LKB1 Mutations Research Articles

Type I interferon signaling pathway enhances immune-checkpoint inhibition in KRAS mutant lung tumors

Lung cancer is the leading cause of cancer mortality worldwide. KRAS oncogenes are responsible for at least a quarter of lung adenocarcinomas, the main subtype of lung cancer. After four decades of intense research, selective inhibitors of KRAS oncoproteins are finally reaching the clinic. Yet, their effect on overall survival is limited due to the rapid appearance of drug resistance, a likely consequence of the high intratumoral heterogeneity characteristic of these tumors. In this study, we have attempted to identify those functional alterations that result from KRAS oncoprotein expression during the earliest stages of tumor development. Such functional changes are likely to be maintained during the entire process of tumor progression regardless of additional co-occurring mutations. Single-cell RNA sequencing analysis of murine alveolar type 2 cells expressing a resident Kras oncogene revealed impairment of the type I interferon pathway, a feature maintained throughout tumor progression. This alteration was also present in advanced murine and human tumors harboring additional mutations in the p53 or LKB1 tumor suppressors. Restoration of type I interferon (IFN) signaling by IFN-β or constitutive active stimulator of interferon genes (STING) expression had a profound influence on the tumor microenvironment, switching them from immunologically "cold" to immunologically "hot" tumors. Therefore, enhancement of the type I IFN pathway predisposes KRAS mutant lung tumors to immunotherapy treatments, regardless of co-occurring mutations in p53 or LKB1.

A novel and potent MICA/B antibody is therapeutically effective in KRAS LKB1 mutant lung cancer models.

Concurrent KRAS LKB1 (STK11, KL) mutant Non-Small Cell Lung Cancers (NSCLC) is particularly difficult to treat and does not respond well to current immune checkpoint blockade (ICB) therapies. This is due to numerous mechanisms including low antigen presentation limiting T cell mediated killing. To activate anti-tumor immunity, we targeted tumor cell - natural killer (NK) cell interactions. We tested whether a novel antibody based therapeutic strategy that predominantly activates natural killer (NK) cells demonstrates efficacy in pre-clinical mouse models of KL NSCLC. NK cells rely on binding of ligands, such as Major Histocompatibility Complex (MHC) class I-related chain A or B (MICA/B), to the activating receptor NKG2D. Importantly MICA and MICB are widely expressed in elevated levels across NSCLC subtypes including KL lung cancers. Proteases with the tumor microenvironment (TME) can cleave these proteins rendering tumor cells less visible to NK cells. We therefore developed a MICA monoclonal antibody, AHA-1031, which utilizes two NK cell activating receptors. AHA1031 prevents ligand shedding without interfering with binding to NKG2D while targeting cancer cells to antibody mediated cell dependent cytotoxicity (ADCC). Our therapeutic novel antibody has significant monotherapy activity in KL cancer models including xenografts of human cell lines and patient derived xenografts. Activating NK cells through MICA/B stabilization and inducing ADCC offers an alternative and potent therapy option in KL tumors. MICA/B are shed across different tumors making this therapeutic strategy universally applicable.

Methionine Restriction Reduces Lung Cancer Progression and Increases Chemotherapy Response.

Targeting tumor metabolism through dietary interventions is an area of growing interest, and may help to improve the significant mortality of aggressive cancers, including non-small cell lung cancer (NSCLC). Here we show that the restriction of methionine in the aggressive KRAS /Lkb1- mutant NSCLC autochthonous mouse model drives decreased tumor progression and increased carboplatin treatment efficacy. Importantly, methionine restriction during early stages of tumorigenesis prevents the lineage switching known to occur in the model, and alters the tumor immune microenvironment (TIME) to have fewer tumor-infiltrating neutrophils. Mechanistically, mutations in LKB1 are linked to anti-oxidant production through changes to cystathionine-β-synthase (CBS) expression. Human cell lines with rescued LKB1 show increased CBS levels and resistance to carboplatin, which can be partially rescued by methionine restriction. Furthermore, LKB1 rescued cells, but not mutant cells, show less G2- M arrest and apoptosis in high methionine conditions. Knock-down of CBS sensitized both LKB1 mutant and non-mutated lines to carboplatin, again rescuing the carboplatin resistance of the LKB1 rescued lines. Given that immunotherapy is commonly combined with chemotherapy for NSCLC, we next wanted to understand if T cells are impaired by MR. Therefore, we examined the ability of T cells from MR and control tumor bearing mice to proliferate in culture and found that T cells from MR treated mice had no defects in proliferation, even though we continued the MR conditions ex vivo . We also identified that CBS is most highly correlated with smoking, adenocarcinomas with alveolar and bronchiolar features, and adenosquamous cell carcinomas, implicating its roles in oxidative stress response and lineage fate in human tumors. Taken together, we have shown the importance of MR as a dietary intervention to slow tumor growth and improve treatment outcomes for NSCLC.

