6503 Background: Adenoid cystic carcinoma (ACC) does not respond to cytotoxic chemotherapy. Several anti-angiogenic agents were evaluated in single arm phase II trials. However, the role of chemotherapy is still controversial, because of natural stable disease course without chemotherapy and lack of randomized trial. We firstly conducted a randomized trial to evaluate the efficacy of axitinib compared to observation. Methods: In this multicenter, prospective phase II trial, we enrolled recurred, metastatic ACC patients who progressed within 9 months. Patients were randomly assigned either axitinib (5mg twice daily) or observation arm with 1:1 ratio. Crossover to the axitinib arm was permitted for patients in the observation arm who had disease progression. The primary endpoint was 6-month progression-free survival (PFS) rate. The secondary endpoints included objective response rate (ORR), overall survival (OS), PFS, duration of response and adverse events. Results: A total of 60 patients randomly allocated to axitinib (N=30) and observation arm (N=30) and response evaluation was conducted in 57 patients. With a median follow-up of 25.4 months, the 6-month PFS rate was 73.2% (95% confidence interval [CI], 54.8 to 88.1%) in the axitinib arm and 23.2% (95% CI, 9.3 to 41.1%) in the observation arm (hazard ratio, 0.19; 95% CI, 0.08 to 0.45; P < 0.001). Median PFS was 10.8 months in axitinib arm and 2.8 months in observation arm ( P < 0.001). The ORR was 3.3% (95% CI, 0.1 to 17.2%) in the axitinib arm, and 0% (95% CI, 0 to 12.8%) in the observation arm. The disease control rate was 100% (95% CI, 88.4 to 100%) in the axitinib arm and 51.9% (95% CI, 32.0 to 71.3%) in the observation arm. After crossover, ORR of axitinib in the observation arm was 11.1% (95% CI, 2.4 to 29.2%). Median OS was not reached in axitinib arm, 28.5 months in observation arm ( P = 0.688). The most frequently reported adverse events of axitinib were grade 1 or 2 oral mucositis and fatigue. Detailed data of adverse events and mutational profile data will be presented. Conclusions: In this first randomized trial in patients with recurred or metastatic ACC, axitinib significantly increased 6-month PFS rate compared to observation. Clinical trial information: NCT02859012 .