FOLFOX-based transarterial infusion chemotherapy for unresectable colorectal cancer: protocol of an open-label, multicentre, randomised, controlled, phase II trial.

introductionColorectal cancer (CRC) is the third leading cause of new cancer cases and the second leading cause of cancer-related deaths worldwide. Current therapeutic modalities for CRC include surgical resection, intravenous chemotherapy (IVC), radiotherapy, immunotherapy, targeted therapy and their combinations. As a mainstream systemic treatment for CRC, IVC leads to widespread drug distribution but relatively low intratumoural drug accumulation. Compared with IVC, transarterial infusion chemotherapy (TAIC) involves selective arterial catheterisation to deliver chemotherapeutic agents directly to the tumour feeding vessels. Hepatic tumours receive their blood supply predominantly through branches of the hepatic artery. Hepatic artery infusion chemotherapy (HAIC) yields significantly superior outcomes compared with IVC and is currently widely employed for the treatment of primary and secondary hepatic malignancies. HAIC in combination with IVC can offer long-term durable disease control in the clinical treatment of liver cancer compared with IVC. CRC is also predominantly grown through angiogenesis. Therefore, we raise the question whether sequential IVC administered after intensive TAIC achieves better clinical efficacy than IVC alone for the treatment of unresectable CRC (uCRC). However, no prospective clinical trials have been conducted to compare the efficacy of these two strategies. This prospective study was therefore designed to fill this clinical knowledge gap. METHODS AND ANALYSIS: This is a prospective, multicentre, randomised, open-label clinical trial. The uCRC is defined as inability to achieve an R0 resection owing to locally advanced CRC with clinical T4 disease confirmed by MRI or CT and/or synchronous liver metastases. This study only includes microsatellite stable or proficient mismatch repair uCRC. A total of 50 eligible patients will be randomly assigned to either the IVC group or the TAIC group. Patients in the IVC group will receive FOLFOX (fluorouracil, leucovorin, oxaliplatin)-based IVC every 2 weeks for a total duration of 8 weeks. Patients in the TAIC group will receive FOLFOX-based TAIC at week 0 and week 4 and receive FOLFOX-based IVC at week 2 and week 6. For patients with colorectal liver metastases, cetuximab or bevacizumab will be administered according to the RAS and BRAF status and the primary tumour site. The primary endpoint is the objective response rate. This study is scheduled to commence on 10 January 2026, and complete follow-up on 31 December 2027. The first subject was enrolled on 20 March 2026. To date, one subject in the IVC group and six subjects in the TAIC group have been enrolled. ETHICS AND DISSEMINATION: The present study protocol has been approved by the Medical Ethics Committee of Guang'anmen Hospital, China Academy of Chinese Medical Sciences (ethical approval number 2025-268 KY). On completion of the study, data cleaning and analysis will be performed, and the results will be disseminated at academic conferences and in international peer-reviewed journals. This trial has been registered at ClinicalTrials.gov. The statistical analysis plan will be finalised and approved before the database lock. The final version is retained in the study documentation and will be made available to support the transparency and interpretation of the study results. TRIAL REGISTRATION NUMBER: NCT07333053.