KRAS Wt Tumors Research Articles

Divergent clinical and immunologic outcomes based on STK11 co-mutation status in resectable KRAS-mutant lung cancers following neoadjuvant immune checkpoint blockade.

Co-mutations of the KRAS and STK11 genes in advanced non-small cell lung cancer (NSCLC) are associated with immune checkpoint blockade (ICB) resistance. While neoadjuvant chemoimmunotherapy is now a standard of care treatment for resectable NSCLC, the clinical and immunologic impact of KRAS andSTK11 co-mutations in this setting are unknown. We evaluated and compared recurrence-free survival of resectable KRAS-mutated NSCLC tumors, with or without co-occuring STK11 mutations, treated with neoadjuvant ICB. Single cell transcriptomics was performed on tumor-infiltrating T cells from 7 KRASmut/STK11wttumors and 6 KRASmut/STK11mut tumors. Relative to KRASmut/STK11wttumors, KRASmut/STK11mut exhibited significantly higher recurrence risk. Single-cell transcriptomics showed enhanced oxidative phosphorylation with evidence of decreased PGE-2 signaling and increased IL-2 signaling in CD8+ tumor-infiltrating lymphocytes (TIL) from KRASmut/STK11mut tumors, a finding that was mirrored in KRASwt tumors that relapsed. TIL from KRASmut/STK11mut tumors expressed high levels of molecules associated with tumor residence, including CD39 and ZNF683 (HOBIT). These divergent T cell transcriptional fates suggest T cell maintenance and residence may be detrimental to anti-tumor immunity in the context of neoadjuvant ICB for resectable NSCLC, regardless of KRAS mutation status. Our work provides a basis for future investigations into the mechanisms underpinning PGE-2 and IL-2 signaling as they relate to T cell immunity to cancer and to divergent clinical outcomes in KRASmut/STK11mut NSCLC treated with neoadjuvant ICB.

KRAS mutations and their prognostic implications in appendiceal cancers.

4177 Background: Despite shared embryonic origin, appendiceal cancers (AC) have distinct clinical and molecular features compared to colorectal cancers (CRC). Detection of mutant KRAS has been associated with worse survival in CRC, whereas in AC the prognostic significance of mutant KRAS (55-65% prevalence) has yet to be characterized. Methods: AC tissues from 852 individual patients that underwent DNA (592, NextSeq, or whole exome sequencing) and whole transcriptome sequencing (NovaSeq) at Caris Life Sciences (Phoenix, AZ) were analyzed. Low-grade appendiceal mucinous neoplasms were excluded. Chi-square, Fishers-exact, and Mann Whitney U tests were used to determine statistical significance and were adjusted for multiple hypothesis testing (p< 0.05). Real-world overall survival (OS) was calculated using insurance claims of AC patients from time of sample collection to last contact. Hazard ratios (HRs) were calculated using the Cox proportional hazards model (log-rank test). Multivariate regression analysis was performed on age, sex, histology, site, comutations and KRASmut vs. KRASwt. Results: AC histological subtypes comprised mucinous adenocarcinoma (37.9%), goblet cell carcinoma (19.6%), signet ring cell carcinoma (12.1%), and adenocarcinoma- not otherwise specified (NOS, 30.4%). Among all AC specimens, KRAS was the most common mutation (49%). KRASmut vs. KRASwt tumors were more frequently associated with TP53mut (51.2% vs. 36.8%, respectively; p< 0.01) and GNASmut (41.1% vs. 5.7%, respectively; p < 0.00001). Most frequent co-mutant gene with KRAS was TP53 (61.2%) in adenocarcinoma-NOS, and GNAS (46.9%) in mucinous adenocarcinomas.Median OS among KRASmut vs. KRASwt was 33.3 vs. 25.1 months, respectively (HR 0.68, 95% CI: 0.58-0.80, p < 0.00001). KRASmut was associated with improved survival in mucinous adenocarcinomas (HR 0.71; 95% CI: 0.52-0.96, p = 0.028) and adenocarcinoma-NOS (HR 0.77; 95% CI: 0.62-0.97, p = 0.025), but not with signet ring cell (HR 1.92; 95% CI: 0.90-4.10, p = 0.087) or goblet cell carcinoma (HR 1.39; 95% CI: 0.50-3.91, p = 0.536). Multivariate analysis showed KRASmut was an independent prognostic factor for improved survival among all AC (HR 0.77, 95% CI: 0.64-0.93, p = 0.007) and mucinous adenocarcinoma (HR 0.60, 95% CI: 0.42-0.84, p<0.0001).Notably, GNASmut was associated with improved survival (HR 0.57, 95% CI: 0.47-0.70, p < 0.00001), while TP53mut was associated with poorer survival (HR 1.58, 95% CI: 1.35-1.86, p < 0.00001) among all AC. Conclusions: KRAS was one of most frequently mutated genes in ACs. In contrast to CRC, KRASmut was associated with significantly improved survival. This observed survival advantage remained consistent in the histologic subgroup of mucinous adenocarcinoma, but not in goblet and signet ring cell cancers. Further studies with population level data understanding the molecular profiles and their survival implications in histologically distinct AC are needed.

