Cyotoxicity in CD8+ T cells differs among adjuvant immune checkpoint blockade therapies

While immune checkpoint blockade therapies are commonly utilized during the course of metastatic cancer treatment, much remains unknown regarding the mechanisms underlying individual therapies. CD8+ T cells from 8 patients that had been treated with either adjuvant Ipilimumab or Nivolumab were compared to assess immunological differences between the therapies. CD8+ T cells from patients that had received Ipilimumab exhibited higher cytotoxic gene expression and pathway enrichment than those from patients that had received Nivolumab. Cytotoxic activity was especially driven by cluster 3 in both groups, with the proportion of CD8+ T cells in the cluster expanding significantly in Ipilimumab patients over the course of treatment, in contrast to Nivolumab patients where this pattern was not seen. This data suggests that, on the CD8+ T cell level, Ipilimumab and Nivolumab exhibit mechanistic differences that are driven by cytotoxic genes and pathways.