156P Stereotactic radiotherapy and immunotherapy for metastatic uveal melanoma: A retrospective observational study

Background: Metastatic uveal melanoma (UM) has unfavorable prognosis.mRNA sequencing based GEP classification is a validated tool for risk stratification of primary UM.However, it can be challenging to use GEP in practice.Meanwhile immunohistochemistry (IHC) based prognostic models are commonly used for different tumors.The majority of UM prognostic models bases on the tumor cells features.At the same time, TCGA project showed that immune microenvironment is of a great importance.Our aim was to develop the IHC based prognostic model for UM accounting the tumor immune microenvironment characteristics.Methods: We included 154 patients with primary UM in the retrospective single center study.IHC was performed with the primary antibodies to IDO1, CD34, FoxP3, CD3, CD68, TGFb1, CD155, CD28, CD80, Lag3 on the tissue microarrays of the enucleated eyeballs.Pathological examination included: histological type, intensity of pigmentation, extent of necrosis, invasion into the ciliary body, sclera, optic nerve, category pT, microvascular bed and the antigen-presenting cells location patterns.Patients were excluded in case of multiple diseases, combined treatment, distant metastases at diagnosis.