Background: The combination of anti-VEGF or anti-EGFR targeted drugs with chemotherapy is considered as the standard first-line therapy for metastatic colorectal cancer (mCRC), and maintenance treatment is proven to be a promising and controversial therapeutic strategy which is mainly involved bevacizumab or capecitabine. However, studies regarding the maintenance strategies based on antiangiogenic TKIs are limited currently. Anlotinib is a novel oral multi-target TKI which can inhibit both tumor angiogenesis and tumor cell proliferation simultaneously. Previous studies indicated that anlotinib demonstrated clinical benefits for patients with mCRC. This study aimed to evaluate the efficacy and safety of anlotinib plus XELOX as first-line treatment followed by anlotinib maintenance therapy for mCRC. Methods: ALTER-C-001 trial was an open label, single-arm, multicenter phase II study. A calculated sample size of 53 patients with previously untreated mCRC, ranging from 18-75 years old and an ECOG performance status ≤ 1 were planned to recruit. Eligible patients were treated with capecitabine (1000 mg/m², po, d1-14, q3w) and oxaliplatin (130 mg/m², iv, d1, q3w) plus anlotinib (10mg, po, d1~14, q3w) for 6 cycles followed by maintenance therapy of anlotinib (12mg, po, d1~14, q3w) until disease progression or intolerable adverse events (AEs). The primary endpoint was progression-free survival (PFS). Secondary endpoints were ORR, DCR, DOR and safety. Results: From January 2020 to September 2020, a total of 9 patients were enrolled, 6 patients were available for efficacy assessment. In best overall response assessment (all confirmed), there were 66.7% PR (4/6), 16.7% SD (1/6) and 16.7% PD (1/6). The preliminary ORR and DCR of the 6 patients was 66.7% (95% CI, 22.3-95.7%) and 83.3% (95% CI, 35.9-99.6%), respectively. The median PFS was not reached. Most treatment-related adverse events (TRAEs) were grade 1-2. Grade 3 or above TRAEs were as follows: hypertriglyceridemia (33.3%), hypertension (16.7%), neutropenia (16.7%) and lipase elevated (16.7%). No grade 5 AEs were observed. Conclusions: The preliminary results indicated that anlotinib plus XELOX regimen followed by anlotinib monotherapy as first-line treatment exhibited antitumor efficacy and manageable toxicity for patients with mCRC. The study is still ongoing and the data will be updated subsequently. Clinical trial information: ChiCTR1900028417.