Epithelial-to-Mesenchymal Transition is a Cause of Both Intrinsic and Acquired Resistance to KRAS G12C Inhibitor in KRAS G12C–Mutant Non–Small Cell Lung Cancer

Synthetic approaches and clinical application of KRAS inhibitors for cancer therapy

Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations are among the most common oncogenic alterations in various cancers, including pancreatic, colorectal, and non-small cell lung cancer (NSCLC). Targeting KRAS has long been considered a difficult challenge due to its high affinity for guanosine triphosphate (GTP) and the lack of a druggable binding site. However, recent advancements in small-molecule inhibitor design have led to the development of targeted therapies aimed at KRAS mutations, particularly the KRASG12C mutation. Inhibitors such as Sotorasib and Adagrasib have shown promise in preclinical and clinical studies by irreversibly binding to the mutant KRAS protein, locking it in an inactive state and disrupting downstream signaling pathways critical for tumor growth and survival. These inhibitors have demonstrated clinical efficacy in treating patients with KRASG12C-mutated cancers, leading to tumor regression, prolonged progression-free survival, and improved patient outcomes. This review discusses the synthetic strategies employed to develop these KRAS inhibitor and also examines the clinical application of these inhibitors, highlighting the challenges and successes encountered during clinical trials. Ultimately, KRAS inhibitors represent a breakthrough in cancer therapy, offering a promising new treatment option for patients with KRAS-driven tumors.

Dealing with KRAS G12C inhibition in non-small cell lung cancer (NSCLC) - biology, clinical results and future directions

KRAS G12C mutation occurs in ∼ 14 % of non-small cell lung cancer (NSCLC) patients and has been historically deemed undruggable, with immune-checkpoint inhibitors (ICIs) and platinum-based chemotherapy (PBC) representing the standard-of-care in the advanced setting. First-in-class, covalent KRAS G12C OFF-inhibitors sotorasib and adagrasib have revolutionized the therapeutic landscape and recently entered clinical practice. However, limited efficacy alongside toxicity profiles strengthen the need to design novel molecules and to optimize therapeutic strategies to address and overcome intrinsic and acquired resistance mechanisms. Moreover, KRAS G12C frequently co-occurs with STK11/KEAP1 mutations, that represent a negative prognostic factor, being associated with increased metastatic potential and reduced overall survival and poorer outcomes with ICIs. Furthermore, the high incidence of brain metastases is common in KRAS G12C-mutant NSCLC, and the efficacy of standard therapies and KRAS G12C inhibitors in treating or preventing central nervous system involvement is still suboptimal. In this context, novel inhibitors, such as broad-spectrum inhibitors targeting the active GTP-bound ON-state, pan-RAS ON inhibitors and allele-selective tricomplex inhibitors, have showed promising early clinical activity although their clinical utility needs to be further elucidated. In addition, targeting upstream, downstream and parallel signaling pathways through combination strategies might enhance the activity of KRAS G12C inhibitors and eventually improve clinical outcomes in this subset of NSCLC patients. Several combinations are currently under clinical investigation and promising approaches include combinations of KRAS G12C inhibitors with ICIs, SOS1, SHP2 inhibitors and PBC. Notwithstanding the potential improved efficacy of combination strategies, tolerability remains a critical challenge that must be carefully assessed and managed.

Genomic landscape of clinically acquired resistance alterations in patients treated with KRASG12C inhibitors

BACKGROUND

Mutant-selective inhibitors of KRASG12C (KRASG12Ci) have demonstrated efficacy in KRASG12C cancers. However, resistance invariably develops, resulting in short-lived responses. We aimed to define the genomic landscape of acquired resistance to KRASG12Ci and to elucidate whether novel classes of KRAS inhibitors can overcome these resistance mechanisms.

METHODS

To assess clinical frequencies of acquired resistance alterations, we evaluated genomic sequencing data from postprogression cell-free DNA samples in patients treated with KRASG12Ci at two United States cancer centers, alongside data from six previously published studies. Cell viability assays using engineered cell models were employed to functionally validate candidate resistance drivers and to evaluate novel classes of KRAS inhibitors.

RESULTS

A total of 143 patients were analyzed. Most patients had non-small-cell lung cancer (NSCLC, n = 68) or colorectal cancer (CRC, n = 58) and were treated with single-agent KRASG12Ci (n = 109) or combined with anti-EGFR antibodies (n = 30). RAS/MAPK alterations emerged in 46% of patients (n = 66), with 39% developing one or more new KRAS alterations (n = 56) and 23% (n = 33) showing multiple concurrent alterations. The genomic landscape of acquired alterations included KRAS-activating mutations (25% of patients), KRAS amplifications (22%), RAF/MAPK mutations/fusions (21%), KRAS switch-II pocket mutations (14%), and NRAS/HRAS mutations (8%). Notably, the proportion of patients with one or more acquired RAS/MAPK alteration was significantly higher in CRC compared with NSCLC (69% versus 26%, P < 0.001). Functional studies confirmed most alterations as resistance drivers. Sotorasib, adagrasib, and divarasib demonstrated distinct activity against KRAS switch-II pocket mutations, yet all were responsive to the RAS(ON) G12C-selective tri-complex inhibitor RM-018. The KRAS-selective inhibitor Pan KRAS-IN-1 effectively targeted KRAS-activating mutations, and the RAS(ON) multiselective tri-complex inhibitor RMC-7797 demonstrated high potency across all RAS alterations.

CONCLUSIONS

Acquired RAS/MAPK alterations are recurrent drivers of resistance to KRASG12Ci detected in CRC and, less frequently, in NSCLC. Preclinical data suggest that novel (K)RAS inhibitors may overcome many of these resistance alterations.

Sotorasib resistance in KRAS G12C-mutant invasive mucinous adenocarcinoma with implications for VEGF-A

Invasive mucinous adenocarcinoma (IMA) is a rare subtype of lung adenocarcinoma with a poor prognosis. Compared to non-small cell lung cancer, IMA more frequently harbors KRAS mutations in the order p.G12V, p.G12D, and p.G12C. This report describes a patient with a KRAS p.G12C-mutant IMA treated with sotorasib. To date, no studies have investigated the therapeutic efficacy or resistance mechanisms of sotorasib in IMA. The patient was treated with carboplatin and pemetrexed, followed by sotorasib upon disease progression. While the primary lung lesions responded well, metastatic thoracic lymph node lesions continued to increase. A pathological autopsy was performed with the family's consent to investigate potential resistance mechanisms. RNA sequencing and additional analyses revealed increased VEGF-A expression in metastatic lymph node lesions, suggesting a role in sotorasib resistance. These findings provide insights into the potential molecular mechanisms underlying treatment resistance in KRAS p.G12C-mutant IMA.

Dual inhibition of GTP-bound KRAS and mTOR in lung adenocarcinoma and squamous cell carcinoma harboring KRAS G12C

BACKGROUND

Kirsten rat sarcoma (KRAS) mutations are somatic variants in lung adenocarcinoma. One of the most prevalent mutations, G12C, has led to the clinical approval of targeted inhibitors for advanced stages in lung cancer. Research has increasingly focused on the efficacy of combination therapies that target multiple tumorigenic pathways. Cases harboring KRAS G12C mutation are heterogenous. We explored alternative changes in genetic pathways and evaluated the effectiveness of combination therapy using several types of cell lines and KRAS inhibitors.

METHODS

We comprehensively investigated genetic changes induced by KRAS G12C inhibition using RNA sequences and the candidate to inhibit in combination therapy was explored. Three lung cancer cell lines (two adenocarcinoma and one squamous cell carcinoma) and three KRAS G12C inhibitors (AMG 510, MRTX849, and ARS-1620) were used. KRAS G12C and candidate gene were simultaneously inhibited in cell lines and the efficiency of combination therapy was evaluated using clonogenic assays and MTS assay. Pathway activation was assessed via western blotting. A combination index (CI) < 0.8 was considered statistically synergistic.

RESULTS

RNA sequences revealed treatment with two of the three KRAS G12C inhibitors led to a significant increase in mTOR expression across all three cell lines. mTOR was targeted in combination therapy; each KRAS G12C inhibitor and mTOR inhibitor (RAD001) combination exhibited synergism (CI < 0.8) in MTS and clonogenic assays. Single inhibition of mTOR induced activation of guanosine triphosphate (GTP)-RAS, thereby activating the RAS-MEK-ERK and PI3K-AKT-mTOR pathways in WB, suggesting mTOR activation is crucial for KRAS-driving lung cancer. A combination strategy targeting KRAS G12C and mTOR abrogated GTP-RAS, pmTOR (Ser2448), and pERK (Thr202/Tyr204) more efficiently.

