Background: Fumarate hydratase-deficient renal cell carcinoma (FH-RCC) is a rare and highly aggressive cancer mainly caused by germline or somatic aberrant of FH gene. Unfortunately, there are no standard treatment. Here we report the preliminary results of a phase II study investigating the efficacy and safety of sintilimab in combination with axitinib in patients with FH-RCC. Methods: Patients were treated at mutli-center in hospitals of the republic of China. Eligibility criteria included age ≥ 18 years and newly diagnosed as FH-RCC by FH immunohistochemistry and next-generation sequencing or multiplex ligation-dependent probe amplification. Patients received sintilimab (intravenous injection, every 3 week) in combination with axitinib (5mg, orally taken per day) as first-line treatment until disease progression or intolerant to treatment. The primary end point was objective response rate (ORR; RECIST v1.1). This study is registered with ClinicalTrials.gov, NCT04387500. Results: Between July 2021 and October 2022, 21 patients were enrolled. At this preliminary analysis (data cutoff, October, 2022), median follow-up was 9 months (0.9-15.2 months). Nineteen patients were available for efficacy assessment. Confirmed complete response rate was 15.8% (3/19), ORR was 63.1% (12/19). Disease-controlled rate (DCR) was 89.4% (17/19). The median of progression-free survival (PFS) was not reached, with a high 12-month PFS rate of 72.3%. All grade and ≥ 3 treatment-emergent adverse events occurred in 95% (20/21) and 23.8% (5/21), respectively. Conclusions: Sintilimab in combination with Axitinib had a manageable safety profile and achieved a promising tumor response rate in patients with advanced FH-RCC. The trial is an ongoing study, with a total of planned 41 patients from 8 sites. The study start date was June 2, 2021. Clinical trial information: NCT04387500.