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The Desmoid Tumor Research Foundation

September 2019

Desmoid tumors display a strong immune infiltration at the tumor margins and no PD-L1-driven immune suppression

Author Information

Siozopoulou V(1)(2), Marcq E(1), Jacobs J(1)(2), Zwaenepoel K(1)(2), Hermans C(1)(2), Brauns J(1)(2), Pauwels S(2), Huysentruyt C(3), Lammens M(2), Somville J(4), Smits E(1)(5), Pauwels P(1)(2).

(1)Center for Oncological Research, Univ of Antwerp, Antwerp, Belgium. (2)Dept of Pathology, Antwerp Univ Hospital, Wilrijkstraat 10, Edegem, 2650, Antwerp, Belgium. (3)PAMM Laboratory for Pathology and Medical Microbiology, Catharina Hospital, Eindhoven, The Netherlands. (4)Dept of Orthopedic Surgery, Antwerp Univ Hospital, Antwerp, Belgium. (5)Center for Cell Therapy and Regenerative Medicine, Antwerp Univ Hospital, Antwerp, Belgium.

Publication

Canc Immunol Immunother

Summary

Characterization of the tumor immune microenvironment (TME) and immune checkpoints can possibly help identify new immunotherapeutic targets for Desmoid tumors (DTs). We performed immunohistochemistry (IHC) on 33 formalin-fixed paraffin-embedded (FFPE) tissue sections from DT samples to characterize the TME and the immune checkpoint expression profile. We stained for CD3, CD4, CD8, CD20, FoxP3, CD45RO, CD56, CD68, NKp46, granzyme B, CD27, CD70, PD1 and PD-L1. We found that most of the tumors showed organization of lymphocytes into lymphoid aggregates at the periphery of the tumor, strongly resembling tertiary lymphoid organs (TLOs). The tumor expressed a significant number of memory T cells, both at the periphery and in the tumoral stroma. In the lymphoid aggregates, we also recognized a significant proportion of regulatory T cells. The immune checkpoint ligand PD-L1 was negative on the tumor cells in almost all samples. On the other hand, PD1 was partially expressed in lymphocytes at the periphery of the tumor. To conclude, we are the first to show that DTs display a strong immune infiltration at the tumor margins, with formation of lymphoid aggregates. Moreover, we demonstrated that there is no PD-L1-driven immune suppression present in the tumor cells.

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