Long-term Local Control Following CEA-targeted Fluorescence-guided Surgery in Patients With Locally Advanced and Recurrent Rectal Cancer.

Purpose: In our previous phase 2 trial, patients with locally advanced (LARC) or locally recurrent rectal cancer (LRRC) received SGM-101, a CEA-targeted fluorescent agent, to enable real-time near-infrared fluorescence (NIRF) guided surgery. This study demonstrated that SGM-101 enabled additional tumor removal in some patients and supported less invasive surgery in others. Despite this positive intraoperative effect, the impact on long-term tumor control is unknown. Therefore, in this article we report the long-term outcomes of all rectal cancer patients that participated to the trial.

Procedures: For all 29 LARC and LRRC patients that participated in the SGM-101 phase 2 trial, follow-up data were collected. Main outcome measure was 5-year local tumor control.

Results: The median follow-up of all patients was 5.0 years (IQR 4.5-5.5). Of the 12 LARC patients, three (25%) patients developed a local recurrence. The two patients in whom NIRF-guided surgery resulted in less invasive surgery remained locally recurrence-free. Among the 17 patients undergoing curative surgery for LRRC, 11 (65%) patients developed a local re-recurrence. Of the three patients who had an R0 instead of R1 as a direct result of SGM-101 guided surgery, one patient developed a local re-recurrence (33%), while the other two remained local recurrence-free.

Conclusions: This is the first study to report follow-up data on patients undergoing tumor-targeted NIRF-guided surgery. Although SGM-101 resulted in warranted changes in surgical management intra-operatively, no improved long-term benefit could be observed for the entire cohort. However, the subset of patients whose surgical approach was modified based on NIRF - either by performing less invasive surgery or removing additional malignant tissue-showed favorable long-term outcomes. Results from ongoing large trials are awaited.