II. To determine differences in pre-treatment vs post-treatment tissue expression of immune markers, including programmed death ligand (PDL)1 and tumor infiltrating lymphocytes (cluster of differentiation [CD]8+, forkhead box P3 [FOXP3]+ regulatory t cells [Tregs], CD45RO, granzyme B), in patients treated with neoadjuvant pembrolizumab-based therapy.