Abstract 1597: The landscape of PD1-PD-L1 axis in the context of immune cells: Tumors versus stromal compartments

Abstract

Abstract Introduction: Immune response, tolerance, suppression, and resistance are the result of a complex dynamic interaction comprising PD1-PD-L1 axis in the context of immune cells (ICs) involving tumor cells, and anti/pro-tumor immune-cells of the stromal compartment. Aim: Here we present the landscape of PD1-PD-L1 axis in the context of CD3, CD4, CD8, PD1, FOXP3, and IL12RB2 positive ICs in the tumor (T) and the tumor-adjacent normal (TAN) tissues from patients with ovarian cancers (OC), and lung cancers (LC). Methods: The study was approved by Avera IRB. Surgically resected paired T and TAN tissue samples (from patients with OC and LC) were used to identify CD3 (ab16669), CD4 (ab133616), CD8 (ab85792), FOXP3 ([236A/E7], PD1 (ab137132), IL12RB2 (NBP1-85983), CD68 (Dako. #M0876), CD163 (Cell Signaling #93498) in ICs and PD-L1 (Clone 22C3; Dako) in T cells & tumor-associated macrophages (TAMs). Tonsil tissue was used for the IHC validation. Paired specimens were morphologically evaluated by H&E stain & Ki-67, cl-caspase 3. Anatomic pathological evaluation for the diagnosis of the disease was carried out by a Pathologist. Results: Expression of CD3, CD4, CD8, PD1, and FOXP3 was heterogeneous, with each tumor presenting an individual pattern of distribution of ICs. However in most tumor samples, the distribution of ICs was of tumor-cooperating phenotypes. PD-L1 expression in tumors did not correlate with any other ICs of the tumor-microenvironment. In TAN tissues from OC, PD1-PD-L1 staining was absent. While macrophages in TAN tissue from LC were moderately positive for PD-L1. In T tissue from OC and LC, PD1-PD-L1 staining was only present in the stroma, lymphocytes, and absent in the tumor compartments while PD-L1 staining was identified only in the macrophages. Tumoricidal cells were rarely observed within the tumor compartment of T tissues from OC. The tumors cells from LC was only positive for PD-L1. Conclusion: Using dual stain of PD1 and PD-L1, we present for the first time, the co-distribution pattern of PD1-PD-L1 axis in the context of the expression of CD3, CD4, CD8, FOXP3 T cells as well as CD68, and CD163 positive TAMs in the paired sample of a T tissue and its TAN tissue in LC and OC. The relationship between the PD1-PD-L1 axis and the expression of IL12 Receptor in the context of immune-landscape is being worked out and will be presented in the meeting. Citation Format: Xiaoqian Lin, Raed Sulaiman, Jennifer C. Aske, Paul Meyer, Luis RojasEspaillat, David Starks, Pradip De, Nandini Dey. The landscape of PD1-PD-L1 axis in the context of immune cells: Tumors versus stromal compartments [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1597.