Abstract 447: Anti-tumor efficacy of ompenaclid, a creatine transporter inhibitor, in KRAS mutant tumors, including NSCLC

Abstract Background: Pre-clinical studies identified creatine metabolism to be activated in KRAS mutant metastatic colorectal cancer (CRC) as a mechanism to fuel the increased energy demands of RAS mutant tumors. Metastatic colon cancer cells overexpress and subsequently release creatine kinase-B (CKB) into the extracellular space, where it phosphorylates creatine to generate the high energy metabolite phosphocreatine. Ompenaclid is a small molecule inhibitor of the creatine transporter SLC6A8. Inhibition of SLC6A8 by ompenaclid prevents import of phosphocreatine/creatine, resulting in depletion of intracellular creatine, phosphocreatine and ATP levels. This results in tumor apoptosis and robust anti-tumor efficacy in CRC models with a wide range of KRAS mutant alleles. Ompenaclid is currently in a Phase 2 trial, in combination with FOLFIRI and bevacizumab, in patients with RAS-mutated second-line advanced/metastatic colorectal cancer. Here, we assessed efficacy of ompenaclid in tumors beyond CRC, including KRAS WT and KRAS mutant NSCLC. Methods: Athymic mice were inoculated with CRC, pancreatic, gastric or NSCLC cancer cell lines and treated with ompenaclid once tumors reached ~150 mm3, until termination. Plasma metabolites were quantified by LC-MS/MS and tumoral expression of CKB and SLC6A8 in NSCLC and CRC tumors was measured by qPCR after treatment with a control or ompenaclid-supplemented diet for ~10 days. Combination treatment with MRTX849, a KRAS G12C inhibitor, was conducted in a pancreatic MiaPaca xenograft model. Results: Our studies demonstrate ompenaclid anti-tumor efficacy in NSCLC and pancreatic xenografts. Notably, and consistent with findings in CRC, efficacy in NSCLC was more robust in RAS mutant cancer models, relative to those bearing KRAS WT tumors. Metabolite analysis of the plasma of tumor-bearing mice at baseline revealed that mice harboring RAS mutant tumors had higher levels of p-creatine and lower levels of ATP, indicating that RAS mutant tumors utilize higher amounts of ATP, which may be converted to phosphocreatine by tumoral CKB, as confirmed by qPCR analysis. This finding is consistent with metastatic RAS mutant CRC tumors utilizing extracellular ATP to generate phosphocreatine and thus exhibiting greater dependency on creatine metabolism relative to RAS WT tumors. Treatment with ompenaclid also demonstrated additive efficacy in combination with KRAS G12C inhibitors. In summary, these data support development of ompenaclid in indications beyond CRC, including NSCLC, as well as in combination with KRAS G12C inhibitors. Citation Format: PuiChi Lo, Victor Sanz Chavez, Shugaku Takeda, Masoud Tavazoie, Isabel Kurth. Anti-tumor efficacy of ompenaclid, a creatine transporter inhibitor, in KRAS mutant tumors, including 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 447.

Abstract C074: Clinico-genomic characterization of N=2,460 pancreatic adenocarcinoma identifies KRASMUT dosage as prognostic of overall survival across disease stages

Abstract Background: The majority (~80%) of patients (pts) with pancreatic adenocarcinomas (PDAC) present with advanced disease. Most sequencing efforts to date have focused on early stage disease. Herein, we leverage a large clinical sequencing cohort of N= 2460 pts with PDAC to characterize the clinico-genomic landscape across different disease stages. Methods: Tumors from 2460 pts were sequenced using MSK-IMPACT clinical sequencing assay and mutations called via CLIA-approved pipelines. Detailed clinical descriptors including lines of treatment and response were abstracted for N=1451 (59%) pts. Intratumor heterogeneity estimates including allele-specific copy number were inferred using FACETS. Results: Of N=2460, at diagnosis 34% of pts had resectable tumors, and 24% and 42% had locally advanced and metastatic disease, respectively. 94% of pts had KRASMUT tumors. Expectedly, MAPK pathway alterations were significantly enriched in KRASWT tumors (60% vs. 7% in KRASMUT, p < 0.001) with gain-of-function kinase oncogene fusions exclusively observed in these tumors (p<0.001). In addition, GNAS, PTEN, FOXP1, SMARCB1 and CREBBP were enriched in the KRASWT tumors (q < 0.05). Collectively, pts with KRASWT/MAPK MUT and KRASWT/MAPK WT tumors comprise 4% and 2% of all pts PDAC, respectively. Germline pathogenic variants in high/moderate penetrance genes were more common in pts with KRASWT tumors compared to pts with KRASMUT tumors (20% vs. 10%, p < 0.001). Pathogenic germline alterations in BRCA1/2 and PALB2 were observed in 6% (N=144) of cohort. Biallelic inactivation of BRCA2 specifically was associated with prolonged response of metastatic pts to PARP-inhibitor maintenance therapy with 10.3 months on treatment prior to progression compared to 3.4 months for those with biallelic inactivation of other HRD genes and 2.2 months for those with non-biallelic inactivation. Among KRASMUT tumors assessed for KRAS copy-number allelic imbalance (AI) (N=1097), 41% (N=452) had AI at the KRAS locus with mutant-allele selected for in 94% of tumors with imbalance. Among KRASMUT tumors with normal genome ploidy, overall, 20% had a mutant allele gain ranging from 10% in resectable to 29% of metastatic tumors. We observe significantly lower OS among pts with KRASMUT dosage gain compared to heterozygous KRASMUT across pts with resectable (HR: 0.66, 95% CI: 0.18-1.15, p<0.01) and metastatic (HR: 0.39, 95% CI: 0.16-0.63, p=0.001) diseases with statistical significance not reached among the locally advanced disease (HR: 0.4, 95% CI: -0.01-0.81, p=0.056). Notably, the OS of pts with loss of the wild-type allele and no mutant copy gain was indistinguishable from that of heterozygous KRASMUT tumors (HR: -0.11, 95% CI: -0.37-0.15, p=0.4). Conclusion: In this large cohort of 2460 pts with PDAC, we observed that KRASMUT dosage gain is a significant negative predictor of OS. These findings highlight the importance of incorporating allelic-dosage into comprehensive molecular testing in PDAC given prognostic importance and the emerging era of direct RAS targeting. Citation Format: Anna M. Varghese, Maria A. Perry, Daniel Muldoon, Subhiksha Nandakumar, Amanda Erakky, Bastien Nguyen, Amanda Zucker, Hulya Sahin Ozkan, Olca Basturk, Debyani Chakravarty, David P. Kelsen, Wungki Park, Kenneth H. Yu, Alice C. Wei, Nikolaus Schultz, Michael F. Berger, Christine Iacobuzio-Donahue, Chaitanya Bandlamudi, Eileen M. O'Reilly. Clinico-genomic characterization of N=2,460 pancreatic adenocarcinoma identifies KRASMUT dosage as prognostic of overall survival across disease stages [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr C074.

