KRAS-mutant Cancer Research Articles

Translational modeling for patients with RAS mutant tumors: Profiling the dual-MEK inhibitor IMM-1-104 in a humanized 3D assay.

e15084 Background: Elevated RAS-RAF-MEK-ERK (MAPK pathway) signaling is observed in over half of all solid human tumors, and mutations in RAS or RAF account for a large fraction. Given MEK’s unique position in the MAPK cascade, it remains an attractive target in cancer. However, FDA-registered MEK inhibitors are susceptible to pathway reactivation events that limit their use to RAF mutant disease and cause on-target toxicities stemming from chronic target engagement. IMM-1-104 is a novel, allosteric dual-MEK inhibitor designed for better applicability to RAS mutant tumors by preventing MEK reactivation. Endowed with a short plasma half-life, IMM-1-104 promotes deep cyclic inhibition with a near-zero drug trough, affording normal cells a chance to recover between doses. Methods: We characterized IMM-1-104’s pharmacologic activity across 52 tumor cell lines that spanned 11 distinct tumor types in a humanized, ECM-based 3D tumor growth assay (3D-TGA). The 3D-TGA has better predicted in vivo tumor responses versus 2D culture and more accurately reflects human tumor biology. Tumor models were categorized based on in vivo drug PK limits as sensitive to IMM-1-104 (EC50 < 1uM), intermediate (1uM≤EC50≤10uM and ≥25% inhibition at 10uM) or resistant otherwise. Models were evaluated by whole exome sequencing, along with RNA sequencing in the 3D context, to profile determinants of sensitivity and resistance and to prioritize patient populations most likely to respond to IMM-1-104. Results: Models sensitive to IMM-1-104 were enriched for MAPK driver mutations, consistent with pathway addiction. We reasoned that activation of parallel compensatory pathways that can reduce reliance on MAPK signaling may increase the likelihood of resistance to IMM-1-104. Pathways and genes suspected of contributing to resistance helped refine signatures based on 3D-TGA outcome data. Models with a MAPK driver mutation and compensatory mutations such as PIK3CA or PTEN deletion were more likely to show intermediate response than those with a greater addiction to MAPK drivers. Models lacking a clear MAPK driver mutation but harboring other putative resistance alterations were more likely to be resistant in the 3D-TGA. Conclusions: To better understand the relevance of tumor model responses in the 3D-TGA relative to RAS mutant patient populations, we computationally compared tumor model data to patient somatic alterations, identified in the public resource GENIE, which has cataloged the molecular profiles of over 100,000 cancer patients. Based on model-to-patient molecular mapping, we identified biomarker-defined subsets of sensitive KRAS mutant lung and colorectal models. The most broadly sensitive patient-aligned models in the 3D assay were KRAS mutant pancreatic cancer and NRAS mutant melanoma patients, supporting the inclusion of such patients in planned clinical studies of IMM-1-104.

Penipentenone A and brefeldin A derivatives potently inhibit KRAS mutant cancer cells from an endophytic fungus Penicillium brefeldianum F4a

Kirsten rat sarcoma viral oncogene homolog (KRAS) mutation is one of the most important carcinogenic factors in many solid tumors, which leads to the poor prognosis and therapy resistance of cancer. In order to develop direct or indirect KRAS inhibitors, one unique asymmetric dicyclopentenone penipentenone A, three undescribed brefeldin A (BFA) derivatives, and five known BFA derivatives were discovered from the endophytic fungus Penicillium brefeldianum guided by LC-MS/MS and cytotoxic activities. Their structures were elucidated by optical rotation, mass spectrometry, and NMR spectroscopic data. The absolute configurations of four undescribed compounds were elucidated by comparison of the experimental and calculated ECD spectra. The antiproliferative activities of obtained compounds against three KRAS mutant tumor cell lines and two BFA derivative-sensitive cell lines were evaluated. Besides 4-epi-15-epi-brefeldin A, the other compounds showed significant inhibitory activities against those tumor cell lines with IC50 values ranging from 0.82 to 18.87 μM. Intriguingly, penipentenone A selectively inhibited KRAS mutant cancer cells SW620 (KRASG12V) and ASPC-1 (KRASG12D). BFA and four derivatives showed potent cytotoxic activities against all selected tumor cell lines H358 (KRASG12C), SW620 (KRASG12V), ASPC-1 (KRASG12D), PC-3, and HepG-2. These findings will provide undescribed lead compounds for developing drugs that target KRAS mutations.

