Hallmarks-of-cancer in stage II-III NSCLC treated with chemoradiotherapy (CRT).

e20052 Background: Stage II-III NSCLC adenocarcinoma (ADC) treated with definitive CRT is clinically heterogeneous. Post-CRT treatment decisions are seldom guided by integrated tumor biology. We tested if a Hallmarks-of-Cancer-based aggregation of routine panel NGS findings can generate biologically interpretable profiles to support translational stratification and therapeutic hypotheses. Osimertinib approval as consolidation for stage III EGFR-mutated NSCLC in 2024 made NGS the new standard-of-care (SOC) test. Methods: 45 stage II-III NSCLC-ADC with definitive CRT had targeted NGS using the QIAGEN Lung Cancer Multimodal Panel (DNA mutations/CNVs and fusion partners) on a NextSeq 2000 (Nextera XT, dual indexes, UMI chemistry). From the first 10 ADC the detected variants were mapped to 14 Hallmarks via a predefined gene-to-hallmark model and aggregated to case-level hallmark scores. Two scoring modes were evaluated: „clean“ (pathogenic (P)/likely pathogenic (LP), LP/P only; VUS weight = 0) and „all“ (LP/P + VUS; VUS weight = 0.25) as a sensitivity analysis. Unsupervised hierarchical clustering was performed on clean hallmark matrices. Results: We found 22 LP/P events across 12 genes. TP53 was most frequent (8/10), followed by KRAS (2/10); single cases carried EGFR, MET, KEAP1, ARID1A, SMARCA4, ATM, BRAF, NF1, RBM10 and APC alterations; one tumor had no LP/P variants. Hallmark profiling (clean) consistently highlighted a dominant „damage-response/senescence“ phenotype with high H10 (Senescent cells/SASP) in 8/10 (mean 16.0) and broad H11 (Genome instability) activity in 9/10 (mean 8.27), accompanied by H2 (growth suppressor evasion) and H3 (cell death resistance). Clustering separated (i) an 8/10 TP53-driven backbone cluster suggestive of shared CRT-relevant stress-adaptation biology, (ii) an LP/P-negative case, and (iii) one distinct outlier harboring ARID1A/SMARCA4 with KEAP1 alterations, characterized by prominent H13 (epigenetic reprogramming) and H9 (phenotypic plasticity) together with H8 (immune destruction avoided), H12 (tumor-promoting inflammation) and H7 (energetics). Including VUS („all“) preferentially increased immune/invasion/angiogenesis hallmarks (H8, H6, H5), indicating potentially actionable biology not captured by strict LP/P filtering. Results of further 35 identified ADC and clinical outcomes (ORR/PFS/OS) will also be shown. Conclusions: Hallmark-level aggregation of SOC panel NGS in CRT-treated stage II-III NSCLC yields translationally interpretable biological subgroups: a prevalent TP53/SASP-genome-instability stress-adaptation backbone and a distinct SWI/SNF-KEAP1 subgroup with epigenetic plasticity and immune-inflammatory features. This approach provides a pragmatic framework to prioritize post-CRT strategies and trial hypotheses (e.g., DDR-informed, epigenetic/immune-microenvironment-directed combinations) beyond single gene drivers.