AACR 2017 | Poster 2657/16 – PD-L1 blockade enhances T-cell cytotoxicity against Primary Mediastinal B-Cell Lymphoma

On Monday 3^rd April during this year’s American Association for Cancer Research (AACR) annual meeting, a poster (2657 / 16) by Tishi Shah, from New York Medical College, Valhalla, NY, et al. titled “PD-L1 blockade enhances T cell cytotoxicity against Primary Mediastinal B-Cell Lymphoma” was presented.

The group aimed to determine if PD-L1 blockade enhances T-cell responses in PD-L1 positive PMBCL.

Key Highlights:

• Karpas 1106p cells express a low level of PD-L1
• After treatment with IFNγ for 48 hrs, PD-L1 expression significantly increased
• Anti-PD-L1 did not significantly affect T-cell mediated inhibition of cell proliferation in Karpas 1106p cells with low PD-L1 expression
• Anti-PD-L1 and T-cell treatment significantly inhibited cell proliferation in IFNγ treated Karpas 1106p cells versus treatment with T-cells alone (32±18% vs 3±3% at E:T = 5:1; P = 0.048)

The poster was concluded by stating that T-cell cytotoxicity was heightened by PD-L1 blockade against PMBCL cells. The blockade was dependent on PD-L1 expression, which can be enhanced by administering IFNγ. Future in vivo NSG xenograft studies are ongoing.