Chemotherapy-free treatment targeting fusions and driver mutations in KRAS wild-type pancreatic ductal adenocarcinoma, a case series.

KRAS wild-type (WT) pancreatic ductal adenocarcinoma (PDAC) represents a distinct entity with unique biology. The therapeutic impact of matched targeted therapy in these patients in a real-world setting, to date, is less established. The aim of our study was to review our institutional database to identify the prevalence of actionable genomic alterations in patients with KRAS-WT tumors and to evaluate the therapeutic impact of matched targeted therapy in these patients. We reviewed electronic medical records of patients with KRAS-WT PDAC and advanced disease (n = 14) who underwent clinical-grade tissue ± liquid next-generation sequencing (315-648 genes for tissue) between years 2015 and 2021. Demographic and disease characteristics were summarized using descriptive parameters. Progression-free survival (PFS) and overall survival (OS) were estimated using the Kaplan-Meier method. Of 236 PDAC patients, 14 had advanced/metastatic disease with KRAS-WT tumors. Median age at diagnosis was 66 years. There was a high frequency of potentially actionable genomic alterations, including three (21%) with BRAF alterations, two (14%) with fusions [RET-PCM1 and FGFR2-POC1B (N = 1 each)]; and one with a druggable EGFR (EGFR E746_A755delISERD) variant; two other patients had an STK11 and a MUTYH alteration. Five patients were treated with matched targeted therapy, with three having durable benefit: (i) erlotinib for EGFR-altered tumor, followed by osimertinib/capmatinib when MET amplification emerged (first-line therapy); (ii) pralsetinib for RET fusion (fifth line); and (iii) dabrafenib/trametinib for BRAF N486_P490del (third line). Duration of time on chemotherapy-free matched targeted therapy for these patients was 17+, 11, and 18+ months, respectively. Sustained therapeutic benefit can be achieved in a real-world setting in a subset of patients with advanced/metastatic KRAS-WT PDAC treated with chemotherapy-free matched targeted agents. Prospective studies are warranted.

Prognostic Role of KRAS G12C Mutation in Non-Small Cell Lung Cancer: A Systematic Review and Meta-Analysis.

KRAS G12C mutation (mKRAS G12C) is the most frequent KRAS point mutation in non-small cell lung cancer (NSCLC) and has been proven to be a predictive biomarker for direct KRAS G12C inhibitors in advanced solid cancers. We sought to determine the prognostic significance of mKRAS G12C in patients with NSCLC using the meta-analytic approach. A protocol is registered at the International Prospective Register for systematic reviews (CRD42022345868). PubMed, EMBASE, The Cochrane Library, and Clinicaltrials.gov.in were searched for prospective or retrospective studies reporting survival data for tumors with mKRAS G12C compared with either other KRAS mutations or wild-type KRAS (KRAS-WT). The hazard ratios (HRs) for overall survival (OS) or Disease-free survival (DFS) of tumors were pooled according to fixed or random-effects models. Sixteen studies enrolling 10,153 participants were included in the final analysis. mKRAS G12C tumors had poor OS [HR, 1.42; 95% CI, 1.10-1.84, p = 0.007] but similar DFS [HR 2.36, 95% CI 0.64-8.16] compared to KRAS-WT tumors. Compared to other KRAS mutations, mKRAS G12C tumors had poor DFS [HR, 1.49; 95% CI, 1.07-2.09, p < 0.0001] but similar OS [HR, 1.03; 95% CI, 0.84-1.26]. Compared to other KRAS mutations, high PD-L1 expression (>50%) [OR 1.37 95% CI 1.11-1.70, p = 0.004] was associated with mKRAS G12C tumors. mKRAS G12C is a promising prognostic factor for patients with NSCLC, negatively impacting survival. Prevailing significant heterogeneity and selection bias might reduce the validity of these findings. Concomitant high PD-L1 expression in these tumors opens doors for exciting therapeutic potential.

Abstract A001: Clinical-genomic analysis of KRAS wild-type pancreatic cancer confirms alternative targetable drivers and provides insight for age and risk related clinical stratification

