1256P Three courses of neoadjuvant camrelizumab combined with chemotherapy in locally advanced esophageal squamous cell carcinoma (ESCC): A prospective phase II clinical trial

Abstract

Neoadjuvant chemotherapy with anti-PD-1 antibody has favorable effect for locally advanced ESCC. However, these trials only applied two courses of neoadjuvant protocols. The efficacy and safety of three courses regimen are poorly known. This study explored the three courses of camrelizumab plus chemotherapy for treating locally advanced ESCC in a prospective phase II trial. We planned to recruit locally advanced ESCC patients to received three courses of camrelizumab (200mg every 3 weeks) plus nab-paclitaxel (260 mg/m2 every 3 weeks) and capecitabine (1250 mg/m2 every 3 weeks) before undergoing surgery. The first endpoint was complete pathological response. The second endpoint was safety and feasibility. To further explore the biomarkers for predicting the efficacy, we performed extensive analyses using immunohistochemistry, WES and mutiplex immunofluorescence. From May 2020 to December 2021, a total of 47 patients was enrolled in Sun Yat-sen university cancer center. The ORR was 83%, 42 patients received surgery and R0 resection was achieved in all cases. 33.3% patients had a pCR and 64.3% had an MPR. The median follow-up was 12 months (range, 3-22 months). Only one patient died at 12th month after surgery due to cardiovascular diseases, and one patient had recurrence in the left main bronchus lymph node at 12th month. 1-year OS rate and 1-year DFS rate was 97.3% and 92.1%, respectively. The most common adverse events were grade 1-2, which did not delay the operation. The density of CD56dim NK cells in pretreatment tissues was significant higher in pCR+MPR group than non-responders group(P=0.0085). And after neoadjuvant treatment, the density of CD56dimNK cells significantly decrease in pCR+MPR group (P=0.00019). However, the PD-L1 expression and TMB had no difference between the two groups (P = 0.165, P = 0.627, respectively). Three courses of neoadjuvant camrelizumab combined with chemotherapy in locally advance ESCC had a favorable pathological response, with a manageable safety profile. Three courses regimen may achieve a better survival and patients with a higher density of CD56dim NK cells might benefit greatly from the regimen.