Single-cell RNA-seq analyses inform necroptosis-associated myeloid lineages influence the immune landscape of pancreas cancer.

Introduction: Tumor-infiltrating myeloid cells (TIMs) are key regulators in tumor progression, but the similarity and distinction of their fundamental properties in pancreatic ductal adenocarcinoma (PDAC) remain elusive. Method: In this study, we conducted scRNA-seq data analysis of cells from 12 primary tumor (PT) tissues, 4 metastatic (Met) tumor tissues, 3 adjacent normal pancreas tissues (Para), and PBMC samples across 16 PDAC patients, and revealed a heterogeneous TIMs environment in PDAC. Result: Systematic comparisons between tumor and non-tumor samples of myeloid lineages identified 10 necroptosis-associated genes upregulated in PDAC tumors compared to 5 upregulated in paratumor or healthy peripheral blood. A novel RTM (resident tissue macrophages), GLUL-SQSTM1- RTM, was found to act as a positive regulator of immunity. Additionally, HSP90AA1+HSP90AB1+ mast cells exhibited pro-immune characteristics, and JAK3+TLR4+ CD16 monocytes were found to be anti-immune. The findings were validated through clinical outcomes and cytokines analyses. Lastly, intercellular network reconstruction supported the associations between the identified novel clusters, cancer cells, and immune cell populations. Conclusion: Our analysis comprehensively characterized major myeloid cell lineages and identified three subsets of myeloid-derived cells associated with necroptosis. These findings not only provide a valuable resource for understanding the multi-dimensional characterization of the tumor microenvironment in PDAC but also offer valuable mechanistic insights that can guide the design of effective immuno-oncology treatment strategies.

PD-1 blockade potentiates neoadjuvant chemotherapy in NSCLC via increasing CD127+ and KLRG1+ CD8 T cells.

The combination of PD-1 blockade with neoadjuvant chemotherapy (NAC) has achieved unprecedented clinical success in non-small cell lung cancer (NSCLC) compared to NAC alone, but the underlying mechanisms by which PD-1 blockade augments the effects of chemotherapy remain incompletely elucidated. Single-cell RNA sequencing was performed on CD45+ immune cells isolated from surgically resected fresh tumors of seven NSCLC patients receiving NAC or neoadjuvant pembrolizumab and chemotherapy (NAPC). Multiplex fluorescent immunohistochemistry was performed on FFPE tissues before and after NAC or NAPC from 65 resectable NSCLC patients, and results were validated with GEO dataset. NAC resulted in an increase only of CD20+ B cells, whereas NAPC increased the infiltration of CD20+ B cells, CD4+ T cells, CD4+CD127+ T cells, CD8+ T cells, CD8+CD127+ and CD8+KLRG1+ T cells. Synergistic increase in B and T cells promotes favorable therapeutic response after NAPC. Spatial distribution analysis discovered that CD8+ T cells and their CD127+ and KLRG1+ subsets were in closer proximity to CD4+ T/CD20+ B cells in NAPC versus NAC. GEO dataset validated that B-cell, CD4, memory, and effector CD8 signatures correlated with therapeutic responses and clinical outcomes. The addition of PD-1 blockade to NAC promoted anti-tumor immunity through T and B cells recruitment in the tumor microenvironment and induced tumor-infiltrating CD8+ T cells skewed toward CD127+ and KLRG1+ phenotypes, which may be assisted by CD4+ T cells and B cells. Our comprehensive study identified key immune cell subsets exerting anti-tumor responses during PD-1 blockade therapy and that may be therapeutically targeted to improve upon existing immunotherapies for NSCLC.