The EGFR family, a family of receptor tyrosine kinases, is composed of the EGFR1, EGFR2, EGFR3 and EGFR4 proteins. As a growth factor receptor, EGFR is considered to be involved in the development of cancer because its activation induces cell differentiation and proliferation (30,31). The EGFR gene is often mutated in cancer cells. EGFR mutations account for ~50% of LUAD cases in Asian patients, whereas they account for 20% of cases in Western patients. Classical EGFR mutations include exon 19 deletions and exon 21 L858R point mutations, whereas uncommon EGFR mutations include G719X, S768I and L861Q (32). EGFR activation initiates intracellular signaling mainly through the following pathways: The Ras/Raf/MAPK, PI3K/AKT, signal transducer and activator of transcription (STAT), Src kinase, stress and autophagy pathways (31). Thus, alterations in EGFR signaling pathways lead to the inhibition of tumor apoptosis and a poor prognosis (33,34). These findings suggested that EGFR is a therapeutic target and supports the development of EGFR-tyrosine kinase inhibitors (TKIs) (35). Furthermore, both the EGFR-MET-targeted bispecific antibody amivantamab and the novel EGFR-TKI mobocertinib have received approval as treatments for patients with advanced NSCLC harboring EGFR exon 20 insertions (36). Although targeted therapy has opened a novel era for lung cancer treatment, drug resistance is inevitable. Of note, EGFR C797S mutation is one of the most notable acquired resistance mechanisms of EGFR-TKIs in NSCLC. The structural changes and its competitive binding with EGFR-TKIs such as osimertinib will lead to drug resistance. The two main subtypes of EGFR C797S mutation include cis- and trans-mutation with EGFR T790M, and their different molecular characteristics result in differential therapeutic responses (37). Therefore, numerous studies have focused on the mechanism of EGFR-TKI resistance and the development of novel drugs (38,39).

Human EGFR 2 (HER2), also known as Erb-b2 receptor tyrosine kinase 2, is another member of the EGFR family. The HER2 gene, located at chromosome 17q11.2-q12, is a proto-oncogene and belongs to the classical superfamily of receptor tyrosine kinases (40,41). HER2 mutations, along with HER2 amplification and protein upregulation, are present in patients with NSCLC at a frequency of 2–4% (42). The HER2 alterations also activate the MAPK, PI3K/AKT, protein kinase C and STAT pathways (43,44). Notably, HER2 upregulation was confirmed to be one mechanism of resistance to EGFR-TKIs (45) and HER2 mutations are acquired in 1% of patients receiving EGFR-TKI treatment (35). In contrast to gastric and breast cancer, anti-HER2 agents have not been considered a standard treatment for HER2-mutant NSCLC (46). Furthermore, compared with ALK rearrangement, chemotherapy produces notably reduced outcomes in patients with HER2-mutant NSCLC (47). However, improved results for two newly developed HER2-specific TKIs (BAY2927088 and zongertinib) with low EGFR wild-type inhibition were recently reported and these HER2-specific TKIs received the breakthrough therapy designation from the Food and Drug Administration (FDA) for HER2⁺ NSCLC (48), highlighting the continuous investigation of HER2-targeting agents.

The ALK gene, located on chromosome 2, encodes the ALK protein, which has a cytoplasmic receptor kinase segment and an extracellular domain, similar to other receptor tyrosine kinases like EGFR and HER2 (49). Rearrangement is the main type of ALK gene mutation and other types include amplification and point mutation (50). As a driver of cancer, ALK rearrangement is associated with never smoking, younger age and generally advanced disease, and has been identified in 3–7% of patients with NSCLC (51–53). Rearrangement of the ALK gene always occurs with partner genes, such as echinoderm microtubule-associated protein-like 4 (EML4). The EML4-ALK fusion represents a novel molecular target and other partner genes, such as TFG, TPR, KIF5B, KLC1, HIP1, SQSTM1, STRN and DCTN1, have also been described (50). ALK fusion proteins can activate multiple signaling pathways, including Janus kinase (JAK)/STAT, PI3K/AKT, Ras/Raf/MEK/ERK1/2 and phospholipase C-γ, all of which are involved in cellular proliferation and survival (54). According to these findings, ALK-TKIs have been developed as a therapeutic strategy and have exhibited promising results in patients with ALK-mutant NSCLC (55,56). In addition to the current FDA-approved ALK-TKIs (crizotinib, ceritinib, alectinib, brigatinib and lorlatinib) (57), other trials of drugs targeting ALK rearrangements, such as ensartinib, are still ongoing and have led to favorable OS in patients with crizotinib-resistant NSCLC (58). Thus, drug resistance strategies require further investigation in the future.