AMPK activation reduces cancer cell aggressiveness via inhibition of monoamine oxidase A (MAO-A) expression/activity

AimAMPK can be considered as an important target molecule for cancer for its unique ability to directly recognize cellular energy status. The main aim of this study is to explore the role of different AMPK activators in managing cancer cell aggressiveness and to understand the mechanistic details behind the process. Main methodsFirst, we explored the AMPK expression pattern and its significance in different subtypes of lung cancer by accessing the TCGA data sets for LUNG, LUAD and LUSC patients and then established the correlation between AMPK expression pattern and overall survival of lung cancer patients using Kaplan-Meire plot. We further carried out several cell-based assays by employing different wet lab techniques including RT-PCR, Western Blot, proliferation, migration and invasion assays to fulfil the aim of the study. Key findings•Expression of AMPK is correlated with survival and prognosis of lung cancer patients.•AMPK activators like Metformin and Phenformin downregulate A549 and HCT-116 cell proliferation and migration via repression of p38MAPK activity, subsequent augmentation of R1 repressor and corresponding downregulation of MAO-A expression/activity resulting reduction in the intracellular ROS.•SRT-1720 directly activates AMPK in LKB1 mutant A549 cells either alone or in combination with Metformin resulting regulation of cancer cell aggressiveness. SignificanceThis study identifies the importance of AMPK activators as a repurposing agent for combating lung and colon cancer cell aggressiveness. It also suggests SRT-1720 as a potent repurposing agent for cancer treatment especially in NSCLC patients where a point mutation is present in LKB1.

Abstract 4455: Metabolic stress induces a double positive feedback loop between AMPK and p62 conferring dual activation of AMPK and NRF2 to synergize antioxidant defense

Abstract Co-occurring mutations in KEAP1 in LKB1-mutant NSCLC activate NRF2 to compensate losing LKB1-AMPK activity during metabolic adaptation and survival. Here, we investigated the regulatory crosstalk between LKB1-AMPK and KEAP1-NRF2 pathways during metabolic stress. We found that metabolic stress activates NRF2 through the expression and phosphorylation of p62, causing the autophagic degradation of KEAP1. Intriguingly, the induction of p62 during metabolic stress is also required to activate AMPK by promoting AXIN-LKB1-AMPK complex formation and recruiting it to the lysosomal membrane. Importantly, the p62-driven dual-activation of AMPK and NRF2 was critical for tumour growth by synergizing antioxidant defences. In turn, the induction of p62 also required LKB1-AMPK activity, suggesting a double positive feedback loop between AMPK and p62. Mechanistically, the increase in lysosomal pH caused by low glucose metabolism and AMPK-dependent reduction of proton generation induced PP2A-dependent dephosphorylation of TFEB/TFE3 which increased the expression of p62. The increase of ROS caused by metabolic stress induced lysosomal MCOLN1-Ca2+ dependent activation of TAK1 which increased p62 phosphorylation. Protons provided by lactic acid abrogated all the effects caused by metabolic stress. This positive feedback loop between AMPK and p62 that activates AMPK and NRF2 can potentially explain why co-occurring mutations in LKB1 and KEAP1 occur and further provide promising therapeutic strategies for lung cancer. Citation Format: Eun-Ji Choi, Hyun-Taek Oh, Seon-Hyeong Lee, Chen-Song Zhang, Mengqi Li, Soo-Youl Kim, Sunghyouk Park, Tong-Shin Chang, Byung-Hoon Lee, Sheng-Cai Lin, Sang-Min Jeon. Metabolic stress induces a double positive feedback loop between AMPK and p62 conferring dual activation of AMPK and NRF2 to synergize antioxidant defense [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4455.

Abstract 4322: Inhibition of ULK and KRASG12C control tumor growth in preclinical models of lung cancer

Abstract Approximately 30% of lung cancers are driven by mutationally activated KRAS. The recent FDA approval of sotorasib, a direct pharmacological inhibitor of KRASG12C, marks a critical milestone in the treatment of this important subset of lung cancer. However, a major obstacle in treating lung cancer is resistance to current therapeutic treatments. In response to cellular stresses such as RAS pathway-targeted therapeutics, RAS-mutated cancer cells have been demonstrated to increase autophagy, an intracellular recycling pathway. However, the mechanism(s) underlying treatment-induced autophagy is not well understood. Here, we demonstrate that KRASG12C-driven lung cancer cells increase autophagy in response to treatment with sotorasib. Currently, the only therapeutics in clinical use to inhibit autophagy are lysosomal inhibitors (hydroxy)chloroquine. High concentrations of these compounds are needed to achieve modest inhibition of autophagy, suggesting that the potency of these compounds may limit clinical responses. ULK kinases are serine/threonine kinases that are necessary for the initiation of autophagy. DCC-3116 is a potent inhibitor of the ULK1/2 protein kinases, master regulators of autophagy. Treatment with sotorasib and DCC-3116 led to superior anti-tumor effects in preclinical models of lung cancer. Additionally, about 30% of lung cancer patients with KRAS mutations also have deletions or inactivating mutations in LKB1, a protein involved in the regulation of nutrient sensing and autophagy. In other KRAS-driven cancers, the LKB1-AMPK-ULK1 signaling axis is a proposed mechanism as to how autophagic flux increases following KRAS pathway inhibition. However, our preliminary data demonstrates that LKB1 is dispensable for sotorasib-induced autophagy, suggesting the mechanism(s) of autophagy induction in KRASG12C-driven lung cancer may be different from those detected in other KRAS mutated cancers. Consequently, we have generated genetically engineered mouse models (GEMMs) of KRASG12C-driven lung cancer in which LKB1 is silenced to further investigate the role of LKB1 in the autophagy response of KRASG12C-driven lung cancers to pathway-targeted blockade of oncogenic KRAS signaling. We have treated KRASG12C-driven GEMMs with sotorasib and/or DCC-3116 to test the sensitivity of lung tumors to these treatment options. Citation Format: Phaedra Ghazi, Kayla O'Toole, Sanjana Boggaram, Michael Scherzer, Madhumita Bogdan, Bryan Smith, Dan Flynn, Conan Kinsey, Martin McMahon. Inhibition of ULK and KRASG12C control tumor growth in preclinical models of lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4322.

