Intra-Tumoral CD8+ T-Cell Infiltration and PD-L1 Positivity in Homologous Recombination Deficient Pancreatic Ductal Adenocarcinoma

oleh: Bryn Golesworthy, Bryn Golesworthy, Yifan Wang, Yifan Wang, Yifan Wang, Amanda Tanti, Amanda Tanti, Alain Pacis, Alain Pacis, Joan Miguel Romero, Joan Miguel Romero, Adeline Cuggia, Adeline Cuggia, Celine Domecq, Celine Domecq, Guillaume Bourdel, Guillaume Bourdel, Robert E. Denroche, Gun Ho Jang, Robert C. Grant, Ayelet Borgida, Barbara T. Grünwald, Anna Dodd, Julie M. Wilson, Guillaume Bourque, Guillaume Bourque, Grainne M. O’Kane, Grainne M. O’Kane, Sandra E. Fischer, Sandra E. Fischer, Chelsea Maedler Kron, Chelsea Maedler Kron, Pierre-Olivier Fiset, Pierre-Olivier Fiset, Atilla Omeroglu, Atilla Omeroglu, William D. Foulkes, William D. Foulkes, Steven Gallinger, Steven Gallinger, Steven Gallinger, Marie-Christine Guiot, Marie-Christine Guiot, Zu-Hua Gao, Zu-Hua Gao, George Zogopoulos, George Zogopoulos, George Zogopoulos

Format: Article
Diterbitkan: Frontiers Media S.A. 2022-04-01

Deskripsi

The immune contexture of pancreatic ductal adenocarcinoma (PDAC) is generally immunosuppressive. A role for immune checkpoint inhibitors (ICIs) in PDAC has only been demonstrated for the rare and hypermutated mismatch repair (MMR) deficient (MMR-d) subtype. Homologous recombination repair (HR) deficient (HR-d) PDAC is more prevalent and may encompass up to 20% of PDAC. Its genomic instability may promote a T-cell mediated anti-tumor response with therapeutic sensitivity to ICIs. To investigate the immunogenicity of HR-d PDAC, we used multiplex immunohistochemistry (IHC) to compare the density and spatial distribution of CD8+ cytotoxic T-cells, FOXP3+ regulatory T-cells (Tregs), and CD68+ tumor-associated macrophages (TAMs) in HR-d versus HR/MMR-intact PDAC. We also evaluated the IHC positivity of programmed death-ligand 1 (PD-L1) across the subgroups. 192 tumors were evaluated and classified as HR/MMR-intact (n=166), HR-d (n=25) or MMR-d (n=1) based on germline testing and tumor molecular hallmarks. Intra-tumoral CD8+ T-cell infiltration was higher in HR-d versus HR/MMR-intact PDAC (p<0.0001), while CD8+ T-cell densities in the peri-tumoral and stromal regions were similar in both groups. HR-d PDAC also displayed increased intra-tumoral FOXP3+ Tregs (p=0.049) and had a higher CD8+:FOXP3+ ratio (p=0.023). CD68+ TAM expression was similar in HR-d and HR/MMR-intact PDAC. Finally, 6 of the 25 HR-d cases showed a PD-L1 Combined Positive Score of >=1, whereas none of the HR/MMR-intact cases met this threshold (p<0.00001). These results provide immunohistochemical evidence for intra-tumoral CD8+ T-cell enrichment and PD-L1 positivity in HR-d PDAC, suggesting that HR-d PDAC may be amenable to ICI treatment strategies.