The MET gene encodes a receptor tyrosine kinase that is involved in multiple oncogenic processes, particularly cell proliferation and tumor growth. The mutations of the MET gene include three main types: Protein upregulation, exon 14-skipping (METex14) mutations and gene amplification (59,60). Notably, the most commonly reported oncogenic MET mutation is METex14, which is present in 2–3% of patients with NSCLC and coexisting mutations of METex14 with other oncogenic drivers are rare (60–62). MET can activate the ERK/MAPK, PI3K/protein kinase B and JAK/STAT pathways when the MET receptor tyrosine kinase binds to its ligand, hepatocyte growth factor (HGF)/scatter factor (63,64). Thus, anti-MET therapies can be divided into selective/non-selective TKIs and antibodies directly targeting MET or HGF (65). For example, novel agents such as amivantamab, a MET and EGFR bispecific monoclonal antibody, have exhibited promising activity against METex14 NSCLC (66). Similarly, acquired drug resistance is still a challenge for MET-TKIs.

ROS1 is a receptor tyrosine kinase gene that is expressed in 1–2% of NSCLCs, typically in younger and never-smoking patients (67). The ROS1 gene rarely fuses with other oncogenic driver mutations (<1%), except for several partner genes, such as CD74. Majority of patients with ROS1⁺ NSCLC present with stage IV disease and brain metastases at the initial diagnosis (20–40%) (68,69). Several studies have explored the downstream pathways of ROS1 fusion proteins, including the autophosphorylation of ROS1 and phosphorylation of MEK, Src homology region 2 domain-containing phosphatase-2, STAT3, AKT and ERK (70–72). Notably, the expression of the CD74-ROS1 fusion resulted in autophosphorylation of ROS1 (68). Due to the high degree of homology between ROS and ALK tyrosine kinase domains, ROS1-mutant tumors are sensitive to ALK-TKIs (73). Currently, FDA-approved TKIs for patients with NSCLC with ROS1 rearrangements include crizotinib and entrectinib (74). In addition, repotrectinib can target ROS1 and is a promising second-line therapy for NTRK fusion⁺ NSCLC (75). ROS1-rearranged NSCLC cases are associated with PD-L1 expression (76); however, ICI monotherapy does not markedly benefit patients with ROS1⁺ NSCLC (77,78). Therefore, further development of strategies for patients with ROS1-TKI-resistant NSCLC is warranted in future research.

STK11/LKB1, a novel human gene that encodes a serine threonine kinase and is located on chromosome 19p13.3, was first identified in early January 1998 (86,87). LKB1 alterations occur in an extensive variety of cancer types such as NSCLC, hepatocellular carcinoma and colorectal cancer, and the rate in NSCLC can reach 20% (14,88,89). The LKB1 protein acts as a metabolic sensor and controls cellular metabolism (90). The loss of LKB1 inactivates AMP-activated protein kinase (AMPK) and salt-inducible kinase signaling, after which abnormal mTOR and hypoxia inducible factor 1α signaling result in an energy imbalance (91,92). LKB1 mutations often occur with other driver genes, such as KRAS. Different comutations affect the biology of LKB1, with diverse phenotypes (93). Patients with NSCLC with LKB1 loss have a worse prognosis, as chemotherapy and immunotherapy exhibit little efficacy, and no targeted agents are available for this subtype (94). These features make LKB1 a research hotspot. Thus, the present review emphasizes the molecular mechanism and treatment of LKB1 and discusses its relationship with immunotherapy in the following section.

KEAP1 was identified in the 1990s and acts as an adaptor for Cul3-based E3 ligases to regulate nuclear factor-E2-related factor 2 (NRF2), and the KEAP1-NRF2 pathway serves a key role in cellular defenses against oxidative and electrophilic stimuli (95–97). KEAP1 mutations are observed in 10–15% of LUAD cases, with a high frequency of co-occurring mutations in LKB1 (98). A previous study has demonstrated that KEAP1 mutation promotes tumor growth mainly through the KEAP1/NRF2 pathway and KEAP1 is considered a tumor suppressor gene (99). Certain clinical studies have provided evidence that patients with KEAP1-mutant NSCLC exhibit a distinct clinicopathological phenotype (100,101). Furthermore, similar to LKB1 mutation, KEAP1 mutations in NSCLC are associated with resistance to various therapeutics, including chemotherapy, radiotherapy, TKI treatment and immunotherapy. Although various KEAP1 inhibitors have been described in previous decades, none of them are currently being explored in clinical applications, to the best of our knowledge (101,102). Thus, the development of KEAP1 inhibitors for NSCLC treatment remains challenging and combination immunotherapeutic strategies may be promising in overcoming immune resistance.

