Human HNSCC lines CAL-33, CAL-27, SCC-9, and SCC-25 were obtained from ATCC and maintained in the Dulbecco’s Modified Eagle Medium/Nutrient Mixture F-12 (DMEM/F-12) + GlutaMAX™ media supplemented with 10% heat inactivated fetal bovine serum (FBS) and 100 U/ml penicillin streptomycin. Mouse oral squamous cell carcinoma models, MOC1-esc1 and MOC2, were maintained in IMDM/Hams-F12 (2:1) supplemented with 5% heat inactivated FBS, 100 U/ml penicillin streptomycin, 5 ng/ml EGF (Millipore), 400 ng/ml hydrocortisone (Sigma Aldrich), and 5 μg/ml insulin (Sigma Aldrich). Cell lines were routinely tested for mycoplasma and underwent short tandem repeat (STR) cell line authentication at the DFCI within 6 months of use. MOC1-esc1, an anti-PD-1 resistant line, is isogenic to the previously described MOC1 model (27 (link)). Derivation and further characterization will be described elsewhere (Zhou et al., in preparation). C57BL/6 mice (6-week-old, females) were from Taconic and OT-1 mice were purchased from Jackson Labs (C57BL/6-Tg (TcraTcrb)1100Mjb).