How Read undersubmission Request Property from CA

Question

I used this code to generate undersubmissionRequest in CA

nDisposition = ICertRequest.Submit(Flag, Request, sAttributes, sServerConfig);

and when nDisposition == 5 (CR_DISP_UNDER_SUBMISSION) I use this code:

 CARequestID = ICertRequest.GetRequestId();
 DespositCode = ICertRequest.RetrievePending(CARequestID , sServerConfig);

but I want to Get undersubmisionRequest PublicKey. How can I get it?