Low frequency KRAS mutations in colorectal cancer patients and the presence of multiple mutations in oncogenic drivers in non-small cell lung cancer patients

Intratumor heterogeneity can confound the results of mutation analyses in oncodriver genes using traditional methods thereby challenging the application of targeted cancer therapy strategies for patients. Ultradeep sequencing can detect low frequency and expanded clonal mutations in primary tumors to better inform treatment decisions. KRAS coding exons in 61 treatment-naïve colorectal cancer (CRC) tumors and KRAS, EGFR, ALK, and MET in lung tumors from three Chinese non-small cell lung cancer (NSCLC) patients were sequenced using ultradeep sequencing methods. Forty-one percent of CRC patients (25/61) harbored mutations in the KRAS active domain, eight of which (13%) were not detected by Sanger sequencing. Three (of eight) had frequencies less than 10% and one patient harbored more than one mutation. Low frequency KRAS active (G12R) and EGFR kinase domain mutations (G719A) were identified in one NSCLC patient. A second NSCLC patient showed an EML4-ALK fusion with ALK, EGFR, and MET mutations. A third NSCLC patient harbored multiple low frequency mutations in KRAS, EGFR, and MET as well as ALK gene copy number increases. Within the same patient, multiple low frequency mutations occurred within a gene. A complex pattern of intrinsic low frequency driver mutations in well-known tumor oncogenes may exist prior to treatment, resulting in resistance to targeted therapies. Current targeted cancer therapies usually lack durability and demonstrate limited overall efficacy in patients. The types of low frequency concurrent mutations in candidate oncogenes presented here suggest necessary modifications both to methods for detection of these variants and to general treatment strategies. To date, Sanger sequencing has been effectively used for detection of treatment-relevant somatic mutations. However, in a heterogeneous mixture of cancerous and normal tissue, Sanger sequencing will likely fail to detect low frequency mutations. More sensitive and cost-effective sequencing methods are required to systematically assess the mutation status within cancer pathway genes or at the whole genome level. Furthermore, because patients often develop resistance to targeted therapy over time that is due to the preexistence of low frequency mutations in oncogenes, treatment strategies based on combination therapy might prove to be the most optimal treatment approach for cancer patients. Ultradeep sequencing can characterize intratumor heterogeneity and identify such mutations to ultimately affect treatment decisions. Citation Format: Christopher Morehouse, Liyan Jiang, Jiagi Huang, Wei Zhu, Susana Korolevich, Xiaoxiao Ge, Kim Lehmann, Zheng Lui, Christine Kiefer, Meggan Czapiga, Xinying Su, Philip Brohawn, Yi Gu, Brandon Higgs, Yihong Yao. Low frequency KRAS mutations in colorectal cancer patients and the presence of multiple mutations in oncogenic drivers in non-small cell lung cancer patients. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2377. doi:10.1158/1538-7445.AM2014-2377

Neoadjuvant immunotherapy has been demonstrated to be effective and safe in resectable non-small cell lung cancer (NSCLC) patients. However, the presence of different oncogenic driver mutations may affect the tumor microenvironment and consequently influence the clinical benefit from immunotherapy. This retrospective study included consecutive NSCLC patients (stage IIA to IIIB) who underwent radical surgery after receiving neoadjuvant immunotherapy at a single high-volume center between December 2019 and August 2022. Pathological response and long-term outcomes were compared based on the driver oncogene status, and RNA sequencing analysis was conducted to investigate the transcriptomic characteristics before and after treatment. Of the 167 patients included in this study, 47 had oncogenic driver mutations. KRAS driver mutations were identified in 28 patients, representing 59.6% of oncogenic driver mutations. Of these, 17 patients had a major pathological response, which was significantly higher than in the non-KRAS driver mutation group (60.7% vs. 31.6%, P = 0.049). Multivariate Cox regression analysis further revealed that the KRAS driver mutation group was an independent prognostic factor for prolonged disease-free survival (hazard ratio: 0.10, P = 0.032). The median proportion of CD8+ T cells was significantly higher in the KRAS driver mutation NSCLCs than in the non-driver mutation group (18% vs. 13%, P = 0.030). Furthermore, immune-related pathways were enriched in the KRAS driver mutation NSCLCs and activated after immunotherapy. Our study suggests that NSCLC patients with KRAS driver mutations have a superior response to neoadjuvant immunotherapy, possibly due to their higher immunogenicity. The findings highlight the importance of considering oncogenic driver mutations in selecting neoadjuvant treatment strategies for NSCLC patients.

