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Purpose Rearranged during transfection (RET) fusions are important genetic drivers in non-small cell lung cancer (NSCLC). Selective RET inhibitors are setting a new paradigm in RET-driven NSCLC. However, the real-world treatment patterns, outcomes and toxicity remain largely unknown. Methods Data from RET fusion-positive NSCLC patients treated in our centre were retrospectively analysed. Of them, patients diagnosed before and after August 2018 were included in analysis of treatment patterns; and patients received selective RET inhibitors were eligible for analysis of adverse events (AEs). Results Patients diagnosed before August 2018 (n = 30) predominantly received chemotherapy and immunotherapy (83%) as initial therapy, while patients diagnosed after August 2018 (n = 39) mainly received selective RET inhibitors (38.5% at first-line; 50.0% at second-line). In the total 69 patients, overall survival (OS) was prolonged in patients treated with selective RET inhibitors versus untreated patients (median 34.3 versus 17.5 months; p = 0.002) during a median follow-up of 28.7 months. But there was no difference between patients treated with immunotherapy versus untreated patients. In the 38 patients received selective RET inhibition, median progression-free survival (PFS) was 11.9 months. AEs ≥ grade 3 occurred in 42.1% patients and were not associated with PFS (p = 0.63) or OS (p = 0.60). Haematological toxicity ≥ grade 3 occurred in 31.6% patients and was the leading cause of drug discontinuation. Conclusion Selective RET inhibitors are increasingly being adopted into clinical practice and are associated with improved OS. However, treatment-related ≥ grade 3 AEs, especially haematologic AEs, occur frequently in real-world setting.

Immune checkpoint inhibitors (ICIs), especially anti-programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) antibodies, have made dramatic progress in the treatment of lung cancer, especially for patients with cancers not driven by oncogenes. However, responses are limited to a subset of patients, and which subset of patients will optimally benefit from ICI remains unknown. With the advantage of being minimally invasive and dynamic, noninvasive biomarkers are promising candidates to predict response, monitor resistance, and track the evolution of lung cancer during ICI treatment. In this review, we focus on the application of circulating tumor DNA (ctDNA) in plasma in immunotherapy. We examine the potential of pre- and on-treatment features of ctDNA as biomarkers, and following multiparameter analysis, we determine the potential clinical value of integrating predictive liquid biomarkers of ICIs to optimize patient management. We further discuss the role of ctDNA in monitoring treatment resistance, as well as challenges in clinical translation.

Discovery of activating mutations in epidermal growth factor receptor (EGFR) as a predictive biomarker for first-generation EGFR tyrosine kinase inhibitors (TKIs) has initiated an era of precision oncology for the treatment of advanced EGFR-mutant non-small cell lung cancer (NSCLC). Despite the robust efficacy of first- and second-generation EGFR TKIs, disease relapse is inevitable. EGFR T790M mutation is the predominant cause of disease relapse and third-generation, irreversible EGFR inhibitors designed for targeting EGFR T790M and activating mutations have demonstrated promising clinical activity and tolerability. Unfortunately, disease progression inevitably occurs and heterogenous resistance mechanisms have been reported with limited subsequent treatment strategies available. Till now, treatment approaches for patients progressed from third-generation EGFR TKIs have not been clearly established. In this review, we summarize the recent findings in resistance mechanisms to third-generation EGFR TKIs and emerging treatment approaches for EGFR-mutant patients after resistance to third-generation EGFR TKIs. We further discuss clinical challenges and future perspectives for management of EGFR-mutant patients resistant to third-generation EGFR TKIs.

