KRAS Mutation Subtypes Research Articles

P59.12 KRAS Mutation Subtypes in Non-Small Cell Lung Cancer and Clinical Outcomes: A Single Centre Experience

KRAS is a common molecular driver in lung adenocarcinoma. KRAS subtypes can be grouped into transversion mutations (exchange of a purine for a pyrimidine bases or vice versa) such as KRAS G12C/G12V and transition mutations (interchange of a purine for another purine or interchange of a pyrimidine for another pyrimidine) such as KRAS G12D. This study assessed the efficacy of treatment and CNS prevalence across different subtypes of KRAS mutant NSCLC. Retrospective review of routine, clinical, molecular testing in NSCLC at a single centre over an 8-year period was performed. Clinicopathological information was obtained from medical records in patients with a KRAS mutation. Overall survival (OS) and Progression free survival (PFS) from diagnosis and OS following immunotherapy (iOS; in any line of treatment) were assessed using the Kaplan-Meier method and differences in survival were assessed by log-rank test. The difference between light/non-smokers and heavy smokers was assessed by Pearsons chi squared test. The presence of CNS disease was assessed by multivariate, nominal, logistic regression. From 1054 assessed 272 (25.8%) were found to be KRAS mutant with 72 patients receiving immunotherapy for stage III/IV disease. Immunotherapy included any PD(L)1, CTLA4 or investigational immunotherapy. KRAS G12C was found in 103 patients (38%), KRAS G12D in 48 patients (18%) and KRAS G12V in 53 patients (19%) (Figure 1). There was no difference in the presence of CNS disease across KRAS subtypes (p = 0.149). Non/light smokers were more likely to have a transition KRAS mutation than transversion mutation (p < 0.001). There was no difference across specific KRAS mutation subtype for PFS, OS or iOS. Transversion KRAS mutations had better iOS than transition KRAS mutations (Figure 2). Transversion KRAS mutations may predict for improved OS following immunotherapy but requires validation in a larger prospective cohort. Retrospective analysis of this cohort by PDL1 is underway.

In-Silico Analysis of The Correlation Between PD-L1 and Pro-Inflammatory Type Interleukins and The Distribution of Their Potential Primary Sources in KRAS-Mutated Non-Small Cell Lung Carcinoma

Objective: Non-Small Cell Lung Cancer has a high incidence and great clinical importance as the cancer subtype with the highest mortality. It is necessary to investigate cytokines associated with the Programmed death-ligand 1, one of the immunotherapeutic target molecules, in KRas mutant lung cancer cells.&#x0D; Materials and Methods: In this study, the expression of Programmed death-ligand 1 as well as pro-inflammatory interleukins was evaluated in 44 lung cancer cell lines harboring KRas mutations and RNAseq expression data of lung adenocarcinoma patients and correlation analyses were performed. Macrophages and dendritic cells, the major immune cells associated with Interleukin-1, Interleukin-6, Interleukin-12 and Interleukin-23, were also evaluated.&#x0D; Results: In KRas mutant lung cancer cells and lung adenocarcinoma tissues, expression of cytokines Interleukin-1A, Interleukin-6, Interleukin-12 and Interleukin-23 showed a positive correlation with Programmed death-ligand 1 expression (p≤0.05). The quantity of M1 macrophages and dendritic cells, both of which are cytokine-producing immune cells, is less in KRas mutant lung cancer tissues than non-mutants.&#x0D; Conclusion: Detailed studies in clinical samples, especially in blood, primary, and metastatic tissues, will help to create and validate cytokine panels that can be used in therapeutic targeting of KRas mutant subtype lung cancer with high Programmed death-ligand 1 expression.

1809P Evaluation of KRAS mutation subtype on survival in patients with metastatic non-small cell lung cancer receiving immunotherapy

Activating mutations in KRAS are the most common driver mutations in metastatic non-small cell lung cancer (mNSCLC). KRAS-mutant NSCLCs are heterogeneous in their biology and the response of the various KRAS alleles to immune checkpoint inhibitors (ICI) remains unclear. We sought to investigate differential outcomes to ICI among KRAS subtypes.

The Prognostic Effect of KRAS Mutations in Non-Small Cell Lung Carcinoma Revisited: A Norwegian Multicentre Study.