Myoferlin targeting triggers mitophagy and primes ferroptosis in pancreatic cancer cells

Myoferlin, an emerging oncoprotein, has been associated with a low survival in several cancer types including pancreas ductal adenocarcinoma where it controls mitochondria structure and respiratory functions. Owing to the high susceptibility of KRAS-mutated cancer cells to iron-dependent cell death, ferroptosis, and to the high iron content in mitochondria, we investigated the relation existing between mitochondrial integrity and iron-dependent cell death. We discovered that myoferlin targeting with WJ460 pharmacological compound triggered mitophagy and ROS accumulation culminating with lipid peroxidation and apoptosis-independent cell death. WJ460 caused a reduction of the abundance of ferroptosis core regulators xc- cystine/glutamate transporter and GPX-4. Mitophagy inhibitor Mdivi1 and iron chelators inhibited the myoferlin-related ROS production and restored cell growth. Additionally, we reported a synergic effect between ferroptosis inducers, erastin and RSL3, and WJ460.

Landscape of KRASG12C, Associated Genomic Alterations, and Interrelation With Immuno-Oncology Biomarkers in KRAS-Mutated Cancers.

PURPOSEPromising single-agent activity from sotorasib and adagrasib in KRASG12C-mutant tumors has provided clinical evidence of effective KRAS signaling inhibition. However, comprehensive analysis of KRAS-variant prevalence, genomic alterations, and the relationship between KRAS and immuno-oncology biomarkers is lacking.MATERIALS AND METHODSRetrospective analysis of deidentified records from 79,004 patients with various cancers who underwent next-generation sequencing was performed. Fisher's exact test evaluated the association between cancer subtypes and KRAS variants. Logistic regression assessed KRASG12C comutations with other oncogenes and the association between KRAS variants and immuno-oncology biomarkers.RESULTSOf the 79,004 samples assessed, 13,758 (17.4%) harbored KRAS mutations, with 1,632 (11.9%) harboring KRASG12C and 12,126 (88.1%) harboring other KRAS variants (KRASnon-G12C). Compared with KRASnon-G12C across all tumor subtypes, KRASG12C was more prevalent in females (56% v 51%, false discovery rate-adjusted P value [FDR-P] = .0006), current or prior smokers (85% v 56%, FDR-P < .0001), and patients age > 60 years (73% v 63%, FDR-P ≤ .0001). The most frequent KRAS variants across all subtypes were G12D (29.5%), G12V (23.0%), G12C (11.9%), G13D (6.5%), and G12R (6.2%). KRASG12C was most prevalent in patients with non–small-cell lung cancer (9%), appendiceal (3.9%), colorectal (3.2%), tumor of unknown origin (1.6%), small bowel (1.43%), and pancreatic (1.3%) cancers. Compared with KRASnon-G12C-mutated, KRASG12C-mutated tumors were significantly associated with tumor mutational burden-high status (17.9% v 8.4%, odds ratio [OR] = 2.38; FDR-P < .0001). KRASG12C-mutated tumors exhibited a distinct comutation profile from KRASnon-G12C-mutated tumors, including higher comutations of STK11 (20.59% v 5.95%, OR = 4.10; FDR-P < .01) and KEAP1 (15.38% v 4.61%, OR = 3.76; FDR-P < .01).CONCLUSIONThis study presents the first large-scale, pan-cancer genomic characterization of KRASG12C. The KRASG12C mutation was more prevalent in females and older patients and appeared to be associated with smoking status. KRASG12C tumors exhibited a distinct comutation profile and were associated with tumor mutational burden-high status.

Classification of KRAS-Activating Mutations and the Implications for Therapeutic Intervention.

Efforts in the recent past to inhibit KRAS oncogenicity have focused on kinases that function in downstream signal transduction cascades, although preclinical successes have not translated to patients with KRAS-mutant cancer. Recently, clinically effective covalent inhibitors of KRASG12C have been developed, establishing two principles that form a foundation for future efforts. First, KRAS is druggable. Second, each mutant form of KRAS is likely to have properties that make it uniquely druggable.