CONCLUSIONS

KRAS G12C inhibitor plus RAD001 consistently revealed synergism. Targeting KRAS G12C and mTOR abrogates the RAS-MEK-ERK and PI3K-AKT-mTOR pathways. Our data suggests that a combined strategy targeting GTP-bound KRAS G12C and mTOR shows promise for primary lung cancers with KRAS G12C mutations. This approach may also be effective even for lung cancers harboring KRAS G12C mutation but having different profiles.

KRASG12C/mTORC1 inhibition: a powerful duo in NSCLC therapeutics

In a recent report in Nature Communications, Kitai et al. designed a combinational treatment based on targeting the active-state KRASG12C-mutant variant that characterizes a substantial subset of non-small-cell lung cancer (NSCLC) cases. The authors highlighted that dual targeting with KRASG12C (ON) and mammalian target of rapamycin (mTOR) complex (mTORC)-1-selective inhibition potentially provides a new strategy to overcome drug resistance.

Oncogenic KRAS addiction states differentially influence MTH1 expression and 8-oxodGTPase activity in lung adenocarcinoma

The efficacy of strategies targeting oncogenic RAS, prevalent in lung adenocarcinoma (LUAD), is limited by rapid adaptive resistance mechanisms. These include loss of RAS addiction and hyperactivation of downstream signaling pathways, such as PI3K/AKT. We previously reported that oncogenic RAS-driven LUAD cells possess an enhanced reliance on MTH1, the mammalian 8-oxodGTPase, to prevent genomic incorporation of oxidized nucleotides, and that MTH1 depletion compromises tumorigenesis and oncogenic signaling. Here, we show that elevated MTH1 correlates with poor prognosis in LUAD and that its redox-protective 8-oxodGTPase activity is variably regulated in KRAS-addicted vs. non-addicted states. Multiple oncogenic KRAS mutants or overexpression of wildtype (wt) KRAS increased MTH1 expression. Conversely, KRAS depletion or its inhibition by AMG-510 (sotorasib) decreased MTH1 in KRASG12C-addicted LUAD cells. Separation-of-function MEK/ERK1/2-activating mutants recapitulated the elevated MTH1 expression induced by oncogenic RAS in wt KRAS LUAD cells. However, upon inhibition of the MEK/ERK1/2 pathway, compensatory AKT activation maintained MTH1 expression. Indeed, elevated AKT signaling maintained high MTH1 expression even when KRAS oncoprotein was low. We previously reported that cancer cells possess variable MTH1-specific and MTH1-independent 8-oxodGTPase activity levels. Whereas both ERK1/2 and AKT could regulate MTH1 protein levels in KRAS-addicted cells, only AKT signaling was associated with elevated MTH1-specific 8-oxodGTPase activity under KRAS-low or KRAS non-addicted states. Our studies suggest that despite loss of KRAS dependency, LUAD cells retain the requirement for high MTH1 8-oxodGTPase activity due to redox vulnerabilities associated with AKT signaling. Thus, MTH1 may serve as a novel orthogonal vulnerability in LUAD that has lost KRAS addiction.

Targeting USP47 enhances the efficacy of KRAS inhibitor in KRASG12C mutated non-small cell lung cancer by controlling deubiquitination of c-Myc

FDA-approved KRASG12C inhibitors, like Sotorasib, target G12C-mutated KRAS in NSCLC. However, issues with insensitivity and drug resistance have emerged, requiring the development of new combination therapies to overcome these limitations. USP47 has been identified as a regulator of cancer-related signaling pathways such as Wnt, Hippo, and p53. However, its role in the KRAS signaling pathway remains largely unexplored and USP47 inhibitors are less developed than those targeting its homolog, USP7. Here, we identify USP47 as a novel therapeutic target in KRASG12C-mutated NSCLC and report K-552, a selective USP47 inhibitor, as a potential treatment strategy. We demonstrate that USP47 stabilizes c-Myc by preventing its proteasomal degradation through deubiquitination, thereby promoting NSCLC cell proliferation. Additionally, the compound K-552, a USP47 inhibitor identified through virtual screening, effectively destabilizes c-Myc and inhibits KRASG12C-mutated NSCLC cell proliferation. Furthermore, USP47 inhibition-either by siRNA knockdown or K-552 treatment-enhances the efficacy of Sotorasib in vitro and in vivo. Together, our findings establish USP47 as a promising therapeutic target in KRASG12C-mutated NSCLC and introduce K-552 as a USP47 inhibitor with potential for combination therapy with KRASG12C inhibitors.

Differential Response and Resistance to KRAS-Targeted Therapy

KRAS is the most frequently mutated oncogene. In epithelial malignancies such as lung, colorectal, and pancreatic tumors, KRAS is mutated in 25 to above 90% cases. KRAS was considered undruggable for over three decades until the recent development of covalent inhibitors targeting the KRAS G12C mutant. The recent approval of the KRAS G12C inhibitors sotorasib and adagrasib has ushered in a new era of KRAS-targeted therapy. Despite this success, a major challenge in KRAS-targeted therapy is intrinsic and acquired resistance to KRAS inhibitors. Clinical studies have shown that many patients with KRAS G12C cancers did not respond to sotorasib and adagrasib. Colorectal cancer, in particular, has a markedly lower response rate to KRAS G12C inhibitors compared to non-small cell lung cancer. Furthermore, the therapeutic response to KRAS G12C inhibition was short-lived, with quick emergence of acquired resistance. In this review, we summarize several major themes that have emerged from recent clinical and preclinical studies on the mechanisms of intrinsic and acquired resistance to KRAS-targeted therapy in colorectal, lung, and pancreatic cancers. We also discuss various combination strategies for targeting these mechanisms to overcome resistance to KRAS inhibitors.

Current status of KRAS G12C inhibitors in NSCLC and the potential for combination with anti-PD-(L)1 therapy: a systematic review

In recent years, precision medicine for non-small cell lung cancer (NSCLC) has made significant strides, particularly with advancements in diagnostic and therapeutic technologies. Targeted 7therapies and Anti-PD-(L)1 Therapies have emerged as vital treatment options, yet KRAS mutations, especially KRAS G12C, have been historically difficult to address. Due to the unique activation mechanism of KRAS G12C has led to the development of specific inhibitors, such as AMG 510 and MRTX849, which show promising therapeutic potential. However, results from the CodeBreaK 200 Phase III trial indicated that AMG 510 did not significantly improve overall survival compared to docetaxel. Resistance after prolonged use of KRAS G12C inhibitors continues to pose a challenge, prompting interest in new drugs and combination strategies. KRAS mutations can impair tumor-infiltrating T cell function and create an immunosuppressive tumor microenvironment, making the combination of KRAS G12C inhibitors with anti-PD-(L)1 therapies particularly appealing. Preliminary data suggest these combinations may enhance both survival and quality of life, though safety concerns remain a barrier. Ongoing research is crucial to refine treatment regimens and identify suitable patient populations. This review focuses on the development of KRAS G12C inhibitors in monotherapy and combination therapies for NSCLC, discussing major clinical trials and future research directions.

Pancreatic Cancer: Pathogenesis and Clinical Studies

Pancreatic cancer (PC) is a highly lethal malignancy, with pancreatic ductal adenocarcinoma (PDAC) being the most common and aggressive subtype, characterized by late diagnosis, aggressive progression, and resistance to conventional therapies. Despite advances in understanding its pathogenesis, including the identification of common genetic mutations (e.g., KRAS, TP53, CDKN2A, SMAD4) and dysregulated signaling pathways (e.g., KRAS-MAPK, PI3K-AKT, and TGF-β pathways), effective therapeutic strategies remain limited. Current treatment modalities including chemotherapy, targeted therapy, immunotherapy, radiotherapy, and emerging therapies such as antibody-drug conjugates (ADCs), chimeric antigen receptor T (CAR-T) cells, oncolytic viruses (OVs), cancer vaccines, and bispecific antibodies (BsAbs), face significant challenges. This review comprehensively summarizes these treatment approaches, emphasizing their mechanisms, limitations, and potential solutions, to overcome these bottlenecks. By integrating recent advancements and outlining critical challenges, this review aims to provide insights into future directions and guide the development of more effective treatment strategies for PC, with a specific focus on PDAC. Our work underscores the urgency of addressing the unmet needs in PDAC therapy and highlights promising areas for innovation in this field.

