Genomic Profiling of Patient-Derived Xenografts for Lung Cancer Identifies B2M Inactivation Impairing Immunorecognition.

Purpose: We aimed to maximize the performance of detecting genetic alterations in lung cancer using high-throughput sequencing for patient-derived xenografts (PDXs).Experimental Design: We undertook an integrated RNA and whole-exome sequencing of 14 PDXs. We focused on the genetic and functional analysis of ß2-microglobulin (B2M), a component of the HLA class-I complex.Results: We identified alterations in genes involved in various functions, such as B2M involved in immunosurveillance. We extended the mutational analysis of B2M to about 230 lung cancers. Five percent of the lung cancers carried somatic mutations, most of which impaired the correct formation of the HLA-I complex. We also report that genes such as CALR, PDIA3, and TAP1, which are involved in the maturation of the HLA-I complex, are altered in lung cancer. By gene expression microarrays, we observed that restitution of B2M in lung cancer cells upregulated targets of IFNα/IFNγ. Furthermore, one third of the lung cancers lacked the HLA-I complex, which was associated with lower cytotoxic CD8+ lymphocyte infiltration. The levels of B2M and HLA-I proteins correlated with those of PD-L1. Finally, a deficiency in HLA-I complex and CD8+ infiltration tended to correlate with reduced survival of patients with lung cancer treated with anti-PD-1/anti-PD-L1.Conclusions: Here, we report recurrent inactivation of B2M in lung cancer. These observations, coupled with the mutations found at CALR, PDIA3, and TAP1, and the downregulation of the HLA-I complex, indicate that an abnormal immunosurveillance axis contributes to lung cancer development. Finally, our observations suggest that an impaired HLA-I complex affects the response to anti-PD-1/anti-PD-L1 therapies. Clin Cancer Res; 23(12); 3203-13. ©2016 AACR.

Association of PD-1, PD-L1, and CTLA-4 Gene Expression and Clinicopathologic Characteristics in Patients With Non-Small-Cell Lung Cancer.

INTRODUCTION: Recent studies show a potential benefit of therapies that target programmed death receptor 1 (PD-1)/programmed death-ligand 1 (PD-L1) and cytotoxic T-lymphocyte antigen 4 (CTLA-4) inhibitory checkpoints in a subgroup of patients with non-small-cell lung cancer (NSCLC), without the clinicopathologic characteristics related to positive responses to these treatments being well determined. The aim of this study was to determine PD-1, PD-L1, and CTLA-4 gene expression at the mRNA level in tumoral tissue from patients with NSCLC and analyze their possible relationship with the clinicopathological characteristics and their potential prognostic role. PATIENTS AND METHODS: PD-1, PD-L1, and CTLA-4 expression levels were analyzed using real-time quantitative reverse transcriptase polymerase chain reaction in fresh-frozen tumor and normal adjacent lung tissue samples from 78 patients with NSCLC. Later, a significant association between mRNA levels, clinicopathologic characteristics, and patient's survival was assessed. RESULTS: No significant correlation between gene expression levels and sex, age, histological type, smoking status, pathologic stage, or tumor differentiation was found. However, higher levels of PD-1 were significantly associated with worse prognosis in patients with NSCLC, and PD-L1 overexpression was associated with a worse prognosis in stage I patients and in Grade 1 to 2 tumors. CONCLUSION: Alterations in PD-1/PD-L1 and CTLA-4 expression in lung tumoral tissue seem not to be related to age, sex, smoking status, histological type, pathological stage, or tumor differentiation degree. However, PD-1 and PD-L1 overexpression might predict worse survival in patients with stage I NSCLC and in well differentiated tumors.