2591 Background: Immune checkpoint inhibitors (ICIs) have suboptimal efficacy in non-small cell lung cancer (NSCLC) patients with ERBB2 mutations, including ERBB2 exon 20 insertions. This study aims to investigate the efficacy of ICIs and immune characteristics in NSCLC patients harboring ERBB2 ex20ins and non-ex20ins mutations. Methods: Advanced NSCLC patients harboring ERBB2 mutations were recruited from January 2016 to December 2020. Pre-ICI tumor tissue samples were collected and performed with targeted next-generation sequencing. Patients received ICIs were followed up every 3 months until November 2021. Genomic features were compared between patients with ERBB2 ex20ins and non-ex20ins mutations. Progression-free survival (PFS), overall survival (OS), and tumor immune microenvironment (TIME) features characterized by multiplex immunohistochemistry (IHC) were further analyzed in patients receiving ICIs. Two-sample T-tests were performed to compare means; Cox models were fitted to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Two external datasets of ERBB2-mutant NSCLC patients, including TCGA (n = 23) and META (n = 33), were used for validation. Results: A total of 117 eligible patients were enrolled (median age: 59 [range: 24-82], males 57.3%, stage IV 68.4%, adenocarcinoma 93.2%), of whom 37 received subsequent ICI treatment. similar PD-L1 tumor proportion score (mean: 8.1% vs. 13.2%, p = 0.25) and significantly lower mutation number (mean: 3.0 vs. 6.2 muts/person, p < 0.01) were detected in patients with ERBB2 ex20ins, compared to patients with ERBB2 mutations other than ex20ins. Similarly, in the TCGA cohort, tumor mutation burden was significantly lower in ERBB2 ex20ins patients (mean: 2.2 vs. 10.3 muts/Mb, p = 0.02). Of 37 patients receiving ICIs, ERBB2 non-ex20ins patients displayed superior PFS (mPFS: 13.5 vs. 4.4 months, HR: 0.31, 95% CI: 0.14-0.71), relatively long OS (mOS: 27.5 vs. 8.1 months, HR: 0.47, 95% CI: 0.20-1.14), and a relatively high rate of durable clinical benefit (64.3% vs. 34.8%, p = 0.10) than ex20ins patients, consistent with what was observed in the META cohort (PFS, mPFS: 13.2 vs. 2.5 months, HR: 0.20, 95% CI: 0.06-0.68; OS, mOS: 23.3 vs. 8.0 months, HR: 0.32, 95% CI: 0.11-0.90). Moreover, the CD4+ T cell density appeared to be lower in the tumor stroma of ERBB2 ex20ins patients than that of non-ex20ins patients (300.5 vs. 1288.0 /mm2, p = 0.08), even though the general TIME features of ex20ins patients were similar to those of non-ex20ins patients. Conclusions: NSCLC patients carrying ERBB2 ex20ins demonstrated worse clinical outcome under ICI treatment, similar PD-L1 expression and lower mutation number when compared to those with non-ex20ins mutations. Genomic and TIME characteristics should be further investigated to elucidate the efficacy of ICIs in lung cancer patients carrying ERBB2 mutations.

Background The third-generation EGFR tyrosine kinase inhibitor osimertinib has been approved in many countries to treat advanced NSCLC in patients with the EGFR T790M mutation. As the development of acquired resistance is inevitable, it is urgent that the mechanisms of such resistance be clarified. Methods DNA samples from a cohort of 340 patients with lung adenocarcinoma who were taking osimertinib were subjected to next-generation sequencing and screened in terms of the frequencies of the L792H and G796R mutations. Ba/F3 cells stably expressing the EGFR L858R/T790M mutations (in cis) with either the L792H or G796R mutation were created to investigate the impact of the two novel mutations on EGFR tyrosine kinase inhibitors and other potential drug combinations in vitro. Structural analyses were performed by using Schrodinger/Maestro software (version 11.1.012, Schrodinger LLC, Cambridge, MA). Results L792H and G796R were detected in 1.76% (six of 340) and 0.56% (two of 340) patients with lung adenocarcinoma treated with osimertinib, respectively. The introduction of L792H or G796R mutations against an L858R/T790M background caused dramatic reductions in osimertinib sensitivity. Structural modeling showed that mutations in cis with T790M either forced the ligand (osimertinib) to rotate out (breaking the binding) or pulled the hinge loop (breaking the hinge). Various other drug combinations. including cetuximab with EAI045, failed to inhibit either cis mutant effectively. Conclusions The EGFR L858R/T790M/L792H and L858R/T790M/G796R mutations conferred resistance to osimertinib both in vitro and in silico. For patients in whom the two resistance mutations occur at low frequency, more precise treatment strategies and additional combinational approaches are required.

