PDCD1 and tongue neoplasm: We observed that administration of the STING agonist ML-RR-CDA into flank tumors as a monotherapy resulted in a significant increase in the frequency of CTL (Granzyme B expressing functional CD8+ T cells) only in flank tumors, but that combined STING agonists and systemic α-PD-1 antibody treatment increased intratumoral CTL in both the flank and the tongue tumors relative to untreated mice.