In this issue of Cancer Prevention Research, Cecil and colleagues show that nonsteroidal anti-inflammatory drugs (NSAID), celecoxib and naproxen, decrease the expression of programmed death-ligand 1 (PD-L1) and increase the influx of Type I tumor-infiltrating lymphocytes in colonic tumors. Importantly, both decrease of PD-L1 expression and increase of CD8+ T cells were associated with the inhibition of COX-2/PGE2 pathway in vitro and syngeneic colonic tumor xenograft models. This study clearly suggests that NSAIDs regulate the intratumoral immunity multiple ways, including suppression of expression of immune checkpoint blockade. Thus, NSAIDs should be considered as chemopreventive for patients with PD-L1-positive colonic polyp. See related article, p. 225.
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