Distribution of NRG1 Gene Fusions in a Large Population of Chinese Patients with NSCLC

Recent progress in targeted therapy for non-small cell lung cancer

The high morbidity and mortality of non-small cell lung cancer (NSCLC) have always been major threats to people's health. With the identification of carcinogenic drivers in non-small cell lung cancer and the clinical application of targeted drugs, the prognosis of non-small cell lung cancer patients has greatly improved. However, in a large number of non-small cell lung cancer cases, the carcinogenic driver is unknown. Identifying genetic alterations is critical for effective individualized therapy in NSCLC. Moreover, targeted drugs are difficult to apply in the clinic. Cancer drug resistance is an unavoidable obstacle limiting the efficacy and application of targeted drugs. This review describes the mechanisms of targeted-drug resistance and newly identified non-small cell lung cancer targets (e.g., KRAS G12C, NGRs, DDRs, CLIP1-LTK, PELP1, STK11/LKB1, NFE2L2/KEAP1, RICTOR, PTEN, RASGRF1, LINE-1, and SphK1). Research into these mechanisms and targets will drive individualized treatment of non-small cell lung cancer to generate better outcomes.

Oncogenic Neuregulin 1 gene (NRG1) fusions in cancer: A potential new therapeutic opportunities

It is widely established that chromosomal rearrangements induce oncogenesis in solid tumors. However, discovering chromosomal rearrangements that are targetable and actionable remains a difficulty. Targeting gene fusion or chromosomal rearrangement seems to be a powerful strategy to address malignancies characterized by gene rearrangement. Oncogenic NRG1 fusions are relatively rare drivers that infrequently occur across most tumor types. NRG1 fusions exhibit unique biological properties and are difficult to identify owing to their large intronic regions. NRG1 fusions can be detected using a variety of techniques, including fluorescence in situ hybridization, immunohistochemistry, or next-generation sequencing (NGS), with NGS-based RNA sequencing being the most sensitive. Previous studies have shown that NRG1 fusion protein induces tumorigenesis, and numerous therapies targeting the ErbB signaling pathway, such as ErbB kinase inhibitors and monoclonal antibodies, have initially demonstrated encouraging anticancer efficacy in malignant tumors carrying NRG1 fusions. In this review, we present the characteristics and prevalence of NRG1 fusions in solid tumors. Additionally, we discuss the laboratory approaches for diagnosing NRG1 gene fusions. More importantly, we outline promising strategies for treating malignancies with NRG1 fusion.

Genomic Profiling and Prognostic Value Analysis of Genetic Alterations in Chinese Resected Lung Cancer With Invasive Mucinous Adenocarcinoma

Background

Invasive mucinous adenocarcinoma (IMA) of the lung is a distinct histological subtype with unique clinical and pathological features. Despite previous genomic studies on lung IMA, the genetic characteristics and the prognosis-related biomarkers in Chinese surgically resected lung IMA remain unclear.

Methods

We collected 76 surgically resected primary tumors of invasive lung adenocarcinoma, including 51 IMA and 25 non-mucinous adenocarcinomas (non-IMA). IMA was further divided into pure-IMA (mucinous features≥90%) and mixed-IMA subgroups. Comprehensive genomic profiling based on targeted next-generation sequencing (NGS) of 425 genes was explored and genomic characteristics were evaluated for the correlation with postoperative disease-free survival (DFS).