Abstract 6491: Epigenetic-based combinatorial therapy is synergistic in KRAS/LKB1 mutant non-small cell lung cancers

Abstract KRAS and LKB1 mutations (KL) in non-small cell lung cancer (NSCLC) patients often results in poor prognosis, a high tumor mutational burden, and resistance to conventional therapy. The metabolic changes with these mutations can create unique vulnerabilities to be targeted therapeutically. HDAC inhibition has been reported as a promising approach to overcome MEK inhibitor resistance in animal models of melanoma, pancreatic cancer, and KL mutant NSCLC. Inhibition of HDAC3 and HDAC6 have independently been shown to have therapeutic activity in KL NSCLC. We now report on the activity of two novel HDAC3/6 inhibitors in cell culture and mouse models of human KL (A549) compared to KRAS/TP53-mutant NSCLC (KP) (CALU-6) alone and individually combined with the MEK inhibitor trametinib. GB-1101 inhibits HDAC3 and HDAC6 and GB-3103 inhibits HDAC1,3,6,10. SynergyFinder multi-dose combination data analytics showed synergistic interactions for both GB-1101 or GB-3103 when combined with trametinib in KL mutant A549 cells with maximum synergy scores of δ = 9.24 and 4.21, using zero interaction potency (ZIP) for synergy scoring. GB-1101 or GB-3103 when combined with trametinib in KP mutant CALU-6 cells did not demonstrate synergistic interaction with synergy scores of δ = -1.58 and -0.53, respectively. Mice were inoculated subcutaneously with 5.0x106 A549 or CALU-6 cells and treatment with GB-1101 (75 mg/kg qd, oral), GB-3103 (5.0 mg/kg qd, subcutaneous), trametinib (1.0 mg/kg qd, oral) and each drug in combination with trametinib was initiated when tumors reached an average of 120mm3. Single agent and combination treatments were well tolerated. GB-1101 exhibited tumor growth inhibition (TGI) of 33.0% in the A549 (KL) compared to 8.5% in CALU-6 (KP). In combination with trametinib, GB-1101 showed increased activity (TGI=92.7%) compared to trametinib alone (TGI=69.5%) in KL mutant A549. In KP mutant CALU-6 tumors, combination benefit was not observed; combination of GB-1101 and trametinib yielded a TGI=93% equivalent to trametinib alone (TGI=91%). GB-3103 resulted in a TGI of 66.7% in the KL mutant A549 and TGI= 55.9% in KP mutant CALU-6. In KL mutant A549, GB-3103 in combination with trametinib, showed increased inhibition (TGI=94.3%) compared to trametinib alone (TGI=69.5%). No combination benefit was seen for GB-3103 in KP mutant CALU-6 with the combination treatment TGI of 93.1% compared to trametinib alone TGI=90.7%. These results confirm and extend the finding that for KL mutant NSCLC, HDAC3/6 inhibitors show therapeutic benefit in combination with trametinib that is not observed in KP tumors. These data reveal a promising epigenetic-based combinatorial strategy for treating lung cancers harboring concurrent KRAS/LKB1 mutations, a path for clinical translation, and the potential to improve treatments for KRAS/LKB1 mutant NSCLC patients where there are currently no robust therapeutic strategies. Citation Format: Matthew Zucker, Kendra Devore, Logan Chesney, Gregg Hirschfeld, Annissa Reyna, Betsy Linnane, Joseph Mascarenhas, Maggie Murray, Alan Miller, Paul Gonzales, Stephen Gately. Epigenetic-based combinatorial therapy is synergistic in KRAS/LKB1 mutant non-small cell lung cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6491.

Abstract 5829: Elucidating the significance of amphiregulin and its implications for EGFR inhibition strategies in LKB1-mutant NSCLC

Abstract LKB1-mutant non-small cell lung cancer (NSCLC) is aggressive and treatment-refractory, underscoring the need for new therapeutic strategies. Our comparative study involving mouse lung tumors driven by oncogenic KrasG12D and LKB1 loss as well as tumors driven solely by KrasG12D, revealed that LKB1 loss upregulated amphiregulin (Areg), a pro-growth EGFR ligand. Therefore, this study investigates how the inactivation of LKB1 enhances AREG expression, the significance of elevated AREG in sustaining lung cancer growth, and the responses of AREG-high lung cancer to EGFR inhibitors. We first evaluated the potential clinical significance of AREG using The Cancer Genome Atlas (TCGA) lung adenocarcinoma dataset and the Cancer Cell Line Encyclopedia (CCLE) database. We observed that LKB1-null tumors with high AREG levels were associated with shorter patient survival and exhibited transcriptional signatures similar to EGFR-mutant tumors. High AREG expression also correlated positively in NSCLC cell lines with LKB1 mutations and Western blot analysis confirmed that elevated AREG levels in lung cancer cells were associated with constitutive EGFR signaling. We next explored the impact of LKB1 loss on AREG expression in lung cancer. Our prior RNA-seq and ChIP-seq investigations demonstrated CRTC2 and CREB enrichment on the AREG promoter in LKB1-null lung cancer cells. Upon LKB1 reintroduction, the enrichment diminished, indicating that CRTC-CREB transcriptionally induces AREG in LKB1-null lung cancer. To corroborate, reintroducing LKB1 or expressing a dominant-negative construct (dnCRTC), disrupting CREB/CRTC interaction, decreased AREG levels, as confirmed by RT-qPCR in LKB1-null lung cancer cells. This supports that AREG is a direct target of CRTC-CREB activation induced by LKB1 loss. To assess the impact of elevated AREG in LKB1-mutant lung cancer growth, we used RNA interference and antibodies to inhibit AREG. Both interventions decreased cell growth and colony formation, underscoring AREG is critical for LKB1-mutant lung cancer growth. Moreover, we investigated the potential correlation between AREG and the response to the EGFR tyrosine-kinase inhibitor Erlotinib in NSCLC cell lines, utilizing AREG expression data from CCLE and Erlotinib response data from the Genomics of Drug Sensitivity in Cancer (CDSC) databases. Stratifying NSCLC cell lines into sensitive, intermediate, and resistant categories revealed a potential positive association between AREG expression and Erlotinib sensitivity. Notably, LKB1-null lung cell lines with high AREG expression demonstrated heightened sensitivity compared to those with low AREG expression. Our study revealed that LKB1 loss increases AREG, triggering aberrant EGFR signaling critical for lung cancer growth, and AREG expression might impact the Erlotinib response in LKB1-inactive cells. Citation Format: Xzaviar Kaymar Solone, Xin Zhou, Mu Yu, Jennifer W. Li, Finn Rimay, Frederic Kaye, Lizi Wu. Elucidating the significance of amphiregulin and its implications for EGFR inhibition strategies in LKB1-mutant NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5829.