The CDKN2A gene is also known as p16INK4a, which belongs to the INK4 family, with CDKN2B (p15INK4b) being another key member (103). As a tumor suppressor gene, CDKN2A is frequently altered in NSCLC, with an incidence rate of 5.7–19.1% in LUAD (104). As a CDK inhibitor, it encodes the protein p16, which can inhibit CDK and CDK4/6-cyclin D complexes by interacting with the kinase catalytic cleft and distorting the ATP binding site (105). When CDK4/6 phosphorylation is inhibited, the G₁/S transition is prevented (106). CDKN2A inactivation results in the activation of the JAK2/STAT3 pathway and influences PI3K/AKT signaling (107,108). Previous studies have reported that CDKN2A mutations in patients with NSCLC are associated with shorter disease-free survival (DFS) and overall survival (OS) compared with its wildtype, with no benefit from ICI treatment (109,110). Therefore, effective strategies targeting CDKN2A/B are urgently needed.

Other tumor genetic mutations, such as RET fusions or rearrangements, and metabolic reprogramming also impact tumor biology, particularly the tumor microenvironment (TME). Thus, the importance of understanding tumor molecular mechanisms is self-evident because these mechanisms influence tumor growth pathways and are key to investigating NSCLC therapeutics.

Alterations in oncogenes/tumor suppressor genes always lead to the development of NSCLC through downstream pathways, including the PI3K/AKT/mTOR, EGF/EGFR, VEGF/VEGFR, Ras/Raf/MAPK, KEAP1/NRF2 and CDK4/6 pathways (35). The abnormal activation of these pathways promotes cell proliferation and inhibits apoptosis, thus resulting in tumor progression. In this section, the present review discusses the classical signaling pathways that are closely associated with NSCLC treatment.

The PI3K signaling pathway, one of the most frequently altered pathways in NSCLC, can be activated by members of the EGFR family/insulin and insulin-like growth factor 1 receptors, which are growth factors that are specific to different RTKs (111,112). In NSCLC, PIK3CA gene mutation is a common mechanism of PI3K activation (113). The incidence of PIK3CA alterations (PIK3CA mutations and amplifications) in lung SCC is higher (33.1 vs. 6.2%) compared with that in LUAD (35,114). Other mechanisms, such as phosphate and tensin homolog mutation, can also result in abnormal activation of the PI3K pathway through the dephosphorylation of phosphatidylinositol-3,4,5-trisphosphate and disruption of further signal transduction (115). After the PI3K signaling pathway is activated, tumors develop and antitumor drug resistance occurs rapidly, leading to disease progression. Notably, the PI3K/AKT pathway also serves a key role in tumors with other known mutations, such as EGFR. In addition, the PI3K/AKT/mTOR pathway is constitutively activated in >50% of EGFR-mutant lung carcinomas (116). Furthermore, a previous study revealed that the PI3K/AKT/mTOR axis persists as a therapeutic component in KRAS G12D-driven NSCLC (117). Due to the effects of PI3K/AKT signaling and its downstream pathway on tumor development and progression, as well as its potential influence on drug response and resistance, it represents a key target for antitumor therapy in NSCLC.

The alteration of EGFR signaling is a common phenomenon in patients with NSCLC, particularly in patients with LUAD from East Asia, suggesting that it is a key orchestrator of epithelial transformation; it is one of the most prevalent studied targets (118). Dysregulation of EGFR signaling is caused mainly by point mutations, receptor amplification or ligand overproduction (119). Several reviews have described that the EGF/EGFR pathway results in intracellular signaling through the MAPK pathway and the PI3K and STAT pathways (120,121). These downstream signaling pathways lead to increased tumor angiogenesis, tumor cell proliferation and metastasis (35). In addition, alterations in the EGFR pathway inhibit tumor apoptosis due to the activation of its kinase function, thus leading to poor outcomes (34,35). These results suggested that EGFR signaling is a therapeutic target, which could improve the development of antitumor agents. Therefore, small-molecule inhibitors that target EGFR signaling have been used in multiple cancer types, including NSCLC, breast cancer and colorectal cancer (122,123). However, drug resistance develops due to novel mutations, bypass signaling mechanisms and other unknown mechanisms, making research on resistance mechanisms associated with the EGFR pathway a hotspot.