Simple SummaryIn this multicentre study of 1117 patients with stage I–IV non-squamous non-small cell lung carcinoma (NSCLC), we investigated associations between KRAS and clinical characteristics and survival. We investigated survival among the following groups of patients: those with no KRAS mutations (wild type) versus those with mutated tumours, those with KRAS wild type versus KRAS G12C versus KRAS non-G12C mutated tumours and among patients with different KRAS mutation subtypes. We also grouped KRAS mutated patients according to mutation preference for the Raf, PI3K/Akt and RalGDS/Ral intracellular signalling pathways and investigated whether there were differences in survival according to their preference for these pathways. We found that the proportion of KRAS mutated patients and frequency of KRAS mutation subtypes in our study is consistent with other studies of non-Asian patients with NSCLC. In multivariable analyses, we found no significant differences in the time to disease progression or overall survival within any of the analysed groups.Background: due to emerging therapeutics targeting KRAS G12C and previous reports with conflicting results regarding the prognostic impact of KRAS and KRAS G12C in non-small cell lung cancer (NSCLC), we aimed to investigate the frequency of KRAS mutations and their associations with clinical characteristics and outcome. Since mutation subtypes have different preferences for downstream pathways, we also aimed to investigate whether there were differences in outcome according to mutation preference for the Raf, PI3K/Akt, or RalGDS/Ral pathways. Methods: retrospectively, clinicopathological data from 1233 stage I–IV non-squamous NSCLC patients with known KRAS status were reviewed. KRAS’ associations with clinical characteristics were analysed. Progression free survival (PFS) and overall survival (OS) were assessed for the following groups: KRAS wild type (wt) versus mutated, KRAS wt versus KRAS G12C versus KRAS non-G12C, among KRAS mutation subtypes and among mutation subtypes grouped according to preference for downstream pathways. Results: a total of 1117 patients were included; 38% had KRAS mutated tumours, 17% had G12C. Among KRAS mutated, G12C was the most frequent mutation in former/current smokers (45%) and G12D in never smokers (46%). There were no significant differences in survival according to KRAS status, G12C status, among KRAS mutation subtypes or mutation preference for downstream pathways. Conclusion: KRAS status or KRAS mutation subtype did not have any significant influence on PFS or OS.

Tumor microenvironment-adjusted prognostic implications of the KRAS mutation subtype in patients with stage III colorectal cancer treated with adjuvant FOLFOX

Several studies have reported that the prognostic effect of KRAS mutations on colorectal cancers (CRCs) varies depending on the type of mutation. Considering the effect of KRAS mutations on tumor microenvironment, we analyzed the prognostic significance of KRAS mutation types after adjusting for the tumor-infiltrating lymphocytes (TIL) and tumor-stromal percentage (TSP) statuses. In two independent cohorts, KRAS mutations were analyzed by Sanger sequencing and/or next-generation sequencing. TIL density and the TSP were quantified from whole-slide immunohistochemical images. KRAS-mutant CRCs were divided into three subgroups (G12D/V, other codon 12 mutations and codon 13 mutations) to examine their differential effect on TIL density, the TSP and recurrence-free survival (RFS). Among the KRAS mutations, only the G12D/V subgroups showed significantly less TIL infiltration than the wild-type CRCs. According to survival analysis, G12D/V mutations were associated with short RFS; codon 13 mutations showed discordant trends in the two cohorts, and other codon 12 mutations showed no significant association. Multivariate analysis further supported the prognostic value of G12D/V mutations. This result is not only consistent with a recent study suggesting the immunosuppressive effect of mutant KRAS but also provides insight into the type-specific prognostic effect of KRAS mutations.

Impact of KRAS mutational variant on response to immunotherapy in metastatic NSCLC.

e21127 Background: KRAS alterations constitute the most common driver mutations in metastatic non-small cell lung cancers (mNSCLC) and occur in approximately 30% of patients. KRAS mutational subtype as well as the presence of co-mutations has been associated with altered activation of downstream signaling pathways in preclinical models. We hypothesize that different KRAS G12C mutational subsets will be associated with variable clinical outcome and response to therapy. To this end, we have performed a retrospective analysis of survival and treatment outcomes by KRAS mutation subtype (G12C vs non-G12C). Methods: A review of KRAS-mutated mNSCLC patients treated with immunotherapy between 2013 and 2020 was conducted. Patient demographics, smoking status, KRAS mutational subtype, co-mutations and PD-L1 status were collected. Overall response rate (ORR) and progression-free survival (PFS) were analyzed in each subgroup. Results: 98 KRAS mutant mNSCLC patients were treated with immune checkpoint inhibitors (ICI): 37% with a KRAS G12C mutation, 62% with a non-G12C mutation. Patients with a G12C mutation were more likely to be of Caucasian ancestry (86% vs 56%; p = 0.01) whereas all other characteristics were similar between the groups including smoking history, PD-L1 expression ≥50% (61% vs 40%) and the presence of a TP53 co-mutation (48% vs. 54%); all p &gt; 0.05. Treatment patterns were similar between the groups, with PD-1 inhibitor monotherapy given in 86% vs 79% of KRAS G12C and non-G12C patients. Overall response rate was 51% vs 27% in G12C vs non-G12C (p = 0.03). PFS was superior in G12C mutants (19.6 months vs 4.0 months), even after adjusting for smoking history, TP53 co-mutation status and PD-L1 expression (adjusted HR 0.51; p = 0.02). In subgroup analyses, the superiority in PFS was driven by the G12C mutants with high PD-L1 expression (n = 19): 26.8 months in G12C, PD-L1 high vs 4.7 months in G12C, PD-L1 low vs. 4.7 months in KRAS transversion mutations, PD-L1 high vs 4.0 months in transversion mutations, PD-L1 low vs. 3.0 months in transition mutations; p &lt; 0.001. Conclusions: The presence of a KRAS G12C mutation is associated with improved ORR and PFS after treatment with ICI compared to non-G12C mutations in mNSCLC. The greatest benefit in PFS was observed in the subgroup with G12C mutation and high PD-L1 expression. Differential activation of downstream signaling associated with specific KRAS codon 12 mutation variants may modulate the composition of the tumor immune microenvironment thereby contributing to the variable response to immunotherapy. Further understanding on these molecular mechanisms may direct the development of new treatment strategies in KRAS mutant lung cancers.

