Non-small cell lung cancer (NSCLC) is the most common type of lung cancer, accounting for approximately 85% of all lung cancer cases. It encompasses several subtypes, including adenocarcinoma, squamous cell carcinoma, and large cell carcinoma (1). Treatment strategies for NSCLC vary depending on the disease stage: early-stage NSCLC is typically treated with surgery, while advanced stages rely on a combination of chemotherapy, targeted therapy, radiation therapy, and immunotherapy. Compared to small cell lung cancer (SCLC), NSCLC demonstrates lower responsiveness to chemotherapy and radiation therapy (2).

Recent advancements in targeted therapies have transformed the treatment landscape by focusing on molecular abnormalities that drive cancer progression. Unlike traditional chemotherapy, which indiscriminately targets rapidly dividing cells, targeted therapies minimize damage to normal tissues by specifically inhibiting genetic mutations or abnormal proteins. These small molecule inhibitors are tailored to specific molecular targets, allowing for more precise treatment with fewer side effects than traditional chemotherapy (3). For instance, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have become standard treatments for EGFR-mutant NSCLC, significantly improving patient outcomes by selectively targeting aberrant signaling pathways involved in tumor growth and survival (4,5).

Among the various molecular targets in cancer treatment, Axl, a member of the TAM (TYRO3, Axl, MER) family of receptor tyrosine kinases (RTKs), has emerged as a critical player in tumor progression and therapy resistance (6-11). Axl is frequently over-expressed in multiple cancers, including lung cancer, and its over-expression is associated with poor prognosis and enhanced tumor aggressiveness. Axl signaling activates key downstream pathways such as PI3K/AKT/mTOR, RAF/MEK/ERK, and NF-kB, promoting cancer cell proliferation, survival, invasion, and migration. Additionally, Axl contributes to EMT, a process essential for metastasis, and plays a significant role in resistance to chemotherapy, radiotherapy, and even targeted therapies.

In parallel with targeted therapies with small molecule inhibitors, immunotherapies using immune checkpoint inhibitors (ICIs) have also revolutionized cancer treatment by harnessing the body’s immune system to target tumors. ICIs such as anti-cytotoxic T-lymphocyte-associated protein (CTLA)-4, anti-programmed death (PD)-1, and anti-programmed death ligand (PDL) antibodies work by blocking immune checkpoint proteins that suppress T-cell activity. By restoring T-cell function, these ICIs enable sustained tumor recognition and destruction of cancer cells. Since their initial approval for melanoma, ICIs have demonstrated significant survival benefits across various malignancies, including NSCLC.

Despite these advancements, challenges persist due to resistance mechanisms and toxicity associated with both targeted therapies and immunotherapies. Factors such as tumor mutational burden (TMB), PD-L1 expression levels, and cytokines like interleukin (IL)-10 influence immunotherapy resistance. Additionally, rare transformations of NSCLC into SCLC pose further therapeutic hurdles. These complexities underscore the need for personalized treatment approaches that integrate molecular profiling with combination therapies to overcome resistance and optimize outcomes. Ongoing clinical trials are exploring the safety and efficacy of combining Axl inhibitors with ICIs in advanced malignancies. This evolving therapeutic strategy holds significant promise for addressing unmet needs in NSCLC treatment.

Since Axl has been reported to be associated with poor prognosis and therapeutic resistance in NSCLC, it has emerged as a critical therapeutic target. Axl inhibitors show promise in overcoming EGFR-TKI resistance and enhancing chemotherapy or targeted therapy efficacy in NSCLC. Preclinical and clinical studies highlight the potential of Axl inhibitors to overcome resistance to EGFR TKIs and improve outcomes. Ongoing research aims to optimize dosing, validate biomarkers, and explore combination regimens to broaden therapeutic impact.

