Abstract 98P
Background
Angiosarcoma is a relatively rare neoplasm of the breast (less than 0.05% of all malignant mammary tumours). Tumours can arise : i) de novo; secondary to a long standing lymphoedema ; iii) secondary to radiation therapy. In the last few years, the importance of studies about tumour microenvironment (TME) has been steadily growing, especially in order to identify potential responders to immune checkpoint inhibitors (ICIs) even in angiosarcoma. The aim of this study was to evaluate some TME features in angiosarcoma of the breast and to correlate such features with clinicopathological and follow up data.
Methods
The retrospective study was performed on tissue samples with medical records available at The Istituto Nazionale Tumori ‘G. Pascale’, Naples, Italy. Immunohistochemical parameters evaluated encompassed lymphoid cell markers (CD3+, CD8+, GrzB+, FoxP3+, CD103+) and immune checkpoint receptors (PD-L1, VISTA, TIM3, OX40). Fluorescence in situ hybridization was used to assess c-myc amplification. The immunohistochemical expression of the mismatch repair proteins was also investigated and, in ‘indeterminate’ cases, followed by automated RT-qPCR examination for microsatellite instability (IdyllaTM platform). Overall survival (OS) was estimated by Kaplan-Meier method and compared with Log-rank test.
Results
Nine cases of primary (pAS) and nine cases of secondary angiosarcoma (sAS) were retrieved. Comparison of mean tumor-infiltrating lymphocytes (TILs) and immune checkpoint receptor (ICrs) densities between pAS and sAS showed a statistically significant difference only in GrzB+ cells, which were more represented in pAS (p=0.042). Furthermore, we simultaneously quantified the number of stained T cells by multiple immunofluorescence to verify the balance between cytotoxic (CT) and immunosuppressive (IS) activity in the TME. In about 50% of cases, we found colocalisation of CD8+ and FOXP3+ cells. Although not significant, a higher degree of immunosuppression was observed in SAS cases (p = 0.266).
Conclusions
Our prelimary data suggest that sAS discloses an immunosuppressive environment; therefore, compared to pAS, sAS might be a better candidate to immunotherapy.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.