Design Issues in Randomized Clinical Trials of Maintenance Therapies

A potential therapeutic strategy for patients who respond (or have stable disease) on a fixed-duration induction therapy is to receive maintenance therapy, typically given for a prolonged period of time. To enable patients and clinicians to make informed treatment decisions, the designs of phase III randomized clinical trials (RCTs) assessing maintenance strategies need to be such that their results will provide clear assessment of the relevant risks and benefits of these strategies. We review the key aspects of maintenance RCT designs. Important design considerations include choice of first-line and second-line therapies, minimizing between-arm differences in follow-up schedules, and choice of the primary endpoint. In order to change clinical practice, RCTs should be designed to accurately isolate and quantify the clinical benefit of maintenance as compared with the standard approach of fixed-duration induction followed by the second-line treatment at progression. To accomplish this, RCTs need to utilize an overall survival (or quality of life) endpoint or, in settings where this is not feasible, endpoints that incorporate the effects of the subsequent line of therapy (eg, time from randomization to second progression or death). Toxicity and symptom information over both the study treatment (maintenance) and the second-line treatment should also be collected and reported.