Outcomes and endpoints of relevance in gynecologic cancer clinical trials

Drug development is paramount to improve outcomes in patients with gynecologic cancers. A randomized clinical trial should measure whether a clinically relevant improvement is detected with the new intervention compared with the standard of care, using reproductible and appropriate endpoints. Clinically meaningful improvements in overall survival and/or quality of life (QoL) are the gold standards to measure benefit of new therapeutic strategies. Alternative endpoints, such as progression-free survival, provide an earlier measure of the effect of the new therapeutic drug, and are not confounded by the effect of subsequent lines of therapy. Yet, its surrogacy with improved overall survival or QoL is unclear in gynecologic malignancies. Of relevance to studies assessing maintenance strategies are other time-to-event endpoints, such as progression-free survival two and time to second subsequent treatment, which provide valuable information on the disease control in the longer term. Translational and biomarker studies are increasingly being incorporated into gynecologic oncology clinical trials, as they may allow understanding of the biology of the disease, resistance mechanisms, and enable a better selection of patients who might benefit from the new therapeutic strategy. Globally, the endpoint selection of a clinical trial will differ according to the type of study, population, disease setting, and type of therapeutic strategy. This review provides an overview of primary and secondary endpoint selection of relevance for gynecologic oncology clinical trials.