Study of Avastin in Combination With Chemotherapy for the First Line Treatment of RAS Mutant Unresectable Colorectal Liver-limited Metastases

Patients will be eligible for inclusion if the patients have histologically confirmed colorectal adenocarcinoma with RAS mutant liver-confined metastases deemed non-resectable. Eligible patients will be randomly assigned to chemotherapy plus avastin (arm A) or chemotherapy alone (arm B). Treatment will continue until tumor response indicates suitability for surgery for liver metastases or until disease progression or unacceptable toxic effects. The primary endpoint is the conversion rate to radical resection for liver metastases，which will be assessed by local multidisciplinary team (includes more than three liver surgeons and one radiologist) with the use of contrast-enhanced CT or MRI after 4 cycles and then every other 4 cycles up to 12 cycles. To provide an objective assessment of changes in resectability, radiological images will be presented by a radiologist to more than 3 liver surgeons, who are blinded to the clinical data. Patients will be considered resectable if 50% or more of surgeons vote for radical resection of LM. For patients whose liver-metastases are assessed resectable, resection should be scheduled to be performed within 2~3 weeks of the last treatment cycle. Following resection, patients will be advised to continue the same therapeutic regimen until the treatments reach a sum of 12 cycles.