Background: Conversion therapy for unresectable colorectal liver metastases (LM) can downsize tumours and create a situation where the patient has no evidence of disease (NED). We assessed the effectiveness of cetuximab plus mFOLFOXIRI or mFOLFOXIRI in this setting. Methods: FOCULM was a prospective 2:1 controlled, multicenter, phase II trial. Given no free drugs offered and the patients' affordability for cetuximab, the study design has been amended from randomization to non-randomization since September, 2016. Patients with unresectable LM were assigned to receive cetuximab (500mg/m²) plus mFOLFOXIRI (oxaliplatin 85 mg/m², irinotecan 165 mg/m², folinic acid 400 mg/m², 5-fluorouracil 2800mg/m² 46h infusion, every 2 weeks) (group A) or mFOLFOXIRI (group B). Primary endpoint was the rate of NED achieved, secondary endpoints were ORR, resection rate, the rate of local and ablative treatment (LAT), OS, PFS and DpR. Results: From February 2014 to July 2019, 114 patients were enrolled at 6 centers in China and 101 patients were in the ITT population (67 group A, 34 group B). Treatment groups were generally well balanced, although more patients with ≥5 LM were in group A. The rate of NED achieved was 62.7% in group A and 38.2% in group B (P = 0.020). At a median follow-up of 19.4 months, patients in group A had significantly prolonged the mOS, increased ORR, the rate of LAT and DpR compared with those in group B (Table). Patients with NED achieved yielded a significant survival benefit, whether in group A (Not reached vs. 49.4 months; P = 0.001) or group B (Not reached vs. 25.1 months; P = 0.007). Conclusions: The addition of cetuximab to a mFOLFOXIRI in patients with RAS/BRAF wild-type unresectable LM colorectal cancer significantly improved the rate of NED achieved, ORR and OS. Clinical trial information: NCT02063529