A single institution study evaluating outcomes of PD-L1 high KRAS-mutant advanced non-small cell lung cancer (NSCLC) patients treated with first line immune checkpoint inhibitors

AimThis study aimed to evaluate the impact of KRAS status on the efficacy of first-line immune checkpoint inhibitors (ICI) in patients with advanced non-small cell lung cancer (NSCLC). Patients and MethodsPatients with advanced incurable or metastatic NSCLC with PD-L1 ≥50% treated with palliative-intent, single-agent PD-1/PD-L1 inhibitors at the Cancer Centre of Southeastern Ontario were included. KRAS mutation status was determined via massively parallel sequencing. Primary study outcome was median overall survival (mOS). ResultsSeventy-eight patients (59 non-squamous, 19 squamous) were identified; only non-squamous patients were included in KRAS mutation analyses. Thirty patients (51%) were KRAS-MT (mutant), with G12C (19%), G12V (15%), and G12D (13%) accounting for the most common KRAS mutation subtypes. There was no difference in mOS between KRAS-MT and KRAS-WT (wild-type) patients (12.9 vs. 19.3 months, p = 0.879). There was a non-significant trend towards worse mOS in KRAS G12C patients compared to non-G12C and KRAS-WT patients (11.4 vs. 44.9 vs. 19.3 months, p = 0.772). On multivariable analysis, KRAS-MT status was not associated with mOS (HR 0.901, 95%CI 0.417–1.946, p = 0.791). ECOG≥2 was an independent prognostic factor for worse mOS (HR 2.853, 95%CI 1.237–6.583, p = 0.014). Immune-related adverse events did not differ between KRAS-MT and KRAS-WT groups (48% vs. 52%, p = 1.000). ConclusionsKRAS mutation status did not have a significant impact on ICI efficacy or safety. However, a non-significant trend towards worse survival was noted in patients treated with ICI whose tumours harboured the KRAS G12C variant. This study provides valuable information for comparative analysis in the future.

Prognostic Characteristics and Immunotherapy Response of Patients With Nonsquamous NSCLC With Kras Mutation in East Asian Populations: A Single-Center Cohort Study in Taiwan

IntroductionKras mutation is the most common driver oncogene present in patients with NSCLC. Recently, the precision medicine for patients with Kras-mutated NSCLC has been under investigation, but the best treatment is still unknown. This study aimed to analyze the clinical characteristics, immune checkpoint inhibitor (ICI) response, and prognostic factors of patients with NSCLC with different Kras mutation subtypes. MethodsFrom 2005 to 2018, we collected nonsquamous NSCLC tissue samples for Kras mutation analysis using direct Sanger sequencing or MassARRAY genotyping (Agena Bioscience, San Diego, CA) at the National Taiwan University Hospital. Clinical characteristics, ICI treatment effectiveness, time-to-tumor recurrence (TTR), and overall survival (OS) were analyzed using multivariate Cox models, to estimate adjusted hazard ratios (HRs). ResultsAmong 5278 patients with nonsquamous NSCLC, 246 (4.7%) had Kras mutations. The major Kras mutation subtypes were G12C (32.9%), G12D (23.7%), and G12V (18.9%). Patients with Kras-G12C had a higher proportion of male individuals (p = 0.018) and smokers (p < 0.001). Among the 25 patients treated with ICIs, patients with Kras-G12C had a higher response rate (53.8% versus 8.3%, p = 0.030) and longer progression-free survival (4.8 mo versus 2.1 mo, p = 0.028) than those with Kras-non-G12C. For the 85 patients with early-stage NSCLC, those with G12C had shorter TTR (22.8 mo) than those with Kras-non-G12C (97.7 mo, p = 0.004). For the 143 patients with advanced-stage NSCLC, there was a significant difference in OS between patients with Kras-G12C and Kras-non-G12C (7.7 mo versus 6.0 mo, p = 0.018) and patients with Kras-G12V had the shortest OS (5.2 mo). Multivariate analysis revealed association of shorter OS with Kras-G12V (HR = 2.47, p = 0.002), stage IV disease status (HR = 2.69, p = 0.008), and NSCLC—not otherwise specified histology (HR = 3.12, p = 0.002). ConclusionsKras-G12C was associated with favorable ICI treatment effectiveness in patients with NSCLC. Kras-G12C mutation was associated with shorter TTR in patients with early-stage NSCLC, and Kras-G12V mutation was associated with shorter OS in patients with advanced-stage NSCLC when comparing with Kras-G12C.

Epidemiologic Features of NSCLC Gene Alterations in Hispanic Patients from Puerto Rico.

