Background: Characterization of the peripheral blood T-cell receptor (TCR) repertoire has become a novel approach to predict the clinical benefit to anti-PD1/PDL1 therapy. However, there is lack of knowledge about the clinical relevance of TCR repertoire in terms of pathological response and clinical outcomes (PFS and OS) in chemo-immunotherapy. To answer this question we have analysed samples from the NADIM study (NCT03081689), in which resectable stage IIIA NSCLC patients were treated with neoadjuvant chemo-immunotherapy with Nivolumab. Methods: Using ION Torrent-based next-generation sequencing we have analysed TCR repertoire of peripheral blood from 30 patients receiving chemo-immunotherapy. Using 25ng of total RNA from PBMCs, clonal convergence, evenness and diversity were calculated at diagnosis (pre-treatment) and after 3 cycles of Nivolumab plus carboplatin (post-treatment). Regarding pathological responses, patients were classified in 3 groups: complete response (pCR) (0% viable tumour at the resection specimen), mayor response (pMR) ( < 10% viable tumour) and incomplete response (pIR) ( > 10% of viable tumour). At data analysis, PFS and OS median follow-up times were longer than 20 months. Results: No statistically significant differences in TCR repertoire in terms of evenness (p = 0,373), diversity (p = 0,691) or convergence (p = 0,054) between pre- and post-neoadjuvant treatment were observed. Similarly, no significant differences were observed in these metrics between pathological response groups. However, a detailed analysis of the clones showed that the percentage of frequent clones (greater than 0.1%) that increase after neoadjuvant therapy does show differences between the different pathological response groups (pIR vs pMR), being elevated in patients who presented responses greater than 90% (p = 0.0385). Regarding the clinical benefit, having this parameter higher than the median (43,90% in this cohort) is associated with a higher PFS (p = 0.0490) and OS (p = 0.078) using KM Log-rank test. Conclusions: Evenness, Diversity and Convergence derived from immune repertoire analysis do not appear to be clinically useful in the context of neoadjuvant chemo-immunotherapy in lung cancer. However, the detailed analysis of the clones seems promising. The increase of the most frequent clones after treatment seems to be associated to different clinical variables such as pathological response and PFS in these patients. Clinical trial information: NCT03081689