ORPHAN DRUG DESIGNATION FOR "SAME DRUG" BASED ON GLYCOSYLATION

ORPHAN DRUG DESIGNATION FOR "SAME DRUG" BASED ON GLYCOSYLATION differences is opposed by the Industrial Biotechnology Association in a May 24 letter to FDA Acting Commissioner Benson. "It is IBA's position that in considering whether two manufacturers' versions of a protein drug are the same drug for the purpose of Orphan Drug Act marketing exclusivity, glycosylation should be irrelevant," the association said. "We trust that FDA will consider these views carefully in the promulgation of any regulation or policy decisions." IBA's letter was sent to the agency in anticipation of the FDA Blood Products Advisory Committee's June 29-scheduled meeting on the similarities and differences of the erythropoietin molecules in Amgen's Epogen and Chugai-Upjohn's Marogen ("The Pink Sheet" May 28, T&G-1). While Epogen and Marogen are identical in their amino acid sequences, Chugai-Upjohn has asserted that Marogen differs from Epogen in its glycosylation pattern. IBA is hoping to participate in the advisory committee meeting either through a presentation or a written submission. IBA stated that with glycosylation, or "the attachment of sugar molecules to the amino acid backbone of the protein," it is "very easy to secure minor differences in the sugar residues associated with a recombinant protein." Because glycosylation "is under enzymatic control, it is a parameter that can be easily manipulated," IBA pointed out. "Simple changes in culture media or cell type result in differing glycosylation patterns even though the primary amino acid sequence of the protein is unchanged. Thus, clinically identical protein therapeutics can be produced that have different patterns of glycosylation." The association is "concerned that the developmental incentives would be subverted if FDA adopts a very broad view of what structural determinants will allow such products to be differentiated for purposes of granting marketing exclusivity under the Orphan Drug Act," the letter states. Voicing its "concern" over the lack of FDA regulations on "same drug" determinations, IBA noted that as a result, individual decisions have carried the weight of policy. In a reference to the approval of Lilly's human growth hormone product (Humatrope) with an orphan designation following the approval of Genentech's Protropin, IBA commented: "FDA has already made one policy decision on the granting of marketing exclusivity in the absence of regulations." In that case, FDA granted Humatrope orphan exclusivity on the basis of a different amino acid sequence; the drugs are not the product of glycosylation. IBA also suggested that use of the advisory committee in reaching a decision on the glycosylation question is inappropriate. "In our view it would be unwise to use an advisory committee that does not consist of sufficient number of experts in glycoproteins. We would be troubled if the agency chose to use a drug specific focus in order to create rules of general applicability to the industry." The "appropriate mechanism," IBA said, "is through notice and comment rulemaking." The IBA board voted to support the position on glycosylation at its May 23 meeting in Chicago. The board also resolved to support an amendment to Rep. Boucher's biotech patent protection bill. The association is proposing an amendment to Section 1 of the bill, which changes U.S. Patent Office practice by directing that patents be granted for production processes where an essential element of the process is novel ("The Pink Sheet" Feb. 12, T&G-3). IBA is supporting a broadening of the provision so that a patent would be granted for processes where a material element of the process is novel -- on the basis that the term "material" is a less demanding criterion than "essential." IBA further suggests that the term "process" be broadened to include processes of use in addition to processes of production. The bill was jointly referred to a House Judiciary/Courts Subcommittee and the Ways & Means/Trade Subcommittee. No further action has been scheduled on the legislation.