Efficacy and safety of camrelizumab and apatinib combined with neoadjuvant concurrent chemoradiation for MSS locally advanced rectal cancer.

Abstract

e15647 Background: Long-term neoadjuvant concurrent chemoradiotherapy (CRT) is the standard therapy for local advanced rectal cancer (LARC).However, the pCR rate is only about 15 %. Immune checkpoint inhibitors (ICIs) and antiangiogenic agents have shown activity in advanced rectal cancer, but their efficacy in the neoadjuvant setting is unclear. In this exploratory trial, we evaluate the efficacy and safety of a combination of ICI (Camrelizumab), anti-angiogenesis (Apatinib) and CRT for neoadjuvant treatment of microsatellite-stable (MSS) LARC. Methods: Patients in experimental group received Camrelizumab injection combined with Apatinib tablets and concurrent CRT. Radiotherapy dose: 5040cGy/28f/180cGy; Capecitabine 825 mg/m2 bid on the radiotherapy day; Apatinib 250mg qd d1-d60; Camrelizumab 200 mg q3w, d22, d43, d64. Surgery with total mesorectal excision was performed 7-9 weeks after the end of CRT. The primary endpoint was pCR rate and the secondary endpoints included major pathological response (MPR) rate, R0 resection rate, 2-year DFS rate, 3-year OS rate and safety. Results: From July/2022 to October/2022, a total of 11 patients were recruited and assessed, 90.91% (10/11) of which is at high-risk (cT3 with any MRF involved, any cT4a/b, lateral node +, HLARC). Out of the 11 patients evaluable for pathological response, 4 (36.36%) patients achieved a pCR (AJCC grade 0) and 7 (63.64%) obtained a MPR(AJCC grade 0+1)(table). All patients achieved R0 resection and downstaging. Treatment-related severe adverse events were observed in 3 patients (grade 3-4 transaminase elevations); all fully recovered and received radical surgery. No treatment-related deaths were observed. Conclusions: A promising pCR rate of 36.36%, with mild toxicities, was shown in MSS LARC patients treated with neoadjuvant Camrelizumab combined with Apatinib and long-term CRT plus radical surgery, suggesting the candidate therapy for the future non-surgical approach. Clinical trial information: ChiCTR2100053040 . [Table: see text]