Axl inhibition has emerged as a promising therapeutic strategy across multiple cancer types by targeting its role in EMT, drug resistance, and immune evasion. Preclinical studies demonstrate that Axl blockade using monoclonal antibodies like 20G7-D9 suppresses tumor growth and metastasis in triple-negative breast cancer by degrading Axl and inhibiting GAS6-dependent signaling pathways implicated in EMT and cell migration (12,13). In prostate cancer, the soluble Axl decoy receptor batiraxcept reduces bone metastasis and cancer stemness markers like CD44 and ALDH1A1 when combined with chemotherapy, while also suppressing PI3K and MAPK signaling pathways critical for tumor progression (14). Axl inhibition further enhances DNA damage response pathways by increasing γH2AX and 53BP1 foci formation, sensitizing ovarian and NSCLC cells to ATR/PARP inhibitors through replication fork destabilization (15,16). These effects are amplified in tumors with high Axl expression, which correlates with poor prognosis in renal, lung, and pancreatic cancers (13).

The therapeutic impact of Axl inhibition extends to overcoming resistance mechanisms in targeted therapies and immunotherapies. In EGFR-mutant NSCLC, combining Axl inhibitors like bemcentinib with osimertinib reverses resistance by suppressing EMT and down-regulating DNA repair genes, leading to G2/M arrest and apoptosis (13,16). Similarly, Axl blockade synergizes with anti-PD-1/PD-L1 therapies by reducing PD-L1 expression via PI3K/Akt pathway inhibition and counteracting immunosuppressive myeloid cells (13,17). CAR T-cell efficacy is enhanced through selective inhibition of Th2-polarized T cells and M2 macrophages, which normally suppress antitumor immunity (17). Clinical trials are exploring these combinations, particularly in STK11-mutant NSCLC where Axl inhibitors have received FDA fast-track designation (15). While these findings highlight Axl's multifaceted role in tumor progression, ongoing research aims to identify optimal biomarker-driven combinations and address challenges like compensatory signaling through c-MET or HER3 (16,18).

Preclinical evidence of Axl inhibitors. Brigatinib as an Axl inhibitor: Brigatinib, a second-generation of anaplastic lymphoma kinase (ALK)-TKI, demonstrated potent Axl inhibition in preclinical models of osimertinib-resistant NSCLC. In Axl-over-expressing cell lines, brigatinib (0.5 μM) synergized with osimertinib (1 μM) to suppress tumor growth by promoting K48-linked ubiquitination and degradation of Axl. In xenograft models, the combination caused significant tumor regression compared to monotherapy (19).

Enapotamab Vedotin (Axl-ADC): The Axl-targeting antibody-drug conjugate (ADC), enapotamab vedotin, showed significant antitumor activity in EGFR-mutant NSCLC resistant to EGFR-TKIs. In patient-derived xenograft (PDX) models, tumor regression correlated with high Axl mRNA expression. Notably, it overcame resistance in osimertinib-resistant PDX models, suggesting its utility in refractory NSCLC (20).

NPS-1034 (Dual MET/Axl inhibitor): NPS-1034 reversed resistance in EGFR-TKI-resistant NSCLC cell lines (HCC827/GR, HCC827/ER) by suppressing MET or Axl activation. Combination therapy with gefitinib or erlotinib induced synergistic cytotoxicity and inhibited Akt signaling. In vivo, NPS-1034 reduced tumor growth in MET-amplified xenografts (21).

Axl inhibition and DNA damage: Bemcentinib (BGB324), a selective Axl inhibitor, induced DNA damage and replication stress in TP53-deficient NSCLC and large-cell neuroendocrine carcinoma cells. Combining bemcentinib with ATR inhibitors (e.g., berzosertib) enhanced cytotoxicity, particularly in SLFN11-low tumors, via increased RPA32 hyperphosphorylation and mitotic catastrophe (22).

ONO-7475 in adaptive resistance: The novel Axl inhibitor ONO-7475 suppressed tolerance to osimertinib and dacomitinib in EGFR-mutant NSCLC. Early combination with osimertinib delayed tumor regrowth in xenograft models, suggesting its role in preventing adaptive resistance (23).

Clinical trials of Axl inhibitors. Bemcentinib + Docetaxel: A phase I trial (NCT02424617) evaluated bemcentinib with docetaxel in advanced NSCLC. At the maximum tolerated dose (200 mg bemcentinib + 60 mg/m² docetaxel with G-CSF), 35% of patients achieved partial responses, and 47% had stable disease. Neutropenia was the primary toxicity, manageable with prophylactic G-CSF (24).