Simple SummaryWe have analyzed the molecular genetic profiles of Hispanic non-small cell lung cancer (NSCLC) patients from Puerto Rico. In addition to the general characteristics, especially on EGFR mutations, we have also reported some novel findings on the incidences of KRAS mutation subgroups, other driver gene alterations, and passenger gene alterations, as well as KRAS/TP53 and KRAS/STK11 co-mutations. Moreover, our study has identified the FGFR2-TACC2 translocation in this population.Targeted therapy has changed the paradigm of advanced NSCLC management by improving the survival rate of patients carrying actionable gene alterations using specific inhibitors. The epidemiologic features of these alterations vary among races. Understanding the racial differences benefits drug development, clinical trial design, and health resource allocation. Compared to Caucasian and Asian populations, current knowledge on Hispanic patients is less and no data of Hispanic patients from Puerto Rico have been reported. We retrieved and analyzed the demographic, clinical, and molecular data of Hispanic NSCLC patients from Puerto Rico with molecular tests performed in the Genoptix Medical Laboratory in Carlsbad, CA, USA between 2011 and 2018. The majority of the NSCLC patients in our study had either adenocarcinoma (75.4%) or squamous cell carcinoma (15.1%). The incidence of EGFR mutations was 24%. They were more common in female and younger patients (<60 years). The deletion of Exon 19 and Exon 21 L858R comprised 55.1% and 31.0% of all EGFR mutations, respectively. The frequency of the T790M mutation was lower compared to that of Hispanic patients reported in the literature (0.5% vs. 2.1%). In addition, 18.7% of the patients were positive for KRAS mutations, which was at the high end of that reported in Hispanic patients. Other driver gene alterations, ALK, MET, RET, ROS1, KRAS, ERBB2, etc., demonstrated similar incidences, as well as gender and age distributions to those previously reported. The KRAS/TP53 and KRAS/STK11 co-mutations were of very low frequencies (3.6%), which could potentially affect the responsiveness to PD1/PD-L1 immunotherapy. Our study demonstrated that the prevalence of NSCLC gene alterations in Hispanic patients from Puerto Rico was comparable to the reported average prevalence in Latin American countries, supporting the intermediate NSCLC gene alteration rate of Hispanic patients between Asian and Caucasian patients. Novel information of the frequencies of KRAS mutation subtypes, driver gene alterations in ROS1, BRAF, and ERBB2, and passenger gene alterations including a rare case with the FGFR2-TACC2 translocation in Hispanic NSCLC patients from Puerto Rico were also described.

KRAS G12D mutation predicts lower TMB and drives immune suppression in lung adenocarcinoma

ObjectivesThe efficacy of anti- programmed cell death 1 (PD-1)/PD-1 ligand (PD-L1) immune checkpoint inhibitors remains controversial in patients with KRAS mutation. In addition, whether and how KRAS gene and its mutant subtypes might influence immunity has not been clarified yet. Here we examine some important biomarkers for the efficacy of immunotherapy in specific KRAS subtypes. Materials and MethodsWe conducted a bioinformatics analysis on somatic mutations data, transcriptome sequencing data and proteomic data from The Cancer Genome Atlas (TCGA) database. CIBERSORT was used to provide an estimation of the abundances of immune cells using gene expression data. ResultsFrom a cohort of 567 patients with lung adenocarcinoma (LUAD) based on TCGA, the overall mutation rate of KRAS was 26.29 %, including KRAS/TP53 co-mutation rate of 9.7 %. We observed increased Tumor mutation burden (TMB) in KRAS mutant group compared with wild type, while no difference in PD-L1 expression and immune cell infiltration. More importantly, TP53 and KRAS/TP53 co-mutation group not only significantly increased tumor mutation burden, but also had higher PD-L1 protein level and immune cell infiltration. We further focused on influence of KRAS mutant subtype on immune biomarker. The most prevalent mutant subtype of KRAS in lung adenocarcinoma was G12C(9.88 %,56/567), followed by G12 V(5.82 %,33/567), G12D(3.00 %,17/567), G12A(3.00 %,17/567), respectively. Among them, G12D mutation appeared to be a special mutant subtype with an obviously lower TMB. This low mutation load was more significant when co-mutation with TP53. Besides, our results also revealed significantly decreased expressions of PD-L1 protein level and immune cell infiltration (activated CD4 memory T cell, helper T cell, M1 macrophage and NK cell) in KRAS G12D/TP53 mutant group. ConclusionKRAS G12D/TP53 co-mutation drives immune suppression and might be a negative predictive biomarker for anti-PD-1/PD-L1 immune checkpoint inhibitors in patients with lung adenocarcinoma.

Abstract 2894: XMT-1592, a site-specific Dolasynthen-based NaPi2b-targeted antibody-drug conjugate for the treatment of ovarian cancer and lung adenocarcinoma

