Wild-type RAS Research Articles

MOUNTAINEER-03 phase III study design: first-line mFOLFOX6 + tucatinib + trastuzumab for HER2+ metastatic colorectal cancer.

Patients diagnosed with metastatic colorectal cancer (mCRC) have a poor prognosis with survival ranging 2-3 years. The prevalence of human epidermal growth factor receptor 2 (HER2) amplification is approximately 3-4% in mCRC and increases up to 8% in patients with KRAS/NRAS/BRAF wild-type (WT) CRC tumors. Tucatinib is a highly selective HER2-directed tyrosine kinase inhibitor that, in combination with trastuzumab, has demonstrated clinically meaningful activity in patients with chemotherapy-refractory, HER2-positive (HER2+), RAS WT mCRC in the MOUNTAINEER trial. The MOUNTAINEER-03 phase III trial is designed to investigate the efficacy and safety of first-line tucatinib in combination with trastuzumab and modified FOLFOX6 (mFOLFOX6) versus standard of care (mFOLFOX6 plus bevacizumab or cetuximab) in patients with untreated HER2+, RAS WT locally advanced unresectable or mCRC. MOUNTAINEER-03 will include two arms of approximately 400 patients randomized 1:1 to either treatment arm. The primary endpoint is progression-free survival per RECIST v1.1 by blinded independent central review (BICR). Key secondary endpoints are overall survival and confirmed objective response rate (according to RECIST v1.1 per BICR). Safety assessments will include surveillance and recording of adverse events, physical examination findings, vital signs, cardiac assessments, Eastern Cooperative Oncology Group performance status, concomitant medications, and laboratory tests.Clinical trial registration: NCT05253651 (ClinicalTrials.gov).

Association between quantitative CT body composition analysis and prognosis in cetuximab-based first-line treatment for advanced colorectal cancer patients

BackgroundThe objective of this study is to investigate the potential association between change in body composition before and after cetuximab-based therapy and the prognostic outcomes among individuals diagnosed with advanced colorectal cancer.MethodsA retrospective analysis was undertaken on a cohort of 81 patients diagnosed with RAS wild-type (WT) metastatic colorectal cancer (mCRC) who were treated with cetuximab-based first-line therapy. To assess relevant body composition parameters, quantitative computed tomography (QCT) scans were conducted both before and after cetuximab treatment. These parameters encompassed measurements of visceral fat area (VFA), subcutaneous fat area (SFA), total muscle area (TMA) at the third lumbar vertebra level (L3), and bone mineral density (BMD) at the first and second vertebrae levels (L1/2). The skeletal muscle index (SMI) was subsequently calculated, and changes in parameters (∆VFA, ∆SFA, ∆SMI, ∆BMD) were standardized.ResultsThe cut-off values for ∆VFA, ∆SFA, ∆SMI, and ∆BMD were 0.28%, -2.76%, -2.97%, and -7.98%, respectively. CEA, ∆VFA, ∆SMI, and ∆BMD were associated with poor outcomes of cetuximab-based first-line chemotherapy (P < 0.05). The risk of disease progression was higher when ∆VFA < 0.28%, ∆SFA < -2.76%, ∆SMI < -2.97%, and ∆BMD < -7.98%. Multivariate analysis indicated that CEA (HR: 0.396, 95% CI: 0.160–0.980, P = 0.045), ∆VFA (HR: 0.307, 95% CI: 0.145–0.651, P = 0.002), and∆SMI (HR: 0.725, 95% CI: 0.322–1.630, P = 0.001) have significant prognostic value for progression-free survival (PFS) in RAS WT mCRC patients treated with cetuximab-based first-line chemotherapy.ConclusionsCEA, ∆VFA, and ∆SMI are independent predictors for PFS in patients with advanced colorectal cancer. High levels of CEA, ∆VFA, and low levels of ∆SMI may indicate poorer outcomes. CEA, ∆VFA, and ∆SMI can be used to predict PFS in mCRC patients receiving cetuximab-based first-line chemotherapy.Trial registrationThis study was approved by the Ethics Committee of Anhui Provincial Cancer Hospital of Anhui Medical University (Batch No:2024-ZNY-02). All subjects signed an informed consent form.

Antibody-Drug Conjugates Targeting the EGFR Ligand Epiregulin Elicit Robust Anti-Tumor Activity in Colorectal Cancer.