Abstract Approximately 8-10% of pancreatic cancers do not harbor mutations in KRAS. Understanding the unique molecular and clinical features of this subset of pancreatic cancer (PC) is important to guide patient stratification for clinical trials of molecularly targeted agents. To this end we investigated a cohort of 795 PC patients from Dana-Farber Cancer Institute who had undergone somatic genomic characterization with OncoPanel, a targeted next-generation sequencing panel with coverage of more than 400 cancer-associated genes. A total of 9.2% (73/795) of cases in our cohort were KRAS WT. The KRAS WT cohort was statistically enriched for MSI-H PC and acinar cell carcinomas (p = 0.0035, p &amp;lt; 0.0001 respectively). Actionable alterations in alternative MAPK drivers were identified in 44% (32/73) of KRAS WT cases. BRAF alterations accounted for 56% (18/32) of detected alternative MAPK drivers, the majority of which (72%) were Class II which exhibit dimer-dependent constitutive activity. Receptor Tyrosine Kinase (RTK) fusion events in BRAF, NTRK1, NRG1, NTRK3, ROS1, and FGFR2 accounted for 25% (8/32) of detected alternative MAPK drivers in KRAS WT tumors. BRAF in-frame deletions showed increased sensitivity to dual pan-RAF and MEK inhibition in organoid models and one patient with a ROS1 fusion received prolonged clinical benefit from targeted therapy. In addition to alternative MAPK drivers, mutations in GNAS (p = 0.0014) and ARID2 (p = 0.045) were significantly enriched in KRAS WT PC, whereas TP53 mutations were significantly less frequent in KRAS WT cases. Interestingly, although not statistically significant, rates of mutation in the other canonical tumor suppressor genes (CDKN2A, SMAD4) were also lower in KRAS WT PC. Clinically, KRAS Mutant (MUT) PC were associated with a decreased overall survival (OS) compared to the KRAS WT cohort [median OS 17.5 vs 24.0 months, HR 1.38, p = 0.036], however this relationship was no longer significant after accounting for other clinical factors. For patients with KRAS WT PC, those with SMAD4 alterations had a significantly decreased OS (HR 6.24, p &amp;lt; 0.001), whereas presence of TP53 or CDKN2A mutations had no significant impact. Lastly, we found that KRAS WT PC was associated with a younger age of onset. Interestingly, we noted that KRAS WT PC patients with a younger age of onset had tumors with few oncogenic alterations whereas no such association was seen in KRAS MUT patients. Validation of this finding in a separate dataset is required and is currently ongoing. In summary, our clinical and genomic characterization of KRAS WT PC identifies a high prevalence of alternative MAPK drivers that are amenable to targeted therapies. Our cohort also recapitulates the previously reported clinical characteristics of KRAS WT PC and identifies the presence of SMAD4 alterations as significantly associated with decreased overall survival in KRAS WT PC. Additional analysis from multiple sources will be critical to risk stratify these patients further and to validate age-related findings. Citation Format: Harshabad Singh, Rachel B. Keller, Kevin S. Kapner, Julien Dilly, Srivatsan Raghavan, Chen Yuan, Eizabeth Cohen, Michael Tolstorukov, Emma Hill, Elizabeth Andrews, Lauren K. Brais, Annacarolina Da Silva, Kimberly Perez, Douglas A. Rubinson, Benjamin L. Schlechter, Michael H. Rosenthal, Jason L. Hornick, Valentina Nardi, Yvonne Li, Hersh Gupta, Andrew Cherniack, Mathew L. Meyerson, James M. Cleary, Jonathan A. Nowak, Brian M. Wolpin, Andrew A. Aguirre. Clinical-genomic analysis of KRAS wild-type pancreatic cancer confirms alternative targetable drivers and provides insight for age and risk related clinical stratification [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr A001.

WIN Symposium 2022 - Abstract Poster Presentations.

WIN Symposium 2022 - Abstract Poster Presentations.

Prognostic Factors of Survival in Patients with Peritoneal Metastasis from Colorectal Cancer.

Objectives: The aim of this study was to analyze the prognostic factors of survival in patients with peritoneal metastasis (PM) from colorectal cancer (CRC). The type of relationship between survival and the PM time of detection was used to determine whether it was synchronous with the primary tumor or metachronous. Patients and Methods: Retrospective observational study. It included patients treated for colorectal adenocarcinoma diagnosed between January 2005 and December 2019 who presented PM at the time of diagnosis or during follow-up. Variables, such as sex, age, differentiation grade, positive adenopathy (pN+), tumor size (pT), tumor location, mucinous component, peritoneal carcinomatosis index (PCI), and KRAS mutational status, were analyzed. Results: During the study period, 1882 patients were surgically treated for CRC in our hospital. Of these, 240 patients (12.8%) were included in the study after evidence of PM. The mean age was 67 ± 12 years (range: 32–92 years), and 114 patients were female (47.5%). The mean follow-up was 20 ± 13 months (median 12 months). The Kaplan–Meier survival at 36 months was higher in patients with metachronous PM (24% vs. 8%; p = 0.002), WT-KRAS tumors (31% vs. 15%; p < 0.001), N0 stage (30% vs. 19%; p < 0.001), T3 stage tumors (18% vs. 19% in T4A and 3% in T4B; p > 0.001), and tumors with classic adenocarcinoma histology (18% vs. 8%; p = 0.011). Patients with a PCI of 1–10 showed a likelihood of survival at 36 months of 56%, which was longer than that found in patients with a PCI of 11–20 (8%) or a PCI of >20 (0%) (p < 0.001). In the multiple regression analysis, the factors with an independent prognostic value were: poor grade of differentiation (HR 1.995; 95% CI: 1.294–3.077), KRAS mutation (HR 1.751; 95% CI: 1.188–2.581), PCI 11–20 (HR: 9.935; 95% CI: 5.204–18.966) and PCI > 20 (HR: 4.011; 95% CI: 2.291–7.023). Conclusions: PCI should continue as the as the most useful prognostic indicator in order to assess prognostic estimations as well as therapeutic and surgical decisions, but tumor grade and KRAS mutational status may help in the treatment decision process by providing complementary information. The time of PM detection did not achieve statistical significance in the multiple regression analysis.

Does Molecular Profiling of KRAS-Mutant Non-Squamous Non-Small Cell Lung Cancer (NSCLC) Help in Treatment Strategy Planning?