Integrative transcriptomic analysis identifies emetine as a promising candidate for overcoming acquired resistance to ALK inhibitors in lung cancer

Anaplastic lymphoma kinase (ALK; also known as ALK tyrosine kinase receptor) inhibitors (ALKi) are effective in treating lung cancer patients with chromosomal rearrangement of ALK. However, continuous treatment with ALKis invariably leads to acquired resistance in cancer cells. In this study, we propose an efficient strategy to suppress ALKi resistance through a meta-analysis of transcriptome data from various cell models of acquired resistance to ALKis. We systematically identified gene signatures that consistently showed altered expression during the development of resistance and conducted computational drug screening using these signatures. We identified emetine as a promising candidate compound to inhibit the growth of ALKi-resistant cells. We demonstrated that emetine exhibited effectiveness in inhibiting the growth of ALKi-resistant cells, and further interpreted its impact on the resistant signatures through drug-induced RNA-sequencing data. Our transcriptome-guided systematic approach paves the way for efficient drug discovery to overcome acquired resistance to cancer therapy.

Progress of KRAS G12C inhibitors in the treatment of refractory colorectal cancer and strategies for drug resistance response

Colorectal cancer is the third most prevalent cancer in the world. Early screening and detection of tumours, active surgical radical treatment, postoperative adjuvant chemotherapy, targeted therapy, and immunotherapy are performed based on pathological staging and immunohistochemistry. Even with these measures, the 5-year survival rate of colorectal cancer is only 65%, and a considerable number of patients still experience tumour recurrence or even metastasis. The KRAS G12C mutation accounts for 3 to 4% of refractory colorectal cancer (advanced or metastatic colorectal cancer), and it was once believed that KRAS did not have a drug target until the emergence of KRAS G12C inhibitors provided targeted treatment for KRAS-mutated colorectal cancer. However, KRAS G12C inhibitors only produce moderate efficacy, and resistance occurs after a short remission. The mechanism of drug resistance in tumour cells is complex and diverse, and existing research has limited understanding of it. This review aims to elucidate the clinical trial progress of KRAS G12C inhibitors in refractory colorectal cancer, the research progress of drug resistance mechanisms, and the combined treatment strategies for drug resistance.

In Situ RAS:RAF Binding Correlates with Response to KRASG12C Inhibitors in KRASG12C-Mutant Non-Small Cell Lung Cancer

PURPOSE

Therapeutic efficacy of KRASG12C(OFF) inhibitors (KRASG12Ci) in KRASG12C-mutant non-small cell lung cancer (NSCLC) varies widely. The activation status of RAS signaling in tumors with KRASG12C mutation remains unclear, as its ability to cycle between the active GTP-bound and inactive GDP-bound states may influence downstream pathway activation and therapeutic responses. We hypothesized that the interaction between RAS and its downstream effector RAF in tumors may serve as indicators of RAS activity, rendering NSCLC tumors with a high degree of RAS engagement and downstream effects more responsive to KRASG12Ci compared with tumors with lower RAS-RAF interactions.

EXPERIMENTAL DESIGN

We developed a method for measuring in situ RAS binding to RAF in cancer samples using proximity ligation assays (PLA) designed to detect panRAS-CRAF interactions.

RESULTS

The panRAS-CRAF PLA signal correlated with levels of both RAS-GTP and phosphorylated ERK protein, suggesting that this assay can effectively assess active RAS signaling. We found that elevated panRAS-CRAF PLA signals were associated with increased sensitivity to KRASG12Ci in KRASG12C-mutant NSCLC cell lines, xenograft models, and patient samples. Applying a similar PLA approach to measure the interactions between EGFR and its adapter protein growth factor receptor-bound protein 2 as a surrogate for EGFR activity, we found no relationship between EGFR activity and response to KRASG12Ci in the same samples.

CONCLUSIONS

Our study highlights the importance of evaluating in situ RAS-RAF interactions as a potential predictive biomarker for identifying patients with NSCLC most likely to benefit from KRASG12Ci. The PLA developed for quantifying these interactions represents a valuable tool for guiding treatment strategies.

ADT-1004: a first-in-class, oral pan-RAS inhibitor with robust antitumor activity in preclinical models of pancreatic ductal adenocarcinoma

BACKGROUND

Oncogenic KRAS mutations occur in nearly, 90% of patients with pancreatic ductal adenocarcinoma (PDAC). Targeting KRAS has been complicated by mutational heterogeneity and rapid resistance. We developed a novel pan-RAS inhibitor, ADT-1004 (an oral prodrug of ADT-007) and evaluated antitumor activity in murine and human PDAC models.

METHODOLOGY

Murine PDAC cells with KRASG12D mutation (KPC-luc or 2838c3-luc) were orthotopically implanted into the pancreas of C57BL/6J mice, and four PDX PDAC tumors with KRAS mutations were implanted subcutaneously in NSG mice. To assess potential to overcome RAS inhibitor resistance, parental and resistant MIA PaCa-2 PDAC cells (KRASG12C mutation) were implanted subcutaneously. Subcutaneously implanted RASWT BxPC-3 cells were used to assess the selectivity of ADT-1004.

RESULTS

ADT-1004 potently blocked tumor growth and RAS activation in mouse PDAC models without discernable toxicity with target engagement and reduced activated RAS and ERK phosphorylation. In addition, ADT-1004 suppressed tumor growth in PDX PDAC models with KRASG12D, KRASG12V, KRASG12C, or KRASG13Q mutations and increased CD4+ and CD8+ T cells in the TME consistent with exhaustion and increased MHCII+ M1 macrophage and dendritic cells. ADT-1004 demonstrated superior efficacy over sotorasib and adagrasib in tumor models resistant to these KRASG12C inhibitors and MRTX1133 resistant KRASG12D mutant cells. As evidence of selectivity for tumors with mutant KRAS, ADT-1004 did not impact the growth of tumors from RASWT PDAC cells.

CONCLUSION/SIGNIFICANCE

ADT-1004 has strong antitumor activity in aggressive and clinically relevant PDAC models with unique selectivity to block RAS-mediated signaling in RAS mutant cells. As a pan-RAS inhibitor, ADT-1004 has broad activity and potential efficacy advantages over allele-specific KRAS inhibitors. These findings support clinical trials of ADT-1004 for KRAS mutant PDAC.

KRAS inhibitors: resistance drivers and combinatorial strategies

In 1982, the RAS genes HRAS and KRAS were discovered as the first human cancer genes, with KRAS later identified as one of the most frequently mutated oncogenes. Yet, it took nearly 40 years to develop clinically effective inhibitors for RAS-mutant cancers. The discovery in 2013 by Shokat and colleagues of a druggable pocket in KRAS paved the way to FDA approval of the first covalently binding KRASG12C inhibitors, sotorasib and adagrasib, in 2021 and 2022, respectively. However, rather than marking the end of a successful assault on the Mount Everest of cancer research, this landmark only revealed new challenges in RAS drug discovery. In this review, we highlight the progress on defining resistance mechanisms and developing combination treatment strategies to improve patient responses to KRAS therapies.

Tumor Cell Spatial Organization Directs EGFR/RAS/RAF Pathway Primary Therapy Resistance through YAP Signaling

Non-small cell lung cancers (NSCLC) harboring common mutations in EGFR and KRAS characteristically respond transiently to targeted therapies against those mutations, but invariably, tumors recur and progress. Resistance often emerges through mutations in the therapeutic target or activation of alternative signaling pathways. Mechanisms of acute tumor cell resistance to initial EGFR (EGFRi) or KRASG12C (G12Ci) pathway inhibition remain poorly understood. Our study reveals that acute response to EGFR/RAS/RAF-pathway inhibition is spatial and culture context specific. In vivo, EGFR mutant tumor xenografts shrink by > 90% following acute EGFRi therapy, and residual tumor cells are associated with dense stroma and have increased nuclear YAP. Interestingly, in vitro EGFRi induced cell cycle arrest in NSCLC cells grown in monolayer, while 3D spheroids preferentially die upon inhibitor treatment. We find differential YAP nuclear localization and activity, driven by the distinct culture conditions, as a common resistance mechanism for selective EGFR/KRAS/BRAF pathway therapies. Forced expression of the YAPS127A mutant partially protects cells from EGFR-mediated cell death in spheroid culture. These studies identify YAP activation in monolayer culture as a non-genetic mechanism of acute EGFR/KRAS/BRAF therapy resistance, highlighting that monolayer vs spheroid cell culture systems can model distinct stages of patient cancer progression.

