FDA reviewers question HyQvia's benefit-risk profile

FDA reviewers said the potential benefits of hematology product HyQvia from Baxter International Inc. (NYSE:BAX) must be weighed against unknown long-term risks of antibodies generated against recombinant human PH20 hyaluronidase ( rHuPH20), one of the product's components. HyQvia is a subcutaneous formulation of IV Gammagard, an IgG antibodies plasma-based therapy, and rHuPH20 from Halozyme Therapeutics Inc. (NASDAQ:HALO). The product is under review as replacement therapy to treat adults with primary immunodeficiency associated with defects in humoral immunity.

The reviewers said although HyQvia's short-term risks in clinical trials are acceptable, it is unknown whether PH20 antibodies developed as a result of HyQvia will penetrate tissues in testes, bowel and brain and cause adverse events such as infertility and inflammation in the bowel and brain. They said a pharmacovigilance plan to monitor such risks may not be feasible "as many years of subject and offspring follow up may be required." The reviewers also noted the main advantage of HyQvia compared to immune globulin without rHuPH20 is the lower frequency of dosing, and patients already have access to a variety of immune globulin products without exposure to rHuPH20. The comments came in briefing documents released ahead of Thursday's meeting of FDA's Blood Products Advisory Committee to discuss the resubmitted BLA for HyQvia. ...