Vascular endothelial growth factor (VEGF) belongs to a protein family that serves a key role in regulating angiogenesis. The tumor-associated neovasculature, a hallmark of cancer, is generated through angiogenesis (124,125). In addition to NSCLC, most human tumors upregulate VEGF, whose expression is associated with an increased vascular density, cancer cell invasiveness and metastasis (126). VEGF signaling, which can be regulated by hypoxia and oncogene signaling at multiple levels, is activated mainly through upregulated VEGF expression and its binding to the VEGF receptor (VEGFR) (127,128). Furthermore, the fibroblast growth factor family is involved in sustaining tumor angiogenesis through proangiogenic signals (129). Thus, the VEGF/VEGFR pathway has been identified as a notable therapeutic target. Bevacizumab was the first monoclonal antibody developed to block VEGF-VEGFR binding and has been reported to be effective against NSCLC as a monotherapy or in combination with platinum-doublet chemotherapy and with EGFR/ALK-TKIs (130,131). Additionally, small-molecule agents that inhibit downstream VEGF/VEGFR signaling can also exert anti-angiogenic and extensive antitumor effects (132).

The three main members of the MAPK family are ERK, JNK/SAPK and p38 MAPK, which serve key roles in several biological functions, including signal transduction from the extracellular matrix to intracellular organelles (133). The MAPK pathway involves three-kinase cascades: The upstream kinase (MAPKKK) directly phosphorylates MAPKK in response to various extra and intracellular signals and the middle kinase (MAPKK) then phosphorylates and activates MAPK. The MAPK pathway is involved in cell proliferation and differentiation, as well as cell survival and apoptosis. The MAPK pathway is always dysregulated in Ras-mutant NSCLC, resulting in uncontrolled cancer cell proliferation and drug resistance (134,135). The Ras/Raf/MAPK pathway serves a key role in this process, making proteins involved in this cascade cancer treatment targets (136). Certain agents that block MAPK signaling, such as Trametinib, have been reported to lead to signal interruption and kinase inhibition (137). Enhancing current understanding on this pathway is key due to its notable functions and the extensive spectrum of crosstalk with other major pathways.

The KEAP1/NRF2 pathway is considered to regulate redox homeostasis and protect cells from oxidative stress. During tumor initiation and progression, this pathway is often hijacked by cancer cells and aberrant KEAP1-NRF2 activity is predominantly observed in NSCLC (138). KEAP1 regulates NRF2 signaling in response to reactive oxygen species (139) and the PI3K signaling pathway also affects this pathway through glycogen synthase kinase 3, which acts as a key mediator (140). Furthermore, KEAP1-NRF2 signaling is involved in crosstalk with other pathways and increasing research has revealed its association with metabolic activities, leading to tumor metabolic reprogramming in lung cancer (141,142). Therefore, the metabolic vulnerability of KEAP1/NRF2-mutant NSCLC is a target (143). Furthermore, KEAP1/NRF2 signaling could be used as a prognostic biomarker for a poor prognosis and as a predictive marker for drug resistance (101). KEAP1/NRF2-mutant NSCLC is associated with a poor prognosis and resistance to platinum-based chemotherapy, radiotherapy, EGFR-TKI and immune checkpoint inhibitors (144–146). Due to the key role of the KEAP1/NRF2 pathway in NSCLC, novel compounds or repurposed agents that target this pathway are of notable interest for clinical cancer treatment.

The 5-year survival rate of patients with lung cancer has improved markedly due to the progress in cancer screening and personalized therapy. However, it varies extensively from 8 to 64% in terms of localized differences and tumor stage (147). For patients with early-stage NSCLC, the recommended treatment is surgery, which can markedly improve survival. Furthermore, the 5-year survival rate for patients with clinical stage IA disease can reach 92% and the survival rate for patients with stage I–IIB disease varies from 68 to 53% (9). For patients with distant metastatic lesions, the survival rate is low. For example, up to 40% of patients with stage IV disease develop brain metastases and current treatments for this subgroup have been suggested to lack efficacy due to the intracranial activity of drugs (148). Except classical chemotherapies or radiotherapies, targeted therapies, immunotherapies and anti-angiogenic therapies, other approaches including ADCs, bispecific antibodies, T-cell engagers, cancer vaccines, cellular therapies and external devices are available for patients with advanced NSCLC (149). In this section, the present review discusses the most commonly applied and potential treatments in clinical practice.

