Tissue B-cell receptor repertoire as biomarker of complete pathological response in NSCLC patients treated with neoadjuvant chemoimmunotherapy (NADIM trials)

Neoadjuvant chemoimmunotherapy (CI) for potentially resectable stage IIIA NSCLC yields high percentages of complete pathological responses (CPR). However, not all patients achieve CPR, and current biomarkers (PD-L1 and TMB) have limited sensitivity for predicting clinical outcomes. On the other hand, the presence of tertiary lymphoid structures has been associated with better responses to immunotherapy, but the role of B-cells and B-Cell Receptor (BCR) repertoire is largely unknown. Here, using tissue samples from NADIM I and II trials, we analyze the tumoral BCR repertoire and its association with CPR. RNAs extracted from pre- and post-neoadjuvant treatment 59 tumor samples of 43 patients enrolled in NADIM I (n = 33) and II (n = 10) trials were sequenced using the Oncomine® BCR IGH SR Assay (ThermoFisher). BCR clones and lineages metrics (count, Shannon diversity, evenness and convergence) were analysed, as well as clonal/lineage space, defined as the summed frequency of clones/lineages belonging to a frequency group (top <1%, 1–2%, 2–5% and >5%) relative to the total BCR repertoire. Results were correlated with pathological response groups: CPR (n = 23) and non-CPR (n = 20). In pre-treatment samples (n = 19), CPR tumors (n = 8) showed significantly lower BCR diversity and evenness than non-CPR tumors (n = 11) in both clones and lineages (p = 0.051 and p = 0.026 for clonal and lineage diversity; p = 0.020 and p = 0.026 for clonal and lineage evenness). Additionally, pre-treatment samples showed higher clonal and lineage space occupied by the top 1% clones/lineages in patients who achieved CPR vs those that did not (p = 0.021 and p = 0.012). No significant differences were found in total clone count and convergence. In post-treatment samples (n = 40), no differences were observed in any clonal/lineage derived metrics between CPR (n = 22) and non-CPR tumors (n = 18). Our results support the association between an uneven and less diverse distribution of B cell clones and lineages proportions at diagnosis with complete pathological response after neoadjuvant CI.