Background: The combination of a checkpoint inhibitor with an anti-VEGF agent is a promising treatment strategy for advanced renal cell carcinoma (aRCC). Avelumab is a fully human IgG1 anti–PD-L1 antibody with clinical activity in aRCC and other tumor types (eg, Apolo et al. ASCO 2016; Gulley et al. ECC 2015). Axitinib is an anti-VEGF receptor tyrosine kinase inhibitor approved for second-line treatment of aRCC (Rini et al. Lancet 2011) that has also shown clinical activity as a first-line (1L) therapy (Hutson et al. Lancet Oncol 2013). In an ongoing phase 1b study in treatment-naïve patients (pts) with aRCC, avelumab + axitinib administered at standard monotherapy doses showed a tolerable safety profile and encouraging antitumor activity (Larkin et al. ESMO 2016). JAVELIN Renal 101 is a randomized, multicenter, phase 3 study (NCT02684006) comparing avelumab + axitinib vs sunitinib in pts with treatment-naïve aRCC. Methods: The primary objective is to demonstrate superiority of avelumab + axitinib vs sunitinib in prolonging progression-free survival (PFS) in the 1L treatment of pts with aRCC. Eligibility criteria include: aRCC with a clear cell component, ECOG PS ≤1, no prior systemic therapy for advanced disease, and measurable disease per RECIST v1.1. Approximately 583 pts will be randomized 1:1 and stratified based on ECOG PS (0 vs 1) and region (US vs Canada/Europe vs rest of the world). Pts receive either avelumab 10 mg/kg IV Q2W + axitinib 5 mg orally BID continuously (cycle length 6 weeks) or sunitinib 50 mg orally once daily for 4 weeks followed by 2 weeks off. Treatment is discontinued for unacceptable toxicity or if any other criteria for withdrawal are met. Pts may continue treatment beyond progression (RECIST v1.1) if investigator-assessed clinical benefit is achieved and treatment is well tolerated. PFS is assessed by blinded central review. Secondary efficacy assessments include overall survival, objective response, disease control, duration of response, and time to response. Safety, PK, and biomarker analyses will also be performed. The trial is currently active at 103 sites across 12 countries and as of Feb 2017, more than 40% of patients have been enrolled. Clinical trial information: NCT02684006