Abstract 115P
Background
Immune checkpoint inhibitor (ICI) has achieved a great success as a promising regime for the treatment of patients with many types of solid malignancies, associated with predictive biomarker of PD-L1 expression. However, generally a low rate of ICI therapy response remains a critical hurdle to overcome for expanding its versatile therapeutic efficacy and necessitates importance of developing a biomarker better predicting response outcome after ICI.
Methods
Peripheral blood CD8+ T cell compartment from patients with stage IV of non-small cell lung cancer (n=121) before ICI treatment targeting programmed cell death 1 (PD-1) or its ligand 1 (PD-L1) was analyzed and correlated with patients’ ICI treatment outcome.
Results
Strong correlation between the patients' response outcome after ICI and the proportion of two distinct subsets of blood CD8+ T cells, namely CD27+ CD28+ CD45RA- CCR7- and CD27+ CD28+ CD45RA+ CCR7- cells was observed. Using these two cellular parameters combined with machine learning based probability graph, we found that both initial discovery (n=72) and later validation cohorts of patients (n=49) showed a power of predicting approximately 55.6% of ICI responders (95% CI, 23.1-88%; PR based on the RECISTv1.1 criteria) compared to that of ∼15.3% (95% CI, 7-23.6%; no biomarker included) and of ∼22.2% (95% CI, 0-49.3%; biomarker based on tumor PD-L1 expression). Mechanistically, the observed strong correlation was due to the basal functional fitness and reactive capacity of responding CD8+ T cells, which was characterized by lower initial levels of perforin, granzyme B and interferon-γ expression in these cells before ICI treatment. As such, the patients with enhanced proportion of this subset in their bloods showed greater capacity to enhance ICI-driven upregulation of cytotoxic molecules and accordingly better ICI response outcomes.
Conclusions
These observations are in line with current notion that a relatively less differentiated subset of CD8+ T cells would be a major target for ICI and provide a potential of developing this non-invasive blood-based approach as an ICI response predictor for patients with cancer.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Chonnam National University Medical School and Chonnam National University Hwasun Hospital.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.