PD-L1, STAT3, IL6, and EGFR Immunoexpressions in High-Grade Osteosarcoma

Introduction. Immunotherapy has been widely used in the treatment of various malignancies with satisfactory results. One of the agents for immunotherapy is an inhibitor of programmed cell death-1 and its ligands (PD-1 and PD-L1). However, attempts at utilizing PD-1/PD-L1 immunotherapy in osteosarcoma have not yielded favorable results. This may be due to differences in PD-L1 regulation and the immune landscape in osteosarcoma, as the mechanism is still poorly understood. Therefore, elucidating PD-L1 regulation in osteosarcoma is paramount in order to improve treatment results using immunotherapy. Methods. This is a cross-sectional study conducted in the Department of Anatomical Pathology of Saiful Anwar Hospital using 33 paraffin blocks of confirmed cases of osteosarcoma. Immunohistochemical staining using PD-L1, STAT3, IL6, and EGFR was performed. Statistical analyses were subsequently performed on the immunoexpression data of these antibodies. Results. PD-L1, STAT3, IL6, and EGFR expressions were found in 6 (18.2%), 6 (18.2%), 28 (84.8%), and 30 (90.9%) cases, respectively. There were significant correlations between PD-L1 and STAT3 (r = 0.620, <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" id="M1"><a:mi>p</a:mi><a:mo>=</a:mo><a:mo><</a:mo><a:mn>0.001</a:mn></a:math> ), PD-L1 and EGFR (r = 0.449, <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" id="M2"><c:mi>p</c:mi><c:mo>=</c:mo><c:mn>0.009</c:mn></c:math> ), as well as STAT3 and EGFR (r = 0.351, <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" id="M3"><e:mi>p</e:mi><e:mo>=</e:mo><e:mn>0.045</e:mn></e:math> ). Conclusion. The existence of a correlation between PD-L1, STAT3, and EGFR indicates the potential role of STAT3 and EGFR in PD-L1 regulation in osteosarcoma, which may become the basis for targeted therapy.