EPO ORPHAN EXCLUSIVITY WILL BE SUBJECT OF ADVISORY COMMITTEE
EPO ORPHAN EXCLUSIVITY WILL BE SUBJECT OF ADVISORY COMMITTEE MEETING scheduled for June 29. FDA's Blood Products Advisory Committee has been asked by FDA to consider the similarities and differences of the erythropoietin molecules in Amgen's Epogen and Chugai-Upjohn's Marogen to determine whether both products can be marketed under the current orphan regs. The EPO meeting marks the first time that FDA has taken an orphan exclusivity issue to an advisory committee. In 1987, the agency faced a similar problem with human growth hormone. However, FDA was confident enough that Genentech's Protropin and Lilly's Humatrope were different products because of the absence of a methionyl group in the Lilly product that the agency approved Humatrope without an advisory committee review. The orphan exclusivity issue again resurfaced with pentamidine; however, although FDA allowed Fisons to present data on its Pneumopent at the advisory committee reviewing Lyphomed's Nebupent, the committee was told that the orphan exclusivity issue was not part of the committee's agenda. Amgen's Epogen was approved in June 1989 and received orphan exclusivity in October for the treatment of anemia associated with chronic renal failure. Since that time, Chugai-Upjohn has petitioned the FDA to either rescind Epogen's orphan exclusivity or approve Marogen as a different product. The two companies, along with Marogen licensor Genetics Institute, have been locked in a legal battle involving the rights to the patent and marketing of EPO ("The Pink Sheet" April 23, T&G-12). Chugai-Upjohn has argued to FDA that EPO is not an orphan drug because the number of patients with chronic renal failure exceeds the 200,000 patient limit that defines an orphan disease ("The Pink Sheet" Feb. 12, p. 7). The company has also argued that FDA improperly granted Epogen orphan exclusivity by expanding the drug's original limited orphan designation of anemia associated with end-stage renal disease to include all chronic renal failure patients ("The Pink Sheet" Nov. 27, T&G-7). However, the committee will most likely focus on Chugai-Upjohn's contention that Marogen differs from Epogen structurally and, therefore, cannot be considered the same product. While Epogen and Marogen are indisputably identical in their amino acid sequences,Chugai-Upjohn has asserted that Marogen differs from Epogen in its glycosylation pattern (attachment of carbohydrates to the basic protein structure). All glycoproteins may exhibit some variations in glycosylation, Amgen has responded ("The Pink Sheet" Oct. 30, p. 5). A competitor might only have to change the host cell or conditions under which the product is synthesized to produce different, but biologically insignificant, patterns of glycosylation, the firm has argued.
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