As colorectal cancer (CRC) remains a leading cause of cancer-related death, identifying therapeutic targets and approaches is essential to improve patient outcomes. The EGFR ligand epiregulin (EREG) is highly expressed in RAS wildtype and mutant CRC with minimal expression in normal tissues, making it an attractive target for antibody-drug conjugate (ADC) development. In this study, we produced and purified an EREG monoclonal antibody (mAb), H231, that had high specificity and affinity for human and mouse EREG. H231 also internalized to lysosomes, which is important for ADC payload release. ImmunoPET and ex vivo biodistribution studies showed significant tumor uptake of 89Zr-labeled H231 with minimal uptake in normal tissues. H231 was conjugated to either cleavable dipeptide or tripeptide chemical linkers attached to the DNA-alkylating payload duocarmycin DM, and cytotoxicity of EREG ADCs was assessed in a panel of CRC cell lines. EREG ADCs incorporating tripeptide linkers demonstrated the highest potency in EREG-expressing CRC cells irrespective of RAS mutations. Preclinical safety and efficacy studies showed EREG ADCs were well-tolerated, neutralized EGFR pathway activity, caused significant tumor growth inhibition or regression, and increased survival in CRC cell line and patient-derived xenograft models. These data suggest EREG is a promising target for the development of ADCs for treating CRC and other cancer types that express high levels of EREG. While the efficacy of clinically approved anti-EGFR mAbs are largely limited by RAS mutational status, EREG ADCs may show promise for both RAS mutant and wildtype patients, thus improving existing treatment options.

Spatially Resolved Molecular Characterization of Noninvasive Follicular Thyroid Neoplasms with Papillary-like Nuclear Features (NIFTPs) Identifies a Distinct Proteomic Signature Associated with RAS-Mutant Lesions.

Follicular-patterned thyroid neoplasms comprise a diverse group of lesions that pose significant challenges in terms of differential diagnosis based solely on morphologic and genetic features. Thus, the identification of easily testable biomarkers complementing microscopic and genetic analyses is a highly anticipated advancement that could improve diagnostic accuracy, particularly for noninvasive follicular thyroid neoplasms with papillary-like nuclear features (NIFTPs). These tumors exhibit considerable morphological and molecular heterogeneity, which may complicate their distinction from structurally similar neoplasms, especially when genetic analyses reveal shared genomic alterations (e.g., RAS mutations). Here, we integrated next-generation sequencing (NGS) with matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) to perform a proteogenomic analysis on 85 NIFTPs (n = 30 RAS-mutant [RAS-mut] and n = 55 RAS-wild type [RAS-wt]), with the aim to detect putative biomarkers of RAS-mut lesions. Through this combined approach, we identified four proteins that were significantly underexpressed in RAS-mut as compared to RAS-wt NIFTPs. These proteins could serve as readily accessible markers in morphologically borderline cases showing RAS mutations. Additionally, our findings may provide insights into the distinct pathogenic pathways through which RAS-mut and RAS-wt NIFTPs arise, highlighting the pivotal role of constitutive RAS-mitogen-activated protein kinase (MAPK) pathway activation in the development and progression of RAS-mut tumors.

Anti-EGFR Rechallenge in Metastatic Colorectal Cancer and the Role of ctDNA: A Systematic Review and Meta-analysis.

Metastatic colorectal cancer (mCRC) remains a significant clinical challenge. While anti-EGFR inhibitors have improved survival rates, their long-term efficacy is limited by disease progression, which is often associated with the development of acquired resistance mutations. However, some patients may regain sensitivity to anti-EGFR agents after alternative therapies, suggesting a potential benefit for rechallenge strategies. Our study aims to conduct a systematic review and meta-analysis to comprehensively evaluate the efficacy and safety of EGFR rechallenge in patients with mCRC. A systematic search of the MEDLINE, EMBASE, and Cochrane databases was conducted between October 28 and December 24, 2023, to identify clinical trials investigating treatment regimens incorporating panitumumab or cetuximab as a rechallenge strategy. Pooled proportions or hazard ratios (HR) were calculated using a random effects model. Inter-study heterogeneity was assessed using the I2. Among the 2105 articles identified through the search, 13 met the predetermined inclusion criteria. Of these, 12 were phase II studies, encompassing 92.3% of the patient population. Cetuximab was administered to 302 patients (75.1%), whereas panitumumab was utilized in 100 patients (24.9%).A pooled analysis of eight studies demonstrated an objective response rate of 20.50% (95% CI 7.94 to 33.07) and a disease control rate of 67.35% (95% CI 58.60 to 76.09). The median progression-free survival was estimated at 3.5months (95% CI 2.68-6.69), with a median OS of 9.8months (95% CI 6.71-12.89). Patients exhibiting RAS wild-type status in circulating tumor DNA (ctDNA) analysis derived enhanced benefits from anti-EGFR rechallenge (HR: 0.41; 95% CI 0.28-0.60, I2 = 60%). Common grade 3 or higher treatment-related adverse events included neutropenia (22.8%) and rash (14.9%). This meta-analysis underscores the efficacy and safety of anti-EGFR rechallenge as a promising therapeutic approach for a subset of patients afflicted with mCRC. The observed correlation between wild-type RAS status, as determined through ctDNA analysis, and improved OS signals the prospect of precision oncology in guiding treatment decisions.