The Role of KRAS Mutations in Colorectal Cancer: Biological Insights, Clinical Implications, and Future Therapeutic Perspectives

Background/Objectives: Colorectal cancer (CRC) remains a leading cause of cancer mortality globally, with KRAS mutations occurring in 30-40% of cases, contributing to poor prognosis and resistance to anti-EGFR therapy. This review explores the biological significance, clinical implications, and therapeutic targeting of KRAS mutations in CRC. Methods: A comprehensive analysis of the existing literature and clinical trials was performed, highlighting the role of KRAS mutations in CRC pathogenesis, their impact on prognosis, and recent advancements in targeted therapies. Specific attention was given to emerging therapeutic strategies and resistance mechanisms. Results: KRAS mutations drive tumor progression through persistent activation of MAPK/ERK and PI3K/AKT signaling pathways. These mutations influence the tumor microenvironment, cancer stem cell formation, macropinocytosis, and cell competition. KRAS-mutant CRC exhibits poor responsiveness to anti-EGFR monoclonal antibodies and demonstrates primary and acquired resistance to KRAS inhibitors. Recent breakthroughs include the development of KRAS G12C inhibitors (sotorasib and adagrasib) and promising agents targeting G12D mutations. However, response rates in CRC remain suboptimal compared to other cancers, necessitating combination therapies and novel approaches, such as vaccines, nucleic acid-based therapeutics, and macropinocytosis inhibitors. Conclusions: KRAS mutations are central to CRC pathogenesis and present a significant therapeutic challenge. Advances in KRAS-targeted therapies offer hope for improved outcomes, but resistance mechanisms and organ-specific differences limit efficacy. Continued efforts in personalized treatment strategies and translational research are critical for overcoming these challenges and improving patient survival.

Mechanisms of KRAS inhibitor resistance in KRAS-mutant colorectal cancer harboring Her2 amplification and aberrant KRAS localization

KRAS-specific inhibitors have shown promising antitumor effects, especially in non-small cell lung cancer, but limited efficacy in colorectal cancer (CRC) patients. Recent studies have shown that EGFR-mediated adaptive feedback mediates primary resistance to KRAS inhibitors, but the other resistance mechanisms have not been identified. In this study, we investigated intrinsic resistance mechanisms to KRAS inhibitors using patient-derived CRC cells (CRC-PDCs). We found that KRAS-mutated CRC-PDCs can be divided into at least an EGFR pathway-activated group and a PI3K/AKT pathway-activated group. In the latter group, PDCs with PIK3CA major mutation showed high sensitivity to PI3K+mTOR co-inhibition, and a PDC with Her2 amplification with PIK3CA minor mutation showed PI3K-AKT pathway dependency but lost KRAS-MAPK dependency by cytoplasmic localization of KRAS. In the PDC, Her2 knockout restored KRAS plasma membrane localization and KRAS inhibitor sensitivity. The current study provides insight into the mechanisms of primary resistance to KRAS inhibitors, including aberrant KRAS localization.

Advances and Challenges in RAS Signaling Targeted Therapy in Leukemia

RAS mutations are prevalent in leukemia, including mutations at G12, G13, T58, Q61, K117, and A146. These mutations are often crucial for tumor initiation, maintenance, and recurrence. Although much is known about RAS function in the last 40 years, a substantial knowledge gap remains in understanding the mutation-specific biological activities of RAS in cancer and the approaches needed to target specific RAS mutants effectively. The recent approval of KRASG12C inhibitors, adagrasib and sotorasib, has validated KRAS as a direct therapeutic target and demonstrated the feasibility of selectively targeting specific RAS mutants. Nevertheless, KRASG12C remains the only RAS mutant successfully targeted with FDA-approved inhibitors for cancer treatment in patients, limiting its applicability for other oncogenic RAS mutants, such as G12D, in leukemia. Despite these challenges, new approaches have generated optimism about targeting specific RAS mutations in an allele-dependent manner for cancer therapy, supported by compelling biochemical and structural evidence, which inspires further exploration of RAS allele-specific vulnerabilities. This review will discuss the recent advances and challenges in the development of therapies targeting RAS signaling, highlight emerging therapeutic strategies, and emphasize the importance of allele-specific approaches for leukemia treatment.

WEE1 confers resistance to KRASG12C inhibitors in non-small cell lung cancer

KRASG12C inhibitors sotorasib and adagrasib have been approved for the treatment of KRASG12C-mutant non-small cell lung cancer (NSCLC). However, the efficacy of single-agent treatments is limited, presumably due to multiple resistance mechanisms. To overcome these therapeutic limitations, combination strategies that potentiate the antitumor efficacy of KRASG12C inhibitors must be developed. Through unbiased high-throughput screening of 1395 kinase inhibitors, we identified adavosertib, a WEE1 inhibitor, as a promising combination partner of sotorasib. The combination of sotorasib and adavosertib exhibited synergistic antiproliferative activities both in vitro and in vivo, irrespective of TP53, STK11, and KEAP1 co-mutation profiles. WEE1 inhibition potentiated MCL-1-mediated apoptosis in sotorasib-treated cancer cells. Mechanistically, the combination downregulated MCL-1 protein levels by attenuating de novo translation and enhancing its degradation. WEE1 overexpression conferred resistance against sotorasib via MCL-1 upregulation. Moreover, cells that acquired sotorasib resistance profoundly upregulated both WEE1 and MCL-1 proteins, highlighting WEE1 as a crucial driver of sotorasib resistance. Importantly, WEE1 inhibition re-sensitized resistant cells to sotorasib treatment. The current findings demonstrate that combined inhibition of KRASG12C and WEE1 not only exhibits synergistic antitumor efficacy but also overcomes resistance to KRASG12C inhibitors, thus representing a novel therapeutic strategy for KRASG12C-mutant NSCLC.

SRC kinase drives multidrug resistance induced by KRAS-G12C inhibition

Direct targeting of the KRAS-G12C-mutant protein using covalent inhibitors (G12Ci) acts on human non-small cell lung cancer (NSCLC). However, drug resistance is an emerging concern in this approach. Here, we show that MRTX849, a covalent inhibitor targeting the KRAS-G12C mutation, leads to the reactivation of the mitogen-activated protein kinase signaling pathway in MRTX849-resistant NSCLC and pancreatic ductal adenocarcinoma. A genome-wide CRISPR screen revealed that the adenosine triphosphate binding cassette transporter ABCC1 mediates MRTX849 resistance. Functional studies demonstrated that the transcription factor JUN drives ABCC1 expression, resulting in multidrug resistance. An unbiased drug screen identified the tyrosine kinase inhibitor dasatinib that potentiates MRTX849 efficacy by inhibiting SRC-dependent JUN activation, avoiding multidrug resistance and tumor suppression in vitro as well as in suitable preclinical mouse models and patient-derived organoids. SRC inhibitors (DGY-06-116, dasatinib, and bosutinib) also exhibit synergistic effects with MRTX849 in eliminating various tumor cell lines carrying KRAS-G12C mutations. Thus, SRC inhibitors amplify the therapeutic utility of G12Ci.

Reactivation of MAPK-SOX2 pathway confers ferroptosis sensitivity in KRASG12C inhibitor resistant tumors

The clinical success of KRASG12C inhibitors (G12Ci) including AMG510 and MRTX849 is limited by the eventual development of acquired resistance. A novel and effective treatment to revert or target this resistance is urgent. To this end, we established G12Ci (AMG510 and MRTX849) resistant KRASG12C mutant cancer cell lines and screened with an FDA-approved drug library. We found the ferroptosis inducers including sorafenib and lapatinib stood out with an obvious growth inhibition in the G12Ci resistant cells. Mechanistically, the G12Ci resistant cells exhibited reactivation of MAPK signaling, which repressed SOX2-mediated expression of cystine transporter SLC7A11 and iron exporter SLC40A1. Consequently, the low intracellular GSH level but high iron content engendered hypersensitivity of these resistant tumors to ferroptosis inducers. Ectopic overexpression of SOX2 or SLC7A11 and SLC40A1 conferred resistance to ferroptosis in the G12Ci resistant cells. Ferroptosis induced by sulfasalazine (SAS) achieved obvious inhibition on the tumor growth of xenografts derived from AMG510-resistant KRASG12C-mutant cells. Collectively, our results suggest a novel therapeutic strategy to treat patients bearing G12Ci resistant cancers with ferroptosis inducers.

Insights into direct KRAS inhibition strategies for cancer treatment

KRAS is the most commonly mutated isoform in RAS-driven cancers. In the early stage, KRAS was deemed as an "undruggable" cancer target due to the lack of suitable binding pockets. With the development of KRAS inhibitors in recent years, strategies that directly suppress oncogenic KRAS have achieved significant breakthroughs. In this review, we summarize recent advances in direct small-molecule KRAS inhibitors used for cancer therapy, highlighting their medicinal chemistry optimization processes. Moreover, new PROTACs targeting the KRAS mutation are also presented. Additionally, we put forward the challenges and prospects for the development of future KRAS inhibitors.

