Maintenance therapy in advanced non-small cell lung cancer: current status and future implications

Maintenance therapy for patients with advanced non-small cell lung cancer has been an area of intense investigation. Maintenance therapy has been divided into two broad categories: continuation maintenance when the chemotherapy or targeted agent was part of a defined number of cycles of combination therapy and in the absence of disease progression is continued as a single agent or switch maintenance when a third agent is initiated after four cycles of platinum-based double-agent chemotherapy in the absence of disease progression. Two monoclonal antibodies, cetuximab and bevacizumab, are used as continuation maintenance, but the incremental benefit of the maintenance therapy with these agents is undetermined. Phase III trials have not revealed an overall survival benefit for continuation maintenance chemotherapy, and this approach should be considered investigational. Phase III trials have demonstrated an improvement in overall survival with switch maintenance therapy with pemetrexed compared with placebo in patients with nonsquamous histology and erlotinib compared with placebo. Phase III trials have not revealed an improvement in quality of life with maintenance therapy. In the trials of maintenance therapy, 30 to 40% of patients enrolled in the observation or placebo arm did not receive second-line therapy, and among the patients who did receive second-line therapy, there was significant heterogeneity in the therapy. The development of maintenance therapy has raised issues about the role of treatment-free intervals in routine clinical care, trial design issues such as the optimal endpoint, the ethics of a placebo arm, and the implications of maintenance therapy for first-line trials.