Liver Endothelium Promotes HER3-Mediated Cell Survival in Colorectal Cancer with Wild-Type and Mutant KRAS.

This body of work highlighted a potential strategy of using HER3 antibodies in combination with standard chemotherapy agents for treating patients with either KRAS wild-type or KRAS mutant metastatic colorectal cancer.

Discovery of novel spiro compound as RAF kinase inhibitor with in vitro potency against KRAS mutant cancer

The development of RAF inhibitors targeting cancers with wild type RAF kinase and/or RAS mutation has been challenging due to the paradoxical activation of the RAS-RAF-MEK-ERK cascade following RAF inhibitor treatment. Herein is the discovery and optimization of a series of RAF inhibitors with a novel spiro structure. The most potent spiro molecule 9 showed excellent in vitro potency against b/c RAF enzymes and RAS mutant H358 cancer cells with minimal paradoxical RAF signaling activation. Compound 9 also exhibited good drug-like properties as demonstrated by in vitro cytochrome P450 (CYP), liver microsome stability (LMS) data and moderate oral pharmacokinetics (PK) profiles in rat and mouse.

An In Vivo Inflammatory Loop Potentiates KRAS Blockade.

KRAS (KRAS proto-oncogene, GTPase) inhibitors perform less well than other targeted drugs in vitro and fail clinical trials. To investigate a possible reason for this, we treated human and murine tumor cells with KRAS inhibitors deltarasin (targeting phosphodiesterase-δ), cysmethynil (targeting isoprenylcysteine carboxylmethyltransferase), and AA12 (targeting KRASG12C), and silenced/overexpressed mutant KRAS using custom-designed vectors. We showed that KRAS-mutant tumor cells exclusively respond to KRAS blockade in vivo, because the oncogene co-opts host myeloid cells via a C-C-motif chemokine ligand 2 (CCL2)/interleukin-1 beta (IL-1β)-mediated signaling loop for sustained tumorigenicity. Indeed, KRAS-mutant tumors did not respond to deltarasin in C-C motif chemokine receptor 2 (Ccr2) and Il1b gene-deficient mice, but were deltarasin-sensitive in wild-type and Ccr2-deficient mice adoptively transplanted with wild-type murine bone marrow. A KRAS-dependent pro-inflammatory transcriptome was prominent in human cancers with high KRAS mutation prevalence and poor predicted survival. Our findings support that in vitro cellular systems are suboptimal for anti-KRAS drug screens, as these drugs function to suppress interleukin-1 receptor 1 (IL1R1) expression and myeloid IL-1β-delivered pro-growth effects in vivo. Moreover, the findings support that IL-1β blockade might be suitable for therapy for KRAS-mutant cancers.

Albumin metabolism targeted peptide-drug conjugate strategy for targeting pan-KRAS mutant cancer

Despite recent breakthroughs in the development of direct KRAS inhibitors and modulators, no drugs targeting pan-KRAS mutant cancers are clinically available. Here, we report a novel strategy to treat pan-KRAS cancers using a caspase-3 cleavable peptide–drug conjugate that exploits enhanced albumin metabolism in KRAS altered cancers to deliver a cytotoxic agent that can induce a widespread bystander killing effect in tumor cells. Increased albumin metabolism in KRAS mutant cancer cells induced apoptosis via the intracellular uptake of albumin-bound MPD1. This allowed caspase-3 upregulation activated MPD1 to release the payload and exert the non-selective killing of neighboring cancer cells. MPD1 exhibited potent and durable antitumor efficacy in mouse xenograft models with different KRAS genotypes. An augmentation of anti-cancer efficacy was achieved by the bystander killing effect derived from the caspase-3 mediated activation of MPD1. In summary, albumin metabolism-induced apoptosis, together with the bystander killing effect of MPD1 boosted by caspase-3 mediated activation, intensified the efficacy of MPD1 in KRAS mutant cancers. These findings suggest that this novel peptide-drug conjugate could be a promising breakthrough for the treatment in the targeting of pan-KRAS mutant cancers.

Special Focus Issue - Targeted protein degradation: a new paradigm in medicinal chemistry.

Special Focus Issue - Targeted protein degradation: a new paradigm in medicinal chemistry.

