Evaluating the Optimal Duration of Immunotherapy in Kidney Cancer.

Immune checkpoint inhibitor (ICI) therapy has rapidly altered the landscape of treatment of metastatic renal cell carcinoma (mRCC), resulting in significant improvements in outcomes for patients with this disease. Nivolumab, an antibody inhibiting the programmed death-1 (PD-1) receptor, was first approved for treatment of refractory mRCC, on the basis of the Phase III CheckMate 025 study comparing nivolumab to everolimus; in this study, patients were treated with nivolumab until development of progression or unacceptable toxicity [1]. More recently, several Phase III randomized controlled trials have established the benefit of incorporating ICI therapy to the first-line treatment of patients with mRCC, conferring durable responses in a subset of patients [2–5]. For patients who do have durable responses to ICI therapy, we are often faced with a quandary of how long to continue treatment. We may be at a point now to examine this clinical question in a prospective fashion. Similar to the CheckMate 025 study, the CheckMate 214 study evaluating nivolumab plus ipilimumab in comparison to sunitinib in patients with treatment-naïve mRCC continued treatment with nivolumab indefinitely until disease progression or toxicity [2]. On the other hand, the KEYNOTE-426