DS-1205c + Gefitinib: A phase I study of the Axl inhibitor DS-1205c combined with gefitinib in EGFR-mutant NSCLC restored TKI sensitivity in preclinical models. Early clinical data indicated tolerability and preliminary efficacy, though detailed results are pending (25).

Ningetinib + Gefitinib: In a phase Ib trial, the MET/Axl inhibitor ningetinib combined with gefitinib showed clinical activity in EGFR-mutant NSCLC. Objective responses were observed in patients with MET/Axl dysregulation, defined by fluorescence in situ hybridization (FISH)/immunohistochemistry (IHC). The regimen was well-tolerated, supporting further evaluation of dual Axl/EGFR targeting (26).

Biomarkers predicting response to immune checkpoint blockade (ICB) therapies, such as anti-PD-1/PD-L1 and anti-CTLA-4 antibodies, are critical for identifying patients who will benefit from these treatments. Tumor PD-L1 expression is one of the most established biomarkers, with higher levels correlating with better outcomes in cancers like NSCLC. Additionally, TMB and microsatellite instability (MSI) are predictive markers, as they reflect increased neoantigen presentation, enhancing immune recognition. Recent studies also highlight the role of tumor-infiltrating lymphocytes (TILs), particularly CD8+ T cells, and their spatial proximity to PD-L1+ cells in predicting responses to ICB therapies (27-29).

Beyond tumor-specific markers, systemic and peripheral biomarkers are gaining attention. Circulating tumor DNA, blood TMB, and soluble PD-L1 levels have shown promise in predicting responses to anti-PD-1/PD-L1 therapies. Proteomic profiling has identified pathways, such as complement and coagulation cascades, that correlate with resistance or sensitivity to ICB in gastric cancer. Moreover, gut microbiome composition has been linked to differential ICB efficacy, suggesting a role for host-environment factors in modulating therapeutic outcomes (28-30).

Emerging research focuses on integrating multiple biomarkers into predictive models. For instance, machine learning-based analyses of proteomic data have achieved high accuracy in identifying responders to ICB in gastric cancer. Similarly, composite signatures combining gene expression levels, pathway activation states, and immune cell profiles have shown robust predictive value across various cancers. These findings underscore the importance of a multifaceted approach to biomarker discovery for optimizing precision immunotherapy (29,30).

Recent preclinical and clinical investigations demonstrate that Axl inhibition holds significant therapeutic potential in NSCLC by counteracting drug resistance and modulating tumor-immune interactions. Preclinical studies reveal that Axl over-expression drives resistance to EGFR TKIs like gefitinib and osimertinib by promoting EMT and activating compensatory signaling pathways. In EGFR wild-type NSCLC, Axl suppression sensitizes tumors to erlotinib by up-regulating E-cadherin and down-regulating mesenchymal markers like vimentin (31). Combination therapies using Axl degraders such as YD with EGFR-TKIs show synergistic effects, delaying resistance in xenograft and patient-derived models by destabilizing Axl protein and suppressing PI3K/MAPK pathways (5,32). Similarly, the mutant-selective EGFR inhibitor naquotinib uniquely inhibits Axl phosphorylation, demonstrating antitumor activity against Axl-over-expressing NSCLC cells resistant to earlier-generation TKIs (33). These findings highlight Axl's role as a central mediator of adaptive resistance mechanisms.

Clinical trials evaluating Axl inhibitors in advanced NSCLC reveal both promise and challenges. A phase I trial of bemcentinib combined with docetaxel and G-CSF support showed a 35% partial response rate and 47% disease stabilization in pretreated patients, though hematologic toxicities like neutropenia (86% incidence) required careful management (24) (Table I and Table II). Notably, tumor-cell Axl expression correlates with divergent outcomes depending on treatment context: high Axl levels predict poor overall survival in chemotherapy-pretreated patients receiving ICIs but associate with improved disease control in PD-L1-high, first-line ICI cohorts (34). This dichotomy suggests Axl's role extends beyond intrinsic tumor biology to modulating microenvironmental immune dynamics. Ongoing studies explore combinations of Axl inhibitors with ICIs, particularly in STK11-mutant NSCLC where Axl-driven immunosuppressive myeloid infiltration may be targeted (24,34).

