A question for topos theorists.

I have recently come across a question, which seems to me natural, and before trying to solve it, I wanted to know if an answer was already known. If E is a category with pullbacks so is the category Cat(E) having as objects the internal categories of E and and as maps the internal functors F: A ---> B. I shall say that such an F is a "Pi-functor" if the pullback functor: Cat(E)/B --->Cat(E)/A has a right adjoint Pi/F: Cat(E)/A---->Cat(E)/B When E=Set there is a well known Conduché-Giraud condition characterizing such functors. Is there such a characterization when E is an (elementary) topos? If there is, what is the condition and where can it be found? Best wishes to all, Jean