AGITG MONARCC: A Randomized Phase 2 Study of Panitumumab Monotherapy and Panitumumab Plus 5-Fluorouracil as First-Line Therapy for Older Patients With RAS and BRAF Wild Type Metastatic Colorectal Cancer. A Study by the Australasian Gastro-Intestinal Trials Group (AGITG).

Panitumumab (pan) plus chemotherapy is a preferred first-line therapy for unresectable RAS and BRAF wild type metastatic colorectal cancer (mCRC). Older patients may not be suitable for combination regimens. We investigated 2 lower intensity pan-containing regimens. Prospective, noncomparative, randomized (1:1) phase 2 study of pan alone (Arm A) or pan plus FU (Arm B). Previously untreated mCRC were ≥70 years; RAS/BRAF wild type. 6-month progression-free survival (PFS). Secondary endpoints included: overall survival (OS), response rate (RR), feasibility of geriatric assessments and overall treatment utility (OTU)-a composite measure based on radiological response, clinical progress, toxicity and patient-reported treatment worth. Planned sample size was 40 patients per arm. 36 patients (Arm A n = 19, Arm B n = 17) were randomized between June 2018 and June 2021. Median age was 79 and 80 years respectively. 6-month PFS 63% (95% CI 38%-80%) arm A 82% (95%CI 55%-94%) Arm B. Median OS 21 months Arm A (95%CI 13-31) 28 (95%CI 14-39) months Arm B. RR 47% and 65% Arms A and B respectively. Baseline comprehensive geriatric assessments were completed in >80% of patients. At week 16, OTU was categorized as good in 92% (Arm A) and 90% (Arm B). No unexpected adverse events were seen. Six-month PFS in both arms was consistent with that achieved with FU/bev, whilst the rate was numerically higher for Arm B. Baseline comprehensive geriatric assessments were feasible and OTU was high. Both treatment arms might be suitable in appropriately selected patients.

Metabolic Adaptations To Acute Glucose Uptake Inhibition Converge Upon Mitochondrial Respiration For Leukemia Cell Survival.

One hallmark of cancer is the upregulation and dependency on glucose metabolism to fuel macromolecule biosynthesis and rapid proliferation. Despite significant pre-clinical effort to exploit this pathway, additional mechanistic insights are necessary to prioritize the diversity of metabolic adaptations upon acute loss of glucose metabolism. Here, we investigated a potent small molecule inhibitor to Class I glucose transporters, KL-11743, using glycolytic leukemia cell lines and patient-based model systems. Our results reveal that while several metabolic adaptations occur in response to acute glucose uptake inhibition, the most critical is increased mitochondrial oxidative phosphorylation. KL-11743 treatment efficiently blocks the majority of glucose uptake and glycolysis, yet markedly increases mitochondrial respiration via enhanced Complex I function. Compared to partial glucose uptake inhibition, dependency on mitochondrial respiration is less apparent suggesting robust blockage of glucose uptake is essential to create a metabolic vulnerability. When wild-type and oncogenic RAS patient-derived induced pluripotent stem cell acute myeloid leukemia (AML) models were examined, KL-11743 mediated induction of mitochondrial respiration and dependency for survival associated with oncogenic RAS. Furthermore, we examined the therapeutic potential of these observations by treating a cohort of primary AML patient samples with KL-11743 and witnessed similar dependency on mitochondrial respiration for sustained cellular survival. Together, these data highlight conserved adaptations to acute glucose uptake inhibition in diverse leukemic models and AML patient samples, and position mitochondrial respiration as a key determinant of treatment success.

Neo-RAS Wild Type or RAS Conversion in Metastatic Colorectal Cancer: A Comprehensive Narrative Review.