Background: Several studies suggest that patients with KRAS-mutant NSCLC fail to benefit from standard systemic therapies and do not respond to EGFR inhibitors. Most recently, KRAS 12c data suggest specific treatment for improving ORR and OS. There is a clear need for therapies specifically developed for these patients. Moreover, data that might be suggestive of a response to specific therapies, such as BRCA1, are needed, and two mutations that were studied in other malignancies show more response to PARP inhibitors. Molecular profiling has the potential to identify other potential targets that may provide better treatment and novel targeted therapy for KRAS-mutated NSCLC. Methods: We purified RNA from archived tissues of patients with stage I and II NSCLC with wild-type (wt) and mutant (mt) KRAS tumors; paired normal tissue adjacent to the tumor from 20 and 17 patients, respectively, and assessed, using real-time reverse transcriptase–polymerase chain reaction (RT-PCR), the expression of four genes involved in DNA synthesis and repair, including thymidylate synthase (TS), BRCA1, ECCR1, RAP80, and the proto-oncogene SRC. Additionally, we assessed the expression of PD-L1 in mt KRAS tumors with immunohistochemistry using an antibody against PD-L1. Results: Our results show that in mt KRAS tumors, the level of expression of ERCC1, TS, and SRC was significantly increased in comparison to paired normal lung tissue (p ≤ 0.04). The expression of BRCA1 and RAP80 was similar in both mt KRAS tumors and paired normal tissue. Furthermore, the expression of BRCA1, TS, and SRC was significantly increased in wt KRAS tumors relative to their expression in the normal lung tissue (p < 0.044). The expression of ERCC1 and RAP80 was similar in wt KRAS tumors and paired normal tissue. Interestingly, SRC expression in mt KRAS tumors was decreased in comparison to wt KRAS tumors. Notably, there was an expression of PD-L1 in the tumor and stromal cells in a few (5 out of 20) mt KRAS tumors. Our results suggest that a greater ERCC1 expression in mt KRAS tumors might increase platinum resistance in this group of patients, whereas the greater expression of BRCA1 in wt KRAS tumor might be suggestive of the sensitivity of taxanes. Our data also suggest that the combination of an SRC inhibitor with a TS inhibitor, such as pemetrexed, might improve the outcome of patients with NSCLC and in particular, patients with wt KRAS tumors. PD-L1 expression in tumors, and especially stromal cells, suggests a better outcome. Conclusion: mt KRAS NSCLC patients might benefit from a treatment strategy that targets KRAS in combination with therapeutic agents based on pharmacogenomic markers, such as SRC and BRCA1. mt KRAS tumors are likely to be platinum-, taxane-, and pemetrexed-resistant, as well as having a low level of PD-L1 expression; thus, they are less likely to receive single-agent immunotherapy, such as pembrolizumab, as the first-line therapy. wt KRAS tumors with BRCA1 positivity tend to be sensitive to taxane therapy and, potentially, platinum. Our results suggest the need to develop targeted therapies for KRAS-mutant NSCLC or combine the targeting of oncogenic KRAS in addition to other therapeutic agents specific to the molecular profile of the tumor.

Abstract LB129: Analysis of KRAS wildtype pancreatic ductal adenocarcinoma reveals mutation and expression-based similarities to cholangiocarcinoma

Abstract Introduction Oncogenic KRAS mutations are absent in 10% of patients with pancreatic ductal adenocarcinoma (PDAC) and may represent a subgroup of PDAC with therapy options beyond standard-of-care chemotherapy. While distinct gene fusions have been implicated in KRAS wildtype (wt) PDAC, other traits unique to KRAS wt PDAC remain unexplored. Methods Patients with treatment-naive metastatic PDAC (n=63) received matched tumor/normal whole-genome and RNA sequencing and clinical follow-up as part of the PanGen trial (NCT02869802). Clinical data and mutation, gene fusion and copy alteration frequency was compared between KRAS wt (n=9) and mutant (n=54) groups. Metastatic colorectal adenocarcinoma and cholangiocarcinoma samples from the POG trial (NCT02155621) were incorporated for sequencing-based comparison. Results KRAS wt tumors showed lower frequency of TP53 SNV/indels (p=0.01) and distinct amplifications affecting chr1q genes NR5A2 (p=9.0e-4), MPC2 (p=0.002) and MCL1 (p=0.02) and chr8q gene SQLE (p=0.02). Oncogenic fusions involving NRG1, FGFR2, NTRK2 or BRAF were unique to KRAS wt tumors (67% of samples; p=1e-6). KRAS wt tumors showed expression patterns indicative of cholangiocytes and, when clustered alongside other tumor types, formed a distinct cluster with cholangiocarcinoma samples. Conclusion These data provide the first identification of distinct chr1q/chr8q amplification events unique to KRAS wt PDAC while highlighting novel and striking molecular similarities to cholangiocarcinoma. Taken together, results of the PanGen trial generate new hypotheses relevant to therapeutic targeting of KRAS wt PDAC and rationale towards incorporating KRAS mutation status as part of routine clinical testing in PDAC. Citation Format: James Topham, Erica Tsang, Joanna Karasinska, Andrew Metcalfe, Hassan Ali, Steve Kalloger, Veronika Csizmok, Laura Williamson, Emma Titmuss, Hui-Li Wong, Richard Moore, Andrew Mungall, Jonathan Loree, Oliver Bathe, Patricia Tang, Rachel Goodwin, Janessa Laskin, Marco Marra, Steven Jones, David Schaeffer, Daniel Renouf. Analysis of KRAS wildtype pancreatic ductal adenocarcinoma reveals mutation and expression-based similarities to cholangiocarcinoma [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 LB129.

Integrative analysis of KRAS-wildtype pancreatic ductal adenocarcinoma reveals unique similarities to extrahepatic cholangiocarcinoma.

