CD4+ T-Cell Program Dynamics Under PD-1/PD-L1 Blockade in NSCLC

Abstract

Immune checkpoint blockade (ICB) targeting PD-1/PDL1 has transformed non-small cell lung cancer (NSCLC) therapy, yet durable benefit remains limited to a subset of patients. While most mechanistic and biomarker frameworks emphasize CD8+ T cells, accumulating single-cell, TCR, and spatial evidence indicates that CD4+ T cells can act as system-level organizers of antitumor immunity and resistance. This paper synthesizes NSCLC studies from 2018-2025 and weighs conclusions using an evidence-tier framework that prioritizes intrapatient longitudinal sampling (paired tumor biopsies and/or serial blood) and spatially resolved profiling. Findings are integrated across five recurring CD4 programs: TLSassociated CXCL13+ Tfh-like states, Th1-oriented helper/effector states, Th17-linked inflammatory states, FOXP3+ regulatory T cells (Tregs), and proliferative/activation-toexhaustion trajectories. Across the strongest longitudinal tumor evidence, response most consistently aligns with coordinated on-therapy remodeling that strengthens TLS/Tfh organization and Th1-oriented output, whereas non-response is repeatedly linked to persistence or accumulation of activated intratumoral Treg states. Th17-associated signals show more variable directionality and remain lower-confidence under PD-1/PD-L1 blockade in NSCLC. Clonal tracking further connects benefit to productive proliferative bursts and blood-tumor clonal exchange within tumor-relevant T-cell pools. Together, these data support biomarker and treatment strategies that move beyond single markers toward composite, timeaware readouts capturing baseline immune infrastructure, suppressive balance, and on-therapy state transitions, and motivate rational combinations that relieve suppressive constraints while preserving productive CD4 help.