The management of metastatic colorectal cancer in patients harboring RAS mutations primarily involves chemotherapy, often combined with bevacizumab, as a standard first-line treatment. However, emerging evidence suggests that tumors in a subset of these patients may experience a conversion from RAS-mutant status to RAS wild type (wt) during or after chemotherapy, a process referred to as "RAS conversion" or "neo-RAS wt". Understanding the mechanisms driving the neo-RAS wt phenomenon is crucial for its application in personalized medicine. Hypotheses suggest that selective pressure from chemotherapy may lead to a decrease in the number of mutant RAS clones or an outgrowth of pre-existing RAS wt clones. Further research is needed to validate these mechanisms and understand the impact of the neo-RAS wt phenomenon on long-term outcomes, such as overall survival and progression-free survival. This review provides a comprehensive overview of the current understanding of the neo-RAS wt phenomenon, including its incidence, potential mechanisms, and clinical implications.

Antibody-Drug Conjugates Targeting the EGFR Ligand Epiregulin Elicit Robust Anti-Tumor Activity in Colorectal Cancer.

As colorectal cancer (CRC) remains a leading cause of cancer-related death, identifying therapeutic targets and approaches is essential to improve patient outcomes. The EGFR ligand epiregulin (EREG) is highly expressed in RAS wildtype and mutant CRC with minimal expression in normal tissues, making it an attractive target for antibody-drug conjugate (ADC) development. In this study, we produced and purified an EREG monoclonal antibody (mAb), H231, that had high specificity and affinity for human and mouse EREG. H231 also internalized to lysosomes, which is important for ADC payload release. ImmunoPET and ex vivo biodistribution studies showed significant tumor uptake of 89Zr-labeled H231 with minimal uptake in normal tissues. H231 was conjugated to either cleavable dipeptide or tripeptide chemical linkers attached to the DNA-alkylating payload duocarmycin DM, and cytotoxicity of EREG ADCs was assessed in a panel of CRC cell lines. EREG ADCs incorporating tripeptide linkers demonstrated the highest potency in EREG-expressing CRC cells irrespective of RAS mutations. Preclinical safety and efficacy studies showed EREG ADCs were well-tolerated, neutralized EGFR pathway activity, caused significant tumor growth inhibition or regression, and increased survival in CRC cell line and patient-derived xenograft models. These data suggest EREG is a promising target for the development of ADCs for treating CRC and other cancer types that express high levels of EREG. While the efficacy of clinically approved anti-EGFR mAbs are largely limited by RAS mutational status, EREG ADCs may show promise for both RAS mutant and wildtype patients, thus improving existing treatment options.

Comparison of efficacy and safety of regorafenib and anti-EGFR targeted therapy in metastatic colorectal cancer: A retrospective study

Aim. To compare the efficacy of regorafenib and the combination of chemotherapy (CT) with anti-EGFR (cetuximab/panitumumab) in the third-line treatment of metastatic colorectal cancer (mCRC). Materials and methods. A retrospective analysis of a prospective database of patients with mCRC from two clinics in the Russian Federation was conducted. Overall survival was considered the primary efficacy criterion. Additional criteria were progression-free survival (PFS), objective effect (OE), and incidence of toxicity. No statistical hypothesis was assumed. Statistical analysis was performed using SPSS (IBM SPPS Statistics v. 20). Results. The database identified 51 patients with morphologically confirmed left-sided mCRC with wild-type RAS and BRAF genes who received more than two lines of antitumor drug therapy from 2010 to 2021, one of which included anti-EGFR antibodies in the third and subsequent lines of treatment. Thirty patients who received regorafenib in the third line and 21 patients who received CT in combination with anti-EGFR in the third line were selected, of which 7 patients had a history of anti-EGFR use, and 14 patients received anti-EGFR for the first time. The median overall survival from the third line initiation date in the CT group in combination with anti-EGFR was numerically higher (21 months, CI 9.0–32.9 months) than in the regorafenib group (10 months, CI 2.4–17.5 months); p=0.1 by log-rank test (Mantel–Cox test); p=0.2 by Breslow–Wilcoxon test; p=0.3 (Tarone–Ware test). PFS was also higher in the anti-EGFR CT group (6 months, CI 3.8–8.2 months) than in the regorafenib group (3 months, CI 1.2–4.7 months); p=0.05 according to Breslow–Wilcoxon test. OE of third-line therapy was reported in 57.1% (n=12) of patients in the CT with anti-EGFR group and significantly less often in the regorafenib group – 10.3% (n=3) of patients (p=0.001). The toxicity of drug therapy of all grades in the regorafenib group was reported in 86.2% (n=25) of patients, while in the CT anti-EGFR group, it was significantly less common – in 52.4% (n=11) of patients (p=0.01). Conclusion. Compared with regorafenib, combining CT with anti-EGFR agents in the third-line treatment of patients with left-sided mCRC with wild-type RAS and BRAF genes is associated with better PFS and the frequency of OE with significantly less toxicity.