587 Background: Oncogenic driver mutations in KRAS represent a hallmark genomic event in approximately 90% of pancreatic adenocarcinoma (PDAC). For the remaining 10% of patients with KRAS wildtype (wt) PDAC, distinct driver mutations have been described, but their transcriptional landscape has not been reported. Here, we leverage sequencing data from the PanGen trial to provide a comprehensive characterization of advanced KRASwt PDAC. Methods: 63 patients with advanced PDAC received whole genome and transcriptome sequencing prior to treatment for metastatic disease as part of the PanGen trial (NCT02869802). Clinical features, somatic mutation data and gene expression patterns were compared between KRASwt and mutant groups. PDAC samples were contrasted with 77 other metastatic carcinoma (colorectal and cholangiocarcinoma) samples from the Personalized OncoGenomics trial (NCT0215562). KRAS wt-associated genes were further investigated using 3 additional PDAC cohorts (COMPASS NCT02750657, TCGA, and ICGC). Results: 9 of 63 (14%) samples were KRASwt, with an earlier median age at diagnosis (51.4 vs. 60.9 years; p=0.03). Clinical features, including diabetes, family history of malignancy, and location of primary tumor, were comparable. CA 19-9 at baseline was lower in the KRASwt group, with median 58 vs. 4900 U/mL in the KRAS-mutant group ( p=0.03). Patients with KRASwt PDAC showed increased overall survival in univariable ( p=0.0024) and multivariable ( p=0.0089) analyses. 6 of 9 (67%) KRASwt tumors had fusions involving NRG1 (n = 3), FGFR2 (n = 1), BRAF (n = 1) or NTRK2 (n = 1), while known actionable fusions were not observed in KRAS mutant patients. KRASwt tumors showed increased expression of genes associated with cholangiocytes and grouped with cholangiocarcinoma samples in unsupervised clustering analysis. Validation using three independent PDAC cohorts revealed a core set of 70 KRAS wt-associated genes that converge on keratinization, ion transport, and hormone metabolism pathways. Conclusions: Patients with KRASwt PDAC show potentially targetable molecular traits with actionable fusions. We also highlight novel mutation and expression-based similarities between KRASwt PDAC and cholangiocarcinoma samples. Recurrent dysregulation of genes involved in cellular structure and metastasis provide impetus for further investigation into the developmental trajectory and potential therapeutic vulnerabilities of KRASwt PDAC.

Uptake of KRAS Testing and Anti-EGFR Antibody Use for Colorectal Cancer in the VA.

We conducted a retrospective cohort study of patients with stage IV CRC diagnosed in the VA 2006-2015. We gathered clinical, demographic, molecular, and treatment data from the VA Corporate Data Warehouse and 29 commercial laboratories. We performed multivariable analyses of associations between patient characteristics, KRAS testing, and EGFR mAb treatment. Among 5,943 patients diagnosed with stage IV CRC, only 1,053 (17.7%) had KRAS testing. Testing rates increased from 2.3% in 2006 to 28.4% in 2013. In multivariable regression, older patients (odds ratio, 0.17; 95% CI, 0.09 to 0.32 for ≥ age 85 v < 45 years) and those treated in the Northeast and South regions were less likely, and those treated at high-volume CRC centers were more likely to have KRAS testing (odds ratio, 2.32; 95% CI, 1.48 to 3.63). Rates of potentially guideline discordant care were high: 64.3% (321/499) of KRAS wild-type (WT) went untreated with EGFR mAb and 8.8% (401/4,570) with no KRAS testing received EGFR mAb. Among KRAS-WT patients, survival was better for patients who received EGFR mAb treatment (29.6 v 18.8 months; P < .001). We found underuse of KRAS testing in advanced CRC, especially among older patients and those treated at lower-volume CRC centers. We found high rates of potentially guideline discordant underuse of EGFR mAb in patients with KRAS-WT tumors. Efforts to understand barriers to precision oncology are needed to maximize patient benefit.

Prognostic and Predictive Impact of Primary Tumor Sidedness for Previously Untreated Advanced Colorectal Cancer.

Unplanned subgroup analyses from several studies have suggested primary tumor sidedness (PTS) as a potential prognostic and predictive parameter in metastatic colorectal cancer (mCRC). We aimed to investigate the impact of PTS on outcomes of mCRC patients. PTS data of 9277 mCRC patients from 12 first-line randomized trials in the ARCAD database were pooled. Overall survival (OS) and progression-free survival (PFS) were assessed using Kaplan-Meier and Cox models adjusting for age, sex, performance status, prior radiation/chemotherapy, and stratified by treatment arm. Predictive value was tested by interaction term between PTS and treatment (cetuximab plus chemotherapy vs chemotherapy alone). All statistical tests were 2-sided. Compared with right-sided metastatic colorectal cancer patients (n = 2421, 26.1%), left-sided metastatic colorectal cancer patients (n = 6856, 73.9%) had better OS (median = 21.6 vs 15.9 months; adjusted hazard ratio [HRadj] = 0.71, 95% confidence interval [CI] = 0.67 to 0.76; P < .001) and PFS (median = 8.6 vs 7.5 months; HRadj = 0.80, 95% CI = 0.75 to 0.84; P < .001). Interaction between PTS and KRAS mutation was statistically significant (Pinteraction < .001); left-sidedness was associated with better prognosis among KRAS wild-type (WT) (OS HRadj = 0.59, 95% CI = 0.53 to 0.66; PFS HRadj =0.68, 95% CI = 0.61 to 0.75) but not among KRAS mutated tumors. Among KRAS-WT tumors, survival benefit from anti-EGFR was confirmed for left-sidedness (OS HRadj = 0.85, 95% CI = 0.75 to 0.97; P = .01; PFS HRadj = 0.77, 95% CI = 0.67 to 0.88; P < .001) but not for right-sidedness. The prognostic value of PTS is restricted to the KRAS-WT population. PTS is predictive of anti-EGFR efficacy, with a statistically significant improvement of survival for left-sidedness mCRC patients. These results suggest treatment choice in mCRC should be based on both PTS and KRAS status.