Abstract 4047: Unraveling synergistic therapeutic strategies involving FAK inhibition and immunotherapy using anti-PD1 antibody in KRAS and LKB1-driven lung cancer

Abstract Lung cancer presents a global health challenge demanding innovative preclinical models forresearch and therapeutic advancement. Genetically engineered mouse models (GEMMs) have seenremarkable growth in complexity and application over the past two decades. Our work leveragesthese models and is specifically designed to address the pressing need for effectiveimmunochemotherapies in the context of KRAS and LKB1 (KL) mutant lung adenocarcinoma,which shows resistance to most immunotherapies. Our study centers around a preclinicalsyngeneic orthotopic mouse model we developed using mouse lung and metastatic tumor cell linesderived from KL-GEMM. This model, optimized to mimic human lung cancer closely, providesan ideal platform for exploring the intricate interplay between the immune system and tumorprogression. Furthermore, we have previously shown the LKB1 mutant cell lines and tumormodels are uniquely sensitive to FAK inhibitors, and therefore we wanted to test whether thecombination of a FAK inhibitor with anti-PD1 therapy can improve sensitivity. The combinatoryadministration of FAK inhibitor (VS-6063) with anti-PD1 mAb synergistically increased anti-tumor response and survival outcome compared with single-agent therapy in the KL-mediatedsyngeneic orthotopic lung cancer model. By using GEMM-derived syngeneic cell lines, we haveevaluated the potential for creating innovative immunochemotherapies, customized for KL co-mutant lung adenocarcinomas with promising clinical potential. Furthermore, using this modelenables a deeper understanding of the KL mutant disease's pathogenesis, the impact of sex-biasedcancer development, and the assessment of novel immunochemotherapy treatment strategies in theKL genetic sub-type of lung adenocarcinoma. Citation Format: Junghui Koo, Carol Tucker-Burden, Melissa Roy, Chunzi Huang, Wei Zhou, Melissa Gilbert-Ross, Haian Fu, Suresh S. Ramalingam, Adam I. Marcus. Unraveling synergistic therapeutic strategies involving FAK inhibition and immunotherapy using anti-PD1 antibody in KRAS and LKB1-driven lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4047.

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-deficientKRASG12C 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.

Abstract PR03: Cooperative anti-tumor effects of combined inhibition of KRASG12C plus autophagy in preclinical models of KRASG12C-driven lung cancer

Abstract Approximately 25% of lung cancers are driven by mutationally-activated KRAS. A major obstacle in treating lung cancer is resistance to current therapeutic treatments. The recent FDA approval of sotorasib, a direct pharmacological inhibitor of KRASG12C, marks a critical milestone in the treatment of this important subset of lung cancer. However, the twin problems of primary or acquired resistance to direct pharmacological inhibition of KRASG12C remain major obstacles in sustaining the deepest and most durable patient responses. In response to cellular stresses such as RAS pathway-targeted therapeutics, RAS-mutated cancer cells have been demonstrated to increase autophagy, an intracellular recycling pathway. Moreover, combined inhibition of RAS pathway signaling plus autophagy had potent anti-tumor effects in preclinical models of melanoma or pancreatic cancer. However, the mechanism(s) underlying treatment-induced autophagy is not well understood. Here, we demonstrate that KRASG12C-driven lung cancer cells increase autophagic flux in response to treatment with KRASG12C inhibitors. Moreover, combined treatment of such cells with a specific, selective and potent inhibitor of the ULK1/2 protein kinases, master regulators of autophagy, led to superior anti-tumor effects in human cell line xenograft models. Previous work to understand why inhibiting autophagy sensitizes KRAS mutant cancer cells to targeted therapy has been confounded by the use of non-specific lysosomal inhibitors such as hydroxychloroquine. Using selective autophagy inhibitors, such as ULK1/2i, provides a unique opportunity to investigate the precise mechanism as to why inhibition of autophagy sensitizes cells to KRASG12C inhibition. Additionally, about 30% of lung cancer patients with KRAS mutations also have deletions or inactivating mutations in LKB1, a protein involved in regulation of nutrient sensing and autophagy. Patients with KRAS-mutated lung cancer whose tumors also lack LKB1 expression are characterized by aggressive behavior and resistance to standard treatment. In other KRAS-driven cancers, the LKB1>AMPK>ULK1 signaling axis is a proposed mechanism as to how autophagic flux increases following KRAS pathway inhibition. However, our preliminary data suggests that LKB1 is dispensable for sotorasib-induced autophagy in KRASG12C-driven lung cancer cells. To this end, KRASG12C-driven lung cancer cell lines with loss of LKB1 expression significantly increased autophagic flux after treatment with either a KRASG12C inhibitor or inhibitors of RAF>MEK>ERK signaling suggesting that the mechanism(s) of autophagy induction in KRASG12C-driven may be different to those detected in other KRAS mutated cancers. Consequently, we have generated new genetically engineered mouse models of KRASG12C-driven lung cancer in which LKB1 is silenced to further investigate the role of LKB1 in the autophagy response of KRASG12C-driven lung cancers to pathway-targeted blockade of oncogenic KRAS signaling. Citation Format: Phaedra C. Ghazi, Conan Kinsey, Madhumita Bogdan, Bryan D. Smith, Daniel L. Flynn, Martin McMahon. Cooperative anti-tumor effects of combined inhibition of KRASG12C plus autophagy in preclinical models of KRASG12C-driven lung cancer [abstract]. In: Proceedings of the AACR Special Conference: Targeting RAS; 2023 Mar 5-8; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Res 2023;21(5_Suppl):Abstract nr PR03.

