The Underlying Tumor Genomics of Predominant Histologic Subtypes in Lung Adenocarcinoma

IntroductionThe purpose of the study is to genomically characterize the biology and related therapeutic opportunities of prognostically important predominant histologic subtypes in lung adenocarcinoma (LUAD).MethodsWe identified 604 patients with stage I to III LUAD who underwent complete resection and targeted next-generation sequencing using the Memorial Sloan Kettering–Integrated Mutation Profiling of Actionable Cancer Targets platform. Tumors were classified according to predominant histologic subtype and grouped by architectural grade (lepidic [LEP], acinar or papillary [ACI/PAP], and micropapillary or solid [MIP/SOL]). Associations among clinicopathologic factors, genomic features, mutational signatures, and recurrence were evaluated within subtypes and, when appropriate, quantified using competing-risks regression, with adjustment for pathologic stage and extent of resection.ResultsMIP/SOL tumors had higher tumor mutational burden (p < 0.001), fraction of genome altered (p = 0.001), copy number amplifications (p = 0.021), rate of whole-genome doubling (p = 0.008), and number of oncogenic pathways altered ( p < 0.001) as compared with LEP and ACI/PAP tumors. Across all tumors, mutational signatures attributed to APOBEC activity were associated with the highest risk of postresection recurrence: SBS2 (p = 0.021) and SBS13 (p = 0.005). Three oncogenic pathways (p53, Wnt, Myc) were altered with statistical significance in MIP/SOL tumors. Compared with LEP and ACI/PAP tumors, MIP/SOL tumors had a higher frequency of targetable BRAF-V600E mutations (p = 0.046). Among ACI/PAP tumors, alterations in the cell cycle (p < 0.001) and PI3K (p = 0.002) pathways were associated with recurrence; among MIP/SOL tumors, only PI3K alterations were associated with recurrence (p = 0.049).ConclusionsThese results provide the first in-depth assessment of tumor genomic profiling of predominant LUAD histologic subtypes, their associations with recurrence, and their correlation with targetable driver alterations in patients with surgically resected LUAD.