FGTI-2734 Inhibits ERK Reactivation to Overcome Sotorasib Resistance in KRAS G12C Lung Cancer

KRAS G12C targeted therapies, such as sotorasib, represent a major breakthrough, but overall response rates and progression-free survival for patients with KRAS G12C lung cancer are modest due to the emergence of resistance mechanisms involving adaptive reactivation of ERK, which requires wild-type (WT) HRAS and NRAS membrane localization. Here, we demonstrate that the dual farnesyltransferase (FT) and geranylgeranyltransferase-1 (GGT-1) inhibitor FGTI-2734 inhibits WT RAS membrane localization and sotorasib-induced ERK feedback reactivation, and overcomes sotorasib adaptive resistance. The combination of FGTI-2734 and sotorasib is synergistic at inhibiting the viability and inducing apoptosis of KRAS G12C lung cancer cells, including those highly resistant to sotorasib. FGTI-2734 enhances sotorasib's anti-tumor activity in vivo leading to significant tumor regression of a patient-derived xenograft (PDX) from a patient with KRAS G12C lung cancer as well as several xenografts from highly sotorasib-resistant KRAS G12C human lung cancer cells. Importantly, treatment of mice with FGTI-2734 inhibited sotorasib-induced ERK reactivation in KRAS G12C PDX, and treatment of mice with the combination of FGTI-2734 and sotorasib were also significantly more effective at suppressing in vivo the levels of P-ERK in sotorasib-resistant human KRAS G12C lung cancer xenografts as well as a PDX. Our findings provide a foundation for overcoming sotorasib resistance and potentially improving the treatment outcomes of KRAS G12C lung cancer.

High expression of ARHGEF5 predicts unfavorable prognosis in acute myeloid leukemia

Acute myeloid leukemia (AML) is a highly heterogeneous hematological neoplasm, highlighting the need for new molecular markers to improve prognosis prediction and therapeutic strategies. While Rho guanine nucleotide exchange factor 5 (ARHGEF5) is known to be overexpressed in various cancers, its role in AML is not well understood. This study investigates the correlation between ARHGEF5 expression and AML using data from the Cancer Genome Atlas (TCGA). ARHGEF5 expression levels in AML patients and normal samples were compared using the Wilcoxon rank-sum test. The Kaplan–Meier method and Cox regression analysis (CRA) assessed the association between ARHGEF5 expression and patient survival. A prognostic nomogram was constructed using CRA, incorporating patient age and cytogenetic risk.Our findings indicate significant overexpression of ARHGEF5 in AML compared to normal samples. Elevated ARHGEF5 levels were associated with poor prognosis, particularly in patients ≤ 60 years, those with NPM1 mutations, FLT3 mutation-positive, and wild-type RAS (P < 0.05). CRA confirmed that high ARHGEF5 expression independently predicts poor prognosis. Additionally, 412 differentially expressed genes (DEGs) were identified between high and low ARHGEF5 expression groups, with 216 genes upregulated and 196 downregulated. Pathway enrichment analyses using GO and KEGG, along with protein–protein interaction network and single sample gene set enrichment analyses, revealed key pathways and immune cell associations linked to ARHGEF5. These findings suggest that ARHGEF5 overexpression could serve as a biomarker for unfavorable outcomes in AML, providing insights into the underlying mechanisms of AML onset and progression.

Abstract C012: Overcoming Cell Subtype-Specific Adaptive Resistance to KRAS G12D Inhibition in KRAS G12D-Mutant Pancreatic Cancer