Abstract 16: The role of innate and adaptive immunity in the sex bias of LKB1-mutant lung adenocarcinoma

Abstract The tumor suppressor gene, LKB1/STK11, is one of the most frequently mutated genes in lung adenocarcinoma (LUAD). A multidimensional analysis of TCGA-LUAD patient data indicates that LKB1 mutation is one of the top sex-biased mutations, being more frequent in males than in females. A similar pattern was observed in other large LUAD cohorts. However, the underlying mechanism was unknown, partially due to a lack of an appropriate mouse model to represent this clinical phenomenon. We previously demonstrated a similar sex bias in a Lenti-Cre-induced KRAS/LKB1-mutant genetically engineered mouse model (GEMM) and a syngeneic tail-vein injection model. Here, we demonstrated that intravenous injection of the same cell line in male and female NOD scid gamma (NSG) mice does not exhibit a sex-bias pattern of lung metastasis formation (P=0.9746). However, sex bias was observed when we used CB17-SCID mice. This data suggest that innate immunity is partly responsible for the sex bias of LKB1-mutant lung cancer formation. We also characterized immune cells from the lung with LKB1-mutant tumors. Monocytes/macrophages decreased from 23% to 19%, and neutrophils increased from 15% to 19%. Lymphoid cells remained the same at 58%, and T-cells account for 34% of all CD45+ cells. Interestingly, T-cells doubled to account for 81% of all CD45+ cells from the lung in female mice resistant to the formation of lung metastasis. Our data indicated that both the innate and the adaptive immunity are responsible for eliminating LKB1-mutant lung adenocarcinoma in female mice. Citation Format: Yijian Fan, Lenore Monterroza, Rui Jin, Xiuju Liu, Periasamy Selvaraj, Rabindra Tirouvanziam, Wei Zhou. The role of innate and adaptive immunity in the sex bias of LKB1-mutant lung adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 16.

Abstract 271: MYC mediates enhanced lactate reutilization and resistance to anti-angiogenesis therapy in preclinical models of LKB1-deficient NSCLC

Abstract Deletion or loss of function mutations of the STK11/LKB1 tumor suppressor are associated with primary resistance to immunotherapy in KRAS-mutant lung adenocarcinoma (LUAD) and drive metabolic reprogramming of tumor cells. We observed that LKB1-deficient tumors were resistant to anti-angiogenic therapy in the hypoxic and nutrient-depleted or acidic tumor microenvironment (TME). We determined that MYC which is elevated in LKB1-deficient cells, regulated the expression of the lactate transporter, MCT4. Moreover, knockdown of MYC decreases glycolysis and cell proliferation. Therefore, we hypothesize that metabolic changes in LKB1-deficient tumor cells is at least partially driven by MYC upregulation, and that depletion of MYC or targeting of key enzymes or transporters downstream of MYC such as MCT4 may abrogate lactate reutilization and sensitize LKB1-deficient tumors to anti-angiogenic therapy. To explore the impact of MYC on lactate metabolism in LKB1-deficient NSCLC cells, we performed isotope tracing in KRAS mutant (K) and KRAS mutant LKB1 knockout (KL) syngeneic murine lung cancer cells. 13C3-lactate tracing revealed that isotopologues were significantly enriched in TCA components such as pyruvate, citrate and a-ketoglutarate in KL cells. Meanwhile, lactate-treated KL cells shows less reactive oxygen species (ROS), suggesting that LKB1-deficient tumor cells reutilize lactate as an energy source more efficiently than LKB1-intact cells. MCT4 KO significantly abrogated lactate incorporation into TCA cycle. Similarly, MYC knockdown or MCT4 KO decreased lactate-induced oxygen consumption, but increased ROS levels. In contrast, exhausted T cells were inefficient at lactate reutilization, and high levels of lactate increased ROS in T cells. Hence, LKB1-deficient tumors have a survival advantage over T cells in the lactate-rich TME. We queried scRNAseq data from K, KL and KL MCT4KO syngeneic models and similarly observed that KL tumor cells exhibited elevated hypoxia and angiogenesis gene expression signatures, which was reversed by MCT4 KO. However, ROS detoxification was decreased in T cells from KL tumors but increased in MCT4 KO tumors. Finally, we injected KL murine tumor cells into immunocompetent mice, and randomly treated them with vehicle or the VEGF blocking antibody, DC101. MYC knockdown or MCT4 KO sensitized KL tumors to VEGF inhibition, and significantly increased overall survival. Collectively, our data indicates that in LKB1-deficient tumors, upregulation of MYC promotes tumor cell metabolic reprogramming and that targeting MYC or MCT4 can inhibit lactate reutilization and enhance the efficacy of anti-angiogenic agents. These findings provide insight into the mechanisms driving the aggressive phenotype of KRAS-mutant LKB1-deficient tumors and identify a novel therapeutic strategy for targeting this patient population. Citation Format: Yu Qian, David Molkentine, Chendong Yang, Ana Galan Cobo, Irene Guijarro, Minghao Dang, Alissa Poteete, Peixin Jiang, Ferdinandos Skoulidis, Linghua Wang, Alexandre Reuben, John D. Minna, Ralph J. DeBerardinis, John V. Heymach. MYC mediates enhanced lactate reutilization and resistance to anti-angiogenesis therapy in preclinical models of LKB1-deficient NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 271.