Dual inhibition of HERs and PD-1 counteract resistance in KRASG12C-mutant head and neck cancer

BACKGROUND

Basket clinical trials targeting the KRASG12C-mutation in solid tumors have shown initial promise, including in orphan KRASG12C head and neck cancer (HNC). However, development of resistance to KRASG12C-mutant-specific inhibitors (KRASG12Ci) remains a major obstacle. Here, we investigated the intrinsic (tumor-cell autonomus) and tumor-microenvironment (TME) mechanisms of resistance to the KRASG12Ci-MRTX849 and AMG510 in a unique syngenic murine KRASG12C-mutated HNC cell line.

METHODS

Western-blotting was used for protein abundance and activation, overexpression, and ligand activation studies to verify the intrinsic mechanism of resistance to KRASG12Ci in KRASG12C-mutated HNC cell line, 4NQO-L. In vitro KRASG12C-acquired-resistant cells were developed from 4NQO-L (4NQO-L-AcR). MRTX849/lapatinib combination efficacy, and CD8+ T-cells depletion, were assessed in C57BL/6 J mice and supplementation of anti-PD-1 (αPD-1) to MRTX849/lapatinib was also performed in 4NQO-L- KRASG12Ci-senisitve and 4NQO-L-AcR tumors. Immunohistochemistry (IHC) and Immunoflourescence (IF) analyses were performed to profile the TME and programmed death-ligand 1 (PD-L1) expression in tumors.

RESULTS

Activation and upregulation of EGFR and HER2/3 (pan-HERs) are the intrinsic mechanism of resistance to KRASG12Ci in 4NQO-L cells, and blocking pan-HERs signaling with lapatinib enhanced MRTX849 efficacy in vitro by inhibiting the MAPK and AKT/mTOR pathways. 4NQO-L-AcR upregulated the expression of pan-HERs, and lapatinib treatment re-sensitized 4NQO-L-AcR to MRTX849. In mice, MRTX849 showed a slight anti-tumor effect, but in combination with lapatinib a significant tumor growth delay was observed, but all tumors progressed over time. Histopathology analysis of the TME revealed infiltration of CD8+ T-cells after treatment combination, and these CD8+ T-cells play a key role in MRTX849/lapatinib efficacy. MRTX849/lapatinib treatment upregulated PD-L1 overexpression in both stromal and tumor cells, which presumably suppressed CD8+ T-cells and enabled immune escape and tumor progression. Supplementation of αPD-1 prolonged the progression-free survival of 4NQO-L-bearing mice treated with MRTX849/lapatinib. MRTX849/lapatinib treatment delayed tumor growth of 4NQO-L-AcR in mice; however, the percentages of CD8+ T-cells in 4NQO-L-AcR were low, and supplementation of MRTX849/lapatinib with αPD-1 did not improve the outcome.

CONCLUSIONS

Our study highlights the critical need for blocking both intrinsic and extrinsic mechanisms of resistance for the prolonged response and shows that such treatment is ineffective in KRASG12Ci-AcR tumors.

The Potential Treatment Options and Combination Strategies of KRAS-Mutated Lung Cancer

In non-small cell lung cancer (NSCLC), Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations are found in up to 30% of all cases, with the most prevalent mutations occurring in codons 12 and 13. The development of KRAS-targeted drugs like sotorasib and adagrasib has generated significant excitement in the clinical arena, offering new therapeutic options. Their potential for combination with other treatments broadens the scope for clinical exploration. Acquired resistance to KRAS exon 2 p.G12C inhibitors is a significant challenge, with several reported mechanisms. In this scenario, combination therapy strategies that include targeting Src Homology Region 2 Domain-Containing Phosphatase-2 (SHP2), Son of Sevenless Homolog 1 (SOS1), or downstream effectors of KRAS exon 2 p.G12C are showing promise in overcoming such resistance. However, the efficacy of immune checkpoint inhibitors in this context still requires comprehensive evaluation. The response to anti-Programmed Cell Death Protein 1/Programmed Cell Death Protein 1 Ligand (anti-PD-1/PD-L1) drugs in NSCLC may be significantly influenced by co-occurring mutations, underscoring the need for a personalized approach to treatment based on the specific genetic profile of each tumor.

NFAT5 governs cellular plasticity-driven resistance to KRAS-targeted therapy in pancreatic cancer

Resistance to KRAS therapy in pancreatic ductal adenocarcinoma (PDAC) involves cellular plasticity, particularly the epithelial-to-mesenchymal transition (EMT), which poses challenges for effective targeting. Chronic pancreatitis, a known risk factor for PDAC, elevates TGFβ levels in the tumor microenvironment (TME), promoting resistance to KRAS therapy. Mechanistically, TGFβ induces the formation of a novel protein complex composed of SMAD3, SMAD4, and the nuclear factor NFAT5, triggering EMT and resistance by activating key mediators such as S100A4. Inhibiting NFAT5 attenuates pancreatitis-induced resistance to KRAS inhibition and extends mouse survival. Additionally, TGFβ stimulates PDAC cells to secrete CCL2, recruiting macrophages that contribute to KRAS bypass through paracrine S100A4. Our findings elucidate the role of TGFβ signaling in EMT-associated KRAS therapy resistance and identify NFAT5 as a druggable target. Targeting NFAT5 could disrupt this regulatory network, offering a potential avenue for preventing resistance in PDAC.

Combining RAS(ON) G12C-selective inhibitor with SHP2 inhibition sensitises lung tumours to immune checkpoint blockade

Mutant selective drugs targeting the inactive, GDP-bound form of KRASG12C have been approved for use in lung cancer, but resistance develops rapidly. Here we use an inhibitor, (RMC-4998) that targets RASG12C in its active, GTP-bound form, to treat KRAS mutant lung cancer in various immune competent mouse models. RAS pathway reactivation after RMC-4998 treatment could be delayed using combined treatment with a SHP2 inhibitor, which not only impacts tumour cell RAS signalling but also remodels the tumour microenvironment to be less immunosuppressive. In an immune inflamed model, RAS and SHP2 inhibitors in combination drive durable responses by suppressing tumour relapse and inducing development of immune memory. In an immune excluded model, combined RAS and SHP2 inhibition sensitises tumours to immune checkpoint blockade, leading to efficient tumour immune rejection. These preclinical results demonstrate the potential of the combination of RAS(ON) G12C-selective inhibitors with SHP2 inhibitors to sensitize tumours to immune checkpoint blockade.

Mechanisms of resistance to KRASG12C inhibitors in KRASG12C-mutated non-small cell lung cancer

The KRAS protein, a product of the KRAS gene (V-ki-ras2 Kirsten rat sarcoma viral oncogene homolog), functions as a small GTPase that alternates between an active GTP-bound state (KRAS(ON)) and an inactive GDP-bound state (KRAS(OFF)). The KRASG12C mutation results in the accumulation of KRASG12C(OFF), promoting cell cycle survival and proliferation primarily through the canonical MAPK and PI3K pathways. The KRASG12C mutation is found in 13% of lung adenocarcinomas. Previously considered undruggable, sotorasib and adagrasib are the first available OFF-state KRASG12C inhibitors, but treatment resistance is frequent. In this review, after briefly summarizing the KRAS pathway and the mechanism of action of OFF-state KRASG12C inhibitors, we discuss primary and acquired resistance mechanisms. Acquired resistance is the most frequent, with "on-target" mechanisms such as a new KRAS mutation preventing inhibitor binding; and "off-target" mechanisms leading to bypass of KRAS through gain-of-function mutations in other oncogenes such as NRAS, BRAF, and RET; or loss-of-function mutations in tumor suppressor genes such as PTEN. Other "off-target" mechanisms described include epithelial-to-mesenchymal transition and histological transformation. Multiple co-existing mechanisms can be found in patients, but few cases have been published. We highlight the lack of data on non-genomic resistance and the need for comprehensive clinical studies exploring histological, genomic, and non-genomic changes at resistance. This knowledge could help foster new treatment initiatives in this challenging context.

