Tamura A1*, Yoshida M2, Yamamoto N1, Nino N1, Ichikawa T1, Nakatani N1, Nakamura S1, Saito A1, Kozaki A1, Kishimoto K1, Ishida K1, Hasegawa D1 and Kosaka Y1
1Department of Hematology and Oncology, Children’s Cancer Center, Kobe Children’s Hospital, Japan
2Department of Diagnostic Pathology, Kobe Children’s Hospital, Japan
Background: Programmed cell death-1 (PD-1) and programmed cell death ligand-1 (PD-L1) expression may be surrogate markers for a response to immune checkpoint inhibitors. However, PD-1 and PD-L1 expressions in Ewing and Ewing-like sarcoma are poorly defined.Methods: Immunohistochemistry analysis was performed on formalin-fixed, paraffin-embedded pre-therapeutic tumor biopsies from patients with Ewing (n=11) and Ewing-like sarcoma (n=6). For the assessment of staining for PD-1/PD-L1 in tumor cells, rates forPD-1/PD-L1 positive tumor cells within total tumor cells: 0% as (–), >0% to <10% as (+), ≥ 10% to <50% as (++), ≥ 50% to <90% as (+++), and ≥ 90% as (++++), were used.Results: None of Ewing (n=11) and Ewing-like (n=6) sarcoma cells expressed PD-L1. PD-1 expressing tumor infiltrating lymphocytes were not prevalent both in Ewing and Ewing-like sarcoma. However, PD-1 was robustly expressed in 4 of 11 (36.4%) Ewing sarcoma tumor cells with ≥ 50% to <90% (+++, n=3) or ≥ 10% to <50% (++, n=1). In contrast, none of 6 Ewing-like sarcoma tumor cells expressed PD-1.Conclusion: In this study, PD-L1 expression was not observed in any of Ewing and Ewing-like sarcoma tumor cells. PD-1 was overexpressed in a subset of Ewing sarcoma, whereas not in Ewing-like sarcoma.
Programmed cell death-1; Ewing sarcoma; Ewing-like sarcoma
Tamura A, Yoshida M, Yamamoto N, Nino N, Ichikawa T, Nakatani N, et al. Robust Programmed Cell Death-1 Expression in a Subset of Ewing Sarcoma in Contrast to Ewing-like Sarcoma. Clin Oncol. 2019; 4: 1586.