Abstract Background: Pancreatic ductal adenocarcinoma (PDAC) has a 5-year survival rate of only 12%, with limited treatment options. Oncogenic KRAS mutations drive PDAC tumor progression, which occur in the majority of PDAC tumors. KRAS G12D is the most common KRAS mutation, found in 36% of PDAC cases, which is associated with the worst clinical outcomes. Mutant-selective KRAS G12D inhibitors (KRASi G12D), such as MRTX1133, have recently demonstrated initial responses in KRAS G12D-mutant preclinical models. However, mechanisms of adaptive resistance to KRAS G12D inhibition are largely under-investigated and novel therapeutic strategies to overcome drug resistance are urgently needed. Results: Adaptive RAS signaling reactivation was found to dampen KRAS G12D inhibition in a library of KRAS G12D PDAC cell lines, thereby minimizing drug efficacy. Quantitative downstream analyses of drug combination screening using a KRAS G12D cell line library further identified this adaption to KRAS inhibition was cell subtype specific. Fibroblast growth factor receptor (FGFRs) drove adaptive RAS reactivation specifically in mesenchymal PDAC cells, which are aggressive, and intrinsically resistant to KRASi. In contrast, epithelial growth factor receptor (EGFR) reactivated RAS G12D signaling in epithelial cells, which are sensitive to KRASi G12D. Genetic and pharmacological inhibition of FGFR1 or FGFR2 improved drug efficacy by decreasing FGFR-mediated RAS reactivation specifically in mesenchymal PDAC lines. Pharmacological blockade of EGFR enhanced drug efficacy by inhibiting EGFR-mediated RAS reactivation specifically in epithelial PDAC lines. Furthermore, low-concentration of a novel pan- RAS inhibitor, which inhibits both wild-type and mutant RAS, completely abrogated MAPK signaling and significantly improved efficacy, when combined with KRASi G12D, suggesting a pro-survival dependency on wild-type RAS as a compensatory mechanism in response to KRAS G12D inhibition. Conclusion: Upstream RTK-mediated adaptive RAS signaling re-activation in response to KRAS inhibition in PDAC is cell subtype specific. Complete inhibition of RAS signaling by overcoming adaptive RAS rebound improves efficacy of KRASi G12D. Citation Format: Qingxiang (Nick) Lin, Alvin Morales, Haley Barnes, Ryan Bruce Corcoran. Overcoming Cell Subtype-Specific Adaptive Resistance to KRAS G12D Inhibition in KRAS G12D-Mutant Pancreatic Cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr C012.

Abstract PR-16: Evaluating direct KRASQ61H inhibition in pancreatic cancer models

Abstract KRASQ61 mutations are associated with the worst prognosis among the various KRAS mutational subtypes of pancreatic ductal adenocarcinoma (PDAC). RMC-7977 is a RAS(ON) multi-selective noncovalent inhibitor with broad spectrum activity against oncogenic RAS mutants and wild-type RAS. The related investigational agent RMC-6236 is currently undergoing clinical trials. Binary complexes of CypA: RMC-7977 bind equipotently to multiple KRAS mutational subtypes however RMC-7977 is less potent at inhibiting growth in KRASQ61H-mutant cell lines. In contrast, RM-047 is a preclinical RAS(ON) Q61H-selective inhibitor tool compound. We evaluated direct KRASQ61H inhibition using both RMC-7977 and RM-047 in cell culture models. We found that in KRASQ61H-rescued RASless mouse embryonic fibroblasts (MEFs), RM-047 inhibited ERK activity and suppressed growth more potently than RMC-7977. Conversely, in a panel of KRASQ61H-mutant PDAC cell lines, RM-047 was less potent than RMC-7977 in two out of three KRASQ61H-mutant PDAC cell lines. Furthermore, we discovered that ERK activity rapidly rebounded with treatment in KRASQ61H-mutant PDAC cell lines, whereas ERK activity remained suppressed in KRASQ61H-rescued RASless MEFS lacking WT RAS alleles. Our analysis of DepMap data indicated that among the KRAS mutational subtypes frequently found in pancreatic cancer, KRASQ61H is the least dependent on KRAS for survival. This suggests that in a KRASQ61H-mutant PDAC setting, additional factors such as WT RAS expression may mediate growth. From our KRAS drug-anchored CRISPR loss-of-function screens, we found that the loss of EGFR sensitized cells to KRAS inhibition, particularly in a KRASQ61H-dependent context. Therefore, we combined erlotinib, an FDA-approved EGFR inhibitor, with either RM-047 or RMC-7977, and found that the addition of erlotinib prevented ERK rebound activity and synergized with RM-047 or RMC-7977 to reduce growth in KRASQ61H-mutant PDAC cell lines. These data provide insights into mechanisms by which KRASQ61H-mutant PDAC may be less dependent on KRAS for survival and further support the clinical evaluation of combined EGFR and RAS(ON) inhibition as a potential therapeutic strategy in the treatment of PDAC patients harboring KRASQ61H mutations. Citation Format: Szu-Aun Long, Amber M Amparo, Haley Todd, Grace Goodhart, Syed A Ahmad, Andrew M Waters. Evaluating direct KRAS inhibition in pancreatic cancer models [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr PR-16.