Metabolic synthetic lethality by targeting NOP56 and mTOR in KRAS-mutant lung cancer

BackgroundOncogenic KRAS mutations are prevalent in human cancers, but effective treatment of KRAS-mutant malignancies remains a major challenge in the clinic. Increasing evidence suggests that aberrant metabolism plays a central role in KRAS-driven oncogenic transformation. The aim of this study is to identify selective metabolic dependency induced by mutant KRAS and to exploit it for the treatment of the disease.MethodWe performed an integrated analysis of RNAi- and CRISPR-based functional genomic datasets (n = 5) to identify novel genes selectively required for KRAS-mutant cancer. We further screened a customized library of chemical inhibitors for candidates that are synthetic lethal with NOP56 depletion. Functional studies were carried out by genetic knockdown using siRNAs and shRNAs, knockout using CRISPR/Cas9, and/or pharmacological inhibition, followed by cell viability and apoptotic assays. Protein expression was determined by Western blot. Metabolic ROS was measured by flow cytometry-based quantification.ResultsWe demonstrated that nucleolar protein 5A (NOP56), a core component of small nucleolar ribonucleoprotein complexes (snoRNPs) with an essential role in ribosome biogenesis, confers a metabolic dependency by regulating ROS homeostasis in KRAS-mutant lung cancer cells and that NOP56 depletion causes synthetic lethal susceptibility to inhibition of mTOR. Mechanistically, cancer cells with reduced NOP56 are subjected to higher levels of ROS and rely on mTOR signaling to balance oxidative stress and survive. We also discovered that IRE1α-mediated unfolded protein response (UPR) regulates this process by activating mTOR through p38 MAPK. Consequently, co-targeting of NOP56 and mTOR profoundly enhances KRAS-mutant tumor cell death in vitro and in vivo.ConclusionsOur findings reveal a previously unrecognized mechanism in which NOP56 and mTOR cooperate to play a homeostatic role in the response to oxidative stress and suggest a new rationale for the treatment of KRAS-mutant cancers.

Hydrophobic Tagging-Induced Degradation of PDEδ in Colon Cancer Cells.

The development of KRAS-PDEδ protein-protein interaction (PPI) inhibitors is generally hampered by limited antitumor activity. Herein, the first hydrophobic tagging (HyT)-based PDEδ degraders were designed. Compound 17c efficiently bound to PDEδ and induced degradation of PDEδ in SW480 colon cancer cells. As compared with PDEδ inhibitor deltazinone, HyT-based degrader 17c exhibited improved antitumor activity toward KRAS mutant cancer cells. This study highlighted the potential of HyT as a valuable chemical tool for tumorigenic PDEδ knockdown, which could be developed into a promising strategy for antitumor drug discovery.

Exploiting macropinocytosis for drug delivery into KRAS mutant cancer.

KRAS mutations are one of the most common gene mutations linked to cancer, presenting in approximately 25% of all tumors, especially pancreatic, lung, and colorectal cancers. Mutant KRAS has long been considered an undruggable target, stalling progress in direct KRAS targeting for many years, while targeted drug delivery into KRAS mutant cells utilizing their transformed metabolic behavior might present an alternative opportunity. Macropinocytosis, a nonselective, fluid-phase, endocytic route, was found to be upregulated as a metabolic feature in KRAS-driven tumors and plays a critical role in nutrient acquisition from extracellular fluids. With the observation that a variety of drug delivery systems could be internalized by KRAS mutant cancer cells through macropinocytosis, exploiting macropinocytosis for intracellular delivery of therapeutics into KRAS mutant tumor cells is emerging as a new drug delivery expedition. In this article, we summarized cancer biology studies that examined KRAS mutation-induced macropinocytosis, reviewed recent studies exploiting macropinocytosis enhancement for KRAS mutant cancer cell-selective drug delivery, and discussed the potential opportunities, challenges and pitfalls of this strategy.

Macropinocytic dextran facilitates KRAS-targeted delivery while reducing drug-induced tumor immunity depletion in pancreatic cancer.