Glucocorticoid mediated inhibition of LKB1 mutant non-small cell lung cancers.

The glucocorticoid receptor (GR) is an important anti-cancer target in lymphoid cancers but has been understudied in solid tumors like lung cancer, although glucocorticoids are often given with chemotherapy regimens to mitigate side effects. Here, we identify a dexamethasone-GR mediated anti-cancer response in a subset of aggressive non-small cell lung cancers (NSCLCs) that harbor Serine/Threonine Kinase 11 (STK11/LKB1) mutations. High tumor expression of carbamoyl phosphate synthase 1 (CPS1) was strongly linked to the presence of LKB1 mutations, was the best predictor of NSCLC dexamethasone (DEX) sensitivity (p < 10-16) but was not mechanistically involved in DEX sensitivity. Subcutaneous, orthotopic and metastatic NSCLC xenografts, biomarker-selected, STK11/LKB1 mutant patient derived xenografts, and genetically engineered mouse models with KRAS/LKB1 mutant lung adenocarcinomas all showed marked in vivo anti-tumor responses with the glucocorticoid dexamethasone as a single agent or in combination with cisplatin. Mechanistically, GR activation triggers G1/S cell cycle arrest in LKB1 mutant NSCLCs by inducing the expression of the cyclin-dependent kinase inhibitor, CDKN1C/p57(Kip2). All findings were confirmed with functional genomic experiments including CRISPR knockouts and exogenous expression. Importantly, DEX-GR mediated cell cycle arrest did not interfere with NSCLC radiotherapy, or platinum response in vitro or with platinum response in vivo. While DEX induced LKB1 mutant NSCLCs in vitro exhibit markers of cellular senescence and demonstrate impaired migration, in vivo DEX treatment of a patient derived xenograft (PDX) STK11/LKB1 mutant model resulted in expression of apoptosis markers. These findings identify a previously unknown GR mediated therapeutic vulnerability in STK11/LKB1 mutant NSCLCs caused by induction of p57(Kip2) expression with both STK11 mutation and high expression of CPS1 as precision medicine biomarkers of this vulnerability.

Histone Deacetylase 6 Inhibition Exploits Selective Metabolic Vulnerabilities in LKB1 Mutant, KRAS Driven NSCLC

IntroductionIn KRAS-mutant NSCLC, co-occurring alterations in LKB1 confer a negative prognosis compared with other mutations such as TP53. LKB1 is a tumor suppressor that coordinates several signaling pathways in response to energetic stress. Our recent work on pharmacologic and genetic inhibition of histone deacetylase 6 (HDAC6) revealed the impaired activity of numerous enzymes involved in glycolysis. On the basis of these previous findings, we explored the therapeutic window for HDAC6 inhibition in metabolically-active KRAS-mutant lung tumors. MethodsUsing cell lines derived from mouse autochthonous tumors bearing the KRAS/LKB1 (KL) and KRAS/TP53 mutant genotypes to control for confounding germline and somatic mutations in human models, we characterize the metabolic phenotypes at baseline and in response to HDAC6 inhibition. The impact of HDAC6 inhibition was measured on cancer cell growth in vitro and on tumor growth in vivo. ResultsSurprisingly, KL-mutant cells revealed reduced levels of redox-sensitive cofactors at baseline. This is associated with increased sensitivity to pharmacologic HDAC6 inhibition with ACY-1215 and blunted ability to increase compensatory metabolism and buffer oxidative stress. Seeking synergistic metabolic combination treatments, we found enhanced cell killing and antitumor efficacy with glutaminase inhibition in KL lung cancer models in vitro and in vivo. ConclusionsExploring the differential metabolism of KL and KRAS/TP53-mutant NSCLC, we identified decreased metabolic reserve in KL-mutant tumors. HDAC6 inhibition exploited a therapeutic window in KL NSCLC on the basis of a diminished ability to compensate for impaired glycolysis, nominating a novel strategy for the treatment of KRAS-mutant NSCLC with co-occurring LKB1 mutations.

Development of an adenosquamous carcinoma histopathology - selective lung metastasis model.

