Real-time 3D confirmation of complete ablation with margins as a local cure for colorectal liver metastases: the ACCLAIM trial

Abstract

Background: Treatment failure and local tumor progression (LTP) after thermal ablation (TA) have been attributed to insufficient minimal margin (MM) ablation zone coverage of the target tumor.

Methods: This prospective, open-label, multicenter, international trial will enroll approximately 275 patients with one to three colorectal liver metastases (CLM) (for a total of 330 tumors) each up to 2.5 cm in largest diameter, eligible for local cure using microwave ablation (MWA). Any FDA cleared or CE-marked MWA device can be used. MWA will be performed with the intent to create a MM of at least 5 mm and ideally ≥ 10 mm. MM size will be documented intraprocedurally with contrast-enhanced computed tomography (CECT) immediately post-MWA and again within 4-8 weeks after MWA using any FDA cleared or CE-marked image-processing software to provide a 3D assessment of the ablation zone (AZ) and MM. An independent assessment of the MM by a central physician reviewer with expertise on AZ assessments will be conducted within 7 days of the MWA with 3D image-processing confirmation software and again within 7 days after the 4-8 weeks post-MWA CECT. A MM of 5.0 mm will represent the necessary condition for technical success of MWA. For MMs under 5 mm, repeat MWA will be performed within the same session whenever feasible/safe, and/or within 30 days from detection of the insufficient MM to create a sufficient MM (> 5 mm). MM size will be correlated with time to local tumor progression (TTLP). Local progression-free (LPFS) and hepatic disease-free survival (accounting for all tumors ablated) stratified by MM of 5.0-9.9 mm and ≥ 10.0 mm will be assessed with Kaplan-Meier and competing risk methodologies.

Discussion: This study aims to demonstrate that MWA of CLM ≤ 2.5 cm with 3D image-processing confirmation software of MM over 5 mm achieves definitive local tumor control. This will help establish margin confirmation as a new standard of care for MWA of CLM.

Trial registration: ClinicalTrials.gov NCT05265169. Registered on January 13, 2023.

Keywords: 3D assessment of the ablation zone; Colorectal liver metastases; Minimal ablative margin; Thermal ablation.

Fig. 1

Study diagram

Fig. 2

Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) timeline. SOC, standard of care; CT, computed tomography; MRI, magnetic resonance imaging; QoL, quality of life. *Visits occur per standard of care every 3 months in the first year and every 6 months during the second year. For patients without local tumor progression for 2 years post-ablation, follow-up may be continued at approximately 1-year intervals, per SOC, until the trial ends. **Patients with technically unsuccessful ablation at the time of margin assessment (MM < 5.0 mm) may undergo repeat MWA at the discretion of the investigator