Background: Pancreatic cancer comprises not only cancer cells but also a collection of cross-talking noncancerous cells within tumor. Therefore, selective delivery of cytotoxic agents towards cancer cells and limiting the collateral damage to tumor suppressive benign cells, such as effector lymphocytes in the tumor microenvironment, is of great value.Methods: Pancreatic cancer cells harbor oncogenic KRAS which induces a constitutively high level of macropinocytosis. Inspired by such uniquity, we sought to explore the targeting potential of dextran, a biomaterial presumed to be endocytosed in the macropinocytosis dependent manner. Cell entry preference, mechanism and subcellular sorting of dextran with different molecular weights were firstly examined. Triptolide (TP), a potent cytotoxin was then set as the model payload for dextran conjugation. KRAS selectivity and the therapeutic effects of dextran-conjugated TP were investigated via both in vitro cellular studies and in vivo tumor model assessment.Results: Dextran, with a specific molecular weight of 70 kDa rather than other weights, was identified as a robust KRAS-responsive intracellular delivery carrier with enhanced entry upon KRAS mutation. The 70 kDa dextran-conjugated TP (DEX-TP) displayed greater efficacy and cellular deposition efficiency towards KRAS mutant cells than KRAS wild-type cells. Treatment with DEX-TP suppressed tumor progression in KRAS mutant pancreatic cancer orthotopic mouse models with reduced toxicity and significantly extended mouse survival time. Furthermore, the conjugate attained a more favorable therapeutic outcome in the tumor immune microenvironment than the free drug, preserving the fraction of T cells and their effector cytokines.Conclusions: In summary, macropinocytic dextran was able to provide drug delivery selectivity towards KRAS mutant cancer cells and reduce tumor immunity depletion caused by the cytotoxic drug in pancreatic cancer.

Components of the phosphatidylserine endoplasmic reticulum to plasma membrane transport mechanism as targets for KRAS inhibition in pancreatic cancer

KRAS is mutated in 90% of human pancreatic ductal adenocarcinomas (PDACs). To function, KRAS must localize to the plasma membrane (PM) via a C-terminal membrane anchor that specifically engages phosphatidylserine (PtdSer). This anchor-binding specificity renders KRAS-PM localization and signaling capacity critically dependent on PM PtdSer content. We now show that the PtdSer lipid transport proteins, ORP5 and ORP8, which are essential for maintaining PM PtdSer levels and hence KRAS PM localization, are required for KRAS oncogenesis. Knockdown of either protein, separately or simultaneously, abrogated growth of KRAS-mutant but not KRAS-wild-type pancreatic cancer cell xenografts. ORP5 or ORP8 knockout also abrogated tumor growth in an immune-competent orthotopic pancreatic cancer mouse model. Analysis of human datasets revealed that all components of this PtdSer transport mechanism, including the PM-localized EFR3A-PI4KIIIα complex that generates phosphatidylinositol-4-phosphate (PI4P), and endoplasmic reticulum (ER)-localized SAC1 phosphatase that hydrolyzes counter transported PI4P, are significantly up-regulated in pancreatic tumors compared to normal tissue. Taken together, these results support targeting PI4KIIIα in KRAS-mutant cancers to deplete the PM-to-ER PI4P gradient, reducing PM PtdSer content. We therefore repurposed the US Food and Drug Administration-approved hepatitis C antiviral agent, simeprevir, as a PI4KIIIα inhibitor In a PDAC setting. Simeprevir potently mislocalized KRAS from the PM, reduced the clonogenic potential of pancreatic cancer cell lines invitro, and abrogated the growth of KRAS-dependent tumors invivo with enhanced efficacy when combined with MAPK and PI3K inhibitors. We conclude that the cellular ER-to-PM PtdSer transport mechanism is essential for KRAS PM localization and oncogenesis and is accessible to therapeutic intervention.

Abstract P183: CRISPR screens identify sensitizers to trametinib in KRAS mutant cancer cell lines