KRAS G12C Mutation Is Associated with Increased Risk of Recurrence in Surgically Resected Lung Adenocarcinoma.

KRAS G12C is the most common KRAS mutation in primary lung adenocarcinoma. Phase I clinical trials have demonstrated encouraging clinical activity of KRAS G12C inhibitors in the metastatic setting. We investigated disease-free survival (DFS) and tumor genomic features in patients with surgically resected KRAS G12C-mutant lung adenocarcinoma. Patients who underwent resection of stage I-III lung adenocarcinoma and next-generation sequencing (NGS) were evaluated. Exclusion criteria were receipt of induction therapy, incomplete resection, and low-quality NGS. Mutations were classified as KRAS wild-type (KRAS wt), G12C (KRAS G12C), or non-G12C (KRAS other). DFS was compared between groups using the log-rank test; factors associated with DFS were assessed using Cox regression. Mutual exclusivity and cooccurrence, tumor clonality, and mutational signatures were assessed. In total, 604 patients were included: 374 KRAS wt (62%), 95 KRAS G12C (16%), and 135 KRAS other (22%). Three-year DFS was not different between KRAS-mutant and KRAS wt tumors. However, 3-year DFS was worse in patients with KRAS G12C than KRAS other tumors (log-rank P = 0.029). KRAS G12C tumors had more lymphovascular invasion (51% vs. 37%; P = 0.032) and higher tumor mutation burden [median (interquartile range), 7.0 (5.3-10.8) vs. 6.1 (3.5-9.7); P = 0.021], compared with KRAS other tumors. KRAS G12C mutation was independently associated with worse DFS on multivariable analysis. Our DFS findings were externally validated in an independent The Cancer Genome Atlas cohort. KRAS G12C mutations are associated with worse DFS after complete resection of stage I-III lung adenocarcinoma. These tumors harbor more aggressive clinicopathologic and genomic features than other KRAS-mutant tumors. We identified a high-risk group for whom KRAS G12C inhibitors may be investigated to improve survival.

Resection of Colorectal Liver Metastasis: Prognostic Impact of Tumor Burden vs KRAS Mutational Status

The prognostic impact of colorectal liver metastasis (CRLM) morphologic characteristics relative to KRAS mutational status after hepatic resection remains ill defined. Patients undergoing hepatectomy for CRLM between 2001 and 2018 were identified using an international multi-institutional database. Tumor burden score (TBS) was defined as distance from origin on a Cartesian plane that incorporated maximum tumor size (x-axis) and number of lesions (y-axis). Impact of TBS on overall survival (OS) relative to KRAS status (wild type [wtKRAS] vs mutated [mutKRAS]) was assessed. Among 1,361 patients, the median number of metastatic lesions was 2 (interquartile range [IQR] 1-3), and median size of the largest metastatic lesion was 3.0 cm (IQR 2.0-5.0 cm), resulting in a median TBS of 4.1 (IQR 2.8-6.1); KRAS status was wtKRAS (n= 420, 30.9%), mutKRAS (n= 251, 18.4%), and unknown (n= 690, 50.7%). Overall median and 5-year OS were 49.5 months (95%CI 45.2-53.8) and 43.2%, respectively. In examining the entire cohort, TBS was associated with long-term prognosis (5-year OS, low TBS: 49.4% vs high TBS: 36.7%), as was KRAS mutational status (5-year OS, wtKRAS: 48.2% vs mutKRAS: 31.1%; unknown KRAS: 44.0%)(both p < 0.01). Among patients with wtKRAS tumors, TBS was strongly associated with improved OS (5-year OS, low TBS: 59.1% vs high TBS: 38.4%, p= 0.002); however, TBS failed to discriminate long-term prognosis among patients with mutKRAS tumors (5-year OS, low TBS: 37.4% vs high TBS: 26.7%, p= 0.19). In fact, patients with high TBS/wtKRAS CRLM had comparable outcomes to patients with low TBS/mutKRAS tumors (5-year OS, 38.4% vs 37.4%, respectively; p= 0.59). On multivariable analysis, while TBS was associated with OS among patients with wtKRAS CRLM (hazard ratio 1.43, 95%CI 1.02-2.00; p= 0.03), TBS was not an independent predictor of survival among patients with mutKRAS CRLM (HR 1.36, 95%CI 0.92-1.99; p= 0.12). While TBS was associated with survival among patients with wtKRAS tumors, CRLM morphology was not predictive of long-term outcomes among patients with mutKRAS CRLM.

The treatment paradigm of right-sided metastatic colon cancer: harboring BRAF mutation makes the difference.

