Abstract 5820: Spatial and cellular immune landscapes of non-small cell lung cancer in association with response to neoadjuvant chemoimmunotherapy

Neoadjuvant and perioperative immunotherapy with checkpoint inhibitors (ICIs) combined with chemotherapy (CT) has improved outcomes for patients with resectable non-small cell lung cancer (NSCLC). However, over half of treated patients experience non-response due to poorly understood mechanisms, underscoring the need to elucidate the factors mediating therapeutic efficacy. Here, we aimed to dissect the tumor-associated immune landscape in lung tissues from patients with varying levels of residual viable tumor (%RVT) following neoadjuvant chemoimmunotherapy. We analyzed 28 lung tissue samples from 24 patients, including non-squamous (n=17) and squamous (n=7) NSCLCs, with pathological complete response (pCR, n=5), major pathological response (MPR, n=1), and no MPR (n=18). Multimodal spatial transcriptomics (ST) (Visium CytAssist, 10x Genomics) and single-cell RNA sequencing analysis of fixed cells (scFFPE-seq) from consecutive tissue sections was performed in association with therapeutic response and clinicopathological variables. ST analysis revealed lymphoid aggregates (LAs) and tertiary lymphoid structure (TLS) signatures in both responders and non-responders. Notably, pCRs were enriched in squamous cases. B cells and plasma cells (PCs) were significantly more enriched in responders (pCR and MPR), with CXCL13-CXCR5 ligand-receptor interactions spatially overlapping with TLS signature expression, suggesting a functional interplay that may be crucial in mediating response to therapy. In responders, PCs appeared to differentiate from the LAs in space into the tumor bed, possibly alluding to active humoral anti-tumor immunity. A significant abundance of macrophages, including CTSK+, C1Q+ and M2-like SELENOP+ subsets, was observed in responders, particularly surroundings TLSs. IL2RB+ natural killer (NK) cells were also more prevalent in cases with pCR and MPR. The abundance of immune populations was inversely correlated with %RVT; we observed incremental increase in immune proportions with decreasing %RVT. Conversely, non-responders exhibited higher levels of migratory dendritic cells (cDC3) and cDC2 subsets, CD4+ naïve T, regulatory T (Tregs), Th17 CD4+, and GZMK+ exhausted T, Th1, and FCGR3A+ NK cells, as well as higher levels of KIT+ AHR+ KLRG1+ group 3 innate lymphoid cells (ILC3). These findings reveal distinct immune cell compositions and states associated with response to neoadjuvant chemoimmunotherapy in NSCLC. Ongoing efforts aim to characterize lineage-restricted subpopulations and immunogenomic features underlying therapeutic response, which thus could inform biomarker discovery and streamline development of personalized therapeutic strategies to further improve patient outcomes. Citation Format: Zahraa Rahal, Tieling Zhou, Alejandra G Serrano, Jiping Feng, Alessandra Vaccaro, Ansam Sinjab, John T. Le, Xin Sun, Michael Wang, Wei Hu, Jianjun Zhang, Tullia Bruno, Hai Tran, Stephen G. Swisher, Cheuk Hong Leung, J. Jack Lee, Jing Wang, John Victor Heymach, Don Lynn Gibbons, Ignacio Ivan Wistuba, Annikka Weissferdt, Jared K. Burks, Luisa Maren Solis Soto, Humam Kadara, Tina Cascone. Spatial and cellular immune landscapes of non-small cell lung cancer in association with response to neoadjuvant chemoimmunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5820.