PD-L1 expression in angiomatoid fibrous histiocytoma

Sci Rep. 2021 Jan 26;11(1):2183. doi: 10.1038/s41598-021-81746-y.

Abstract

Angiomatoid fibrous histiocytoma (AFH) is a rare tumor of intermediate malignancy. Treatment options for unresectable and/or metastatic tumors are very limited. Immunotherapy with PD-1/PD-L1 inhibitors may be worth exploring. The aim of this study was to evaluate the expression of PD-L1 in AFHs. PD-L1 expression was assessed on 36 AFHs from 36 pediatric patients by immunohistochemical staining of PD-L1 (clone 22C3). Positivity was defined as membranous expression in ≥ 1% of either tumor or immune cells. The correlations between PD-L1 expression and clinicopathologic features were assessed. Two patients had lymph node metastasis. All patients underwent surgical resection; three of them also had systemic chemotherapy. Three patients had recurrence after initial resection; all patients were alive with a median follow-up of 2.5 years. Overall, twenty-two (61%) tumors were positively stained for PD-L1 and positivity was seen on both tumor and immune cells in eighteen of the 22 tumors. A positive correlation was found between tumor cell PD-L1 expression and CD8+ T-cell infiltration. There were no statistically significant differences between the status of PD-L1 expression and the clinicopathological features assessed. PD-L1 expression was identified in 61% of AFHs with a predominantly adaptive pattern. Our findings provide a rationale for future studies evaluating the potential of checkpoint immunotherapy for patients with unresectable and/or metastatic tumor.

MeSH terms

  • Adolescent
  • B7-H1 Antigen / metabolism*
  • CD8-Positive T-Lymphocytes / immunology
  • Child
  • Child, Preschool
  • Female
  • Histiocytoma, Malignant Fibrous / immunology
  • Histiocytoma, Malignant Fibrous / metabolism*
  • Histiocytoma, Malignant Fibrous / pathology
  • Humans
  • Leukocytes / metabolism
  • Lymphocytes, Tumor-Infiltrating / immunology
  • Male

Substances

  • B7-H1 Antigen

Supplementary concepts

  • Histiocytoma, Angiomatoid Fibrous