They have to measure how much (if any) systemic absorption there is. The enema-version trial tells us that it works when applied locally. The question is going to be in which portion of the intestines is the stuff released, and does it survive to coat the area that they want treated? So we know that it works from the enema trial, but we do not know if the pill is the best way to administer it.

That means that the enema-form trial is not really going to help with this clinical trial, as the method of delivery is so very different.