The immune microenvironment of uterine adenosarcomas.

Background: Uterine adenosarcoma (UA) is an extremely rare sarcoma subtype. There has been limited evaluation of the immune microenvironment in these tumors. The objective of this study is to examine and describe the immune infiltrate and PD-1/PD-L1 expression in UA and to correlate these changes in the tumor micro-environment with the overall survival status or the disease-free survival status (DFSS), respectively.

Methods: Patients (pts) treated at our center from 1982 to 2014 with UA were identified. Fifteen cases had tumor paraffin-embedded blocks available. Immunohistochemistry studies for CD3, CD8, FOXP3, CD163, PD-1 and PD-L1 (clone 22C3) were performed. Image analysis was used to assess the density (cells/mm²), except in PD-L1, where the percentage of membranous staining on tumor cells was noted.

Results: Immune infiltrate analysis median (range) density in cells/mm² varied broadly: CD3 178 (15-802); CD8 117 (11-661); FoxP3 4.8 (0.2-82); CD163 791 (264-1861); and PD1 5 (1-65). 3 cases had rare (1%) PD-L1 tumor membranous labeling. The reports yielded that ten pts were alive, and 5 were dead. Pts who were alive had significant higher CD3 and CD8 median densities in tumors than those who were dead (p = 0.040). There was no correlation between DFSS and CD3 or CD8 median densities. Patients who had no local recurrence had significantly higher CD3 and CD8 median densities in tumors than those who had local recurrence (p = 0.040).

Conclusions: In conclusion, this is the first report characterizing the presence of immune infiltrate and PD-1/PD-L1 expression in UA. CD3+ CD8+ T-cells density may be prognostic. The immune-responsiveness of UA needs to be further investigated in a larger study.