Mutation and immune profiling of non-small cell lung cancer

• Several novel therapies that target molecular alterations and immune checkpoints in lung cancer have been introduced in the last decade. Still, only a minority of patients obtain long term disease control and overall survival remains poor. The aim of this thesis was to characterize the landscape of genetic alterations and immune cell infiltrates in tumor tissues from a large representative patient cohort of non-small cell lung cancer (NSCLC).The mutational status of 82 genes related to lung cancer development were evaluated, in paper I, by a targeted re-sequencing approach adapted to work on “real-life” samples of mixed quality. We observed a remarkably high prevalence of activating KRAS mutations. Otherwise, the mutation spectrum resembled other western lung cancer populations. Poor survival was linked to subgroups of lung adenocarcinoma with mutations in TP53, STK11 and SMARCA4, independent of concomitant KRAS mutations. In lung squamous cell carcinoma, patients with mutations in CSMD3 had better survival.The infiltration of tumor-associated immune cells was assessed by immunohistochemical analysis in paper II. Previously described immune response patterns termed “inflamed” and “desert” were confirmed in our dataset. In addition, we discovered a new immune phenotype characterized by overall sparse presence of most immune cell types except for a distinct infiltration of NK and plasma cells. This novel immune class displayed a favorable prognosis and was therefore designated “oasis”.In paper III, infiltration of macrophage subtypes was evaluated by immunohistochemical analysis of CD68, CD163, MSR1 and MARCO. The majority of macrophages exhibited a tumor promoting phenotype and expression of MARCO, a targetable scavenger receptor, was detected in a distinct subset of NSCLC patients. Further investigation of the functional roles of MARCO in a human NSCLC setting was carried out in paper IV. Here, MARCO expression on cultured myeloid cells could be induced by NSCLC cell lines. The MARCO+ cells displayed an immunosuppressive phenotype and could effectively suppress the cytolytic effect of NK cells and CD8+ T cells. A monoclonal antibody targeting MARCO removed these inhibitory effects of the MARCO+ cells.In summary, this thesis contributes knowledge on the genetic and immunologic underpinning of lung cancer that forms the basis for current and future treatment strategies in the evolving era of personalized oncology and pathology.

Nyckelord

Non-small cell lung cancer

Tumor microenvironment

Tumor-associated macrophages

Immune infiltrates

PD-L1

Mutation patterns

Immune therapy

MARCO

TP53

STK11

KRAS

Publikations- och innehållstyp

vet (ämneskategori)

dok (ämneskategori)