RAS mutation associated with short surgically controllable period in colorectal liver metastases: a retrospective study

BackgroundThe prognostic implications of the RAS status in colorectal cancer liver metastasis (CRLM) remain unclear. This study investigated the prognostic significance of RAS status after curative hepatectomy, focusing on surgical controllability.MethodsThis retrospective study included liver-only CRLM patients who underwent the first hepatectomy between 2015 and 2022 at the National Cancer Center Hospital. Recurrence-free survival (RFS), surgically controllable period (SCP), and overall survival (OS) were compared between RAS wild-type (RAS-wt) and mutant (RAS-mt) patients. Multivariate analyses were conducted to identify independent prognostic factors for each outcome and independent risk factors for less than 1 year SCP.ResultsA total of 150 patients were evaluated, comprising 63 patients with RAS-mt status. There was no significant difference in RFS between RAS-mt and RAS-wt (7.00 vs. 8.03 months, p = 0.48). RAS-mt patients exhibited worse SCP (11.80 vs.21.13 months, p < 0.001) and OS (44.03 vs. 70.03 months, p < 0.001) compared to RAS-wt. Multivariate analysis identified RAS-mt as an independent prognostic factor for both OS (hazard ratio [HR]: 3.37, p < 0.001) and SCP (HR: 2.20, p < 0.001), and as an independent risk factor for less than 1 year of SCP (odds ratio, 2.31; p = 0.03).ConclusionsCRLM with RAS mutations should be considered for strict surgical indications with preoperative chemotherapy and thorough examination, considering the possibility of short SCP.

Tislelizumab plus cetuximab and irinotecan in refractory microsatellite stable and RAS wild-type metastatic colorectal cancer: a single-arm phase 2 study

Immunotherapy confers little to no benefit in the treatment of microsatellite stable (MSS) metastatic colorectal cancer (mCRC). Mechanistic insights suggested that epidermal growth factor receptor (EGFR) antibody plus irinotecan might augment the tumor immune response in mCRC. Therefore, we conducted a proof-of-concept, single-arm, phase 2 study (ChiCTR identifier: ChiCTR2000035642) of a combination treatment regimen including tislelizumab (anti-PD-1), cetuximab (anti-EGFR) and irinotecan in 33 patients with MSS and RAS wild-type (WT) mCRC who were previously treated with ≥2 lines of therapy. The primary endpoint was met, with a confirmed objective response rate of 33%. As secondary endpoints, the disease control rate was 79%, and the median progression-free survival and overall survival were 7.3 and 17.4 months respectively. Among the 33 patients, 32 (97.0%) had treatment-related adverse events (AEs). Three (9.1%) reported grade ≥ 3 AEs, including rash (n = 1), neutropenia (n = 2). The post-hoc evaluation of dynamic circulating tumor DNA using next generation sequencing and the analysis of peripheral immune proteomics landscape using Olink revealed that lower variant allele frequency (VAF) at baseline, greater reduction in VAF on treatment, and a hot peripheral macroenvironment were associated with the treatment response independently. Our study showed the antitumor activity of tislelizumab, cetuximab, and irinotecan combination with a tolerable safety profile in previously treated MSS and RAS WT mCRC.

Difference in serum cytokines between metastatic colorectal cancer patients with mutant and wild type RAS in response to targeted treatment with monoclonal antibodies

Difference in serum cytokines between metastatic colorectal cancer patients with mutant and wild type RAS in response to targeted treatment with monoclonal antibodies

Efficacy of anti-epidermal growth factor antibody rechallenge in RAS/BRAF wild-type metastatic colorectal cancer: a multi-institutional observational study

PurposeTo investigate circulating tumor DNA (ctDNA) RAS mutant (MT) incidence before salvage-line treatment and the clinicopathological features and molecular biological factors associated with the efficacy of anti-epithelial growth factor receptor (EGFR) monoclonal antibody (mAb) rechallenge for tissue RAS/BRAF wild type (WT) metastatic colorectal cancer (mCRC).MethodsThis multi-institutional retrospective observational study included 74 patients with mCRC with tissue RAS/BRAF WT refractory to first-line chemotherapy containing anti-EGFR mAb. ctDNA RAS status was assessed using the OncoBEAM™ RAS CRC Kit. We explored the clinicopathological features associated with ctDNA RAS status and the factors related to anti-EGFR mAb rechallenge efficacy in multivariate Cox proportional hazard regression.ResultsThe incidence of RAS MT in ctDNA was 40.5% (30/74), which was associated with primary tumor resection (P = 0.016), liver metastasis (P < 0.001), and high tumor marker levels (P < 0.001). Among the 39 patients treated with anti-EGFR mAb rechallenge, those with ctDNA RAS WT showed significantly longer progression-free survival (PFS) than those with ctDNA RAS MT (median 4.1 vs. 2.7 months, hazard ratio [HR] = 0.39, P = 0.045). Patients who responded to first-line anti-EGFR mAb showed significantly longer PFS (HR = 0.21, P = 0.0026) and overall survival (OS) (HR = 0.23, P = 0.026) than those with stable disease.ConclusionsThe incidence of ctDNA RAS MT mCRC was 40.5%, which was associated with liver metastases and high tumor volumes. Anti-EGFR mAb rechallenge may be effective for patients with mCRC who responded to first-line chemotherapy containing anti-EGFR mAb. No patients with RAS MT in ctDNA responded to anti-EGFR mAb rechallenge.

