Table 2.

Treatment of human tumor cell lines with IFNγ increases PD-L1 surface expression in all cell lines tested, but increases ADCC sensitivity using anti–PD-L1 avelumab plus PBMCs in only some of the cell lines

Cell lineTissue type% Positive cellsNormalized MFIPD-L1 scoreADCC (% lysis)
SW900 + IFNγLung10071728
H460 + IFNγLung10020524.3
H520 + IFNγLung971556.5
COLO205 + IFNγColon8212518.4
HT29 + IFNγColon9218519.6
SW403 + IFNγColon57642.7
SW1116 + IFNγColon921356.7
HTB1 + IFNγBladder9931620.6
HTB4 + IFNγBladder10053724.4
HTB5 + IFNγBladder10015513.3

NOTE: Ten human tumor cell lines were untreated or treated with 20 ng/mL of IFNγ for 24 hours before flow cytometry and being used in in vitro ADCC assays as described in Materials and Methods. Data are presented as % PD-L1–positive cells and normalized PD-L1 MFI (ratio of PD-L1 MFI to control MFI). Each tumor cell line was also scored on a quartile scale (range, 1–4) for both % PD-L1–positive cells and PD-L1 MFI. The combined score of % PD-L1–positive cells and MFI (range, 2–8) was termed the PD-L1 score for the tumor cell line. All data were analyzed using PBMCs as effectors, an avelumab concentration of 40 μg/mL, and an E:T ratio of 100:1. Lysis shown is the mean of triplicate wells. No lysis was observed in the presence of avelumab and absence of PBMCs.