During persistent antigen stimulation, CD8(+) Tcells show a gradual decrease in effector function, referred to as exhaustion, which impairs responses in the setting of tumors and infections. Here we demonstrate that the transcription factor NFAT controls the program of Tcell exhaustion. When expressed in cells, an engineered form of NFAT1 unable to interact with AP-1 transcription factors diminished Tcell receptor (TCR) signaling, increased the expression of inhibitory cell surface receptors, and interfered with the ability of CD8(+) Tcells to protect against Listeria infection and attenuate tumor growth invivo. We defined the genomic regions occupied by endogenous and engineered NFAT1 in primary CD8(+) Tcells and showed that genes directly induced by the engineered NFAT1 overlapped with genes expressed in exhausted CD8(+) Tcells invivo. Our data show that NFAT promotes Tcell anergy and exhaustion by binding at sites that do not require cooperation with AP-1.

The treatment paradigm of non-small cell lung cancer (NSCLC) has evolved into oncogene-directed precision medicine. Identifying actionable genomic alterations is the initial step towards precision medicine. An important scientific progress in molecular profiling of NSCLC over the past decade is the shift from the traditional piecemeal fashion to massively parallel sequencing with the use of next-generation sequencing (NGS). Another technical advance is the development of liquid biopsy with great potential in providing a dynamic and comprehensive genomic profiling of NSCLC in a minimally invasive manner. The integration of NGS with liquid biopsy has been demonstrated to play emerging roles in genomic profiling of NSCLC by increasing evidences. This review summarized the potential applications of NGS-based liquid biopsy in the diagnosis and treatment of NSCLC including identifying actionable genomic alterations, tracking spatiotemporal tumor evolution, dynamically monitoring response and resistance to targeted therapies, and diagnostic value in early-stage NSCLC, and discussed emerging challenges to overcome in order to facilitate clinical translation in future.

The diagnosis and treatment of lung cancer have evolved into the era of precision medicine. Liquid biopsy, a minimally invasive approach, has emerged as a promising practice in genetic profiling and monitoring of lung cancer. Translating liquid biopsy from bench to bedside has encountered various challenges, including technique selection, protocol standardisation, data analysis and cost management. Regarding these challenges, the 2016 Chinese Lung Cancer Summit expert panel organised a trilateral forum involving oncologists, clinicians, clinical researchers, and industrial expertise on the 13th Chinese Lung Cancer Summit to formally discuss these controversies. Six consensuses were reached to guide the use of liquid biopsy and perform precision medicine in both clinic and research.

Squamous cell lung cancer (SQCLC) is an aggressive type of lung cancer and most are diagnosed at advanced stage. Patients with advanced SQCLC tend to be older, current or former smoker, with central type tumour located near large blood vessels and seldom with druggable genetic alternations. Consequently, progress of targeted therapy and antivascular agents available in lung adenocarcinoma could not be duplicated in this subset of patients. The treatment paradigms have long been dominant by cytotoxic agents and posed many therapeutic challenges. Until recent years, immune checkpoint inhibitors, other monoclonal antibodies and afatinib have been approved for treatment of advanced SQCLC, presenting a novel treatment landscape and initiating the era of precision medicine in this subset of patients. This review will summarise the recent treatment progresses in advanced SQCLC with a focus on checkpoint inhibitors of programmed cell death-1 receptor or its ligand, and discuss the emerging challenges in this new era.