Abstract 939P
Background
RNAseq is a promising approach to monitor changes in the tumor microenvironment since it allows for multiple genes evaluation. We analyzed the differential immune expression pattern between pre- and post-treatment tissue samples of stage III NSCLC patients treated with neoadjuvant chemoimmunotherapy from the NADIM trial.
Methods
Tissue samples derived from pre- and post- neoadjuvant treatment bulk tumor were sequenced using the Oncomine® Immune Response panel which targets 395 genes related to immunological processes. Differential-expressed genes between paired samples and pathway enrichment analysis were assessed using DESeq2 and Gene Set Enrichment Analysis (GSEA). CIBERSORTx was used to estimate the proportions of immune cells subtypes. Results were correlated with pathological response: complete (CPR, n=7) and non-complete (non-CPR, n=4) tumors.
Results
CPR tumors showed differential expression of up to 74 genes between paired pre- and post-treatment tissue samples. Further analysis with GSEA reported an upregulation of interferon signalling, tumor antigens, type II interferon signalling and proliferation pathways in pre-treatment samples; whereas post-treatment samples revealed an upregulation of pathways related to lymphocyte infiltrate, antigen processing and TCR coexpression. In addition, post-treatment samples of CPR tumors showed higher proportion of CD8+ T cells (p=0.018), memory resting CD4+ T cells (p=0.018) and resting dendritic cells (p=0.028); and lower proportions of follicular helper T cells (p=0.028) and M1 macrophages (p=0.018). Regarding non-CPR, 8 genes were differentially expressed between pre- and post-treatment samples. GSEA analysis revealed an upregulation of lymphocyte infiltrate and TCR co-expression in post-treatment samples of non-CPR tumors. No differences were seen in the proportions of immune cells subtypes analysed.
Conclusions
The greatest changes in the immune expression profile during neoadjuvant treatment were observed in CPR tumors reflecting an active immune response. There were little differences between paired samples of non-CPR tumors that denotes ineffective immune stimulation after treatment.
Clinical trial identification
NCT03081689.
Editorial acknowledgement
Legal entity responsible for the study
Spanish Lung Cancer Group.
Funding
BMS, Thermofisher provided reagents for RNA-seq. Spanish Lung Cancer Group promoted the NADIM study. ‘‘Instituto de Salud Carlos III’’ (ISCIII), European Regional Development Fund (ERDF), Ministry of Science and Innovation, European Social Fund (ESF) and Comunidad de Madrid supported authors’ contracts.
Disclosure
All authors have declared no conflicts of interest.