Clonal Evolution and Intratumoral Heterogeneity in Metachronous Oligometastatic Non-small Cell Lung Cancer: The Role of Surgery for Multiregional Tissue Analysis

Background In oligometastatic non-small cell lung cancer (NSCLC), the combination of systemic therapy and local ablative treatment (LAT) including surgery and radiotherapy has been shown to provide a substantial survival improvement. However, patient selection for LAT remains a central challenge – mostly because the biology and molecular characteristics of “true” oligometastatic disease (OMD) is still poorly understood. Aims Here we aimed to perform a comprehensive next-generation sequencing (NGS) of sequentially resected tissue specimens from metachronous OMD. Methods Patients with metachronous oligorecurrent NSCLC (≤5 metastases in ≤3 organs) and representative sequential tissue specimens were identified from a prospectively maintained RedCap Database. Primary tumor resection was performed between 01/2016 and 12/2024 at a single institution. NGS was performed using the Oncomine Comprehensive Assay Plus. Clonal hierarchies were reconstructed for each tumor based on variant allele frequencies (VAF) of somatic alterations. Results NGS was successfully performed on 19 cancer specimens (primary tumors and metastases) from 6 patients. Adenocarcinoma was present in five patients and squamous-cell carcinoma in one patient. Initial UICC stages were IA3 (n=1), IIIA (n=3) and IVB (OMD; n=2). Oligorecurrence occurred after a median (IQR) of 16.5 (9.2-47.6) months. Analysis of clonal hierarchy revealed KRAS, TP53, EGFR, and NRAS as truncal mutations in three, two, one and one patients, respectively. Subclonal somatic changes were common and included low-level genetic alterations in known therapy relevant genes such as STK11 and KEAP1. Among three patients with consecutive brain metastases, genetic profiles of the resected tissue specimens showed a high clonality in evolution with maintained mutational profiles in all paired specimens. Conversely, extracranial metastases demonstrated a more divergent evolution where only the truncal mutations were maintained in metastases. Conclusion Surgical resection of primary tumors and distant metastases not only offers LAT, but also allows a multiregional tissue analysis to understand clonal evolution in OMD. Subclonal alterations may eventually occur but the complexity of clonal evolution appears to be highly variable among patients with OMD.