Total neoadjuvant treatment to increase the clinical complete response rate for distal locally advanced rectal cancer (TESS): A study protocol of a prospective, open-label, multicenter, single-arm, phase 2 trial.

Background: Standard treatment of locally advanced rectal cancer (LARC) was neoadjuvant chemoradiotherapy (CRT), followed by total mesorectal excision (TME). Total neoadjuvant treatment (TNT), a new concept, attempts to deliver both systemic chemotherapy and neoadjuvant CRT prior to surgery. Patients treated with neoadjuvant chemotherapy were more likely to show higher tumor regression. The objective of this trial was to increase complete clinical rate (cCR) for LARC patients by optimizing tumor response, using TNT regimen as compared to conventional chemoradiotherapy. TESS, a prospective, open-label, multicenter, single-arm, phase 2 study, is underway.

Methods: Main inclusion criteria include cT3-4aNany or cT1-4aN+ rectal adenocarcinoma aged 18-70y; Eastern Cooperative Oncology Group (ECOG) performance 0-1; location ≤5 cm from anal verge. Ninety-eight patients will receive 2 cycles of neoadjuvant chemotherapy Capeox (capecitabine + oxaliplatin) before, during, and after radiotherapy 50Gy/25 fractions, before TME (or other treatment decisions, such as Watch and Wait strategy) and adjuvant chemotherapy capecitabine 2 cycles. Primary endpoint is the cCR rate. Secondary endpoints include ratio of sphincter preservation strategy; pathological complete response rate and tumor regression grade distribution; local recurrence or metastasis; disease-free survival; locoregional recurrence-free survival; acute toxicity; surgical complications; long-term anal function; late toxicity; adverse effect, ECOG standard score, and quality of life. Adverse events are graded per Common Terminology Criteria for Adverse Events V5.0. Acute toxicity will be monitored during antitumor treatment, and late toxicity will be monitored for 3 years from the end of the first course of antitumor treatment.

Discussion: The TESS trial aims to explore a new TNT strategy, which is expected to increase the rate of cCR and sphincter preservation rate. This study will provide new options and evidence for a new sandwich TNT strategy in patients with distal LARC.