Abstract 6421: Tracking the evolution of non-small-cell lung cancer: Completion of the TRACERx longitudinal cohort

Abstract Lung cancer continues to be a leading cause of cancer-related incidence and mortality worldwide. High genomic intratumour heterogeneity (ITH) has been identified as a driving mechanism of therapeutic resistance and treatment failure, and hence presents a clinical challenge. In lung cancer, genomic ITH as the result of tumour evolution has been shown to be associated with poor outcome and decreased overall survival. Tracking non-small-cell lung cancer (NSCLC) evolution through therapy (Rx) (TRACERx) is a prospective multi-center longitudinal study designed to delineate tumour evolution from surgical resection to disease recurrence or cure. Since recruitment began in April 2014, preliminary findings from the TRACERx cohort have been presented for the first 100 patients and for an interim cohort of 421 patients. With follow-up of the last patients due to conclude at the end of 2025, we now present the completed TRACERx cohort with high-depth multi-region whole-exome sequencing of over 3, 000 regions from over 700 patients with early-stage NSCLC. Patient ethnicity, age, sex, smoking status are largely reflective of the United Kingdom early-stage NSCLC patient population, and surgically-resected tumours constitute stages I to III across adenocarcinoma, squamous cell carcinoma and other non-small-cell histologies. The completed TRACERx cohort also includes over 200 patients with sequencing of metastatic disease. This large cohort of paired primary-metastasis whole-exome sequencing enables further in-depth study of the timing and mode of metastatic divergence and dissemination in lung cancer. Our preliminary results replicating prior findings from TRACERx give insights on the influence of clonal tumour evolution on patient outcome. To this end, we investigated mutational and copy number differences between regions of the same primary lesion and constructed phylogenetic trees that enabled the recapitulation of tumour evolution. We traced mutations shared by or unique to individual subclones in primary and metastatic lesions, and examined their potential impact on subclonal immune evasion capabilities. We also characterised the contribution of mutational signatures to primary- and metastasis-unique mutations to evaluate the influence of mutational processes on tumour evolution and disease relapse. The completion of the TRACERx cohort will enable the reporting of the primary objectives of TRACERx prospective observational clinical trial on the association of ITH and clinical endpoints and the impact of adjuvant therapy upon ITH in relapsed disease. These data will also power the investigation of the drivers and correlates of lung cancer evolution, metastasis and immune evasion, and inform strategies for developing evolutionary biomarkers for lung cancer prognosis. Citation Format: Lydia Y. Liu, Kerstin Haase, Aino-Maija Leppä, Alexander Azizi, Emma Hazelwood, Takahiro Karasaki, Woody Z. Zhang, Charlotte Grieco, Katherine Honan, Olivia Lucas, Carlos Martinez Ruiz, Ariana Huebner, Selvaraju Veeriah, Cristina Naceur-Lombardelli, Andrew Rowan, Sophia Ward, Maise Al Bakir, Nnennaya Kanu, Crispin T. Hiley, Allan Hackshaw, David A. Moore, TRACERx Consortium, Simone Zaccaria, Nicholas McGranahan, Alexander M. Frankell, Mariam Jamal-Hanjani, Charles Swanton. Tracking the evolution of non-small-cell lung cancer: Completion of the TRACERx longitudinal cohort [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 6421.