Much attention has been paid to immune checkpoint inhibitors to various cancer treatments. In urothelial cancer, pembrolizumab was initially approved for patients who either recurred or progressed following platinum-based chemotherapy. For the platinum-fit population, although the standard first-line treatment is still platinum-based systemic chemotherapy, avelumab has been recently approved as a maintenance therapy for patients who have not had disease progression with four to six cycles of first-line chemotherapy. In addition, adjuvant nivolumab has just prolonged disease-free survival (DFS) by ~10 months, compared with placebo in patients with muscle-invasive bladder urothelial cancer or upper tract urothelial cancer at high-risk of recurrence after radical surgical resection. On the other hand, in kidney cancer, nivolumab was initially approved for advanced renal cell carcinoma patients after one or two prior anti-angiogenic therapies. Next, combinations of two immune checkpoint inhibitors (nivolumab + ipilimumab) and immune checkpoint inhibitor + tyrosine kinase inhibitors (pembrolizumab + axitinib and avelumab + axitinib) were approved for the first-line treatment for patients with advanced renal cell carcinoma. Recently, new generation tyrosine kinase inhibitors, such as cabozantinib and lenvatinib have been combined with immune checkpoint inhibitors. Both nivolumab + cabozantinib and pembrolizumab + lenvatinib have demonstrated superior progression-free survival and objective response rate, compared with sunitinib. So far, no prospective trials have demonstrated the duration of immune checkpoint inhibitor treatments. We are now doing the Japan Clinical Oncology Group 1905 trial, where patients with advanced renal cell carcinoma who have received an immune checkpoint inhibitor for 24 weeks are divided into two groups: those who continue immune checkpoint inhibitor treatment and those who discontinue immune checkpoint inhibitor treatment.
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