Loss-of-function mutation of REV1 (p.R704Q) mediates cetuximab primary resistance by activating autophagy in RAS-wild type metastatic colorectal cancer

Cetuximab in combination with FOLFIRI/FOLFOX is the standard first-line treatment for patients with RAS wild-type metastatic colorectal cancer (mCRC). However, some patients experience rapid tumor progression after treatment with cetuximab (primary resistance). Our previous research identified a gene mutation, REV1 p.R704Q, which may be a key biomarker for primary cetuximab resistance. This study aimed to study the mechanism of cetuximab resistance caused by REV1 p.R704Q mutation and reveal a novel mechanism to induce cetuximab resistance. Sanger sequencing and multivariate clinical prognostic analysis of 208 patients with mCRC showed that REV1 p.R704Q mutation is an independent risk factor for tumor progression after treatment with cetuximab in patients with RAS wild-type mCRC (Hazard ratio = 2.481, 95 % Confidence interval: 1.389–4.431, P = 0.002). The sensitivity of REV1 p.R704Q mutant cell lines to cetuximab decreased in vitro Cell Counting Kit-8 assay and in vivo subcutaneous tumor model. In vitro, we observed that decreased stability and accelerated degradation of REV1 mutant protein results in REV1 dysfunction, which activated autophagy and mediated cetuximab resistance. These findings suggested that REV1 p.R704Q mutation could predict cetuximab primary resistance in mCRC. REV1 p.R704Q mutation caused decreased stability and degradation of REV1 protein, as well as dysfunction of p.R704Q protein. REV1 p.R704Q mutation activates autophagy and mediates cetuximab resistance; further, inhibition of autophagy could reverse cetuximab resistance.

Radiomic Parameters for the Evaluation of Response to Treatment in Metastatic Colorectal Cancer Patients with Liver Metastasis: Findings from the CAVE-GOIM mCRC Phase 2 Trial.

CAVE is a single arm, Phase 2 trial, that demonstrated anti-tumor activity of cetuximab rechallenge plus avelumab in patients with RAS wild type (wt) metastatic colorectal cancer (mCRC). We conducted a post hoc analysis to identify potential radiomic biomarkers for patients with CRC liver metastasis (LM). Patients with LM that could be measured by enhanced contrast phase computed tomography (CT) imaging at baseline and at first response evaluation were included. Multiple texture parameters were extracted with the LifeX Software. Delta-texture (D-TA) variations were calculated by comparing data at baseline and after treatment. Overall, 55/77 patients (71%) had LM; 39 met the inclusion criteria for the current analysis. The D-TA parameters that significantly correlated at univariate analysis with median progression-free survival (mPFS) were EntropyHistogram (p = 0.021), HomogeneityGLCM (p < 0.001) and Dissimilarity GLCM (p = 0.002). At multivariate analysis, only HomogeneityGLCM resulted significant for PFS (p = 0.001). Patients (19/39, 48.7%) with reduction of HomogeneityGLCM experienced better mPFS (4.6 vs 2.9 months; HR 0.45; 95% CI 0.23-0.88; p = 0.021) and median overall survival (mOS) (17.3 vs 6.8 months; HR 0.40, 95% CI 0.21-0.80; p = 0.010). A trend to better mPFS, was also observed in patients with RAS/BRAF wt circulating tumor DNA and reduction of HomogeneityGLCM. Overall survival was significantly better in this subgroup of patients with low HomogeneityGLCM: mOS was 17.8 (95% CI 15.5-20.2) versus 6.8 months (95% CI 3.6-10.0) (HR 0.34, 95% CI 0.14-0.81; p = 0.016). Reduction in the D-TA parameter HomogeneityGLCM by radiomic analysis correlates with improved outcomes in patients with LM receiving cetuximab rechallenge plus avelumab therapy. Larger prospective studies are needed to validate and confirm these findings.