KRAS G12C Inhibitors in the Treatment of Metastatic Colorectal Cancer

KRAS mutations contribute substantially to the overall colorectal cancer burden and have long been a focus of drug development efforts. After a lengthy preclinical road, KRAS inhibition via the G12C allele has finally become a therapeutic reality. Unlike in NSCLC, early studies of KRAS inhibitors in CRC struggled to demonstrate single agent activity. Investigation into these tissue-specific treatment differences has led to a deeper understanding of the complexities of MAPK signaling and the diverse adaptive feedback responses to KRAS inhibition. EGFR reactivation has emerged as a principal resistance mechanism to KRAS inhibitor monotherapy. Thus, the field has pivoted to dual EGFR/KRAS blockade with promising efficacy. Despite significant strides in the treatment of KRAS G12C mutated CRC, new challenges are on the horizon. Alternative RTK reactivation and countless acquired molecular resistance mechanisms have shifted the treatment goalpost. This review focuses on the historical and contemporary clinical strategies of targeting KRAS G12C alterations in CRC and highlights future directions to overcome treatment challenges.

Co-targeting SOS1 enhances the antitumor effects of KRASG12C inhibitors by addressing intrinsic and acquired resistance

Combination approaches are needed to strengthen and extend the clinical response to KRASG12C inhibitors (KRASG12Ci). Here, we assessed the antitumor responses of KRASG12C mutant lung and colorectal cancer models to combination treatment with a SOS1 inhibitor (SOS1i), BI-3406, plus the KRASG12C inhibitor, adagrasib. We found that responses to BI-3406 plus adagrasib were stronger than to adagrasib alone, comparable to adagrasib with SHP2 (SHP2i) or EGFR inhibitors and correlated with stronger suppression of RAS-MAPK signaling. BI-3406 plus adagrasib treatment also delayed the emergence of acquired resistance and elicited antitumor responses from adagrasib-resistant models. Resistance to KRASG12Ci seemed to be driven by upregulation of MRAS activity, which both SOS1i and SHP2i were found to potently inhibit. Knockdown of SHOC2, a MRAS complex partner, partially restored response to KRASG12Ci treatment. These results suggest KRASG12C plus SOS1i to be a promising strategy for treating both KRASG12Ci naive and relapsed KRASG12C-mutant tumors.

Therapeutic targeting of Syndecan-1 axis overcomes acquired resistance to KRAS-targeted therapy in gastrointestinal cancers

The therapeutic benefit of recently developed mutant KRAS (mKRAS) inhibitors has been limited by the rapid onset of resistance. Here, we aimed to delineate the mechanisms underlying acquired resistance to mKRAS inhibition and identify actionable targets for overcoming this clinical challenge. Previously, we identified Syndecan-1 (SDC1) as a key effector for pancreatic cancer progression whose surface expression is driven by mKRAS. By leveraging both pancreatic and colorectal cancer models, we found that surface SDC1 expression was initially diminished upon mKRAS inhibition, but recovered in tumor cells that bypass mKRAS dependency. Functional studies showed that these tumors depended on SDC1 for survival, further establishing SDC1 as a driver for the acquired resistance to mKRAS inhibition. Mechanistically, we revealed that the YAP1-SDC1 axis was the major driving force for bypassing mKRAS dependency to sustain nutrient salvage machinery and tumor maintenance. Specifically, YAP1 activation mediated the recovery of SDC1 localization on cell surface that sustained macropinocytosis and enhanced the activation of multiple RTKs, promoting resistance to KRAS-targeted therapy. Overall, our study has provided the rationale for targeting the YAP-SDC1 axis to overcome resistance to mKRAS inhibition, thereby revealing new therapeutic opportunities for improving the clinical outcome of patients with KRAS-mutated cancers.

Current perspectives of KRAS in non-small cell lung cancer

NSCLC has a diverse genomic background with mutations in key proto-oncogenic drivers including Kirsten rat sarcoma (KRAS) and epidermal growth factor receptor (EGFR). Roughly 40% of adenocarcinoma harbor Kras activating mutations regardless of smoking history. Most KRAS mutations are located at G12, which include G12C (roughly 40%), G12V (roughly 20%), and G12D (roughly 15%). KRAS mutated NSCLC have higher tumor mutational burden and some have increased PD-1 expression, which has resulted in better responses to immunotherapy than other oncogenes. While initial treatment for metastatic NSCLC still relies on chemo-immunotherapy, directly targeting KRAS has proven to be efficacious in treating patients with KRAS mutated metastatic NSCLC. To date, two G12C inhibitors have been FDA-approved, namely sotorasib and adagrasib. In this review, we summarize the different drug combinations used to target KRAS G12c, upcoming G12D inhibitors and novel therapies targeting KRAS.

Fibroblasts Promote Resistance to KRAS Silencing in Colorectal Cancer Cells

Colorectal cancer (CRC) responses to KRAS-targeted inhibition have been limited due to low response rates, the mechanisms of which remain unknown. Herein, we explored the cancer-associated fibroblasts (CAFs) secretome as a mediator of resistance to KRAS silencing. CRC cell lines HCT15, HCT116, and SW480 were cultured either in recommended media or in conditioned media from a normal colon fibroblast cell line (CCD-18Co) activated with rhTGF-β1 to induce a CAF-like phenotype. The expression of membrane stem cell markers was analyzed by flow cytometry. Stem cell potential was evaluated by a sphere formation assay. RNAseq was performed in KRAS-silenced HCT116 colonospheres treated with either control media or conditioned media from CAFs. Our results demonstrated that KRAS-silencing up-regulated CD24 and down-regulated CD49f and CD104 in the three cell lines, leading to a reduction in sphere-forming efficiency. However, CAF-secreted factors restored stem cell marker expression and increased stemness. RNA sequencing showed that CAF-secreted factors up-regulated genes associated with pro-tumorigenic pathways in KRAS-silenced cells, including KRAS, TGFβ, NOTCH, WNT, MYC, cell cycle progression and exit from quiescence, epithelial-mesenchymal transition, and immune regulation. Overall, our results suggest that resistance to KRAS-targeted inhibition might derive not only from cell-intrinsic causes but also from external elements, such as fibroblast-secreted factors.

Combined inhibition of KRASG12C and mTORC1 kinase is synergistic in non-small cell lung cancer

Current KRASG12C (OFF) inhibitors that target inactive GDP-bound KRASG12C cause responses in less than half of patients and these responses are not durable. A class of RASG12C (ON) inhibitors that targets active GTP-bound KRASG12C blocks ERK signaling more potently than the inactive-state inhibitors. Sensitivity to either class of agents is strongly correlated with inhibition of mTORC1 activity. We have previously shown that PI3K/mTOR and ERK-signaling pathways converge on key cellular processes and that inhibition of both pathways is required for inhibition of these processes and for significant antitumor activity. We find here that the combination of a KRASG12C inhibitor with a selective mTORC1 kinase inhibitor causes synergistic inhibition of Cyclin D1 expression and cap-dependent translation. Moreover, BIM upregulation by KRASG12C inhibition and inhibition of MCL-1 expression by the mTORC1 inhibitor are both required to induce significant cell death. In vivo, this combination causes deep, durable tumor regressions and is well tolerated. This study suggests that the ERK and PI3K/mTOR pathways each mitigate the effects of inhibition of the other and that combinatorial inhibition is a potential strategy for treating KRASG12C-dependent lung cancer.

CCL2 promotes EGFR-TKIs resistance in non-small cell lung cancer via the AKT-EMT pathway

Acquired resistance to EGFR tyrosine kinase inhibitors (EGFR-TKIs) represents a primary cause of treatment failure in non-small cell lung cancer (NSCLC) patients. Chemokine (C-C motif) ligand 2 (CCL2) is recently found to play a pivotal role in determining anti-cancer treatment response. However, the role and mechanism of CCL2 in the development of EGFR-TKIs resistance have not been fully elucidated. In the present study, we focus on the function of CCL2 in the development of acquired resistance to EGFR-TKIs in NSCLC cells. Our results show that CCL2 is aberrantly upregulated in EGFR-TKIs-resistant NSCLC cells and that CCL2 overexpression significantly diminishes sensitivity to EGFR-TKIs. Conversely, CCL2 suppression by CCL2 synthesis inhibitor, bindarit, or CCL2 knockdown can reverse this resistance. CCL2 upregulation can also lead to enhanced migration and increased expressions of epithelial-mesenchymal transition (EMT) markers in EGFR-TKI-resistant NSCLC cells, which could also be rescued by CCL2 knockdown or inhibition. Furthermore, our findings suggest that CCL2-dependent EGFR-TKIs resistance involves the AKT-EMT signaling pathway; inhibition of this pathway effectively attenuates CCL2-induced cell migration and EMT marker expression. In summary, CCL2 promotes the development of acquired EGFR-TKIs resistance and EMT while activating AKT signaling in NSCLC. These insights suggest a promising avenue for the development of CCL2-targeted therapies that prevent EGFR-TKIs resistance in NSCLC.