Results

IMA had a unique genetic profile, with more diverse driver mutations and more tumor drivers/suppressors co-occurrence than that of non-IMA. The frequency of EGFR (72.0% vs. 40.0% vs. 23.1%, p=0.002) and ALK (undetected vs. 20.0% vs. 26.9%, p=0.015) alterations showed a trend of gradual decrease and increase from non-IMA to mixed-IMA to pure-IMA, respectively. The frequency of KRAS mutations in pure-IMA was higher than that in mixed-IMA, albeit statistically insignificant (23.1% vs. 4.0%, p=0.10). TP53 mutation was significantly less in pure-IMA compared to mixed-IMA and non-IMA (23.1% vs. 52.0% vs. 56.0%, p=0.03). Besides, IMA exhibited less arm-level amplifications (p=0.04) and more arm-level deletions (p=0.004) than non-IMA, and the frequency of amplification and deletion also showed a trend of gradual decrease and increase from non-IMA to mixed-IMA to pure-IMA, respectively. Furthermore, prognosis analysis in stage III IMA patients showed that patients harboring alterations in EGFR (mDFS=30.3 vs. 16.0 months, HR=0.19, P=0.027) and PI3K pathway (mDFS=36.0 vs. 16.0 months, HR=0.12, P=0.023) achieved prolonged DFS, while patients with poorly differentiated tumors (mDFS=14.1 vs. 28.0 months, HR=3.75, p=0.037) or with KRAS mutations (mDFS=13.0 vs. 20.0 months, HR=6.95, p=0.027) had shorter DFS. Multivariate analysis showed that KRAS mutations, PI3K pathway alterations, and tumor differentiation status were independent factors that have statistically significant influences on clinical outcomes of IMA patients.

Conclusion

Our study provided genomic insights into Chinese surgically resected lung IMA. We also identified several genomic features that may serve as potential biomarkers on postoperative recurrence in IMA patients with stage III disease.

Is there any place for immune-checkpoint inhibitors in the treatment algorithm of fusion-driven non-small cell lung cancer?-a literature review

The advent of immune-checkpoint inhibitors (ICIs) targeting the programmed death-1 (PD-1)/programmed death ligand-1 (PD-L1) axis, produced a paradigm change of the treatment algorithm for metastatic, non-oncogene addicted, non-small cell lung cancer (NSCLC). However, the majority of patients with oncogene-addicted disease have been excluded from the "immunotherapy revolution", thus the clinical efficacy of these agents in this subset of patients remains largely unknown. Although pre-clinical evidence provided a good rationale to pursue the investigation of ICI treatment in specific subgroups of oncogene-addicted NSCLC, current available evidence suggested that tumors harboring molecular alterations likely do not represent the best candidate to single agent ICI therapy. Furthermore, the prospect of further improving overall survival (OS) with the combination of tyrosine kinase inhibitors (TKIs) and ICIs led to unexpected poor results and safety issues in recent phase I trials exploring different therapeutic associations. Conversely, the combination of immunotherapy and chemotherapy is emerging as a potential effective strategy in specific subsets of NSCLC patients harboring oncogenic drivers. In this review we particularly focus on the subgroup of patients whose disease harbor oncogenic rearrangements, summarizing current evidence from preclinical and clinical studies and discussing their practical implications, in order to define the potential role of ICIs in the clinical management of fusion-driven NSCLC.

Emerging oncogenic fusions other than ALK, ROS1, RET, and NTRK in NSCLC and the role of fusions as resistance mechanisms to targeted therapy

Recent evidence has shown that gene fusions caused by chromosomal rearrangements are frequent events in the initiation and during progression of solid tumors, including non-small cell lung cancers (NSCLCs). Since the discoveries of ALK and ROS1 fusions in 2007 and the subsequent successes of pharmacological targeting for these fusions, numerous efforts have identified additional oncogenic driver fusions in NSCLCs, especially in lung adenocarcinomas. In this review, we will summarize recent advances in this field focusing on novel oncogenic fusions other than ALK, ROS1, NTRK, and RET fusions, which are summarized in other articles in this thematic issue. These novel gene fusions include neuregulin-1 (NRG1) fusions, MET fusions, fusion genes involving fibroblast growth factor receptor (FGFR) family members, EGFR fusions, and other rare fusions. In addition, evidence has suggested that acquisition of gene fusions by cancer cells can be a molecular mechanism of acquired resistance to targeted therapies. Most of the current data are from analyses of resistance mechanisms to EGFR tyrosine kinase inhibitors in lung cancers with oncogenic EGFR mutations. However, a few recent studies suggest that gene fusions can also be a resistance mechanism to ALK-tyrosine kinase inhibitors in lung cancers with oncogenic ALK fusions. Detection, validation, and pharmacological inhibition of these fusion genes are becoming more important in the treatment of NSCLC patients.