The Food and Drug Administration has approved the first “follow-on” version of a human growth hormone, Omnitrope, a recombinant somatotropin made by Sandoz International GmbH.
The approval is notable in that it raises questions about the FDA's process for approving generic biologics. The agency says it still does not have the authority to license such generics. In the case of Omnitrope, the agency determined that it is not therapeutically equivalent to the human growth hormones currently on the market. Thus, Omnitrope is not considered a generic, but is instead deemed to be a follow-on product because it is “sufficiently similar” to Pfizer Inc.'s Genotropin, said the FDA.
Pfizer had filed a petition to block Omnitrope's approval, objecting to Sandoz's use of Pfizer data in its application, which was submitted in mid-2003. Sandoz, meanwhile, sued the FDA last September to force some action on its long-languishing application. In early April, a federal court ordered the agency to move one way or another.
The FDA said its Omnitrope approval did not set an automatic precedent for the approval of other follow-on or generic biologics, as human growth hormone has certain characteristics that make it uniquely suited to a relatively simple approval. Recombinant human growth hormone has only one known active ingredient, and its mechanism of action, toxicity, and efficacy is well understood, said the FDA.
Sandoz used both published data from Pfizer and conducted its own trial in pediatric patients to prove Omnitrope's safety and efficacy. In the 89-patient study, 44 children received Omnitrope and 45 another Genotropin for 9 months in a daily subcutaneous injection of 0.03 mg/kg. At 9 months, height velocity was similar for both, with a mean of 10.7 cm per year.
Omnitrope was approved for growth failure in pediatric patients and growth hormone deficiency in adults. The warnings and precautions for Omnitrope are similar to those for other growth hormone formulations. Patients with diabetes or glucose intolerance should be watched carefully as the drug can induce insulin resistance, according to the FDA-approved label.
In a press release announcing the approval, Sandoz did not comment on whether Omnitrope would cost less than competitors.