For patients with unresectable NSCLC and a good performance status, platinum-based chemotherapy is the cornerstone of treatment and other therapeutic options involve thoracic radiotherapy (150). Although the side effects of chemoradiotherapies are apparent, cytotoxic therapies exert notable effects and have been extensively used in clinical practice: i) As a monotherapy or in combination with immunotherapy/anti-angiogenic therapy in patients with advanced NSCLC who have no actionable molecular target; ii) as an alternative to targeted therapy when drug resistance occurs; iii) and as adjuvant chemotherapy/neoadjuvant therapy in surgical cases. An open phase II study using concurrent cisplatin-oral vinorelbine and radiotherapy reported that comprehensive geriatric assessment was able to select fit elderly patients with locally advanced NSCLCs eligible for concurrent chemoradiotherapy (151). Furthermore, the combination of chemotherapy and thoracic radiation has a survival advantage, with an improvement of four months in median survival (152). However, previous studies have demonstrated that neoadjuvant chemoradiotherapy only improved the downstaging rates and R0 resection rates, with no benefit in terms of OS (153). In addition, postoperative radiotherapy (PORT), an adjuvant type of radiotherapy, can only reduce the rate of local recurrence, with no benefits in terms of DFS and OS (154). Another open-label, randomized, phase III trial demonstrated that conformal PORT cannot be recommended as the standard of care in patients with stage IIIA (N2) NSCLC (NCT00410683) (155). In recent years, radiotherapy has been integrated into neoadjuvant approaches, concurrent chemotherapy and/or immunotherapy due to technological innovations (156). Although chemoresistance which may be caused by impaired DNA repair pathways and inhibition of apoptosis (157), and adverse reactions limit its clinical utility in patients with advanced NSCLC, we hypothesize that the adverse effects of cytotoxic therapies will decrease in the near future with pharmaceutical development and that more patients with advanced lung cancer will benefit from this therapeutic option through toxicity monitoring and patient management.

In the era of precision medicine, targeted therapy has advanced the treatment of patients with NSCLC with driver gene alterations. Molecular detection has become a key part of the clinical management of NSCLC. Kinase inhibitors targeting EGFR, ALK, ROS1 and MET are commonly generated through genetic cues in clinical practice (158). However, >50% of LUAD patients have targetable oncogenic drivers and the use of targeted therapy is associated with improved outcomes (159,160). EGFR mutations, which are identified in exon 21 (L858R) or exon 19 (deletions), are the most predominant alterations and occur in 40% of Asian patients, mostly among never-smoking women (32,161). Currently, three generations of EGFR-TKIs are approved by the FDA; however, nearly all patients eventually experience drug resistance and disease progression (162). The common mechanism of acquired resistance to first-generation EGFR-TKIs is a second EGFR mutation (T790M), which can be overcome by osimertinib (a third-generation EGFR-TKI). Other resistance mechanisms include bypass or alternative activation, such as MET/HER2 amplification and insulin growth factor receptor 1 activation (163). For patients with HER2-mutant NSCLC, only one targeted therapy has been approved by the FDA/European Medicines Agency, trastuzumab deruxtecan, which is an ADC (48). Furthermore, three generations of ALK inhibitors have exhibited promising outcomes. Notably, due to their homologous domains, ALK-TKIs can also target ROS1-mutant NSCLCs (73). However, drug resistance inevitably occurs due to alterations in the expression of ALK genes, including mutations and amplification, and the upregulation of genes involved in bypass pathways (EGFR and MAPK). The predominant resistance mechanism is secondary ALK mutation, such as G1202R (164). Currently, several TKIs, including crizotinib and tepotinib, are on the market or in clinical trials to target MET. Tepotinib is recommended for patients with NSCLC with MET exon 14 skipping mutations (165,166). The development of therapeutics to target other potential alterations, such as those in KRAS, has been notably challenging. Several KRAS G12C inhibitors, including sotorasib (AMG510) and adagrasib (MRTX849), have demonstrated notable preclinical and clinical efficacy and gained accelerated approval in 2021 as monotherapies for patients with KRAS G12C NSCLC (29). Notably, all targeted therapies cannot avoid drug resistance, making the next generation of TKIs an emerging issue. Several clinical trials are ongoing; for example, amivantamab plus chemotherapy with and without lazertinib have been used to treat EGFR-mutant advanced NSCLC after disease progression on osimertinib (167). Primary results from the phase II SAVANNAH study (NCT03778229) revealed that savolitinib plus osimertinib provide a novel oral targeted treatment approach for patients with EGFR-mutated, advanced NSCLC with MET upregulation or amplification following disease progression on osimertinib (168).

