Review of SWOG S1314: Lessons from a Randomized Phase II Study of Co-Expression Extrapolation (COXEN) with Neoadjuvant Chemotherapy for Localized, Muscle-Invasive Bladder Cancer

SWOG1314 is a randomized phase II study of co-expression extrapolation (COXEN) with neoadjuvant chemotherapy for localized, muscle-invasive bladder cancer. COXEN is a biomarker approach in which predictive biomarkers are developed using in vitro data, which may then be applied directly into a clinical testing application. Two separate Gene Expression Models (GEMs), one for the Methotrexate, Vinblastine, Doxorubicin, Cisplatin (MVAC) regimen and another for gemcitabine plus cisplatin (GC) were tested in S1314. The lessons learned from the development and operationalization of the S1314 clinical trial are described in detail, which may help to inform the future trials of predictive biomarkers for urothelial carcinoma in the neoadjuvant setting. Specific areas addressed include: The need for broad support from the bladder cancer community, planning for non-evaluable subjects, defining adequate neoadjuvant treatment, defining adequate tissue collection, setting expectations in phase II clinical studies of predictive biomarkers, and maximizing the impact of the samples collected in these studies for broader biomarker development. With a large number of newly available treatments in advanced urothelial carcinoma in the last few years, more investigations of these agents in the neoadjuvant setting is anticipated. There will be a great need for the development of predictive biomarkers in conjunction with the use of these agents in the preoperative setting. Insights from S1314 may provide useful information and lessons learned in this development.