Neoadjuvant short-course radiotherapy followed by camrelizumab and chemotherapy for locally advanced rectal cancer: 3-year survival from a phase 2 study.

Background: Neoadjuvant short-course radiotherapy (SCRT) followed by camrelizumab and chemotherapy has shown an encouraging pathological complete response rate (48.1%, primary endpoint) in patients with locally advanced rectal cancer (LARC). Here, we present the 3-year survival outcomes.

Methods: In this phase 2 trial, patients with previously untreated T3-4N0M0 or T1-4N + M0 rectal adenocarcinoma received 5 × 5 Gy SCRT over 5 days, followed by two cycles of camrelizumab (200 mg) and CAPOX regimen every 3 weeks after 1 week. Total mesorectal excision (TME) was scheduled 1 week after the completion of neoadjuvant treatment. The 3-year disease-free survival (DFS) and overall survival (OS) were evaluated in this analysis.

Results: A total of 30 patients were enrolled, of whom 28 (93.3%) had microsatellite stable status (MSS) and 27 (90.0%) underwent TME. With a median follow-up of 40.8 months, the median DFS and OS were both not reached, with the 3-year DFS and OS rates of 80.2% (95% CI 58.6-91.3) and 93.3% (95% CI 75.9-98.3), respectively. Additionally, there was a trend toward improved 3-year DFS and OS in patients with pCR, postoperative pathological node-negative status (pN0), baseline negative circumferential resection margin as assessed by MRI, baseline negative extramural venous invasion and a PD-L1 combined positive score of 1 or higher, as compared with those without these characteristics.

Conclusions: Our data support the potential efficacy of neoadjuvant SCRT followed by camrelizumab and CAPOX regimen in LARC, as indicated by 3-year survival outcomes, suggesting that this may be an alternative therapeutic strategy, especially with the potential to address an unmet need for MSS patients.

Trial registration: www.

Clinicaltrials: gov . NCT04231552.