Shares of Halozyme Therapeutics (NASDAQ: HALO) plunged by more than 55 percent this evening, after the 14-year-old biopharmaceutical said FDA regulators have raised concerns about the potential effects its adjunctive enzyme technology might have on human fertility and reproduction.
In a statement released after regular trading, San Diego-based Halozyme says a complete response letter issued by the FDA’s Center for Biologics Evaluation and Research (CBER) asks for additional preclinical data to support a Biologics License Application submitted by Baxter, the Illinois pharmaceutical giant.
Until key questions can be addressed, the regulators asked Halozyme to halt the use of its enzyme in human patients in clinical studies with Baxter and ViroPharma, a Pennsylvania pharmaceutical focused on viral diseases. Baxter had submitted its application for an experimental drug called HyQ, which combines Baxter’s disease-fighting immunoglobulin product with Halozyme’s proprietary product, an enzyme called recombinant human hyaluronidase, or rHuPH20. Baxter is developing HyQ as a treatment for immune deficiency disorders that would be faster acting and easier to administer than an intravenous drip.
Baxter and Halozyme had disclosed on April 16 that the FDA was seeking additional information “related to the long-term chronic use of HyQ” to complete its review. No details were provided at the time.
In today’s statement, Halozyme says, “The primary issues raised in the letter focused on non-neutralizing antibodies generated against recombinant human hyaluronidase and the possible effects of these antibodies on reproduction, [fetal] development, and fertility.”
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