What was different here is the relative levels of antibodies or titers. Levels of these antibodies in both the insulin and Herceptin studies were within the same levels posttreatment as seen in the pretreatment populations, or in other words, no signals of treatment boosting.
In the HyQ registration study, we observed antibody levels that were orders of magnitude higher than have previously been observed in any other repeat dose clinical trial, which is suggestive of some form of immune response with this combination. So it is possible that there is some form of interaction between these plasma derivatives that's leading to these high antibody levels, but further investigation is required.
However, it's still important to note that the antibodies have not been associated with any adverse events, and again, none of the samples were neutralizing against the rHuPH20 enzyme.
The Complete Response Letter for HyQ has requested additional preclinical data to support the BLA application and primarily focused on these elevated levels of non-neutralizing antibodies generated against rHuPH20 and any possible effects of these antibodies.So I want to reiterate that no adverse events related to these antibodies were seen in the Phase III HyQ registration trial. However, much like the standard battery of toxicology tests we've already completed in order to establish the safety profile of the rHuPH20 enzyme, the CRL has requested that we address any potential risk of exposure to the elevated enzyme antibody titers observed in the HyQ program through this similar battery of tests. Read the rest of this transcript for free on seekingalpha.com