BRAF and KRAS are two key oncogenes in the RAS/RAF/MEK/MAPK signaling pathway. Concomitant mutations in both KRAS and BRAF genes have been identified in non-small cell lung cancer (NSCLC). They lead to the proliferation, differentiation, and apoptosis of tumor cells by activating the RAS/RAF/MEK/ERK signaling pathway. To date, agents that target RAS/RAF/MEK/ERK signaling pathway have been investigated in NSCLC patients harboring BRAF mutations. BRAF and MEK inhibitors have gained approval for the treatment of patients with NSCLC. According to the reported findings, the combination of MEK inhibitors with chemotherapy, immune checkpoint inhibitors, epidermal growth factor receptor-tyrosine kinase inhibitors or BRAF inhibitors is highly significant for improving clinical efficacy and causing delay in the occurrence of drug resistance. This review summarized the existing experimental results and presented ongoing clinical studies as well. However, further researches need to be conducted to indicate how we can combine other drugs with MEK inhibitors to significantly increase therapeutic effects on patients with lung cancer.

Currently, chemotherapy remains the standard treatment for first- and second-line management of small cell lung cancer (SCLC). Immunotherapy has made progress in the treatment of SCLC, and nivolumab, pembrolizumab, atezolizumab, and durvalumab have led to significant improvements in clinical outcomes of SCLC. Regarding options in other classes of therapy, the cytotoxic drug lurbinectedin was granted orphan drug status based on a remarkable objective response rate of 39.3%. In addition, an increase in progression-free survival (PFS) was achieved in a phase II study of anlotinib (ALTER 1202). Future prospects for even better outcomes in SCLC lie in novel ways to integrate immunotherapy and small-molecule TKI drugs. Innovative clinical trial designs are needed to efficiently explore the increasing number of options with new drugs and new combinations thereof for SCLC.

PURPOSE: Aumolertinib (formerly almonertinib; HS-10296) is a novel third-generation epidermal growth factor receptor tyrosine kinase inhibitor approved in China. This double-blind phase III trial evaluated the efficacy and safety of aumolertinib compared with gefitinib as a first-line treatment for locally advanced or metastatic EGFR-mutated non–small-cell lung cancer (NSCLC; ClinicalTrials.gov identifier: NCT03849768 ). METHODS: Patients at 53 sites in China were randomly assigned 1:1 to receive either aumolertinib (110 mg) or gefitinib (250 mg) once daily. The primary end point was progression-free survival (PFS) per investigator assessment. RESULTS: A total of 429 patients who were naïve to treatment for locally advanced or metastatic NSCLC were enrolled. PFS was significantly longer with aumolertinib compared with gefitinib (hazard ratio, 0.46; 95% CI, 0.36 to 0.60; P < .0001). The median PFS with aumolertinib was 19.3 months (95% CI, 17.8 to 20.8) versus 9.9 months with gefitinib (95% CI, 8.3 to 12.6). Objective response rate and disease control rate were similar in the aumolertinib and gefitinib groups (objective response rate, 73.8% and 72.1%, respectively; disease control rate, 93.0% and 96.7%, respectively). The median duration of response was 18.1 months (95% CI, 15.2 to not applicable) with aumolertinib versus 8.3 months (95% CI, 6.9 to 11.1) with gefitinib. Adverse events of grade ≥ 3 severity (any cause) were observed in 36.4% and 35.8% of patients in the aumolertinib and gefitinib groups, respectively. Rash and diarrhea (any grade) were observed in 23.4% and 16.4% of patients who received aumolertinib compared with 41.4% and 35.8% of those who received gefitinib, respectively. CONCLUSION: Aumolertinib is a well-tolerated third-generation epidermal growth factor receptor tyrosine kinase inhibitor that could serve as a treatment option for EGFR-mutant NSCLC in the first-line setting.

Treatment of non-small cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) activating mutation with EGFR-TKIs has achieved great success, yet faces the development of acquired resistance as the major obstacle to long-term disease remission in the clinic. MET (or c-MET) gene amplification has long been known as an important resistance mechanism to first- or second-generation EGFR-TKIs in addition to the appearance of T790 M mutation. Recent preclinical and clinical studies have suggested that MET amplification and/or protein hyperactivation is likely to be a key mechanism underlying acquired resistance to third-generation EGFR-TKIs such as osimertinib as well, particularly when used as a first-line therapy. EGFR-mutant NSCLCs that have relapsed from first-generation EGFR-TKI treatment and have MET amplification and/or protein hyperactivation should be insensitive to osimertinib monotherapy. Therefore, combinatorial therapy with osimertinib and a MET or even a MEK inhibitor should be considered for these patients with resistant NSCLC carrying MET amplification and/or protein hyperactivation.