Abstract The Dolasynthen platform incorporates the highly potent anti-mitotic agent auristatin F-HPA (AF-HPA), with its associated DolaLock mechanism of controlled bystander effect, and enables the synthesis of antibody-drug conjugates (ADCs) with precise control of the drug-to-antibody ratio (DAR) and site-specific bioconjugation. XMT-1592 is a novel ADC comprised of an anti-NaPi2b antibody and Dolasynthen, conjugated in a site-specific manner to yield DAR 6. NaPi2b, also known as SLC34A2, is a transmembrane sodium-phosphate transporter that is broadly expressed on tumor cells in ovarian carcinoma, NSCLC lung adenocarcinoma and other tumor types. Recent studies have shown that NaPi2b expression is enriched in the EGFR and KRAS mutant subtypes of lung adenocarcinoma. Binding studies showed a specific, high-affinity interaction of XMT-1592 with NaPi2b that was not affected by conjugated Dolasynthen. XMT-1592 elicited potent and specific in vitro cytotoxicity against NaPi2b-expressing ovarian carcinoma cells. XMT-1592 exhibited potent and specific in vivo activity in NaPi2b-expressing tumor xenografts derived from ovarian carcinoma or lung adenocarcinoma. Consistent with the targeted delivery benefits of the ADC approach, XMT-1592 yielded high and sustained concentrations of AF-HPA to tumors but not normal tissues. To evaluate the benefits of site-specific bioconjugation of Dolasynthen, we conducted in vitro and in vivo comparisons of XMT-1592 to a stochastically conjugated version of the ADC. XMT-1592 had improved in vivo activity, pharmacokinetics, and clinical pathology relative to its stochastic counterpart. Taken together, these results support XMT-1592 as a development candidate for the treatment of NaPi2b-expressing tumors. Citation Format: Shawn Fessler, Anouk Dirksen, Scott D. Collins, Ling Xu, Winnie Lee, Jason Wang, Ron Eydelloth, Elena Ter-Ovanesyen, Jeffrey Zurita, Elizabeth Ditty, Barrett Nehilla, Susan Clardy, Susan Clardy, Tyler Carter, Kenneth Avocetien, Mark Nazzaro, Nam Le, Kalli C. Catcott, Alex Uttard, Bingfan Du, Chen-Ni Chin, Rebecca Mosher, Kelly Slocum, Liuliang Qin, David Lee, Dorin Toader, Marc Damelin, Timothy B. Lowinger. XMT-1592, a site-specific Dolasynthen-based NaPi2b-targeted antibody-drug conjugate for the treatment of ovarian cancer and lung adenocarcinoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2894.

Prognostic Value of KRAS Mutation Subtypes and PD-L1 Expression in Patients With Lung Adenocarcinoma

BackgroundThe prognostic value of different KRAS (Kirsten rat sarcoma viral oncogene) mutation subtypes and their association with programmed death ligand 1 (PD-L1) expression in lung adenocarcinoma (LADC) remain unclear. We examined the association of KRAS mutation subtypes with clinical outcomes and PD-L1 expression status. Patients and MethodsPatients diagnosed with KRAS-mutated LADC were evaluated for PD-L1 expression, cancer staging, overall survival (OS), and relapse-free survival. ResultsA cohort of 254 KRAS-mutated LADC patients (median follow-up, 17 months) was studied. The 3 major subtypes of KRAS mutations were G12C (46.1%), G12V (21.7%), and G12D (15.7%). We found that all these subtypes had no impact on cancer stages, brain metastasis at diagnosis, OS, and relapse-free survival. Among this cohort, 33% of 94 patients who had PD-L1 staining data available had PD-L1–positive disease (≥ 1% of tumor cells). PD-L1 expression status was not significantly different among the 3 major mutation subtypes. Of interest, among patients with G12C mutation, positive PD-L1 expression was associated with significantly shorter OS (median survival, 5.7 vs. 12.8 months, P = .007). In multivariable analysis, PD-L1 positivity remained as an adverse factor for OS, with hazard ratio of 4.44 (P = .0007). PD-L1 status did not affect OS in other subtypes of mutations. ConclusionKRAS mutation subtype is not associated with patient clinical outcomes or PD-L1 expression status. However, PD-L1 positivity appears to negatively affect OS in LADC patients with G12C mutation. Further study is needed to confirm our observation and to determine if programmed cell death 1/PD-L1 antagonist may affect the clinical outcome of patients with different KRAS mutation subtypes.

Therapeutic impact of mutation subtypes and concomitant STK11 mutations in KRAS–mutated non-small cell lung cancer (NSCLC): A result of nationwide genomic screening project (LC-SCRUM-Japan).

9589 Background: KRAS mutations are one of the common oncogene drivers in non-small cell lung cancer (NSCLC), and the development of several targeted drugs for KRAS-mutated NSCLC is now ongoing. However, the clinical impact of KRAS mutation subtypes or concomitant other gene mutations in NSCLC patients (pts) remains unclear. Methods: In a nationwide genomic screening project (LC-SCRUM-Japan), we have prospectively analyzed lung cancer pts for genetic alterations and tumor mutation burden (TMB) by next-generation sequencing system, and for PD-L1 expression by immunohistochemistry (22C3 antibody). The therapeutic efficacy and survival of KRAS-mutated non-squamous (non-sq) NSCLC pts were evaluated using a clinico-genomic database of the LC-SCRUM-Japan. Results: A total of 5166 non-sq NSCLC pts enrolled from 2015 to 2019. KRAS mutations were detected in 794 pts (15%; G12C/G12D/G12V/G12A/G13X/others = 232/186/165/66/61/84). Among the 794 pts, TMB and PD-L1 expression were analyzed in 128 and 79, respectively, and 218 received PD-1/PD-L1 inhibitors (IO) after 1st-line chemotherapy. The median age was 66 years (range, 29-89). 142 pts (65%) were male and 172 (78%) were smokers. Concomitant STK11 mutations were detected in 33 pts (15%) with no difference in the mutation frequency among KRAS mutation subtypes. KRAS G12C was significantly associated with high TMB (≥ 10 mut/Mb) (p = 0.03), and KRAS G12C or G12V with high PD-L1 expression (≥ 50%) (p = 0.02). In pts who received IO, median progression-free survival (mPFS) was significantly longer in pts with KRAS G12C or G12V than in those with other KRAS mutations (4.7 vs 2.0 months, hazard ratio (HR) 0.58 [95%CI 0.43-0.78], p &lt; 0.01). Among pts with KRAS G12C or G12V, mPFS of IO was significantly shorter in pts with concomitant STK11 mutations than in those without (1.8 vs. 5.7 months, HR 1.97 [95%CI 1.06-3.41], p = 0.02). These correlations were not observed in platinum-containing chemotherapy (Plt-CTx). There were also no significant differences in IO and Plt-CTx efficacies between with and without other concomitant mutations, such as TP53, RB1, CDKN2A and PTEN mutations. Conclusions: Non-sq NSCLC pts with KRAS G12C/V were more sensitive to IO therapies than those with other KRAS mutations, but KRAS G12C/V-positive pts with concomitant STK11 mutations were less sensitive than those without. These results could be highly informative in the development of novel targeted therapies for KRAS-mutated NSCLC.

