Independent Nurse Prescribers in Clinical Trials

We are aware that it is acceptable for nurses who have undertaken the appropriate training, is within the scope of their job roles, is supported by the host site and delegated by the PI etc , to prescribe in CTIMPs.

We are still a little confused as to what oversight is required by a physician in these cases. It seems that we as as site are having the same question raised by many Sponsors and are being told that the decision to dose should be that of the medically qualified doctor. What is the interpretation of decision to dose ...
As the nurse in general is prescribing within the context of the study protocol which are usually clear when dose modifications /interruptions etc are required to be made is the nurse still expected to demonstrate that the medic has been involved with giving the go ahead /initiate the modifcation for the treatment ?

Our nurses are prescribing in oncology trials and patients may have many cycles of treatment, would it be an expectation for the medic to be involved at each cycle of treatment ?

Any further guidance on this point is welcomed.
Thank you

MHRA GCP guide (11.2.1) states "A PI must1 be an authorised health care professional, however they do not have to be a medically qualified doctor, although it should be noted that there are a number of trial related activities that are required2 to be performed by a medically qualified doctor (such as eligibility, [B]decision to dose[/B] and safety reviews)." The MHRA quotes a Regulation requiring this, schedule 1, part 2 (11) of SI 2004/1031. Therefore decision to dose must be conducted by a medically qualified doctor.

FDA final Guidance for Industry Investigator Responsibilities, Protecting the Rights, Safety, and Welfare of Study Subjects (Oct 2009), states "In all cases, a qualified physician (or dentist) should be responsible for all trial-related medical (or dental) decisions and care". This is also a theme shared by EU GCP Inspectors but specification as to what exactly are these "medical decisions" varies. Some of them do require eligibility, decision to dose and safety reviews to be performed only by a medically qualified doctor.