Preclinical tumor models with native tissue microenvironments provide essential tools to understand how heterogeneous tumor phenotypes relate to drug response. Here we present syngeneic graft models of aggressive, metastasis-prone histopathology-specific NSCLC tumor types driven by KRAS mutation and loss of LKB1 (KL): adenosquamous carcinoma (ASC) and adenocarcinoma (AC). We show that subcutaneous injection of primary KL; ASC cells results in squamous cell carcinoma (SCC) tumors with high levels of stromal infiltrates, lacking the source heterogeneous histotype. Despite forming subcutaneous tumors, intravenously injected KL;AC cells were unable to form lung tumors. In contrast, intravenous injection of KL;ASC cells leads to their lung re-colonization and lesions recapitulating the mixed AC and SCC histopathology, tumor immune suppressive microenvironment and oncogenic signaling profile of source tumors, demonstrating histopathology-selective phenotypic dominance over genetic drivers. Pan-ERBB inhibition increased survival, while selective ERBB1/EGFR inhibition did not, suggesting a role of the ERBB network crosstalk in resistance to ERBB1/EGFR. This immunocompetent NSCLC lung colonization model hence phenocopies key properties of the metastasis-prone ASC histopathology, and serves as a preclinical model to dissect therapy responses and metastasis-associated processes.

1056P KRAS and LKB1 mutation conferring prognostic and predictive role on liquid biopsy in advanced NSCLC

Liquid biopsy (LB) is a feasible tool able to detect genomic alterations in cancer at baseline and also as a longitudinal monitoring to identify resistance mutations. In patients (pts) with mNSCLC, when tissue biopsy remains a difficult procedure, LB might be crucial for therapeutical options, especially in the immunotherapy (IO) and target therapy era. The aim of this bicentric study is to assess the prognostic value of LB in mNSCLC. Data from mNSCLC with any gene alteration/PD-L1 expression were collected at Istituto Nazionale Tumori of Milan and Policlinico Universitario of Naples. Liquid biopsy was performed by 73-gene Guardant360® CDx / 29-gene Archer® LiquidPlex™panels. Effects of circulating genomic alterations on Overall Survival (OS) (from 4-stage diagnosis to death/last FUP) were assessed using Cox proportional hazard model cell free. Kaplan-Meier curves were performed to assess OS between IO and non-IO treatments arms. Of 488 pts underwent LB, most were male (56.9%), former smoker (46.3%), with adenocarcinoma (73.6%) and PD-L1 > 1% (55.6%). 301/488 patients (62.6%) were treated with IO alone or in combination with chemotherapy, in first (47.0%) or second line (102 – 29.2%). In 133 (32.1%) cases, LB was performed at IO baseline, while in 101 (24.5%) cases at IO progression. Among the most relevant genes, STK11+/LKB1+ confers the worst OS (HR for OS 2.12 months, CI 95% 1.26 – 3.56; p = 0.005), regardless treatments. LKB1+/KRAS+ have a poorer OS than LKB1-/KRAS- (OS: 13 vs 24 m, HR 2.34 95% IC 1.19 – 4.61) and LKB1-/KRAS+ (OS: 13 vs 34 m HR 2.99 95% IC 1.36-6.54). When analyzing the effect of KRAS on IO and non-IO arms, KRAS-/IO have the best prognosis compared to KRAS+/non-IO which have the worst prognosis, while KRAS+/IO seems to have a similar prognosis to KRAS-/non-IO pts (HR 0.82 95% IC 0.43 – 1.58). Results reported on LB confirmed previous reports on tissue: STK11+ pts, have the worst prognosis regardless treatments. KRAS+ compare to STK11+/KRAS+ pts and STK11-/KRAS- pts seems to have the best prognosis. IO seems to play a relevant role on survival regardless KRAS status, in fact when using IO the negative prognostic effect of KRAS+ pts decreases and becomes similar to KRAS-/non-IO pts.

PTEN and LKB1 are differentially required in Gli1-expressing mesenchymal cells to suppress gastrointestinal polyposis.

PTEN and LKB1 are intimately associated with gastrointestinal tumorigenesis. Mutations of PTEN or LKB1 lead to Cowden syndrome and Peutz-Jeghers syndrome characterized by development of gastrointestinal polyps. However, the cells of origin of these polyps and underlying mechanism remain unclear. Here, we reveal that PTEN or LKB1 deficiency in Gli1+ gut mesenchymal cells, but not intestinal epithelium, drives polyp formation histologically resembling polyposis in human patients. Mechanistically, although PTEN and LKB1 converge to regulate mTOR/AKT signaling in various tumor contexts, we find that mTOR is essential for PTEN-deletion-induced polyp formation but is largely dispensable for polyposis induced by mesenchymal LKB1 deficiency. Altogether, our studies identify Gli1-expressing mesenchymal cells as a common cell of origin for polyposis associated with PTEN and LKB1 and reveal their engagement of different downstream pathways in gut mesenchyme to suppress gastrointestinal tumorigenesis.

Abstract 2160: MCT4 blockade reverses lactate-mediated immunosuppression in LKB1-deficient NSCLC