Emerging biomarker analyses underscore the complexity of Axl-mediated resistance. Increased AXL expression was reported to be linked to adverse mutations such as CUB and Sushi multiple domains (CSMD1) and low-density lipoprotein receptor-related protein 1B (LRP1B), which are associated with immunosuppression and poor ICI outcomes, as well as PD-L1-related mutations (MUC4, ZNF469), particularly in chemotherapy-treated patients (34). Spatial immunophenotyping reveals Axl-high tumors exhibit neutrophil-dominated microenvironments with reduced CD8+ T-cell infiltration, creating a permissive niche for progression (34). Paradoxically, immune-cell Axl expression correlates with improved outcomes, suggesting distinct roles for tumor vs. stromal Axl in treatment response. These findings advocate for context-specific therapeutic strategies, potentially combining Axl inhibitors with chemotherapy or ICIs to counteract microenvironment-driven resistance while leveraging predictive mutational signatures for patient stratification (24,34) (Table I and Table II).

ICIs have transformed the treatment landscape for NSCLC, particularly through targeting PD-1/PD-L1 and CTLA-4 pathways. Clinical trials have demonstrated significant improvements in overall survival (OS) and progression-free survival compared to traditional therapies. For example, nivolumab has shown durable responses and lower toxicity compared to docetaxel, with two-year OS rates of 23% in squamous NSCLC and 29% in non-squamous NSCLC. Similarly, pembrolizumab has proven effective as a first-line therapy in patients with high PD-L1 expression, offering long-term benefits and manageable safety profiles (35-37).

Despite these successes, ICIs are not universally effective. Many patients fail to respond due to primary or acquired resistance, often linked to tumor heterogeneity, lack of immunogenicity, or up-regulation of alternative immune checkpoints like LAG-3 and TIM-3. Additionally, immune-related adverse events (irAEs) remain a concern, affecting organs such as the lungs, liver, and endocrine glands. Real-world studies have also highlighted discrepancies between clinical trial outcomes and broader patient populations, with factors like smoking status and bone metastases influencing survival outcomes (35,36).

Future directions aim to overcome these limitations through combination therapies and biomarker-driven approaches. Combining ICIs with chemotherapy or anti-angiogenic agents has shown promise but requires careful balancing of efficacy and toxicity. Emerging biomarkers like TMB and PD-L1 expression are being refined to better predict responses. Continued research into resistance mechanisms and personalized treatment strategies is essential to maximize the potential of ICIs in NSCLC (35-37).

The synergistic potential of combining Axl inhibition with ICB in NSCLC has gained significant attention due to Axl's dual role in promoting tumor progression and immune evasion. Axl receptor tyrosine kinase drives resistance to ICB by up-regulating PD-L1 expression, inducing EMT, and recruiting immunosuppressive myeloid cells, which collectively suppress cytotoxic T-cell activity (13,34). Preclinical studies demonstrate that Axl signaling fosters an immune-cold tumor microenvironment (TME) characterized by reduced CD8+ T-cell infiltration and increased neutrophil recruitment, creating a biological rationale for combining Axl inhibitors with PD-1/PD-L1 blockers (13,34,38).

Preclinical models consistently show that Axl inhibition reprograms the TME to enhance ICB efficacy. In immunocompetent NSCLC mouse models, Axl-targeted therapies increased CD103+ dendritic cell activation and CD8+ T-cell proliferation while reducing PD-L1 expression on tumor cells (17,38). Combination therapy with bemcentinib (Axl inhibitor) and anti-PD-1 antibodies achieved complete tumor regression in 40% of treated mice, compared to marginal responses with monotherapies (3,5). Similarly, Axl inhibition reversed chemotherapy-induced immunosuppression in NSCLC patient-derived organoids by restoring antigen presentation and reducing neutrophil infiltration (34). These findings correlate with improved tumor immunogenicity and prolonged survival in Axl-high tumor models (13,17).

