Genetic and Immune Profiles of Solid Predominant Lung Adenocarcinoma Reveal Potential Immunotherapeutic Strategies.

INTRODUCTION: Subtype classification of lung adenocarcinoma (LUAD) divides different survivals and therapeutic vulnerabilities; however, little is known about the disease's underlying molecular mechanism. This study sought to determine the genetic and immune profiles of histologic subtypes and identify the evidence for adjuvant immunotherapy.

METHODS: We performed an integrated analysis of multidimensional data from a discovery set consisting of cohorts of The Cancer Genome Atlas and the Broad Institute data set from the LUAD public database and a validation set from the Guangdong Lung Cancer Institute. Immunohistochemical staining was carried out to determine the expression of the proteins programmed cell death 1 ligand (PD-L1) and CD8.

RESULTS: Patients with solid predominant LUAD showed poor disease-free survival and a high frequency of relapse/metastasis compared with those with the nonsolid subtype of LUAD. The solid subtype tended to occur more frequently in those with a history of smoking. Solid predominant LUAD exclusively showed increased expression of PD-L1 and a high proportion of dual positive PD-L1- and tumor-infiltrating lymphocytes. Meanwhile, a notable increase in the tumor mutation burden and higher frequency of GC>TA transversions were specifically identified in tumors of the solid subtype. Furthermore, the solid subtype of tumor displayed an active cytotoxic immune signature and increased incidence of genetic mutations related to immunogenicity.

CONCLUSION: Solid predominant LUAD was identified as a subtype with adaptive immune resistance, higher cytotoxic activity, and enhanced immunogenicity. These findings suggest that patients with solid predominant LUAD may represent a potential selective group that will benefit from adjuvant programmed cell death 1 blockade immunotherapy.