T-cell infiltration and clonality correlate with programmed cell death protein 1 and programmed death-ligand 1 expression in patients with soft tissue sarcomas

Abstract

Background: Patients with metastatic sarcomas have poor outcomes and although the disease may be amenable to immunotherapies, information regarding the immunologic profiles of soft tissue sarcoma (STS) subtypes is limited.

Methods: The authors identified patients with the common STS subtypes: leiomyosarcoma, undifferentiated pleomorphic sarcoma (UPS), synovial sarcoma (SS), well-differentiated/dedifferentiated liposarcoma, and myxoid/round cell liposarcoma. Gene expression, immunohistochemistry for programmed cell death protein (PD-1) and programmed death-ligand 1 (PD-L1), and T-cell receptor Vβ gene sequencing were performed on formalin-fixed, paraffin-embedded tumors from 81 patients. Differences in liposarcoma subsets also were evaluated.

Results: UPS and leiomyosarcoma had high expression levels of genes related to antigen presentation and T-cell infiltration. UPS were found to have higher levels of PD-L1 (P≤.001) and PD-1 (P≤.05) on immunohistochemistry and had the highest T-cell infiltration based on T-cell receptor sequencing, significantly more than SS, which had the lowest (P≤.05). T-cell infiltrates in UPS also were more oligoclonal compared with SS and liposarcoma (P≤.05). A model adjusted for STS histologic subtype found that for all sarcomas, T-cell infiltration and clonality were highly correlated with PD-1 and PD-L1 expression levels (P≤.01).

Conclusions: In the current study, the authors provide the most detailed overview of the immune microenvironment in sarcoma subtypes to date. UPS, which is a more highly mutated STS subtype, provokes a substantial immune response, suggesting that it may be well suited to treatment with immune checkpoint inhibitors. The SS and liposarcoma subsets are less mutated but do express immunogenic self-antigens, and therefore strategies to improve antigen presentation and T-cell infiltration may allow for successful immunotherapy in patients with these diagnoses. Cancer 2017;123:3291-304. © 2017 The Authors. Cancer published by Wiley Periodicals, Inc. on behalf of American Cancer Society. This is an open access article under the terms of the Creative Commons Attribution NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

Keywords: T-cell receptors; gene expression; immunotherapy; leiomyosarcoma; liposarcoma; pleomorphic; programmed cell death protein (PD-1); programmed death-ligand 1 (PD-L1); sarcoma.

Figure 1

(A) Heat map of 367 genes found to be significantly different between at least 2 sarcoma subtypes (P<.05) after unsupervised clustering. (B) Gene expression by sarcoma subtype in selected genes related to antigen presentation. (C) Selected genes reflecting T‐cell infiltration. (D) Gene expression for programmed death‐ligand 1 (PD‐L1) and PD‐L2. (D) Selected markers found on infiltrating tumor‐associated macrophages. * indicates P≤.05; **, P≤.01; ***, P≤.001; ****, P≤.0001; HLA, human leukocyte antigen; IL7R, interleukin 7 receptor; Lipo, liposarcoma; LMS, leiomyosarcoma; MRCL, myxoid/round cell liposarcoma; PDCD1LG2, programmed cell death 1 ligand 2; SS, synovial sarcoma; TAP1, transporter‐associated with antigen processing 1; UPS, undifferentiated pleomorphic sarcoma; WD/DD, well‐differentiated/dedifferentiated liposarcoma.

Figure 2

(A) Programmed death‐ligand 1 (PD‐L1) delineated undifferentiated pleomorphic sarcoma (UPS) tumor on low power; no staining was observed in adjacent normal tissue. (B) Very high tumor cell staining for PD‐L1 in a UPS noted on high power. (C) High programmed cell death protein (PD‐1) staining in a UPS. (D) Very high levels of PD‐1‐positive infiltrates in a leiomyosarcoma (LMS) tumor. (E) PD‐1 and PD‐L1 scores in sarcoma subtypes. * indicates P<.05; **, P<.01; ***, P = .001; ****, P = .0001; IHC, immunohistochemistry; MRCL, myxoid/round cell liposarcoma; SS, synovial sarcoma; WD/DD Lipo, well‐differentiated/dedifferentiated liposarcoma.

Figure 3

T‐cell receptor sequencing in sarcoma subtypes examining (A) T‐cell fraction, B) clonality, and C) maximum clonal frequency. * indicates P<.05; **, P<.01; ***, P =  .001; ****, P =  .0001; Lipo MRCL, myxoid/round cell liposarcoma; Lipo WD/DD, well‐differentiated/dedifferentiated liposarcoma; LMS, leiomyosarcoma; SS, synovial sarcoma; UPS, undifferentiated pleomorphic sarcoma.

Figure 4

(A) Gene correlation with clonality. B) Correlation of T‐cell fraction and clonality with programmed cell death protein (PD‐1) and programmed death‐ligand 1 (PD‐L1) expression. Coef indicates coefficient; CXCL9, C‐X‐C motif chemokine ligand 9; Expr, expression; IHC, immunohistochemistry; ITK, IL‐2 (interleukin‐2 )‐inducible T‐cell kinase; NKG7, natural killer cell granule protein 7; SLAMF6, SLAM family member 6.