A prospective, single-arm, single-center observational clinical study on envafolimab (PD-L1 inhibitor) in combination with XELOX for neoadjuvant treatment of locally advanced colon cancer.

Abstract

e15654 Background: Accumulating evidence supports the application of neoadjuvant chemotherapy for locally advanced colon cancer. The FOxTROT trial has demonstrated the feasibility of oxaliplatin-based neoadjuvant chemotherapy, yet only 8% of patients achieved major pathological response. There is urgent need to explore more effective therapeutic regimens. This study aimed to preliminarily investigate the efficacy and safety of envafolimab combined with XELOX as neoadjuvant therapy for locally advanced colon cancer. Methods: This was a prospective, single-arm, single-center observational clinical study enrolling newly diagnosed patients with locally advanced colon cancer (cT4 N0 M0 or cTx N+ M0). Eligible patients who signed the informed consent received 3 cycles of preoperative neoadjuvant therapy with XELOX (Oxaliplatin 130 mg/m², intravenous infusion, once every 3 weeks; Capecitabine 1000 mg/m², oral administration, once every 3 weeks) plus envafolimab 300 mg, subcutaneous injection, once every 3 weeks. Imaging evaluation was performed after treatment completion, followed by surgical resection. The primary endpoint was the proportion of patients achieving grade 0/1 tumor regression grading (TRG); secondary endpoints included R0 resection rate, pathological complete response (PCR) rate, objective response rate (ORR), disease-free survival (DFS), and safety profile. Results: As of November 28, 2024, a total of 29 eligible patients were enrolled. All 29 patients completed the planned 3 cycles of neoadjuvant therapy, with a 100% full-cycle completion rate (29/29), and the primary endpoint was evaluable in all cases. In the surgical population, 34.5% (10/29) of patients achieved grade 0/1 TRG, the R0 resection rate was 100%, and the PCR rate was 17.2% (5/29). With a median follow-up of 19.7 months (range, 10.2–30.4 months), the DFS rate was 100%. Notably, in the proficient mismatch repair (pMMR) population, the proportion of grade 0/1 TRG was significantly increased to 27.3% (6/22), with a PCR rate of 13.6% (3/22). No patients discontinued treatment due to grade ≥3 treatment-related adverse events. Conclusions: Subcutaneous injection of the anti-PD-L1 monoclonal antibody envafolimab induced significant tumor regression with a favorable safety profile in patients with locally advanced colon cancer. The combination of envafolimab and XELOX yielded encouraging efficacy and a high treatment completion rate. Clinical trial information: NCT05335460 .