Outcomes of Patients With Advanced NSCLC From the Intergroupe Francophone de Cancérologie Thoracique Biomarkers France Study by KRAS Mutation Subtypes

IntroductionKRAS mutations are detected in 20% to 30% of NSCLC. However, KRAS mutation subtypes may differently influence the outcome of patients with advanced NSCLC. MethodsIn the Biomarkers France study, 4894 KRAS mutations (26.2%) were detected in 4634 patients from the 17,664 enrolled patients with NSCLC. Survival and treatment data on noncurative stage III to IV NSCLC were available for 901 patients. First- and second-line treatment effects on progression-free survival and overall survival were analyzed according to the KRAS mutations subtype. ResultsOver 95% of patients with KRAS mutation were smokers or former smokers who were white (99.5%), presenting with adenocarcinoma (82.5%). The most common KRAS mutation subtype was G12C (374 patients; 41.5%), followed by G12V (168; 18.6%), G12D (131; 14.5%), G12A (62; 6.9%), G13C (45; 5.0%), G13D (31; 3.4%), and others (10; 1%). Approximately 21% of patients had transition mutation and 68.2% had a transversion mutation. G12D and transition mutations were predominant in never-smokers. The median overall survival for patients with KRAS-mutated NSCLC was 8.1 months (95% confidence interval [CI]: 7.5–9.5), without any differences according to the different KRAS subtypes mutations. The median progression-free survival was 4.6 months (95% CI: 4.2–5.1) for first-line treatment and 4.8 months (95% CI: 4.3–6.8) for second-line treatment, without any differences according to the different KRAS subtypes mutations. ConclusionsKRAS mutation subtypes influenced neither treatment responses nor outcomes. The KRAS G12C mutation was detected in 41.5% of patients, who are now eligible for potent and specific G12C inhibitors.

A Real-World Study in Advanced Non–Small Cell Lung Cancer with KRAS Mutations

BACKGROUND: KRAS gene mutations are well known as a key driver of advanced non–small cell lung cancer (NSCLC). The impact of KRAS-mutant subtypes on the survival benefit from salvage chemotherapy is controversial. Here, we present a real-world study in patients across China with advanced NSCLC with KRAS mutations using a website-based patient self-report system. METHODS: We identified a total of 75 patients diagnosed with KRAS-mutant (determined by molecular sequencing) advanced NSCLC between 2014/5/9 and 2019/5/30. KRAS mutation subtypes were divided into G12C and non-G12C groups for statistical analysis. The clinicopathological characteristics and treatment survival benefit in all patients with a KRAS mutation were evaluated. Programmed death-ligand 1 (PD-L1) expression data were collected from 30 patients in the same cohort. RESULTS: In this study, 23 patients with stage IIIB NSCLC and 52 patients with stage IV NSCLC were enrolled with 58 men and 17 women; the median age was 60 years (39–84). All patients received regular chemotherapy/radiotherapy/targeted therapy/immune therapy as per the disease condition. Four main KRAS mutation subtypes were detected: G12C (33%), G12V (19%), G12A (12%), and G12D (12%). Three predominant KRAS comutations were detected: TP53-KRAS (31%), EGFR-KRAS (11%), and STK11-KRAS (8%). Compared with the KRAS non-G12C mutation subtype, patients with the KRAS G12C mutation had potentially longer progression-free survival (PFS) after first-line chemotherapy (4.7 vs. 2.5 months, p < 0.05). Pemetrexed-based chemotherapy appeared to be superior to taxanes- and gemcitabine-based chemotherapies in all patients (PFS: 5.0 vs. 1.5 and 2.3 months, respectively, p > 0.05). Cox regression analysis showed that the KRAS G12C mutation and pemetrexed-based first-line chemotherapy were positive influencers for PFS after first-line (hazard ratios = 0.31 and 0.55, respectively, P < 0.05), but not second-line chemotherapies. CONCLUSION: The KRAS G12C mutation could be a predictive biomarker for better survival benefit from first-line chemotherapy in patients with advanced NSCLC and KRAS mutations. The first-line chemotherapy regimen could possibly influence the outcome in patients with KRAS mutations. Larger and prospective clinical trials are warranted to confirm our conclusions.