In addition to targeted therapies for specific gene mutations, the development of immunotherapy, which is based on ICIs, has revolutionized the treatment of patients with non-targetable NSCLC. Since the first immunotherapy drug, nivolumab (anti-PD-1), was approved by the FDA for lung cancer in 2015, several FDA-approved ICIs have been developed that target PD-1/PD-L1 or cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) in advanced NSCLC (169). These inhibitors are generated upon T-cell activation because CTLA-4-B7.1 suppresses T-cell activation through the regulation of the immunological synapse between T and dendritic cells, and PD-1/PD-L1 hampers immune rejection or the response of T cells to tumor cells (170). Furthermore, the initiation and progression of lung cancer depend on the interaction between cancer cells and the immune system (171). Despite the marked survival outcomes observed in a subset of patients with NSCLC receiving ICI therapy, majority of patients demonstrate primary or secondary resistance to ICIs. Primary resistance is due to extrinsic modulation of TME or intrinsic adaptive changes in cancer cells, resulting in the lack of an immune response. Secondary resistance occurs when the disease progresses after the initial benefit from ICIs, as tumor cells acquire specific alterations that allow them to escape the immune response (172). The mechanisms include impaired antigen presentation, cGMP-AMP synthase-stimulator of interferon genes (STING) pathway dysregulation, tumor antigen loss, metabolic reprogramming in TME, immune cell exhaustion and microbiomes (173). Thus, investigating novel drugs to prevent and overcome immunotherapy resistance is crucial, as these drugs would benefit more patients, such as patients with LKB1-mutant NSCLC. Of note, a series of clinical studies focused on overcoming immunotherapy resistance are ongoing. Lifileucel, an autologous tumor-infiltrating lymphocyte monotherapy, was observed to improve the response rate in patients with advanced NSCLC who are resistant to ICIs, including patients with a low TMB and patients with LKB1 mutations (174). A phase I/II dose-escalation study demonstrated that the TEIPP24 vaccine is a novel immunotherapeutic approach for HLA-A positive checkpoint-resistant NSCLC (NCT05898763) (175). Furthermore, certain studies have described the molecular mechanism of LKB1-mediated immune resistance and proposed possible solutions, and certain clinical studies have also confirmed the poor outcomes of immunotherapy in LKB1-mutant NSCLC and verified potential therapeutics for overcoming immune resistance (176,177).

Abnormal vasculature is a major cancer hallmark and the TME consists of numerous pro-angiogenic factors, including VEGF, which are secreted by tumor or immune cells (178). Thus, antitumor angiogenesis has garnered attention and become one of the most effective cancer treatments (179). Anti-angiogenic agents reduce tumor blood supply by inhibiting VEGF pathway, limiting tumor growth and metastasis. Several agents, such as bevacizumab and ramucirumab, have been developed and applied clinically, often in combination with chemotherapy or other therapies. These combinations have demonstrated promising results, particularly in advanced NSCLC where conventional therapies alone have proven inadequate (180,181). However, notable challenges and limitations persist that hinder its efficacy and application. Safety and tolerability are key considerations in clinical application and common side effects of anti-angiogenic agents include hypertension, proteinuria and gastrointestinal complications (182). Another major challenge is the development of resistance mechanisms, which could be attributed to changes within the TME. Several studies have highlighted that despite initial responses to anti-VEGF therapies, tumors can develop compensatory mechanisms that bypass the effects of these agents, such as upregulating other pro-angiogenic factors or activating alternative signals (183,184). Recent research focuses on novel compounds that can effectively target these alternative pathways, such as the δ-like canonical Notch ligand 4-Notch1 signaling pathway, which serves a notable role in vascular function (185). In the future, the development of novel agents and selection of appropriate patients for anti-angiogenic therapy is key to maximizing treatment efficacy, highlighting the importance of identifying specific genetic mutations or biomarkers. The integration of biomarkers into clinical practice will facilitate the selection of patients and improve treatment outcomes. Thus, while anti-angiogenic treatments represent a notable advancement in the management of NSCLC, a multifaceted approach that includes drug development, resistance mechanisms and personalized treatment strategies is key to the treatment of this disease.