PURPOSE: The CHOICE-01 study investigated the efficacy and safety of toripalimab in combination with chemotherapy as a first-line treatment for advanced non–small-cell lung cancer (NSCLC). PATIENTS AND METHODS: Patients (N = 465) with treatment-naive, advanced NSCLC without EGFR/ALK mutations were randomly assigned 2:1 to receive toripalimab 240 mg (n = 309) or placebo (n = 156) once every 3 weeks in combination with chemotherapy for 4-6 cycles, followed by the maintenance of toripalimab or placebo once every 3 weeks plus standard care. Stratification factors included programmed death ligand-1 expression status, histology, and smoking status. The primary end point was progression-free survival (PFS) by investigator per RECIST v1.1. Secondary end points included overall survival and safety. RESULTS: At the final PFS analysis, PFS was significantly longer in the toripalimab arm than in the placebo arm (median PFS, 8.4 v 5.6 months, hazard ratio = 0.49; 95% CI, 0.39 to 0.61; two-sided P < .0001). At the interim OS analysis, the toripalimab arm had a significantly longer OS than the placebo arm (median OS not reached v 17.1 months, hazard ratio = 0.69; 95% CI, 0.53 to 0.92; two-sided P = .0099). The incidence of grade ≥ 3 adverse events was similar between the two arms. Treatment effects were similar regardless of programmed death ligand-1 status. Genomic analysis using whole-exome sequencing from 394 available tumor samples revealed that patients with high tumor mutational burden were associated with significantly better PFS in the toripalimab arm (median PFS 13.1 v 5.5 months, interaction P = .026). Notably, patients with mutations in the focal adhesion-PI3K-Akt signaling pathway achieved significantly better PFS and OS in the toripalimab arm (interaction P values ≤ .001). CONCLUSION: Toripalimab plus chemotherapy significantly improves PFS and OS in patients with treatment-naive advanced NSCLC while having a manageable safety profile. Subgroup analysis showed the OS benefit was mainly driven by the nonsquamous subpopulation.

Background: RNA 5-methylcytosine (m⁵C) modification plays critical roles in the pathogenesis of various tumors. However, the function and molecular mechanism of RNA m⁵C modification in tumor drug resistance remain unclear. Methods: The correlation between RNA m⁵C methylation, m⁵C writer NOP2/Sun RNA methyltransferase family member 2 (NSUN2) and EGFR-TKIs resistance was determined in non-small-cell lung cancer (NSCLC) cell lines and patient samples. The effects of NSUN2 on EGFR-TKIs resistance were investigated by gain- and loss-of-function assays in vitro and in vivo. RNA-sequencing (RNA-seq), RNA bisulfite sequencing (RNA-BisSeq) and m⁵C methylated RNA immunoprecipitation-qPCR (MeRIP-qPCR) were performed to identify the target gene of NSUN2 involved in EGFR-TKIs resistance. Furthermore, the regulatory mechanism of NSUN2 modulating the target gene expression was investigated by functional rescue and puromycin incorporation assays. Results: RNA m⁵C hypermethylation and NSUN2 were significantly correlated with intrinsic resistance to EGFR-TKIs. Overexpression of NSUN2 resulted in gefitinib resistance and tumor recurrence, while genetic inhibition of NSUN2 led to tumor regression and overcame intrinsic resistance to gefitinib in vitro and in vivo. Integrated RNA-seq and m⁵C-BisSeq analyses identified quiescin sulfhydryl oxidase 1 (QSOX1) as a potential target of aberrant m⁵C modification. NSUN2 methylated QSOX1 coding sequence region, leading to enhanced QSOX1 translation through m⁵C reader Y-box binding protein 1 (YBX1). Conclusions: Our study reveals a critical function of aberrant RNA m⁵C modification via the NSUN2-YBX1-QSOX1 axis in mediating intrinsic resistance to gefitinib in EGFR-mutant NSCLC.