Clinical trials testing this combination have shown mixed but promising results. The phase II BGBC008 trial (NCT03184571) reported a 26% overall response rate in patients with advanced NSCLC receiving bemcentinib plus pembrolizumab, with responses lasting >12 months in Axl-positive tumors (39). Ongoing trials like NCT04681131 are evaluating CAB-Axl-ADC (an antibody-drug conjugate) with PD-1 inhibitors, leveraging Axl's over-expression in metastatic NSCLC (39). However, the phase I DS-1205c trial combining Axl/EGFR inhibitors was terminated due to dose-limiting toxicities, highlighting challenges in therapeutic index optimization (39,40) (Table II). Biomarker analyses from the GETUG AFU 26 trial revealed that NSCLC patients with high Axl/PD-L1 co-expression had the poorest survival after anti-PD-1 monotherapy, further supporting the rationale for combination approaches (41).

Emerging evidence suggests Axl inhibition may overcome both primary and acquired ICB resistance. In nivolumab-resistant NSCLC cohorts, Axl up-regulation correlated with T-cell exhaustion markers (TIM-3, LAG-3) and impaired antigen presentation (1,2). Post-progression tumor biopsies from patients treated with ICB monotherapy showed increased Axl expression in 62% of cases, with corresponding declines in CD8+ T-cell density (34,41). Early-phase trials demonstrate that Axl inhibitors can re-sensitize tumors to ICB, particularly in PD-L1-low populations where response rates improved from 9% to 33% when combined with bemcentinib (39).

While these results are encouraging, challenges persist in patient selection and toxicity management. Current biomarkers like tumor Axl expression (assessed via IHC H-score) and plasma soluble Axl levels show variable predictive value across studies (34,39). Second-generation Axl inhibitors like batiraxcept and INCB081776 are being designed to improve target specificity and reduce off-target effects observed in earlier compounds (39,40). With 23 active clinical trials investigating Axl/ICB combinations in NSCLC as of 2025, this strategy holds promise for expanding the therapeutic window of immunotherapy in genetically diverse lung cancer populations (39).

Combining Axl inhibition with ICB in NSCLC presents both therapeutic opportunities and challenges. This approach aims to overcome primary and acquired resistance to immunotherapy while managing toxicity risks and optimizing patient selection. Below is a synthesis of current research findings addressing these challenges.

IrAEs from ICB therapies such as anti-PD 1/PD L1 agents range from mild fatigue to life-threatening pneumonitis and hepatotoxicity, particularly in elderly patients requiring vigilant monitoring (42). Combining Axl inhibitors with ICB introduces additional considerations, as preclinical models suggest Axl inhibition may exacerbate inflammatory responses by altering immune cell dynamics. For instance, Axl inhibitors like bemcentinib combined with pembrolizumab showed manageable toxicity profiles in clinical trials (39). However, chemotherapy-pretreated patients exhibited higher rates of neutrophil-mediated inflammation when Axl was inhibited, necessitating tailored toxicity management protocols (34,40). Proactive monitoring of liver function and early intervention for immune-related complications are critical to mitigate risks in combinatorial regimens.

Axl expression exhibits dual predictive roles depending on treatment context. In PD L1-high, chemotherapy-naïve patients, tumor Axl (tAxl) correlates with improved disease control rates, likely due to its association with immunogenic mutations like MUC4 and ZNF469 5 (34). Conversely, in chemotherapy-exposed patients, tAxl up-regulation links to immunosuppressive phenotypes mediated by CSMD1 and LRP1B mutations, necessitating Axl inhibition to reverse resistance (34,40). Biomarker studies highlight Axl's interaction with PD L1 and TMB, where high tAxl/PD L1 co-expression identifies subsets likely to benefit from combination therapy (34,43). Additionally, STK11/LKB1 mutations, which confer ICB resistance, are associated with Axl-driven immune suppression, suggesting genetic profiling could refine patient selection (44). Blood-based Axl monitoring and spatial immunophenotyping are emerging tools to stratify patients dynamically during therapy.

Axl mediates resistance through tumor-intrinsic and microenvironmental mechanisms. In EGFR mutant NSCLC, Axl activation drives cross-resistance to EGFR TKIs and ICB by promoting EMT and suppressing immunogenic cell death (18,45). Preclinical models demonstrate that Axl inhibition restores T-cell infiltration and synergizes with PD 1 blockade to eradicate tumors (38,46). However, chemotherapy-induced Axl up-regulation in stromal cells fosters adaptive resistance via neutrophil recruitment and CD8 T cell exclusion, which may limit long-term efficacy (34). Sequential therapy strategies, such as initiating Axl inhibitors after chemotherapy, show promise in delaying resistance by counteracting these microenvironmental shifts (47). Persistent Axl signaling in residual tumor cells underscores the need for continuous biomarker monitoring to adjust therapeutic combinations.