In addition to these classical treatments, novel therapies, such as ADC, are being integrated into treatment guidelines. For example, sacituzumab tirumotecan, a novel TROP2-directed ADC, exhibited notable single-agent activity and manageable tolerability in patients with advanced NSCLC with EGFR mutations. Telisotuzumab vedotin, an ADC that targets MET factor (c-Met) protein upregulation, plus osimertinib had promising activity in patients with c-Met protein-upregulating, EGFR-mutated non-squamous NSCLC after progression on osimertinib. Patritumab deruxtecan (HER3-DXd), an ADC consisting of a HER3 antibody attached to a topoisomerase I inhibitor, displayed clinical activity in metastatic EGFR-mutated NSCLC after disease progression on EGFR-TKI therapy. For HER2-upregulating cases, trastuzumab-deruxtecan has the potential to address the unmet clinical need (186–189). Recently, Scott and Levy (190) discussed the biomarker identification and drug resistance of these ADCs. Bispecific antibodies such as amivantamab, which targets both EGFR and MET, yielded promising efficacy in patients with EGFR-mutant NSCLC (191). Ivonescimab is another bispecific antibody which targets PD-1 and VEGF had improved progression-free survival (PFS) in TKI-treated NSCLC (192). Furthermore, first-line treatment with KN046 (a bispecific antibody against PD-L1 and CTLA-4) and chemotherapy is also effective in metastatic NSCLC (193). As a form of active immunotherapy, therapeutic cancer vaccines which include cancer cell vaccine, peptide/protein vaccine and DNA/RNA vaccine could improve survival in patients with advanced NSCLC. For instance, personalized neoantigen peptide vaccination was confirmed to be feasible and safe for patients with advanced NSCLC (194). Furthermore, data from a Phase Ib clinical trial of NEO-PV-01 (a personalized neoantigen-vaccine) supported the safety and immunogenicity in patients with advanced non-squamous NSCLC (195). The limitations of cancer vaccines include lack of standardized design and manufacturing processes, and various barriers in clinical translation. Furthermore, T-cell engagers also demonstrate potential clinical translation value. ACE-05 was a T-cell engager and exhibited promising antitumor efficacy in peripheral blood mononuclear cell-reconstituted humanized mouse harboring human NSCLC tumors (196). Furthermore, Shen et al (197) identified a bispecific antibody which was termed ‘secretion of T-cell-redirecting bispecific antibodies’, could simultaneously binds CD3 on T cells and S15 on tumor cells, resulting in increased activated T cells and inhibition of NSCLC. These strategies potentially provide hope for patients with NSCLC, particularly for those with LKB1 mutations (Table I). As patients with LKB1-mutant NSCLC still have no effective therapeutics, the most promising treatment may be immunotherapy or novel strategies. Thus, the present review emphasizes the molecular mechanism and treatment of LKB1-mutant NSCLC next, with a particular focus on immunotherapy and combined therapies.

These approaches are currently hindered by multiple interrelated barriers, such as tumor heterogeneity and adaptive drug resistance, which lead to inconsistent therapeutic responses across patients, along with the mechanisms of antigen escape, bypass pathway activation and epigenetic regulation reducing the efficacy of targeted and immunotherapies in both early and advanced stages. Furthermore, incomplete translational validity of preclinical models limits the predictability of clinical efficacy, as cell or animal models fail to recapitulate the complex TME and genomic co-alterations in human lung cancer. Furthermore, on-target or off-target toxicities of novel agents and poor delivery efficiency to special sites restrict their clinical application (198). Multi-faceted strategies are warranted to address these challenges, for example, developing personalized combinatorial regimens based on multi-omics profiling to overcome drug resistance, optimizing preclinical research systems by establishing patient-derived xenografts and organoid models that mimic human tumor heterogeneity, and integrate artificial intelligence to predict drug sensitivity and clinical outcomes (199), validating and standardizing clinical biomarkers to achieve accurate patient stratification.