The prognostic value of KRAS mutation subtypes and PD-L1 expression in patients with lung adenocarcinoma.

e20022 Background: KRAS gene mutations are found in 20-30% of non-small cell lung cancer (NSCLC), especially in adenocarcinoma. Compared to EGFR and ALK mutations, KRAS mutation in NSCLC may be associated with poorer prognosis. However, prognostic value of different KRAS mutation subtypes in NSCLC remains unknown. The goal of this study is to evaluate the association of KRAS mutation subtypes, PD-L1 expression and clinical outcome in patients diagnosed with primary lung adenocarcinoma. Methods: A total of 256 patients diagnosed with KRAS mutated (determined by pyrosequencing) lung adenocarcinoma between 2011 and 2015 in AdventHealth-Orlando were evaluated for their cancer staging, Relapse-free survival (RFS) and overall survival (OS). PD-L1 staining was performed in a subgroup of 95 patients from the same cohort. PD-L1 expression was determined with immunohistochemistry staining using Ventana PD-L1 (SP263) assay. Results: In this cohort of patients, 65 had stage I disease, 29 stage II, 49 stage III, 110 stage IV and 3 with no clinical stage information; 104 male, 152 female; median age 67. All patients received standard surgical/chemo/radio therapy according to the disease stages. Only one single patient received immunotherapy. Nine subtypes of KRAS mutation were detected, predominantly in codon 12. Three major subtypes account for 83.6% KRAS mutations, namely G12C (45.7%), G12V (21.9%) and G12D (16.0%). We found that these three major subtypes had no difference in cancer stages (P = 0.58) or brain metastasis at diagnosis (P = 0.78). Kaplan Meier analysis also showed similar OS and RFS among all KRAS subtype. 34% of KRAS mutated patients were found to be PD-L1 positive with tumor proportion score of greater than or equal to 1. PD-L1 expression status was indistinct among the three major mutation subtypes (P = 0.38). Of interest, among patients with G12C mutation, positive PD-L1 expression was associated with significantly shorter OS (5.7 vs 12.8 months; P = 0.007). In contrast, for patients with other KRAS mutation subtypes, PD-L1 expression status had no impact on OS (P = 0.63). Conclusions: The clinical courses, including tumor stage at diagnosis, presence of brain metastasis, OS and RFS, are similar among lung adenocarcinoma patients with different KRAS mutation subtypes. Additionally, PD-L1 expression status appears to be independent of KRAS mutation subtypes. Of note, concurrent PD-L1 expression and G12C mutation is associated with particularly poorer prognosis. Further study is needed to see if PD1/PD-L1 block may improve outcome of this group of patients.

Impact of KRAS mutation subtype and concurrent pathogenic mutations on non-small cell lung cancer outcomes

ObjectivesConcurrent genetic mutations are prevalent in KRAS-mutant non-small cell lung cancer (NSCLC) and may differentially influence patient outcomes. We sought to characterize the effects of KRAS mutation subtypes and concurrent pathogenic mutations on overall survival (OS) and PD-L1 expression, a predictive biomarker for anti-PD-1/PD-L1 immunotherapy. Materials and methodsWe retrospectively identified patients with KRAS-mutant NSCLC at a single institution and abstracted clinical, molecular, and pathologic data from electronic health records. Cox regression and multinomial logistic regression were used to determine how KRAS mutation subtypes and concurrent pathogenic mutations are associated with OS and tumor PD-L1 expression, respectively. ResultsA total 186 patients were included. Common KRAS mutation subtypes included G12C (35%) and G12D (17%). Concurrent pathogenic mutations were identified in TP53 (39%), STK11 (12%), KEAP1 (8%), and PIK3CA (4%). On multivariable analysis, KRAS G12D mutations were significantly associated with poor OS (hazard ratio [HR] 2.43, 95% confidence interval [CI] 1.15–5.16; P = 0.021), as were STK11 co-mutations (HR 2.95, 95% CI 1.27–6.88; P = 0.012). Compared to no (<1%) PD-L1 expression, KRAS G12C mutations were significantly associated with positive yet low (1–49%) PD-L1 expression (odds ratio [OR] 4.94, 95% CI 1.07–22.85; P = 0.041), and TP53 co-mutations with high (≥50%) PD-L1 expression (OR 6.36, 95% CI 1.84–22.02; P = 0.004). ConclusionKRAS G12D and STK11 mutations confer poor prognoses for patients with KRAS-mutant NSCLC. KRAS G12C and TP53 mutations correlate with a biomarker that predicts benefit from immunotherapy. Concurrent mutations may represent distinct subsets of KRAS-mutant NSCLC; further investigation is warranted to elucidate their role in guiding treatment.

