Peripheral CD4 Memory T Cells Predict Efficacy of Immune Checkpoint Inhibitor Treatment in Patients With Non-Small Cell Lung Cancer

The patients

Patients diagnosed with NSCLC and receiving ICI treatment at Toyama University Hospital between 2020 and 2022 were prospectively included in this study. Selection criteria were established as follows: (1) Patients with a cytological or histological diagnosis of NSCLC, including adenocarcinoma or squamous cell lung cancer; (2) Patients eligible for systemic therapy who would receive ICI therapy, including ICI monotherapy or combination therapy with cytotoxic anticancer agents. Patients who had been treated with ICI prior to the study period were also eligible. However, patients diagnosed with neuroendocrine cancer, sarcomatoid carcinoma or poorly differentiated NSCLC were excluded.

Clinical examinations and treatments

Evaluation of driver gene mutation and tumor PD-L1 expression was outsourced to commercial laboratories, and information was extracted from medical records. The absence or existence of a driver gene mutation was assessed by PCR, immunohistostaining, or next-generation sequencing, and the PD-L1 tumor proportion score (TPS) was assessed using the antibody 22C3. Clinical information, including age, performance status (PS), disease stage, and neutrophil-lymphocyte ratio (NLR) at the start of treatment with ICIs, was assessed. The stage of the disease was redefined based on the most recent imaging examination before treatment. Treatment regimens, withdrawal and discontinuation of treatment were determined by clinical judgement. Disease progression was defined as tumor growth or emerging lesions according to the response endpoints described in Solid Tumors version 1.1 or based on clinical judgment of exacerbation.

Flow cytometry

Peripheral blood was collected at the start of ICI therapy. The antibodies used in this study were anti-CD3-Fluorescein isothiocyanate (clone HIT3a), anti-CD4-allophycocyanin/Cy7 (clone A161A1), anti-PD1 (CD279)-phycoerythrin/Cy7 (clone EH12.2H7), anti-CCR7 -PE (clone G043H7) and anti-CD45RA-APC (clone HI100) (BioLegend, San Diego, CA, USA). Flow cytometry was outsourced to SRL Inc (Tokyo, Japan), performed using whole blood.

statistical analyzes

The endpoints of this study were PFS and overall survival (OS), after the start of ICI treatment. PFS events were defined as progression or death and were censored at the date of last visit or start of next treatment with no events. The OS event was death and was censored to the date of last visit without death. The survival analysis was performed after an observation period of 3 months from the last patient recruitment.

Patients were subdivided according to the median of the proportion of each subset to CD3+CD4+T cells, including CCR7+CD45RA+CD4+T cells (naive T cells), CD45RA-CD4+T cells (memory T cells), CCR7+ CD45RA-CD4+ T cells (central memory T cells), CCR7-CD45RA-CD4+ T cells (effector memory T cells) and CCR7-CD45RA+ CD4+ T cells (main memory T cells) T effectors). The NLR threshold value was set at 5, based on previous reports¹⁷.

Survival among the subdivided patient groups was analyzed by univariate analysis using the log-rank test and by multivariate analysis using the Cox proportional hazards model, adjusting for PS, expression level of PD-L1, epidermal growth factor receptor (EGFR) mutation status and combination therapy. with cytotoxic agents. Fisher’s exact test was used to test the nominal scale. A p-value of less than 0.05 was considered significant. Statistical analysis was performed using JMP version 15.0.0 (SAS, Cary, USA).

Ethics approval

This study was conducted in accordance with the Declaration of Helsinki and the Ethical Guidelines for Medical and Biological Research Involving Human Subjects (Ministry of Health, Labor and Welfare, Japan), with the approval of the Committee of Ethics from Toyama University (approval number: R2020042).

Consent to participate

Informed consent was obtained from all individual participants included in the study.