Hypoxic transcriptomes predict survival and tumor-infiltrating immune cell composition in cutaneous melanoma

Hypoxia has established associations with aggressive tumor phenotypes in many cancers. However, it is not currently understood whether tumor hypoxia levels map to distinct immune infiltrates in cutaneous melanoma, potentially unveiling novel therapeutic targets. To this end, we leveraged a previously identified seven-gene hypoxia signature to grade hypoxia levels of 460 cutaneous melanomas obtained from the Broad Institute GDAC Firehose portal. CIBERSORTx (https://cibersortx.stanford.edu/) was employed to calculate the relative abundance of 22 mature human hematopoietic populations. Clinical outcomes and immune cell associations were assessed by computational means. Results indicated that patients with high-hypoxia tumors reported significantly worse overall survival and correlated with greater Breslow depth, validating the in-silico methodology. High-hypoxia tumors demonstrated increased infiltration of activated and resting dendritic cells, resting mast cells, neutrophils, and resting NK cells, but lower infiltration of gamma-delta T cells. These data suggest that high tumor hypoxia correlates with lower survival probability and distinct population differences of several tumor-infiltrating leukocytes in cutaneous melanomas.