Short-course radiotherapy (SCRT) followed by fruquintinib plus adebrelimab and CAPOX in the total neoadjuvant therapy of locally advanced rectal cancer (LARC): A multicenter, single-arm, open-label, phase II study.

Abstract

TPS3643 Background: For LARC patients (pts), long-course concurrent chemoradiotherapy or SCRT followed by chemotherapy is recommended by the NCCN guidelines (Version 1.2024) as neoadjuvant therapy. Compared with chemoradiotherapy, the addition of immune checkpoint inhibitors (ICIs) or anti-angiogenic drugs could further improve complete response (CR) rate in the neoadjuvant treatment of LARC. Fruquintinib, a highly selective small-molecule inhibitor of VEGFR-1, -2, and -3, has gained FDA approval for pts with metastatic colorectal cancer previously treated. For pts with LARC at high risk of recurrence, the CR rate of SCRT followed by chemotherapy was 29%. There is an urgent need for new therapeutical options to improve the CR rate in these pts. This study introduces an innovative approach, combining SCRT, chemotherapy, Fruquintinib, and ICIs as a total neoadjuvant therapy for high-risk LARC pts. Methods: This is a multicenter, single-arm, open-label, phase II study (NCT06234007) investigating the efficacy and safety of SCRT sequential fruquintinib, combined with adebrelimab (an anti-PD-L1 monoclonal antibody) and CAPOX in pts with LARC. Eligible participants were 18 years or older, with an ECOG PS of 0–1, and a biopsy-proven, newly diagnosed, primary, LARC, classified as high risk on pelvic MRI (with at least one of the following criteria: clinical tumour [cT] stage cT4a or cT4b, extramural vascular invasion, clinical nodal [cN] stage cN2, involved mesorectal fascia, or enlarged lateral lymph nodes), were mentally and physically fit for surgery. Total neoadjuvant therapy included SCRT (5 × 5 Gy over 5 days, 1-week rest) followed by six cycles of fruquintinib (4mg, qd, po, q3w. For the initial 6 pts in the safety run-in period, dosage was adjusted based on dose-limited toxicities in the 1st cycle) combined with adebrelimab (1200mg, iv, d1, q3w) and CAPOX (q3w). Subsequently, pts who did not reach clinical CR underwent total mesorectal excision, others received the “Watch and Wait” policy or surgery. Primary endpoint was CR rate (including clinical CR & pathologic CR). Secondary endpoints included 3-year event free survival rate, overall survival, R0 resection rate and adverse events (AEs). Exploratory endpoints aimed to evaluate the correlation between potential biomarkers and efficacy. Using PASS 15 software (version 15.0.5.0), in the Tests for One Proportion analysis, with a two-sided α of 5% and to guarantee the power over 80%. The null hypothesis of CR rate was 29%, and the alternative hypothesis was 51%, accounting for a 10% drop-out rate, resulting in a sample size of 39 pts. With the 6 pts in the safety run-in period, a total of 45 pts would be enrolled in the study. Until Feb 1, 2024, 7 of planned 45 pts have been enrolled. Clinical trial information: NCT06234007 .