Since LKB1 was identified, previous studies have focused on its biological functions and associations with cancer. LKB1 functions as a metabolic switch, its inactivation suppresses lipid metabolism and abrogates KRAS-induced immunogenicity (177,201). Loss of function of LKB1 has emerged as a major driver of the cold TIME in NSCLC, characterized by low levels of tumor-infiltrating CD4⁺ and CD8⁺ T cells, and PD-L1 expression (176,202,203). The immune evasion noted in LKB1-inactivated lung cancer is due to subsequent AMPK inactivation and attenuation of antigen presentation (204). AMPK activation will lead to the promotion of catabolic processes such as autophagy, which is key to cellular recycling and maintenance (205). This pathway also regulates glucose and lipid metabolism, contributing to the balance between energy intake and expenditure. Dysregulation of this pathway is often implicated in the pathogenesis of cancer (206). LKB1 mutation also leads to the abnormal activation of poly(ADP-ribose) polymerase-1 (PARP1) and deficiency in the DNA damage repair process. Hyperactivated PARP1 suppresses IFNγ signaling by physically interacting with and increasing the poly(ADP-ribosyl)ation of STAT1 (207). Furthermore, LKB1 inactivation induces the epigenetic repression of STING, thus promoting immune escape in KRAS-mutant lung cancer (177,208). Mechanistically, LKB1 deficiency is associated with STING loss, resulting in STING/type I interferon dysfunction and diminished immunotherapy efficacy in NSCLC (209,210). In patients with lymph node metastases, the loss of LKB1 expression is markedly associated with the concurrent loss of STING and p-AMPK in metastatic tumors (209). Notably, LKB1 is also a key regulator of T-cell development, viability and activation. T-cell-specific ablation of LKB1 is associated with blocked thymocyte development and reduced peripheral T cells (211). A recent study revealed that LKB1 deficiency in group 2 innate lymphoid cells, which serve key roles in regulating tumor immunity, leads to an exhausted-like phenotype. Blockade of PD-1 could reverse this phenotype and result in enhanced antitumor immune responses, revealing the antitumor immunity role of LKB1 (212). These results may explain why LKB1 mutations are associated with poor progresses and immune resistance.

According to the aberrant pathways induced by LKB1 deficiency, targeting metabolic vulnerabilities with mTOR inhibitors or AMPK agonist could restore metabolic control and inhibit tumor growth. Preclinical studies have demonstrated that LKB1-mutant tumors exhibit sensitivity to glutaminase inhibitors and biguanides, which impair glutamine metabolism and mitochondrial respiration, respectively (213,214). Clinical trials are investigating combination therapies of metabolic inhibitors with conventional chemotherapy or targeted agents to overcome resistance (91,215). For patients with KRAS/LKB1 co-mutant NSCLC, co-inhibition of KRAS and downstream effectors such as MEK, along with metabolic modulators such as autophagy inhibitors, has demonstrated synergistic antitumor effects (216,217). The FDA-approved antibody daratumumab, as an ADC, has been demonstrated to target CD38 in LKB1-mutant NSCLC (218). Due to the limited efficacy of single-agent ICIs in LKB1-mutant NSCLC, combination therapies have been explored to overcome immune resistance by modulating the TME and enhancing immune activation. A promising strategy involves combining ICIs with chemotherapy or radiotherapy, which can induce immunogenic cell death, and potentiate T-cell priming and infiltration (219). Furthermore, clinical trials are actively investigating various combinations of ICIs with PARP inhibitors, metabolic modulators and other targeted agents such as STAT3 inhibitors and CDK4/6 inhibitors, aiming to remodel the immunosuppressive TME and overcome immune evasion (207,220,221). Beyond conventional immune checkpoint blockade and combination regimens, novel immunotherapeutic modalities are being investigated to address the unique challenges posed by LKB1-mutant NSCLC. For example, hyper-interferon-sensitive influenza virus-based in situ vaccination has exhibited efficacy in overcoming anti-PD-1 resistance by eliciting robust type I interferon responses and augmenting cytotoxic T-cell activity in murine LKB1-mutant NSCLC models (222). Furthermore, adoptive cell therapies targeting tumor antigens are under exploration, with research focusing on enhancing immune recognition and overcoming the immunosuppressive microenvironment characteristic of LKB1 loss. Epigenetic therapies targeting the corepressor of RE1-silencing transcription factor complex have also been developed to reprogram the tumor epigenome, increase immune gene expression and synergize with ICIs to induce durable tumor regressions in STK11-mutant tumors (223,224). Collectively, these novel findings make notable breakthroughs and provide potential treatment options for STK11-mutant NSCLC in the future.