Abstract 1022P
Background
The tumor microenvironment plays a key role in the development and progression of breast cancer. Immune checkpoint inhibitors for the PD-1/PD-L1 pathway activate the immune cells of the tumor microenvironment. Current knowledge suggests that the effectiveness of therapy depends on the ratio of the types of TH1 and TH2 immune cells in the tumor microenvironment. TH1 type of immune cells is associated with a favorable prognosis, and the TH2 type of immune cells with a poor prognosis. Innate lymphoid cells (ILCs) are analog of T-helper lymphocytes and remain one of the least studied groups of immune cells. It is of interest to evaluate the expression of PD-1 on ILCs depending on the status of PD-L1 in breast cancer.
Methods
The study enrolled 37 patients with estrogen-positive and triple-negative breast cancer (52.7 ± 9.3, T1-3N0-3M0). ILCs analyzed by flow cytometry using Anti EpCAM, anti-cytokeratin AE1/3, anti-CD45, anti-CD3, anti-CD4, anti-CD8, anti-CD20, anti-Tbet and anti-GATA3 antibodies. The phenotypic characteristics of ILCs was analyzed on the Novocyte 3000 (ACEA Biosciences, USA).
Results
The frequency of occurrence of PD1-negative (94.1% (16/17)) and PD1-positive (100% (20/20)) ILC1 in PD-L1 negative patients did not differ compare with PD-L1 positive patients (58.8% (10/17) and 40.0% (8/20), respectively). However, more often PD1-negative and PD1-positive ILC1 were found in PD-L1 negative patients (p=0.039, p=0.001, respectively). PD1-negative ILC2 occurred in 97.3% (36/37) of patients, PD1-positive ILC2 - in 81.0% (30/37) of patients and not differ in the groups of patients depending on the PD-L1 status (94.1% (16/17) and 100% (20/20), respectively, in PD-L1 negative patients and 88.2% (15/17) and 75.0% (15/20), respectively, in PD-L1 positive patients).
Conclusions
PD1-negative and PD-1-positive ILCs are found in the primary tumor of breast cancer patients with a high incidence regardless of PD-L1 status. Potentially, these cells can contribute to the effectiveness of anti-PD-L1/PD1 therapy.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
The Russian Science Foundation (Grant #20-75-10033).
Disclosure
All authors have declared no conflicts of interest.