Abstract KRAS is the most frequently mutated oncogene in human tumors and drives tumorigenesis across multiple lineages. Specifically, KRAS is mutated in about 30% of lung cancer and over 90% of pancreatic cancer. Despite recent progress in developing mutant selective KRASG12C inhibitors, patient treatment options for RAS activated cancers remain very limited. Targeting the MAPK pathway by means of MEK and ERK inhibitors has been explored as an alternative strategy for KRAS mutant cancer. However, the clinical benefit is modest due to drug resistance caused by reactivation of the MAPK pathway and potentially other pathways and/or bypass mechanisms. Here we used CRISPR-based screens to identify potential combination therapy targets to enhance trametinib response in KRAS mutant cancers. We screened in five KRAS mutant cell lines of lung and pancreatic lineages and identified both known as well as novel modulators of MEK inhibitor response. Consistent with previous reports, gene knockouts that impair the reactivation of ERK downstream of MEK inhibition scored as top hits in our drop-out screens. Knocking out MAPK1, RAF1, BRAF and PTPN11 sensitized all five cell lines to trametinib treatment supporting these as candidate drug combination targets for MAPK pathway inhibition. Our screens also identified multiple genes within the heparan sulfate pathway (EXT1, EXT2, EXTL3, XYLT2, ALG6, B3GAT3, B4GALT7 and HS2ST1) and the MAPK7 pathway (MAPK7 and MAP2K5) that sensitize multiple but not all cell lines to trametinib. As part of our target discovery platform, we further validated these screening results using various phenotypic assays. Altogether, our results suggest that resistance to MEK inhibitors is driven by reactivation of the MAPK pathway as previously demonstrated and that impairing such reactivation restores the sensitivity of KRAS mutant cancer cells to trametinib. The genetic mechanisms driving the MAPK pathway rebound are likely different in different cancers and understanding such mechanisms will be key for achieving clinical success. Citation Format: Silvia Fenoglio, Aileen M. Cristo, James Tepper, Teng Teng, Samuel R. Meier, Ashley Choi, Hongxiang Zhang, Shan-chuan Zhao, Shangtao Liu, Leanne G. Ahronian, Daniel Aird, Nikitha M. Das, Yi Yu, Robert Tjin Tham Sjin, Jannik N. Andersen, Alan Huang, Fang Li, Xuewen Pan. CRISPR screens identify sensitizers to trametinib in KRAS mutant cancer cell lines [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P183.

Abstract P256: Pan-ErbB inhibition enhances activity of KRASG12C inhibitors in preclinical models of KRASG12C mutant cancers

Abstract Sotorasib (AMG 510) is the first KRAS inhibitor to be FDA-approved for the treatment of KRASG12C mutant lung adenocarcinomas which comprise ~42% of KRAS mutations in lung adenocarcinomas. Preclinical studies have shown that within hours of KRASG12C inhibition, synthesis of new KRASG12C protein and increased KRAS signaling was observed, leading to enhanced tumor cell growth and survival. This appeared to be due, at least in part, to a feeback loop leading to activation of EGFR signaling but the role of other ErbB family members including ErbB2 (HER2), ErbB3 (HER3), and ErbB4 (HER4) has not been fully evaluated. We hypothesize that short-term adaptation to KRAS inhibition is driven by multiple ErbB family members, and that the combination of pan-ErbB inhibitors with KRASG12C inhibitors could enhance KRASG12C inhibitor activity and prolong survival in preclinical models harboring KRASG12C mutations to a greater extent than more specific EGFR inhibitors. To investigate the role of different ErbB family members in this feedback signaling, we evaluated the impact of an EGFR specific inhibitor, erlotinib, an EGFR/HER2 inhibitor, afatinib, or pan-ErbB inhibitor (EGFR/HER2/3/4), poziotinib on anti-tumor activity of KRASG12C inhibitors in KRASG12C mutant NSCLC cell lines. We initially tested the different inhibitors in combination with sotorasib and adagrasib (MRTX849) and calculated the BLISS index (BI) for each drug pair matrix, using SynergyFinder. We found that when combined with either sotorasib or adagrasib, poziotinib had a synergistic effect (BI&amp;gt;10) in H23 (BI: 17, p=0.01), HCC44 (BI: 11, p=0.04), and H1792 (BI: 13, p=0.01) and an additive effect (BI= -10–10) in H2122 (BI: 2.8). Afatinib and erlotinib were additive in H23 (BI: 9.2 &amp; 9.4), HCC44 (BI:8.8 &amp; 7.9), H2122 (BI: -4.5 &amp; -3.3) and H1792 (BI: 6.6 &amp; 3.3). Poziotinib yielded a higher BI across all four cell lines compared to afatinib (p&amp;lt;0.0001) or erlotinib (p=0.0004). To determine if poziotinib prevented upregulation of ErbB-signaling after treatment with KRASG12C inhibitors, we treated KRASG12C mutant cell lines (NSCLC: H23 and Bladder Cancer: UM-UC-3) with KRASG12C inhibitors, sotorasib or adagrasib, for four hours and found by Western blotting that phosphorylated EGFR, HER2, HER3, and HER4 were increased after treatment. The addition of 10 nM poziotinib prevented the upregulation of phosphorylated EGFR, HER2, HER3, and HER4 in both cell lines. Together these data demonstrate that inhibition of EGFR, HER2, HER3, and HER4 signaling by the pan-ErbB inhibitor poziotinib resulted in greater synergy with KRASG12C inhibitors than EGFR or EGFR/HER2 inhibitors and highlight the potential importance of HER3 and HER4, in addition to EGFR and HER2, in feedback signaling after KRAS G12C inhibition. Additional studies of pan-ErbB and ErbB-specific inhibitors with KRASG12C inhibitors are warranted to determine tolerability and optimal dosing to prolong survival in KRAS mutant cancers. Citation Format: Jacqulyne P. Robichaux, Ana Galan-Cobo, Ried T. Powell, Kelly A. Gale, Jun He, Fahao Zhang, Monique B. Nilsson, Xiang Zhang, Mary M. Sobieski, Nghi Nguyen, Stephan C. Clifford, John V. Heymach. Pan-ErbB inhibition enhances activity of KRASG12C inhibitors in preclinical models of KRASG12C mutant cancers [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P256.

