Figure S4.
A. Heatmap of CXC chemokines ligands (CXCL) based on pretreatment bulk RNA-seq data between responders and non-responders.
B. CCL5 expression in each MOC model cultured media with or without IFN-γ stimulation (100U/ml for 48 hours) were analyzed by CCL5-ELISA. n=2-3.
C. p value and r squared value calculated from Pearson correlation coefficient of cDC score and chemokine RNA expression are plotted. Broken line
represents a p value of 0.05.
D. Number of Xcr1+ DCs migrated using the migration assay described in Methods.
E. Distribution plots showing cumulative expression levels of CCL5 in various immune subtypes other than CD8+ T cells, based on scRNA-seq of
HNSCC patients prior to pembrolizumab. Left panel responders, right panel non-responders.
F, G. Comparison of CCL5 expression in bulk RNA-seq data from pre and post treatment samples in responders (F) and non-responders (G), shown
as z-score. n=6.
H. Violin plot showing CCL5 expression level in human dendritic cells between responders pre- and post-treatment based on scRNA-seq data
ARTICLE ABSTRACT
Neoadjuvant anti-PD1 (aPD1) therapies are being explored in surgically resectable head and neck squamous cell carcinoma (HNSCC). Encouraging responses have been observed, but further insights into the mechanisms underlying resistance and approaches to improve responses are needed.
We integrated data from syngeneic mouse oral carcinoma (MOC) models and neoadjuvant pembrolizumab HNSCC patient tumor RNA-sequencing data to explore the mechanism of aPD1 resistance. Tumors and tumor-draining lymph nodes (DLN) from MOC models were analyzed for antigen-specific priming. CCL5 expression was enforced in an aPD1-resistant model.
An aPD1-resistant mouse model showed poor priming in the tumor DLN due to type 1 conventional dendritic cell (cDC1) dysfunction, which correlated with exhausted and poorly responsive antigen-specific T cells. Tumor microenvironment analysis also showed decreased cDC1 in aPD1-resistant tumors compared with sensitive tumors. Following neoadjuvant aPD1 therapy, pathologic responses in patients also positively correlated with baseline transcriptomic cDC1 signatures. In an aPD1-resistant model, intratumoral cDC1 vaccine was sufficient to restore aPD1 response by enhancing T-cell infiltration and increasing antigen-specific responses with improved tumor control. Mechanistically, CCL5 expression significantly correlated with neoadjuvant aPD1 response and enforced expression of CCL5 in an aPD1-resistant model, enhanced cDC1 tumor infiltration, restored antigen-specific responses, and recovered sensitivity to aPD1 treatment.
These data highlight the contribution of tumor-infiltrating cDC1 in HNSCC aPD1 response and approaches to enhance cDC1 infiltration and function that may circumvent aPD1 resistance in patients with HNSCC.
