Design of Clinical Trials

Clinical trial design for nuclear medicine diagnostic imaging radiopharmaceuticals must include a design for preclinical safety studies. These studies should establish that the investigational product (IP) does not have a toxic effect. As a further requirement, radiopharmaceutical clinical trials include a human study (phase 1) that provides biodistribution, pharmacokinetics, and radiation dosimetry information. These studies demonstrate to the Food and Drug Administration that the IP either meets or exceeds the toxicology and radiation exposure safety limits. Satisfying this requirement can result in the Food and Drug Administration approving the performance of late-phase (phase 2/3) clinical trials that are designed to validate the clinical efficacy of the diagnostic imaging agent in patients who have a confirmed diagnosis for the intended application. Emphasis is placed on the most typical trial design for diagnostic imaging agents that use a comparator to demonstrate that the new IP is similar in efficacy to an established standard comparator. Such trials are called equivalence, or noninferiority, trials that attempt to show that the new IP is not less effective than the comparator by more than a statistically defined amount. Importantly, the trial design must not inappropriately favor one diagnostic imaging agent over the other. Bias is avoided by the use of a core laboratory with expert physicians who are not involved in the trial for interpreting and objectively scoring the image sets obtained at the clinical trial sites. Clinical trial design must also follow Good Clinical Practice (GCP) guidelines. GCP stipulates the clinical trial process, including protocol and Case Report Form design, analyses planning, as well as analyzing and preparing interim and final clinical trial/study reports.