Distribution of novel immune-checkpoint targets in ovarian cancer tumor microenvironment: A dynamic landscape

Background. The disappointing activity of single agent immune-checkpoint inhibitors in epitherlial ovarian cancer (EOC) has been attributed in part to its unique tumor microenvironment (TME). IDO. PDL1, LAG3 and TIM3 have been implicated in the immunotolerance of EOC. We investigated the expression of these coregulators, their change with neoadjuvant chemotherapy (NACT), and their association with outcome. Method. We identified 98 patients with EOC treated with NACT and performed IDO, PDL1, LAG3 and TIM3 immunohistochemistry on samples obtained before and after NACT. The cut-off threshold to consider a positive sample was set at 5%. Results. In our cohort, TIM3 was the most prevalent co-regulator, with more than 75% of the samples being TIM3 positive. In comparison, only 22%, 28% and 17% of the samples were considered IDO, PDL1 and IAG3 positive. More than half of ovarian tumors expressed 2, 3 or even all 4 co-inhibitory molecules. However. biomarkers were not correlated with each other. NAG had a marked impact on immune co-regulator expression with over 70% of patients showing a change in biomarker status from negative to positive or vice versa. There was no significant difference in the pattern of co-regulator expression between platinum-sensitive and resistant patients. Co-expression of multiple inhibitory molecules did not appear to affect overall and progression-free survival. Conclusion. TIM3 is the most abundant co-inhibitory molecule in OC and may represent an attractive target. In addition, OC frequently co-expressed 2 or more markers supporting ICI combinatorial approaches. Finally. NAG significantly altered the expression of immunosuppressive molecules suggesting that the choice of ICI combinations should be adapted to the composition of the post-NAG immune TME. (C) 2020 Elsevier Inc. All rights reserved.

Automated summary

This study investigated the expression of immune co-regulators in epithelial ovarian cancer (EOC) and found that TIM3 was the most prevalent co-regulator. Most ovarian tumors expressed 2 or more co-inhibitory molecules, but these biomarkers were not correlated with each other. Neoadjuvant chemotherapy significantly impacted the expression of immune co-regulators, and there was no significant difference in the pattern of co-regulator expression between platinum-sensitive and resistant patients.