Kidney injury molecule 1 (KIM-1) is a promising biomarker in adjuvant clear cell renal cell carcinoma (ccRCC), but its relevance in advanced ccRCC or papillary RCC (pRCC) remains unclear. CALYPSO (NCT02819596) was a prospective, multi-arm trial that evaluated durvalumab alone or in combination with tremelimumab or savolitinib in metastatic ccRCC and pRCC.