Abstract P216: IK-930 mediated TEAD inhibition decreases and delays tumor growth and enhances targeted apoptosis in lung and colon cancer xenografts when combined with MEK or EGFR inhibitors

Abstract The Hippo signaling cascade is an important pathway that plays a role in controlling cell proliferation and limiting apoptosis, but when dysregulated can contribute to cancer initiation, progression, and therapeutic resistance. The TEAD family of transcription factors, in conjunction with YAP1 or WWTR1/TAZ, are regulated by Hippo pathway signaling and modulate cell growth and proliferation. IK-930 inhibits the growth of TEAD-dependent human cancer xenografts. By exploiting synthetic lethality, the IK-930 single agent activity in TEAD-dependent cancers could expand to other indications upon inhibition of certain oncogenic pathways. Literature indicates that activation of TEAD-dependent transcription by other oncogenes such as mutant EGFR or KRAS mediates resistance to multiple targeted therapies. Additionally, genetic loss of YAP1 leads to increased apoptosis in osimertinib and trametinib treated mutant EGFR NSCLC cell lines (Kurppa, 2020). Here, we present preclinical data that support the use of IK-930 combination therapies to enhance anti-tumor impact of EGFR and MEK blockade in mutant EGFR NSCLC, or with MEK inhibition in several BRAF and KRAS mutant cancers. In these studies, EGFR and MEK1/2 were inhibited and IK-930 used to enhance anti-tumor activity in EGFR-mutant NSCLC cells. These NSCLC cell lines that are largely insensitive to osimertinib and/or trametinib, were observed to have a marked increase in apoptosis in vitro when treated with the combination of osimertinib, trametinib, and IK-930. We also observed increased nuclear accumulation of YAP1 after treatment of NSCLC cells with osimertinib alone, or osimertinib and trametinib and upregulation of TEAD-dependent transcription. In NSCLC xenografts, the combination of osimertinib and IK-930 prevented tumor growth and the triple combination of osimertinib, IK-930, and trametinib drove complete tumor regression and demonstrated greater efficacy than any single agent or double combination. A second set of studies tested the synthetic lethality effect of IK-930 and MEK inhibition in RAF- and RAS-mutant tumors. The combination of TEAD inhibition with MEK inhibition enhanced apoptosis in several KRAS-mutant NSCLC, PDAC, CRC KRAS-mutant cell lines and BRAF-mutant melanoma. The combination of trametinib and IK-930 prevented tumor growth in these xenografts, where either single agent had either modest or little activity. In summary, the Hippo pathway has been implicated in multiple tumor types, including those with resistance mechanisms to EGFR and MEK blockade. IK-930-mediated TEAD inhibition has been investigated to suppress the bypass pathway activation mechanism to the targeted therapies. These data demonstrated the potential to further expand single agent patient benefit by combining IK-930 with MEK and/or EGFR inhibition in a wide variety of cancer indications, including mutant EGFR-driven NSCLC and mutant KRAS colon, lung, and pancreatic cancers. Taken together, these data are informing the clinical development plan and combination strategy for IK-930, a novel TEAD inhibitor. Citation Format: Benjamin Amidon, Hyejin Frosch, Sakeena Syed, Jill Cavanaugh, Chelsea Turcotte, Katie O'Callaghan, Prabitha Natarajan, Jeffrey Ecsedy, Karen McGovern, Alfredo Castro. IK-930 mediated TEAD inhibition decreases and delays tumor growth and enhances targeted apoptosis in lung and colon cancer xenografts when combined with MEK or EGFR inhibitors [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P216.