MCL1 inhibition enhances the therapeutic effect of MEK inhibitors in KRAS-mutant lung adenocarcinoma cells

ObjectivesMCL1 is an anti-apoptotic BCL2 family member that is highly expressed in various malignant tumors. However, little is known about the role of MCL1 in KRAS-mutant lung adenocarcinomas. In this study, we aimed to clarify whether MCL1 could be a therapeutic target in KRAS-mutant lung adenocarcinomas for which no effective molecular targeted drugs are available. Materials and methodsWe examined to what extent MCL1 knockdown either alone or in combination with MEK inhibitor trametinib suppressed growth or induced apoptosis in the KRAS-mutant lung adenocarcinoma cell line H441 and EGFR-mutant lung adenocarcinoma cell line H1975. Furthermore, we investigated the therapeutic effects of dual inhibition of MCL1 and Bcl-xL, another anti-apoptotic BCL2 family member, in these two cell lines. ResultsMCL1 knockdown alone did not induce apoptosis in H441 or H1975 cells. However, MCL1-depleted H441 and H1975 cells underwent apoptosis and decreased in number in the presence of trametinib. We also confirmed that combined therapy by MCL1 knockdown and trametinib almost completely suppressed the growth of H441 cells in vivo. Moreover, dual knockdown of MCL1 and Bcl-xL induced extensive apoptosis in H441 and H1975 cells. ConclusionThese findings suggest that combined treatments of MCL1 knockdown and trametinib or dual inhibition of MCL1 and Bcl-xL would be effective therapies for lung adenocarcinomas including the KRAS-mutant subtype.

Efficacy of Immune Checkpoint Inhibitors in KRAS-Mutant Non-Small Cell Lung Cancer (NSCLC)

IntroductionKRAS mutation is the most frequent molecular alteration found in advanced NSCLC; it is associated with a poor prognosis without available targeted therapy. Treatment options for NSCLC have been recently enriched by the development of immune checkpoint inhibitors (ICIs), and data about its efficacy in patients with KRAS-mutant NSCLC are discordant. This study assessed the routine efficacy of ICIs in advanced KRAS-mutant NSCLC. MethodsIn this retrospective study, clinical data were extracted from the medical records of patients with advanced NSCLC treated with ICIs and with available molecular analysis between April 2013 and June 2017. Analysis of programmed death ligand 1 (PD-L1) expression was performed if exploitable tumor material was available. ResultsA total of 282 patients with ICI-treated (in the first line or more) advanced NSCLC (all histological subgroups) who were treated with ICIs (anti–programmed death 1, anti–PD-L1, or anti–cytotoxic T-lymphocyte associated protein 4 antibodies), including 162 (57.4%) with KRAS mutation, 27 (9.6%) with other mutations, and 93 (33%) with a wild-type phenotype, were identified. PD-L1 analysis was available for 128 patients (45.4%), of whom 45.3% and 19.5% had PD-L1 expression of 1% or more and 50%, respectively (49.5% and 21.2%, respectively, in the case of the 85 patients with KRAS-mutant NSCLC). No significant difference was seen in terms of objective response rates, progression-free survival, or overall survival between KRAS-mutant NSCLC and other NSCLC. No significant differences in overall survival or progression-free survival were observed between the major KRAS mutation subtypes (G12A, G12C, G12D, G12V, and G13C). In KRAS-mutant NSCLC, unlike in non–KRAS-mutant NSCLC, the efficacy of ICIs is consistently higher, even though not statistically significant, for patients with PD-L1 expression in 1% or more of tumor cells than for those with PD-L1 expression in less than 1% of tumor cells, and this finding is especially true when PD-L1 expression is high (PD-L1 expression ≥50%). ConclusionFor patients with KRAS-mutant NSCLC (all mutational subtypes), the efficacy of ICI is similar to that for patients with other types of NSCLC. PD-L1 expression seems to be more relevant for predicting the efficacy of ICIs in KRAS-mutant NSCLC than it is in other types of NSCLC.

K-ras Mutation Subtypes in NSCLC and Associated Co-occuring Mutations in Other Oncogenic Pathways

IntroductionAlthough KRAS mutations in NSCLC have been considered mutually exclusive driver mutations for a long time, there is now growing evidence that KRAS-mutated NSCLC represents a genetically heterogeneous subgroup. We sought to determine genetic heterogeneity with respect to cancer-related co-mutations and their correlation with different KRAS mutation subtypes. MethodsDiagnostic samples from 4507 patients with NSCLC were analyzed by next-generation sequencing by using a panel of 14 genes and, in a subset of patients, fluorescence in situ hybridization. Next-generation sequencing with an extended panel of 14 additional genes was performed in 101 patients. Molecular data were correlated with clinical data. Whole-exome sequencing was performed in two patients. ResultsWe identified 1078 patients with KRAS mutations, of whom 53.5% had at least one additional mutation. Different KRAS mutation subtypes showed different patterns of co-occurring mutations. Besides mutations in tumor protein p53 gene (TP53) (39.4%), serine/threonine kinase 11 gene (STK11) (19.8%), kelch like ECH associated protein 1 gene (KEAP1) (12.9%), and ATM serine/threonine kinase gene (ATM) (11.9%), as well as MNNG HOS Transforming gene (MET) amplifications (15.4%) and erb-b2 receptor tyrosine kinase 2 gene (ERBB2) amplifications (13.8%, exclusively in G12C), we found rare co-occurrence of targetable mutations in EGFR (1.2%) and BRAF (1.2%). Whole-exome sequencing of two patients with co-occurring phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha gene (PIK3CA) mutation revealed clonality of mutated KRAS in one patient and subclonality in the second, suggesting different evolutionary backgrounds. ConclusionKRAS-mutated NSCLC represents a genetically heterogeneous subgroup with a high frequency of co-occurring mutations in cancer-associated pathways, partly associated with distinct KRAS mutation subtypes. This diversity might have implications for understanding the variability of treatment outcome in KRAS-mutated NSCLC and for future trial design.