Differential Expression of Novel Immune Checkpoint Receptors on Tumor Infiltrating Lymphocytes in Patients with Locally Advanced Breast Cancer after Neoadjuvant Chemotherapy.

ABSTRACT

Immune checkpoint receptors (ICRs) were recently found to modulate the anti-tumoral immune response. This study aimed to determine the clinical and pathological associations of ICRs expression on tumor-infiltrating lymphocytes (TILs) in patients with locally advanced breast cancer (LABC) treated with neoadjuvant chemotherapy (NAC). Expressions of ICRs including PD-1, LAG-3, TIM-3, TIGIT, and CTLA-4 on CD8+ T lymphocytes and Natural Killer (NK) cells on TILs were analyzed by flow cytometry. Patients <50 years were more likely to express CTLA-4 on CD8+ T lymphocytes compared to those ≥50 years (p=0.004). In addition, patients with ypT3-4 tumors were more likely to have increased LAG-3 expression on CD16-CD56bright NK cells (p=0.042) and PD-1 (p=0.014) and CTLA-4 (p=0.018) expressions on CD8+ T cells in regard to those with ypT1-T2, respectively. Contrarily, PD-1 expression on CD16-CD56bright NK cells was found to be decreased in patients with ypN+ compared to those with ypN- (p=0.022). Furthermore, patients with HER2+ tumors were more likely to have increased TIM-3 expression on CD8+ T cells (p=0.043), whereas patients with a better response to NAC were more likely to express TIGIT on CD8+ T (p=0.014) and CD16-CD56bright NK cells (p=0.003), respectively. The new generation ICRs, TIM-3, LAG-3, and TIGIT are highly expressed in LABC following NAC in patients with poor prognostic factors. Therefore, new evolving therapies using inhibitory mAbs directed to TIM-3, LAG-3, and TIGIT could be also be considered in locally advanced breast cancers expressing these ICRs.