BRAF mutations represent the main negative prognostic factor for metastatic colorectal cancer and a supposed negative predictive factor of response to standard chemotherapy. We have explored survival difference in right-sided colon cancer (RCC) patients according to BRAF mutations, with the aim to identify any predictive factors of response to targeted-based therapy. A retrospective study of RCC patients, with BRAF known mutation status, treated with chemotherapy (CT) from October 2008 to June 2019 in 5 Italian centers, was conducted. We identified 207 advanced RCC patients: 20.3% BRAF mutant and 79.7% BRAF wild type (wt). BRAF-mutant cancers were more likely to be pT4 (50.0% v 25.7%, p = 0.016), undifferentiated (71.4% v 44.0%, p = 0.004), KRAS wt (90.5% v 38.2%, p < 0.001), and MSI-H (41.7% v 16.2%, p = 0.019) tumors, with synchronous (52.4% v 31.5%, p = 0.018) and peritoneal metastases (38.1% v 22.4%, p = 0.003). Median overall survival (OS) was 16 v 27months in BRAF mutant and BRAF wt (P = 0.020). In first-line setting, BRAF-mutant showed a 2ys OS of 80% in clinical trials, 32% in anti-VEGF, 14% in epidermial growth factor receptor (EGFR), and 0% in chemotherapy alone regimens (P = 0.009). BRAF-mutant patients demonstrated worse survival, regardless of targeted therapy administered. However, survival difference was statistically significant in the anti-EGFR-treated subgroup (16 v 28months, P = 0.005 in BRAF mutant v BRAF wt, respectively). Our study demonstrated that BRAF status makes the difference in treatment's outcome. Therefore, the anti-EGFR should not be excluded in all advanced RCC but considered on a case-by-case basis.

Circulating T cell subsets are associated with clinical outcome of anti-VEGF-based 1st-line treatment of metastatic colorectal cancer patients: a prospective study with focus on primary tumor sidedness

BackgroundIn a prospective study with long-term follow-up, we analyzed circulating T cell subsets in patients with metastatic colorectal cancer (mCRC) in the context of primary tumor sidedness, KRAS status, and clinical outcome. Our primary goal was to investigate whether baseline levels of circulating T cell subsets serve as a potential biomarker of clinical outcome of mCRC patients treated with an anti-VEGF-based regimen.MethodsThe study group consisted of 36 patients with colorectal adenocarcinoma who started first-line chemotherapy with bevacizumab for metastatic disease. We quantified T cell subsets including Tregs and CD8+ T cells in the peripheral blood prior to therapy initiation. Clinical outcome was evaluated as progression-free survival (PFS), overall survival (OS), and objective response rate (ORR).Results1) mCRC patients with KRAS wt tumors had higher proportions of circulating CD8+ cytotoxic T cells among all T cells but also higher measures of T regulatory (Treg) cells such as absolute count and a higher proportion of Tregs in the CD4+ subset. 2) A low proportion of circulating Tregs among CD4+ cells, and a high CD8:Treg ratio at initiation of VEGF-targeting therapy, were associated with favorable clinical outcome. 3) In a subset of patients with primarily right-sided mCRC, superior PFS and OS were observed when the CD8:Treg ratio was high.ConclusionsThe baseline level of circulating immune cells predicts clinical outcome of 1st-line treatment with the anti-VEGF angio/immunomodulatory agent bevacizumab. Circulating immune biomarkers, namely the CD8:Treg ratio, identified patients in the right-sided mCRC subgroup with favorable outcome following treatment with 1st-line anti-VEGF treatment.

Targeting CD137 enhances the efficacy of cetuximab.

Treatment with cetuximab, an EGFR-targeting IgG1 mAb, results in beneficial, yet limited, clinical improvement for patients with head and neck (HN) cancer as well as colorectal cancer (CRC) patients with WT KRAS tumors. Antibody-dependent cell-mediated cytotoxicity (ADCC) by NK cells contributes to the efficacy of cetuximab. The costimulatory molecule CD137 (4-1BB) is expressed following NK and memory T cell activation. We found that isolated human NK cells substantially increased expression of CD137 when exposed to cetuximab-coated, EGFR-expressing HN and CRC cell lines. Furthermore, activation of CD137 with an agonistic mAb enhanced NK cell degranulation and cytotoxicity. In multiple murine xenograft models, including EGFR-expressing cancer cells, HN cells, and KRAS-WT and KRAS-mutant CRC, combined cetuximab and anti-CD137 mAb administration was synergistic and led to complete tumor resolution and prolonged survival, which was dependent on the presence of NK cells. In patients receiving cetuximab, the level of CD137 on circulating and intratumoral NK cells was dependent on postcetuximab time and host FcyRIIIa polymorphism. Interestingly, the increase in CD137-expressing NK cells directly correlated to an increase in EGFR-specific CD8+ T cells. These results support development of a sequential antibody approach against EGFR-expressing malignancies that first targets the tumor and then the host immune system.

KRAS mutational status impacts pathologic response to pre-hepatectomy chemotherapy: a study from the International Genetic Consortium for Liver Metastases

BackgroundA major response to pre-hepatectomy chemotherapy has been associated with improved survival in patients who undergo resection of colorectal liver metastases (CRLM). However, the role of tumor biology, as exemplified by overall and codon-specific KRAS mutational status, in predicting response to chemotherapy is not well defined. MethodsPathologic response was characterized as minor or major depending on the percentage of remnant viable cells (>50% vs <50%, respectively). Multivariable logistic regression was used to identify factors associated with major response. Results319 patients met inclusion criteria. 229 patients had a KRAS wild-type (wtKRAS) tumor and 90 harbored KRAS mutations (mutKRAS). A major pathologic response was more commonly noted in patients with wtKRAS compared to mutKRAS (48.5% vs 33.3%, P = 0.01) and wtKRAS status remained independently associated with a major response (P = 0.04). On a codon-specific level, major pathologic response occurred less frequently in those with codon 13 mutations (17.7%) compared to those with codon 12 (35.4%), and other KRAS mutations (33.3%). Importantly, codon 13 mutations were independently associated with minor pathologic response (P = 0.023). ConclusionsPatients with wtKRAS tumors appear to have the highest likelihood of experiencing a major response after preoperative chemotherapy. Future studies in “all-comer” cohorts are needed to confirm these findings and further investigate the response of codon 13 mutations.