Novel RAF-directed approaches to overcome current clinical limits and block the RAS/RAF node

Mutations in the RAS-RAF-MEK-ERK pathway are frequent alterations in cancer and RASopathies, and while RAS oncogene activation alone affects 19% of all patients and accounts for approximately 3.4 million new cases every year, less frequent alterations in the cascade's downstream effectors are also involved in cancer etiology. RAS proteins initiate the signaling cascade by promoting the dimerization of RAF kinases, which can act as oncoproteins as well: BRAFV600E is the most common oncogenic driver, mutated in the 8% of all malignancies. Research in this field led to the development of drugs that target the BRAFV600-like mutations (Class I), which are now utilized in clinics, but cause paradoxical activation of the pathway and resistance development. Furthermore, they are ineffective against non-BRAFV600E malignancies that dimerize and could be either RTK/RAS independent or dependent (Class II and III, respectively), which are still lacking an effective treatment. This review discusses the recent advances in anti-RAF therapies, including paradox breakers, dimer-inhibitors, immunotherapies, and other novel approaches, critically evaluating their efficacy in overcoming the therapeutic limitations, and their putative role in blocking the RAS pathway.

Omics-based molecular classifications empowering in precision oncology

BACKGROUND

In the past decades, cancer enigmatical heterogeneity at distinct expression levels could interpret disparities in therapeutic response and prognosis. It built hindrances to precision medicine, a tactic to tailor customized treatment informed by the tumors' molecular profile. Single-omics analysis dissected the biological features associated with carcinogenesis to some extent but still failed to revolutionize cancer treatment as expected. Integrated omics analysis incorporated tumor biological networks from diverse layers and deciphered a holistic overview of cancer behaviors, yielding precise molecular classification to facilitate the evolution and refinement of precision medicine.

CONCLUSION

This review outlined the biomarkers at multiple expression layers to tutor molecular classification and pinpoint tumor diagnosis, and explored the paradigm shift in precision therapy: from single- to multi-omics-based subtyping to optimize therapeutic regimens. Ultimately, we firmly believe that by parsing molecular characteristics, omics-based typing will be a powerful assistant for precision oncology.

Global research trends in immunotherapy for non-small cell lung cancer patients with KRAS mutations: a bibliometric analysis

Background

Immunotherapy, frequently combined with conventional chemotherapy, is crucial for treating NSCLC. Kirsten rat sarcoma virus (KRAS) is a poor prognostic factor in patients with NSCLC, particularly lung adenocarcinoma, where binding of conventional inhibitors to mutated KRAS proteins is challenging. Field profiles, research hotspots, and prospects for immunotherapy for patients with NSCLC-carrying KRAS mutations were uncovered in this study.

Methods

Microsoft Excel 2019, Bibliometrix, VOSviewer software, and Citespace were utilized to conduct a comprehensive scientometric analysis and understand a specific research field's knowledge base and frontiers aided by bibliometrics.

Results

Between 2014 and 2023, 398 eligible documents in the English language were acquired using the WoSCC database, of which 113 and 285 were reviews and articles, respectively. The growth rate per year was 34.25 %. The most cited articles were from the United States, and China published the highest number of articles. Cancers was the journal, with increased publications in recent years. The keywords with the strongest citation bursts were analyzed using Citespace. "Immune checkpoint inhibitors," "co-occurring genomic alterations," and "KRAS" are among the research hotspots in this field.

Conclusion

Using bibliometric and visual analyses, we examined immunotherapy for patients with KRAS-mutant NSCLC over the previous decade. The whole analysis showed a steady, quick increase in yearly publications in this area. Our findings will provide a roadmap for future research on the mechanisms of immunotherapy and immune checkpoint inhibitor action in treating KRAS-mutant NSCLC.

Targeting KRASG12C in Non-Small-Cell Lung Cancer: Current Standards and Developments

Among the most common molecular alterations detected in non-small-cell lung cancer (NSCLC) are mutations in Kristen Rat Sarcoma viral oncogene homolog (KRAS). KRAS mutant NSCLC is a heterogenous group of diseases, different from other oncogene-driven tumors in terms of biology and response to therapies. Despite efforts to develop drugs aimed at inhibiting KRAS or its signaling pathways, KRAS had remained undruggable for decades. The discovery of a small pocket in the binding switch II region of KRASG12C has revolutionized the treatment of KRASG12C-mutated NSCLC patients. Sotorasib and adagrasib, direct KRASG12C inhibitors, have been approved by the US Food and Drug Administration (FDA) and other regulatory agencies for patients with previously treated KRASG12C-mutated NSCLC, and these advances have become practice changing. However, first-line treatment in KRASG12C-mutated NSCLC does not differ from NSCLC without actionable driver genomic alterations. Treatment with KRASG12C inhibitors is not curative and patients develop progressive disease, so understanding associated mechanisms of drug resistance is key. New KRASG12C inhibitors and several combination therapy strategies, including with immune checkpoint inhibitors, are being studied in clinical trials. The aim of this review is to explore the clinical impact of KRAS, and outline different treatment approaches, focusing on the novel treatment of KRASG12C-mutated NSCLC.

AXL signal mediates adaptive resistance to KRAS G12C inhibitors in KRAS G12C-mutant tumor cells

Recently, novel Kirsten rat sarcoma viral oncogene homolog (KRAS) inhibitors have been clinically developed to treat KRAS G12C-mutated non-small cell lung cancer (NSCLC) patients. However, achieving complete tumor remission is challenging. Therefore, the optimal combined therapeutic intervention with KRAS G12C inhibitors has a potentially crucial role in the clinical outcomes of patients. We investigated the underlying molecular mechanisms of adaptive resistance to KRAS G12C inhibitors in KRAS G12C-mutated NSCLC cells to devise a strategy preventing drug-tolerant cell emergence. We demonstrate that AXL signaling led to the adaptive resistance to KRAS G12C inhibitors in KRAS G12C-mutated NSCLC, activation of which is induced by GAS6 production via YAP. AXL inhibition reduced the viability of AXL-overexpressing KRAS G12C-mutated lung cancer cells by enhancing KRAS G12C inhibition-induced apoptosis. In xenograft models of AXL-overexpressing KRAS G12C-mutated lung cancer treated with KRAS G12C inhibitors, initial combination therapy with AXL inhibitor markedly delayed tumor regrowth compared with KRAS G12C inhibitor alone or with the combination after acquired resistance to KRAS G12C inhibitor. These results indicated pivotal roles for the YAP-GAS6-AXL axis and its inhibition in the intrinsic resistance to KRAS G12C inhibitor.

Emerging Therapies in Kirsten Rat Sarcoma Virus (+) Non-Small-Cell Lung Cancer

Kirsten rat sarcoma virus (KRAS) is the most frequently found oncogene in human cancers, including non-small-cell lung cancer (NSCLC). For many years, KRAS was considered "undruggable" due to its structure and difficult targeting. However, the discovery of the switch II region in the KRAS-G12C-mutated protein has changed the therapeutic landscape with the design and development of novel direct KRAS-G12C inhibitors. Sotorasib and adagrasib are FDA-approved targeted agents for pre-treated patients with KRAS-G12C-mutated NSCLC. Despite promising results, the efficacy of these novel inhibitors is limited by mechanisms of resistance. Ongoing studies are evaluating combination strategies for overcoming resistance. In this review, we summarize the biology of the KRAS protein and the characteristics of KRAS mutations. We then present current and emerging therapeutic approaches for targeting KRAS mutation subtypes intending to provide individualized treatment for lung cancer harboring this challenging driver mutation.

Targeting KRAS in cancer

RAS family variants-most of which involve KRAS-are the most commonly occurring hotspot mutations in human cancers and are associated with a poor prognosis. For almost four decades, KRAS has been considered undruggable, in part due to its structure, which lacks small-molecule binding sites. But recent developments in bioengineering, organic chemistry and related fields have provided the infrastructure to make direct KRAS targeting possible. The first successes occurred with allele-specific targeting of KRAS p.Gly12Cys (G12C) in non-small cell lung cancer, resulting in regulatory approval of two agents-sotorasib and adagrasib. Inhibitors targeting other variants beyond G12C have shown preliminary antitumor activity in highly refractory malignancies such as pancreatic cancer. Herein, we outline RAS pathobiology with a focus on KRAS, illustrate therapeutic approaches across a variety of malignancies, including emphasis on the 'on' and 'off' switch allele-specific and 'pan' RAS inhibitors, and review immunotherapeutic and other key combination RAS targeting strategies. We summarize mechanistic understanding of de novo and acquired resistance, review combination approaches, emerging technologies and drug development paradigms and outline a blueprint for the future of KRAS therapeutics with anticipated profound clinical impact.

