeness of the principles set forth are more akin to hints than rules and provide little other than further evidence that the Administration will act with utmost caution (a stance understandable when taken with regard to substantive grounds for biosimilar approval but somehow less so in the context of this Guidance).

The critical date with which the Guidance is concerned is the "date of first licensure" of the reference product under PHSA Sec. 351(k)(7)(C).  This date determines not only the length of the market exclusivity of the reference product but also the time (4 years) that a biosimilar applicant must wait before filing an application for biosimilar approval.  The Guidance notes that "[n]ot every licensure of a biological product under 351(a) is considered a 'first licensure' that gives rise to its own exclusivity period," where some changes in "previously licensed" reference products, from either the same or "related" reference product sponsors are expressly excluded from being considered as a date of first licensure.  Because the agency recognizes that it is the reference drug sponsor who will have "superior information" about such changes or such relationships between companies, the Guidance sets forth "the types of information that reference product sponsors should provide to facilitate FDA's determination of the date of first licensure for their products."

The Guidance then sets forth these types of "superior information."  Typically, the date of first licensure is "the initial date the particular product at issue was licensed in the United States."  But there are exceptions codified into the statute; these include

• a supplement for the biological product that is the reference product; or

• a subsequent application filed by the same sponsor or manufacturer of the biological product (or a licensor, predecessor in interest, or other related entity) for:

-- a change (not including a modification to the structure of the biological product) that results in a new indication, route of administration, dosing schedule, dosage form, delivery system, delivery device, or strength; or

-- a modification to the structure of the biological product that does not result in a change in safety, purity, or potency.

(These can be seen as "anti-evergreening" provisions.)  The Guidance notes that the Agency has "experience in construing other provisions that require examination of the relationships between business entities to determine eligibility of a new drug application for exclusivity" (citing "Abbreviated New Drug Application Regulations; Patent and Exclusivity Provisions" (patent and exclusivity final rule), published in the Federal Register of October 3, 1994 (59 FR 50338 at 50359 and 50362).  In view of this experience, the Guidance asserts that the Agency will construe certain terms of the statute consistently to its previous determinations.  Thus:

• the term "predecessor in interest" will be "any entity that the sponsor has taken over, merged with, or purchased, or that has granted the sponsor exclusive rights to market the biological product under the 351(a) application, or had exclusive rights to the data underlying that application";

• a "licensor" will be "any entity that has granted the sponsor a license to market the biological product, regardless of whether such license is exclusive" and shall "include, for instance, entities that continue to retain rights to develop, manufacture, or market the biological product, and/or rights to intellectual property that covers the biological product";

• one corporate entity will be considered an "other related entity" "if (1) either entity owns, controls, or has the power to own or control the other entity (either directly or through one or more other entities) or (2) the entities are under common ownership or control" or "if the entities are or were engaged in certain commercial collaborations relating to the development of the biological product(s) at issue."  In this regard, the FDA "expects to consider not only ownership and control of the investigational new drug application (IND) and the BLA, but also the level of collaboration between the entities during the development program as a whole."

Regarding the statutory proscriptions against considering for the date of first licensure situations wherein there is "a new indication, route of administration, dosing schedule, dosage form, delivery system, delivery device, or strength" unless there are "modifications in the structure of the biological product" that results in a change in "safety, purity or potency," the Agency will need to determine what qualifies as "modifications in the structure of the biological product" that satisfy the statute.  To do so, "a sponsor seeking to assist FDA in determining the date of first licensure for a reference product licensed under 351(a), should describe the structural similarities and differences between its proposed product and any previously licensed biological product that was the subject of a 351(a) application filed by the same sponsor or manufacturer (or its licensor, predecessor in interest, or other related entity)."  Specifically, for a protein product the reference drug sponsor should describe "any differences in amino acid sequence, glycosylation patterns, tertiary structures, post-translational events (including any chemical modifications of the molecular structure such as pegylation), and infidelity of translation or transcription, among others."  In addition, the Agency will perform a structural comparison of the reference drug product and the modified product, including "whether the modified product affects the same molecular target as the previously licensed product."  For changes in cell lines to make the reference product, the Agency asserts that "modification of the structure will not simply be presumed" but rather require the product sponsor to submit relevant evidence that establishes the change.

In addition, according to the statute, the reference product sponsor will be required by the Agency to show the structural modification "results in a change in safety, purity or potency" (or alternatively and interchangeably, "safety and effectiveness").  The Agency will do this on a "case-by-case basis" based on scientific data (as provided by the sponsor).  The Agency is willing to presume such a change if the sponsor establishes that the modified "product demonstrates that it affects a different molecular target than the original product" (where the Guidance defines "a difference molecular target" to mean any molecule in the body whose activity is modified by the product, resulting in a desirable therapeutic effect," including "receptors, enzymes, ion channels, structural or membrane transport proteins, nucleic acids, and pathogens, among others").

The final section of the Guidance sets forth expressly the information the Agency "suggests" the reference product sponsor should submit to support its date of first licensure.  This information includes:

1. A list of all licensed biological products that are structurally related to the biological product that is the subject of the 351(a) application being considered. This list should include products that share some of the same principal molecular structural features of the product being considered, but generally can be limited to products that affect the target should be included. Where specific molecular targets have not been defined, this list should include products that share the narrowest target that can be characterized. This may be a pathway, cell type, tissue, or organ system. If this assessment results in the conclusion that no product that has the same molecular target or shares some of the same principal molecular structural features has been licensed, a sponsor should provide an adequate justification to support the assertion that there are no previously licensed products that are relevant for purposes of determining the date of first licensure.

2. Of those licensed biological products identified in item 1 above, a list of those for which the sponsor or one of its affiliates, including any licensors, predecessors in interest, or related entities, are the current or previous license holder.

3. Description of the structural differences between the proposed product and any products identified in item 2 above. For protein products, this should include, but is not limited to, changes in amino acid sequence, differences due to post-translational events, infidelity of translation or transcription, differences in glycosylation patterns or tertiary structure, and differences in biological activities.

4. Evidence of the change in safety, purity, and/or potency between the proposed product and any products identified in item 2 above. This should include, but is not limited to, a description of how the structural differences identified in item 3 above relate to changes in safety, purity, and/or potency.

And, of course, "any other information and data that would assist the FDA in making its determination."

Finally, the Guidance notes that it "is reviewing options for making information publicly available regarding reference product 303 exclusivity and dates of first licensure" and will provide the information to the public on its website when the Agency decision has been made.