Background: The CORRECT study showed significant overall survival (OS) improvement in the regorafenib (REG), compared with the placebo group in metastatic colorectal cancer (mCRC) which progressed after standard chemotherapy. In Japanese subgroup analysis, the hazard ratio of OS also indicated a tendency similar to overall population. The standard starting dose of REG is 160mg/body/d, and not adjusted according to body weight and height, race of the patients, or other parameters, however, some cases require dose reduction to 120mg/d or less due to adverse events (AE). Dose modification due to AE was observed frequently in Japanese compared with non-Japanese during the study (84.6% and 51.3%). Therefore, we performed this dose titration study to investigate efficacy and safety of REG. Methods: This single arm, multicenter phase II study evaluated lower initial dose of REG (120mg/d, for 21 days, followed by 7-day break) in mCRC progressed after standard chemotherapy. Dose escalation to 160mg was allowed in 2^nd and subsequent cycle, if patients developed < grade 2 AE, except for liver toxicity. Patients underwent radiographic evaluation every 8 wks. The primary endpoint was disease control rate (DCR: CR+PR+SD ≥ 6 wks). The major secondary endpoints included progression free survival (PFS), OS and safety. Results: Between September 10, 2015, and March 7, 2017, total 60 patients were enrolled into the study. Median age was 68.5 (range: 30-84), and ECOG PS 0/1 were 70%/30%. DCR was 36.7% (22/60); 7% (4/60) have had SD for 6 months or longer. Median PFS was 2.3 months (95% CI: 1.8 - 2.8). 3.3% of patients (2/60) had protocol defined REG dose escalation to 160mg; one case was from the cycle 2, and the other case was from the cycle 4. 42% (25/60) had dose reduction to 80mg due to AE, and that dose reduction was needed in 10% (6/60) at the first cycle. Grade 3-4 adverse events were observed in 55% (33/60). Conclusions: Starting dose of REG 120mg appears to have comparable efficacy to 160mg. Adverse events were generally consistent with the known safety profile of REG in this setting. Final results with additional follow-up on efficacy and safety outcome measures will be provided at the meeting. Clinical trial information: UMIN000018968.