Neoadjuvant camrelizumab combined with metronomic chemotherapy in patients with advanced esophageal squamous cell carcinoma: a pilot randomized phase 2 trial

Abstract Background Compared to conventional chemotherapy, metronomic chemotherapy (MCT), with lower drug dosage which may cause less damage to the immune system, has shown potential for synergy in combination with PD-1-based immunotherapy. However, this synergistic immunotherapy efficacy in neoadjuvant setting for advanced esophageal squamous cell carcinoma (ESCC) requires further clinical validation. Methods This pilot phase 2, single-center, randomized clinical trial enrolled 30 untreated patients with resectable stage II or III ESCC. Participants were randomly assigned to either the MCT group (paclitaxel, cisplatin, and 5-fluorouracil) or the IO + MCT group (same regimen plus camrelizumab). Primary outcomes included the pCR rate after neoadjuvant therapy, and the safety of each regimen assessed by adverse events. Digital spatial profiling (DSP-WTA), multiplex immunofluorescent staining (mIF), and bulk RNA sequencing were performed to explore the possible therapeutic mechanisms. Results Twenty-four patients (13 in MCT, 11 in IO + MCT) underwent R0 resection. The pCR rates were 15.4% in the MCT group and 54.5% in the IO + MCT group. Both treatments were well tolerated, with manageable side effects. DSP-WTA and mIF revealed that IO + MCT effectively decreased the number of tumor-infiltrating T cells with the positive expression of terminal exhaustion marker CD39 and increased the number of primary and secondary follicle-like tertiary lymphoid structures (TLSs), particularly in pCR patients. Conclusions Neoadjuvant MCT combined with camrelizumab led to an increased pCR rate (54.5 vs. 16.7%) in ESCC patients compared to MCT alone. This combination therapy may offer a promising approach for enhancing cancer treatment outcomes. Trial registration ClinicalTrials.gov identifier: ChiCTR2000039638.