Background: Immunotherapy based combinations recently revolutionized the treatment of patients (pts) with advanced HCC, but its significance in earlier stages remains to be determined. TACE is commonly used as first line treatment in intermediate HCC, but outcome of patients treated with TACE in real-life cohorts is still poor with a median overall survival (OS) below 20 months. The aim of this study was to determine the safety and efficacy of TACE combined with nivolumab. Methods: This is a phase II trial, that recruited 59 patients at 10 sites in Germany between 06/2018 and 06/2020. Pts received up to two TACE treatments followed by nivolumab (240 mg/ Q2W), initiated on day 2-3 after the first TACE session and continued until progression for a maximum treatment duration of two years. Primary endpoint was ORR (mRECIST; with ORR exceeding 55% (power = 80%; actual beta 0.17) as promising for further investigations). Secondary endpoints include mPFS, mTTFS (median time to failure of strategy), mOS, QoL, and safety/tolerability. Tumor tissue was obtained at baseline and blood samples were collected longitudinally for translational research. Results: 49 pts (14.3% HCV and 8.2% HBV) were enrolled and received at least one dose of nivolumab, median tumor size was 4.5 cm (0.9 – 15 cm) and median number 3 (1 – 12). ORR by mRECIST was 71.4% (CR: 16.3%, PR: 55.1%, SD 4.1%, PD: 14.3%). At a median follow-up of 20 months, mPFS was 7.2 mo (95% CI; 5.3 – 11.2; 40 events), mTTFS was 11.2 mo (95% CI; 7.2, 13.5; 42 events) and mTTSST (median time to subsequent systemic therapy) was 24.9 mo (95% CI; 12.2, - ; 21 events). Median duration of Nivolumab was 8.3 months and mOS was 28.3 mo (95% CI; 20 – not estimable; 23 events). Grade ≥3 treatment-related adverse events occurred in 34.7% of patients. Correlative analysis of efficacy with genetic alterations, gene expression signatures and changes of immune cell populations will be reported soon. Conclusions: The study met its primary endpoint and provides evidence for the efficacy of TACE in combination with nivolumab without new safety signals in pts with intermediate HCC and no prior systemic therapy. Our findings support further evaluation of nivolumab-based combinations for the treatment of intermediate HCC. Disclaimer: This study was supported with drug and funding by Bristol-Myers-Squibb. Clinical trial information: NCT03572582.