Analysis Of Immune Correlates Using Anti-Pd-1 Checkpoint Blockade Immunotherapy Combined With Stereotactic Body Radiation Therapy

ResultsRT increased the population of tumor cells expressing ICAM-1 from 8.7+/-2.3% to 23.4+/-4.2%(p< 0.01) as well as VCAM-1. The increase in cell adhesion molecules correlated with an increase in antigen-specific T-lymphocytes in tumor-draining lymph nodes (DLN) and CD8 tumor infiltrating lymphocytes (TIL) when combined with anti-PD-1 CBI. Preliminary flow cytometric analysis from a Phase II clinical trial demonstrated an increase in a population of CD8+ CD45RA+ cells, from 37.5% before treatment to 55.7% after treatment in a patient who demonstrated a near complete response to combined therapy.ConclusionRT alone can modify expression of cell adhesion molecules and alter the tumor microenvironment. RT combined with CBI is clinically feasible and preliminary evidence suggests activation of specific anti-tumor T-cell subsets. Ongoing prospective studies will characterize the efficacy of RT …