Restricted mean duration of response as a novel efficacy measure, in patients receiving nivolumab+ipilimumab immunotherapy or sunitinib for advanced kidney cancer

In clinical trials investigating novel drug regimens for patients with advanced cancers, one measure of how well a treatment is working is to examine the change in size of tumor as seen on imaging (e.g., CT scan or MRI); if the tumor size has reduced by at least 30% then this is denoted as a “response” to treatment according to a standard set of criteria (called Response Evaluation Criteria in Solid Tumors (RECIST)). A complementary measure aims to helps to understand if this response is durable; the measure called “duration of response,” is the interval of time between the imaging when the tumor first is documented to have reduced by at least 30% until subsequent imaging shows the tumor has increased in size by more than 20% from where it began, or tumor “progression.” When duration of response is analyzed for participants of a clinical trial, the analysis uses the information only from the subset of patients whose tumors respond; for those whose tumors do not meet the designation of response, their experience is not included.
A new approach, calculating and analyzing a measure called “restricted mean duration of response,” proposes to use the experiences of all patients to better understand if tumor responses are durable, and in doing so to also incorporate both the proportion of patients whose tumor responds and how long it takes from initiation of treatment until the tumor responds. This measure provides a more complete picture of the experiences of all patients.
In this project, I will apply the new approach and the traditional approach to the experiences of people with metastatic kidney cancer (kidney cancer that has spread to other parts of the body) who participated in a clinical trial comparing a immunotherapy regimen (nivolumab in combination with ipilimumab) to a standard targeted therapy regimen (sunitinib). By doing this, I hope to better provide insight to the research community about the analysis and interpretation of this new approach.