Abstract Genomic alterations that result in loss of function of the tumor suppressor serine/threonine kinase STK11/LKB1 occur in 20-30% of lung adenocarcinomas. We previously observed that STK11/LKB1 mutations are genomic drivers of primary resistance in lung adenocarcinoma. Moreover, LKB1-mutant NSCLCs exhibit higher hypoxia and glycolysis rates, resulting in enhanced production and secretion of lactate. Accordingly, we hypothesize that high production of lactate of LKB1 mutant tumor may contribute to its immunologically cold phenotype and that blockade of the lactate pathway may potentiate the efficacy of immune checkpoint blockade (ICB) therapies. We characterized the immune landscape of LKB1 mutant clinical samples and performed scRNAseq analysis in KRAS mutant (K) and KRAS mutant LKB1 knockout (KL) syngeneic murine models. To evaluate inhibition of lactate metabolism as a therapeutic strategy, we knocked out the lactate transporter SLC16A3/MCT4 and characterized the impact on the tumor microenvironment (TME), and response to ICB. Clinical analysis of LKB1 mutant NSCLC patients from the MD Anderson’s ICON and PROSPECT cohorts suggested that LKB1 mutant tumors showed reduced immune cell infiltration, restricted T cell function, and enhanced M2-like macrophages phenotypes. Moreover, in preclinical models, LKB1 mutant tumors showed enhanced glycolysis and upregulation of MCT4 expression in a variety of human and murine cell lines. Deletion of MCT4 dramatically reduced glycolysis, energy production, and cell proliferation. By scRNAseq, we identified distinct immune subclusters modulated by LKB1 mutation. Hypofunctional T cells and M2-like macrophages were abundant in LKB1 mutant tumors, while these populations were significantly reduced in KL tumors with MCT4 KO. The conditioned medium from KL cells impaired T cell activation and decreased T cell killing, IFNγ production and glycolysis rate. Moreover, conditioned medium from KL cells induced M2-associated genes expression, as well as CD206+ expression in both peritoneal macrophages and Raw264.7 cells. These effects were at least in part MCT-dependent, as medium from MCT4 KO cells induced the opposite effects on T cells and macrophages, and the effects could be reversed by introducing exogenous lactate, suggesting that blockade of lactate transport reactivated T cells and reversed M2 polarization. Importantly, MCT4 KO in LKB1-mutant tumors sensitized tumors to anti-PD1 immunotherapy in syngeneic murine tumors and promoted long-term anti-tumor immunity. Collectively, our data indicate that LKB1 mutant tumors enhanced lactate secretion into the TME and this results in decreased T cell cytotoxic potential as well as higher pro-tumor M2 polarization, leading to resistance to immunotherapy. These data suggest that therapeutic inhibition of MCT4 is a promising strategy to overcome immunotherapy resistance in NSCLC patients harboring LKB1 mutant tumors. Citation Format: Yu Qian, Irene Guijarro, Ana Galan-Cobo, Minghao Dang, Alissa Poteete, Fahao Zhang, Qi Wang, Jing Wang, Edwin Parra, Ferdinandos Skoulidis, Ignacio Wistuba, Svena Verma, Taha Merghoub, Linghua Wang, Jedd Wolchok, Alexandre Reuben, John Heymach. MCT4 blockade reverses lactate-mediated immunosuppression in LKB1-deficient NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2160.

Abstract 3276: Overcoming immune checkpoint blockade resistance via EZH1/2 dual inhibition by HM97662 in KRAS/LKB1 mutated NSCLC

Abstract Immune checkpoint blockades (ICBs) are known as a promising treatment option against in advanced non-small-cell lung cancer (NSCLC). And KRAS is the most frequently mutated oncogene in NSCLC. However, KRAS mutation is not a significantly associated with survival benefit of ICBs. Mutations in LKB1 (aka STK11) and frequently co-occurring KRAS mutations are accompanied with poor survival in metastatic NSCLC immuno-oncology trials. Even tumor mutational burden is a proposed-potential biomarker for response to ICBs, there are therapeutic unmet needs in NSCLC patient with KRAS/LKB1 (KL) mutation. Epigenetic regulation lead to enhanced anti-tumor immunity of innate immune responses via inducing type I interferons. Also it drives to enhance adaptive immune responses by targeting T cell recognition factors as well as recruitment immune cells to tumor microenvironments (TMEs). Thus, we demonstrated the pharmacological inhibition of Enhancer of zeste homolog (EZH)1/2 enhance the efficacy of clinically available immunotherapies in KRAS/LKB1 mutated NSCLC. Previously, we reported that a novel EZH1/2 dual inhibitor, HM97662, has showed potently decreased global H3K27me3 and strong anti-proliferative activities against various hematological cancer cell lines with EZH2 activating mutations as well as solid tumor cell lines with negatively mutated components of regulatory protein complexes. In this study, we evaluated that HM97662 could induce of STING expression and STING-dependent cytokine production in KL mutant NSCLC cell lines. Furthermore, we explored anticancer effect by inducing immune modulation by EZH2 inhibitors in combination with an anti-PD-(L)1 agent was evaluated. As a result, HM97662 potently restored STING expression in KL mutated cell lines such as A549 and H460, but did not KRAS/p53 (KP) mutated H358 cells. HM97662 also dose-dependently increased the mRNA expression of CXCL10, IFN-α and IFN-β and secretion of CXCL10, IFN-α, CCL2, CCL3 and CCL5 at nanomolar concentrations in H460 cells. In accordance with this, HM97662 showed potent growth inhibition against H460 cells under co-culture condition with activated T cells. Moreover, HM97662 had superior anti-proliferation efficacy among the tested compounds in H460 cells with activated T cells, when it combined with anti-PD-L1 antibody avelumab. In our exploratory study, HM97662 increments the sensitivity of immune checkpoint inhibitor by restoration of STING expression and STING pathway related chemo/cytokine production in KRAS/LKB1 mutated NSCLC cell lines. These results demonstrate that HM97662 drives anti-cancer effect by immune modulation in combination with anti-PD-(L)1 agent, suggesting therapeutic potency to combination with ICBs by turning non-inflamed to inflamed TME. Clinical trials to prove the effectiveness of HM97662 identified in preclinical studies need to be carried out immediately. Citation Format: Jooyun Byun, DongJin Hong, Miyoung Lee, Soonho Kweon, Seung Hyun Jung, Yu-Yon Kim, Hyunjin Park, Junghwa Park, Young Gil Ahn, Young Hoon Kim, Kwee Hyun Suh. Overcoming immune checkpoint blockade resistance via EZH1/2 dual inhibition by HM97662 in KRAS/LKB1 mutated NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3276.