Pre-existing immunity that describes the endogenous tumor-specific adaptive immunity, before treatment may represent a valuable novel predictive biomarker for ICI treatment. In this study we estimate the potential value of pre-existing cancer-antigen specific CD8+ T cells as circulating predictive biomarkers. Additionally, we evaluate the major differences of known immune cell phenotypes between Pre-existing positive (PreI+) and Pre-existing negative (PreI-) NSCLC patients in circulation.
Blood was collected before initiation of immunotherapy from 24 NSCLC patients stage IIIb, PD-L1+ that receiving Durvalumab. PBMCs were isolated with Ficoll density gradient centrifugation including 15 healthy donors (HD). PreI was calculated by detecting endogenous IFNg expressing cells after in-vivo co-cultures of PBMCs with hTERT, MAGEA1, NY-ESO-1 and Survivin antigens. Immunophenotyping was performed by multi-color flow cytometry using antibodies against CD3, CD4, CD8, CD45RA, CD45RO, CCR7, PD-1, PD-L1 for CD4 and CD8 T-cells and CD3, CD4, FoxP3, CD25, CD127, CTLA-4, CD39 for Tregs.
From 24 patients receiving Durvalumab 10/24 (41,6%) had peptide specific T-cells (PreI + patients). 60% had detectable peptide specific T cells for all (4/4) antigens tested. Survival analysis revealed better PFS in PreI+ than PreI– patients (Log-rank = 0.06, median 333,5 and 185 days ) and better OS (*Log-rank = 0.032, median undefined and 254 days). Patients with PreI+ and low CD25+CD127-CTLA-4+ Tregs (n=8) had better OS (*Log-rank 0,036, median undefined and 251 days) than those with PreI- and high Tregs (n=9). The levels of CD3CD4PD-1 were higher in NSCLC patients compairing to HD (*0,019) but there was not a difference between PreI+ and PreI- patients. PreI+ patients had significantly higher numbers of CD3CD8PD-1 cells comparing to PreI- (*p= 0,024) but not CD3CD8PD-L1. Prei+ patients had high numbers of Teff (CD3+CD8+CD45RA+CD45RO-CCR7-) compairing with both HD (**0.0039) and PreI- (*0.032). Both T cm and Tem do not differ between all tests.
Pre-existing tumor antigen specific T-cells in circulation before initiation of immune checkpoint inhibitors in NSCLC patients serve as a good prognostic factor of response.
The authors.
This research has been co-financed by the European Union and Greek national funds through the Operational Program Competitiveness, Entrepreneurship and Innovation, under the call Research-Create-Innovate (project code: T2EΔK-02218).
All authors have declared no conflicts of interest.