The interplay between Axl and immune checkpoint pathways reveals context-dependent effects. While Axl inhibition enhances antigen presentation and T-cell priming in PD L1-high tumors, it may inadvertently activate pro-metastatic pathways in chemotherapy-resistant microenvironments (34,46). Clinical trials like NCT03184571 demonstrate that Axl/PD 1 co- inhibition achieves objective responses in STK11/LKB1-mutant NSCLC, a population typically refractory to ICB (44). However, heterogeneous Axl expression across tumor subclones and dynamic changes during therapy complicate biomarker application. Emerging strategies focus on dual targeting of Axl and complementary pathways like TGF β or TIM 3 to broaden efficacy (39,46).

Overcoming challenges in Axl/ICB combination therapy requires optimizing dosing schedules to balance efficacy and toxicity. Adaptive trial designs incorporating real-time biomarker feedback, such as tAxl quantification via liquid biopsy, could personalize treatment intervals (40). Furthermore, elucidating Axl's role in modulating myeloid cells and tertiary lymphoid structures may uncover novel therapeutic vulnerabilities. Prospective studies evaluating Axl inhibitors in PD L1-low populations and those with acquired ICB resistance are warranted to expand the therapeutic landscape for NSCLC.

Axl inhibition represents a transformative strategy in NSCLC treatment, addressing critical challenges of therapy resistance and immune evasion. Preclinical studies demonstrate that Axl-targeted agents (e.g., bemcentinib, brigatinib) reverse EGFR-TKI resistance by suppressing EMT and DNA repair pathways while enhancing chemotherapy and immunotherapy efficacy. Clinically, combining Axl inhibitors with ICB shows promise, particularly in STK11/LKB1-mutant NSCLC, with the phase II BGBC008 trial reporting a 26% response rate and durable benefits in Axl-positive tumors. Biomarker analyses reveal Axl’s dual role: tumor-cell Axl correlates with immunosuppressive microenvironments in chemotherapy-exposed patients, whereas immune-cell Axl may predict favorable outcomes. However, challenges persist in toxicity management, with neutropenia and transaminitis requiring proactive monitoring, especially in combinatorial regimens.

These findings underscore the need for biomarker-driven integration of Axl inhibitors into clinical practice. Tumor Axl expression, PD-L1 status, and genetic profiles (e.g., STK11 mutations) should guide patient selection, while dynamic monitoring via liquid biopsies could optimize dosing. Current trials highlight the potential of Axl/ICB combinations to overcome primary and acquired resistance, particularly in PD-L1-low populations. Future efforts must prioritize rational combination strategies (e.g., with TGF-β inhibitors) and standardized biomarker assays to maximize therapeutic windows. As 23 active trials explore Axl-targeted approaches, this paradigm offers a roadmap for personalized, mechanism-based NSCLC care, balancing efficacy with manageable toxicity.

The continued exploration of Axl inhibitors combined with ICIs represents a promising frontier in the treatment of NSCLC. This approach addresses critical challenges such as drug resistance, immune evasion, and tumor progression. However, the complex interplay between Axl signaling, TME dynamics, and immune modulation necessitates further investigation to optimize therapeutic efficacy and minimize adverse effects. Collaboration across research disciplines is essential to refine biomarker-driven strategies, improve patient selection, and develop innovative combination regimens. By integrating molecular profiling, preclinical insights, and clinical trial data, researchers can unlock the full potential of Axl-targeted therapies. Such efforts will not only enhance treatment outcomes for NSCLC patients but also pave the way for broader applications in other malignancies.

The Authors have no conflicts of interest to declare.

All Authors contributed to the writing of the manuscript and approved the final version.

No artificial intelligence (AI) tools, including large language models or machine learning software, were used in the preparation, analysis, or presentation of this manuscript.