The majority of advanced non-small cell lung cancer (NSCLC) patients who receive PD-L1/PD-1 blockade immunotherapy as a second-line treatment do not respond. These treatments might not only affect the tumor microenvironment, but also alters the systemic dynamics of immune cell populations. Thus, the role of CD4 immunity in patients undergoing PD-L1/PD-1 blockade therapy remains unclear.
Peripheral blood samples from 51 NSCLC patients were obtained previous to the initiation of the PD-L1/PD-1 blockade therapy. Baseline T cell differentiation subsets based on CD27/CD28 expression were quantified by flow cytometry and correlated with responses. Baseline CD4 and CD8 T cells from NSCLC patients were co-cultured with T cell-stimulator cell line by expressing a membrane-bound anti-CD3 single-chain antibody in A549 human lung adenocarcinoma cells line (A549-SC3 cells) and PD-1, LAG-3 and Ki67 markers were assessed by flow cytometry.
In our cohort study NSCLC patients were separated in two groups by a cut-off value of 40% CD4 THD (CD27-CD28low/-) cells: “G1 cohort” patients with more than 40% THD cells, and “G2 cohort” patients with less than 40%. Objective responders were found only within the G1 cohort (P = 0.0001). Interestingly, CD4 T cells from G2 patients were remarkably impaired in proliferation after ex vivo activation with A549-SC3 cells compared to CD4 T cells from G1 patients. CD8 T cells from both G1 and G2 patients were equally impaired in proliferation. CD4 T cells from G2 donors presented a significantly higher co-expression of PD-1 and LAG-3 compared with CD4 T cell from G1 donors after stimulation. CD4 T cells from both G1 and G2 patient cohorts were proficient in cytokine expression. Moreover, the proliferative capacities of CD8 T cells were recovered during after immunotherapy but only in patients with functional proliferative CD4 immunity.
This study uncovers that proliferative functionality of systemic CD4 immunity is required for clinical responses to PD-L1/PD-1 blockade therapy. Moreover, CD4 T cells from G2 patients were not exhausted, indeed they responded to stimulation by producing cytokines although with strong co-upregulation of PD-1/LAG-3 associated with diminished proliferative capacities.
Clinical trial identification
Legal entity responsible for the study
Immunomodulation group-Navarrabiomed Research Center.
Asociación Española Contra el Cáncer (AECC).
All authors have declared no conflicts of interest.