Dual blockade of macropinocytosis and asparagine bioavailability shows synergistic anti-tumor effects on KRAS-mutant colorectal cancer

Mutations of KRAS gene are found in various types of cancer, including colorectal cancer (CRC). Despite intense efforts, no pharmacological approaches are expected to be effective against KRAS-mutant cancers. Macropinocytosis is an evolutionarily conserved actin-dependent endocytic process that internalizes extracellular fluids into large vesicles called macropinosomes. Recent studies have revealed macropinocytosis's important role in metabolic adaptation to nutrient stress in cancer cells harboring KRAS mutations. Here we showed that KRAS-mutant CRC cells enhanced macropinocytosis for tumor growth under nutrient-depleted conditions. We also demonstrated that activation of Rac1 and phosphoinositide 3-kinase were involved in macropinocytosis of KRAS-mutant CRC cells. Furthermore, we found that macropinocytosis was closely correlated with asparagine metabolism. In KRAS-mutant CRC cells engineered with knockdown of asparagine synthetase, macropinocytosis was accelerated under glutamine-depleted condition, and albumin addition could restore the glutamine depletion-induced growth suppression by recovering the intracellular asparagine level. Finally, we discovered that the combination of macropinocytosis inhibition and asparagine depletion dramatically suppressed the tumor growth of KRAS-mutant CRC cells in vivo. These results indicate that dual blockade of macropinocytosis and asparagine bioavailability could be a novel therapeutic strategy for KRAS-mutant cancers.

Abstract P111: Therapeutic KRASG12C inhibition alleviates KRAS-driven immunosuppression

Abstract Therapeutic KRASG12C inhibitors may substantially improve KRAS-mutant cancer patient care, considering the encouraging clinical data emerging from ongoing clinical trials. Since oncogene-targeting therapies often lead to resistance, the development of combinatorial therapies will be of utmost importance to achieve long-lasting tumour control. Given the known immunosuppressive role of KRAS, clinical trials investigating the combination of KRASG12C inhibitors with immune checkpoint blockade are currently underway for NSCLC patients. Here, we show that KRASG12C inhibition using MRTX1257 alleviates KRAS-driven immune suppression, through a myriad of mechanisms including the augmentation of tumour cell-intrinsic interferon responses. Despite harbouring a large number of somatic mutations, orthotopic 3LL (KRASG12CDNRAS) tumours are able to evade anti-tumour immune responses. Combining multicolour flow cytometry, RNA sequencing and imaging mass cytometry, we observed significantly increased T cell activation and infiltration after MRTX1257 treatment in addition to enhanced antigen presentation cells and gene sets, and reduced myeloid cells, creating an immune permissive microenvironment in these lung tumours. Despite these profound changes, combination of KRASG12C inhibitors and anti-PD-(L)1 antibodies fail to show synergism in our model, in contrast with Amgen’s published data using an immunogenic model of colorectal cancer. This data suggests that a pre-existing anti-tumour immunity may be crucial for clinical responses to KRAS inhibitors and immune checkpoint blockade combinations. Henceforth, ongoing clinical trials investigating this approach will likely only benefit a subset of patients and further research will be needed to examine novel therapeutic approaches and combinations for refractory patients. Citation Format: Edurne Mugarza, Febe Van Maldegem, Jesse Boumelha, Chris Moore, Sareena Rana, Miriam Llorian Sopena, Phil East, Miriam Molina Arcas, Julian Downward. Therapeutic KRASG12C inhibition alleviates KRAS-driven immunosuppression [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P111.