Intra-tumoural RAMP1+ B cells promote resistance to neoadjuvant anti-PD-1-based therapy in oesophageal squamous cell carcinoma.

INTRODUCTION: The application of neoadjuvant immunotherapy in oesophageal squamous cell carcinoma (ESCC) reactivates anti-tumour immune responses and prolong postoperative survival. However, due to the heterogeneity of tumour microenvironment, limited patients have achieved pathological regression after treatment. The dual roles of B cells were recently highlighted in ESCC. The study aimed to investigate the role of B cell subclusters and the upstream signalling of B cell differentiation in ESCC resistant to immunotherapy. METHODS: Single-cell RNA sequencing was employed for ESCC specimens with distinct responses to neoadjuvant immunotherapy to map the landscape of intra-tumoural B cells. RESULTS: A novel subset of neuropeptide receptor, receptor activity-modifying protein 1 (RAMP1) positive B cells was revealed to accumulate in ESCC that is resistant to neoadjuvant immunotherapy. Stimulated by nociceptor neurons secreting calcitonin gene-related peptide (CGRP), RAMP1(+) B cells exhibit an immunosuppressive phenotype. The elevated secretion of immune-regulating cytokines by RAMP1(+) B cells blunts the cytotoxicity of Cluster of Differentiation (CD)8(+) T cell and leads to tumour immune evasion. A combination of RAMP1 blocker and anti-Programmed cell death protein (PD)-1 therapies synergistically reinvigorated anti-tumour immunity, reducing tumour progression in vitro. CONCLUSION: The study suggests that RAMP1(+) B cells play a critical role in mediating resistance to neoadjuvant immunotherapy in ESCC. Targeting the CGRP-RAMP axis remodels B cells and enhance the efficacy of current immunotherapies, providing new strategies for overcoming treatment resistance.