All investigators must conduct the trial in strict compliance with which directive?

• A. The protocol, and as required by sponsor preference only.
• B. The protocol, and what the IRB/IEC approves.
• C. The protocol, and approvals by IRB/IEC or regulatory authorities as applicable.
• D. Any personal protocol changes the investigator desires.

Answer: (C)

Investigators must conduct the trial in strict compliance with the protocol and with the approvals by IRB/IEC or regulatory authorities as applicable. The protocol is the approved plan for how the study is conducted, while IRB/IEC approvals ensure ethical protection of participants and regulatory authorities’ approvals (where required) ensure lawful, compliant conduct in the jurisdiction. Sponsor preferences cannot override these approvals, and any changes to the protocol must go through proper amendments and approvals rather than being made at the investigator’s discretion.