The Underlying Tumor Genomics of Predominant Histologic Subtypes in Lung Adenocarcinoma

Introduction: The purpose of the study is to genomically characterize the biology and related therapeutic opportunities of prognostically important predominant histologic subtypes in lung adenocarcinoma (LUAD).

Methods: We 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.

Results: MIP/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).

Conclusions: These 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.