From bench to bedside: current development and emerging trend of KRAS-targeted therapy

Kirsten rat sarcoma 2 viral oncogene homolog (KRAS) is the most frequently mutated oncogene in human cancers with mutations predominantly occurring in codon 12. These mutations disrupt the normal function of KRAS by interfering with GTP hydrolysis and nucleotide exchange activity, making it prone to the GTP-bound active state, thus leading to sustained activation of downstream pathways. Despite decades of research, there has been no progress in the KRAS drug discovery until the groundbreaking discovery of covalently targeting the KRASG12C mutation in 2013, which led to revolutionary changes in KRAS-targeted therapy. So far, two small molecule inhibitors sotorasib and adagrasib targeting KRASG12C have received accelerated approval for the treatment of non-small cell lung cancer (NSCLC) harboring KRASG12C mutations. In recent years, rapid progress has been achieved in the KRAS-targeted therapy field, especially the exploration of KRASG12C covalent inhibitors in other KRASG12C-positive malignancies, novel KRAS inhibitors beyond KRASG12C mutation or pan-KRAS inhibitors, and approaches to indirectly targeting KRAS. In this review, we provide a comprehensive overview of the molecular and mutational characteristics of KRAS and summarize the development and current status of covalent inhibitors targeting the KRASG12C mutation. We also discuss emerging promising KRAS-targeted therapeutic strategies, with a focus on mutation-specific and direct pan-KRAS inhibitors and indirect KRAS inhibitors through targeting the RAS activation-associated proteins Src homology-2 domain-containing phosphatase 2 (SHP2) and son of sevenless homolog 1 (SOS1), and shed light on current challenges and opportunities for drug discovery in this field.

Farnesyl-transferase inhibitors show synergistic anticancer effects in combination with novel KRAS-G12C inhibitors

BACKGROUND

Inhibition of mutant KRAS challenged cancer research for decades. Recently, allele-specific inhibitors were approved for the treatment of KRAS-G12C mutant lung cancer. However, de novo and acquired resistance limit their efficacy and several combinations are in clinical development. Our study shows the potential of combining G12C inhibitors with farnesyl-transferase inhibitors.

METHODS

Combinations of clinically approved farnesyl-transferase inhibitors and KRAS G12C inhibitors are tested on human lung, colorectal and pancreatic adenocarcinoma cells in vitro in 2D, 3D and subcutaneous xenograft models of lung adenocarcinoma. Treatment effects on migration, proliferation, apoptosis, farnesylation and RAS signaling were measured by histopathological analyses, videomicroscopy, cell cycle analyses, immunoblot, immunofluorescence and RAS pulldown.

RESULTS

Combination of tipifarnib with sotorasib shows synergistic inhibitory effects on lung adenocarcinoma cells in vitro in 2D and 3D. Mechanistically, we present antiproliferative effect of the combination and interference with compensatory HRAS activation and RHEB and lamin farnesylation. Enhanced efficacy of sotorasib in combination with tipifarnib is recapitulated in the subcutaneous xenograft model of lung adenocarcinoma. Finally, combination of additional KRAS G1C and farnesyl-transferase inhibitors also shows synergism in lung, colorectal and pancreatic adenocarcinoma cellular models.

DISCUSSION

Our findings warrant the clinical exploration of KRAS-G12C inhibitors in combination with farnesyl-transferase inhibitors.

Targeting KRAS mutations in pancreatic cancer: opportunities for future strategies

Targeting the RAS pathway remains the holy grail of precision oncology. In the case of pancreatic ductal adenocarcinomas (PDAC), 90-92% harbor mutations in the oncogene KRAS, triggering canonical MAPK signaling. The smooth structure of the altered KRAS protein without a binding pocket and its affinity for GTP have, in the past, hampered drug development. The emergence of KRASG12C covalent inhibitors has provided renewed enthusiasm for targeting KRAS. The numerous pathways implicated in RAS activation do, however, lead to the development of early resistance. In addition, the dense stromal niche and immunosuppressive microenvironment dictated by oncogenic KRAS can influence treatment responses, highlighting the need for a combination-based approach. Given that mutations in KRAS occur early in PDAC tumorigenesis, an understanding of its pleiotropic effects is key to progress in this disease. Herein, we review current perspectives on targeting KRAS with a focus on PDAC.

Adeno-to-squamous transition drives resistance to KRAS inhibition in LKB1 mutant lung cancer

KRASG12C inhibitors (adagrasib and sotorasib) have shown clinical promise in targeting KRASG12C-mutated lung cancers; however, most patients eventually develop resistance. In lung patients with adenocarcinoma with KRASG12C and STK11/LKB1 co-mutations, we find an enrichment of the squamous cell carcinoma gene signature in pre-treatment biopsies correlates with a poor response to adagrasib. Studies of Lkb1-deficient KRASG12C and KrasG12D lung cancer mouse models and organoids treated with KRAS inhibitors reveal tumors invoke a lineage plasticity program, adeno-to-squamous transition (AST), that enables resistance to KRAS inhibition. Transcriptomic and epigenomic analyses reveal ΔNp63 drives AST and modulates response to KRAS inhibition. We identify an intermediate high-plastic cell state marked by expression of an AST plasticity signature and Krt6a. Notably, expression of the AST plasticity signature and KRT6A at baseline correlates with poor adagrasib responses. These data indicate the role of AST in KRAS inhibitor resistance and provide predictive biomarkers for KRAS-targeted therapies in lung cancer.

Insights into how adeno-squamous transition drives KRAS inhibitor resistance

The histologic transformation of adenocarcinoma (ADC) to squamous cell carcinoma (SCC), known as adeno-squamous transition or AST, is frequently observed in patients with lung cancer undergoing cancer therapy. In this issue, Tong and colleagues investigate genetic and epigenetic mechanisms that drive AST to confer resistance to KRAS inhibitors in preclinical models and patients.

FBXL16 promotes cell growth and drug resistance in lung adenocarcinomas with KRAS mutation by stabilizing IRS1 and upregulating IRS1/AKT signaling

Lung cancer is the leading cause of cancer-related deaths worldwide. Lung adenocarcinomas (LUADs) are a major subtype of non-small-cell lung cancers (NSCLCs). About 25% of LUADs harbor GTPase KRAS mutations associated with poor prognosis and limited treatment options. While encouraging tumor response to novel covalent inhibitors specifically targeting KRASG12C has been shown in the clinic, either intrinsic resistance exists or acquired therapeutic resistance arises upon treatment. There is an unmet need to identify new therapeutic targets for treating LUADs with activating KRAS mutations, particularly those with resistance to KRASG12C inhibitor(s). In this study, we have revealed that F-box/LRR-repeat protein 16 (FBXL16) is selectively upregulated in LUAD with KRAS mutations. It promotes LUAD cell growth and transforms lung epithelial cells. Importantly, FBXL16 depletion greatly enhances sensitivity to the KRASG12C inhibitor (sotorasib) in resistant cells by downregulating phosphatidylinositol 3-kinase (PI3K)/protein kinase B (PKB; also known as AKT) signaling. Mechanistically, FBXL16 upregulates insulin receptor substrate 1 (IRS1) protein stability, leading to an increase of IGF1/AKT signaling, thereby promoting cell growth and migration. Taken together, our study highlights the potential of FBXL16 as a therapeutic target for treating LUAD with KRAS activating mutations.

A Potent SOS1 PROTAC Degrader with Synergistic Efficacy in Combination with KRASG12C Inhibitor

AMG510, as the first approved inhibitor for KRASG12C mutation, has shown promising efficacy in nonsmall-cell lung cancer and colorectal cancer harboring KRASG12C mutation. However, the moderate response rate and the rapid emergence of acquired resistance limit the therapeutic potential of AMG510, highlighting the need for the development of combination strategies. Here, we observed the suppression of RAS-MAPK signaling induced by AMG510 was prolonged and enhanced by SOS1 knockdown. Thus, we design, synthesize, and characterize a potent and specific SOS1 degrader 23. Compound 23 showed efficient SOS1 degradation in KRAS-driven cancer cells and achieved significant antiproliferative potency. Importantly, the combination of 23 with AMG510 suppressed RAS signaling feedback activation, showing synergistic effects against KRASG12C mutant cells in vitro and in vivo. Our findings demonstrated that KRASG12C inhibition plus SOS1 degradation as a potential therapeutic strategy to improve antitumor response and overcome acquired resistance to KRASG12C inhibitor.