To evaluate the impact of histology on efficacy of pemetrexed in Chinese non-small cell lung cancer (NSCLC) patients. This report summarized the results of two clinical trials of pemetrexed in Chinese patients with advanced NSCLC in 2nd line setting and maintenance setting after 1st line (JMID study and Chinese subgroup from JMEN study) treatment. For the Chinese JMID study (second-line), Chinese patients with locally advanced or metastatic (stage IIIA, IIIB or IV) NSCLC who had prior chemotherapy were enrolled. The study was designed to investigate the noninferiority of pemetrexed (500 mg/m(2), day 1 of each 21-day cycle) to docetaxel (75 mg/m(2), day 1 of each 21-day cycle) in terms of overall survival (OS). For the global JMEN study (maintenance), patients initially diagnosed with IIIB or IV NSCLC, those who had not progressed after completing at least four cycles of platinum-based chemotherapy were enrolled to test for the superiority of pemetrexed (500 mg/m(2), day 1 of each 21-day cycle) over placebo with progression free survival (PFS) as primary endpoint. In JMID study, the OS was similar between the pemetrexed group (Pem group) and docetaxel group (Doc group). Retrospective histological subtype analysis showed survival benefits (both OS and PFS) numerically of non-squamous patients over squamous patients in the Pem group (OS: HR 0.74, 95% CI 0.45-1.21, P = 0.2267, median 11.7 vs. 9.7 months; PFS: HR 0.77, 95% CI 0.44-1.34, P = 0.3585, median 3.0 vs. 1.7 months). In the Chinese subgroup of JMEN study, the median PFS in the Pem group for squamous and nonsquamous patients was 4.2 and 1.5 months for squamous patients, the median OS in the Pem group for squamous and nonsquamous patients was 22.5 and 6.2 months for squamous patients. In JMEN China subgroup analysis, the HR on histology was not analyzed due to the small sample size. In terms of safety profile, drug-related grade 3 or 4 hematological toxicities (leukocytopenia and neutropenia) events occurring after second-line treatment were significantly lower in the Pem group than in the Doc group (both P < 0.001). Similarly in patients receiving pemetrexed maintenance after first-line treatment, incidences of toxicity events were low. Consistent with global results, in Chinese NSCLC patients, histology has an impact on the efficacy of pemetrexed, in which non-squamous histology predicts a positive outcome for patients treated with pemetrexed. In terms of overall safety, pemetrexed is better than docetaxel with a lower incidence of adverse events and anticipates manageable safety profile in NSCLC patients. Based on consistent Chinese data from the two studies, pemetrexed is recommended as a standard chemotherapy regime in both second-line and maintenance setting after first-line treatment for Chinese non-squamous NSCLC patients.

BackgroundThe KRAS mutation is the second most common genetic variant in Chinese non-small cell lung cancer (NSCLC) patients. At the 2019th World Conference of Lung Cancer, the KRAS G12C-specific inhibitor AMG510 showed promising results in the phase I clinical trial. However, the frequency, clinical characteristics, and prognostic significance of the KRAS G12C mutation in Chinese NSCLC patients are rarely reported.MethodsNext-generation sequencing was used to confirm the KRAS mutation status in 40,804 NSCLC patients from multiple centers (mCohort). Survival data were collected retrospectively from 1456 patients at one of the centers, the Guangdong Lung Cancer Institute (iCohort).ResultsIn the mCohort, 3998 patients (9.8%) were confirmed to harbor a KRAS mutation, of whom 1179 (29.5%) had the G12C subtype. In the iCohort, 130 NSCLC patients (8.9%) had a KRAS mutation and 42 (32.3%) had the G12C subtype. The G12C subgroup included more male patients (85.2% vs 67.4%, P < 0.0001) and more smokers (76.2% vs 53.4%, P = 0.02) than did the non-G12C subgroup. Both the KRAS mutation group and KRAS G12C mutation subgroup were associated with a shorter median overall survival (OS) than wildtype tumors (15.1 vs 26.7 months, hazard ratio [HR]KRAS = 1.50, P = 0.002; 18.3 vs 26.7 months, HRG12C = 1.66, P = 0.007). In Cox regression analysis, smoking (HR = 1.39, P = 0.05) and stage IV disease (HR = 2.72, P < 0.001) remained as independent predictors of shorter OS. Both the KRAS mutation (HR = 1.30, P = 0.07) and KRAS G12C mutation (HR = 1.47, P = 0.07) reached borderline significance.ConclusionsIn the largest sample used thus for, our study found that approximately 10% of Chinese NSCLC patients had KRAS mutations. Of these, nearly 30% harbored the KRAS G12C mutation subtype, which was most common in male smokers. The KRAS G12C mutation is a biomarker of poor prognosis in Chinese NSCLC patients, which could potentially be improved by G12C-specific inhibitors in the future.(296 words)

HighlightsMET exon 14 skipping is an oncogenic targetable driver mutation in lung cancer.Two novel non-canonical splice site variants identified in MET genome.Predicted splicing strength using in silico splicing prediction tools.Tested routine cytological smear slides for RNA-based molecular diagnostics.RT-PCR and Sanger sequencing analysis confirmed MET exon 14 skipping.Simple SummaryNon-small Cell Lung cancer (NSCLC) contributes to 85% of total lung cancer diagnoses in the United States. With the discovery of various targetable genetic markers and FDA approval of drugs against these markers, genetic testing has become a routine part of the diagnosis and staging process of NSCLC. MET gain of function mutations have been of particular interest as FDA has recently approved two MET inhibitors for the treatment of NSCLC patients with MET exon 14 skipping (METex14) mutations. However, an effective workflow for the classification of various METex14 mutations in the clinical testing laboratory has not been explored. In this report, we reveal two novel METex14 variants and propose a cost-effective and robust workflow for molecular diagnosis of MET variants contributing to exon 14 skipping with the use of readily available specimen sources.Background and aims: The MET exon 14 skipping (METex14) is an oncogenic driver mutation that provides a therapeutic opportunity in non-small cell lung cancer (NSCLCs) patients. This event often results from sequence changes at the MET canonical splicing sites. We characterize two novel non-canonical splicing site variants of MET that produce METex14. Materials and Methods: Two variants were identified in three advanced-stage NSCLC patients in a next-generation sequencing panel. The potential impact on splicing was predicted using in silico tools. METex14 mutation was confirmed using reverse transcription (RT)-PCR and a Sanger sequencing analysis on RNA extracted from stained cytology smears. Results: The interrogated MET (RefSeq ID NM_000245.3) variants include a single nucleotide substitution, c.3028+3A>T, in intron 14 and a deletion mutation, c.3012_3028del, in exon 14. The in silico prediction analysis exhibited reduced splicing strength in both variants compared with the MET normal transcript. The RT-PCR and subsequent Sanger sequencing analyses confirmed METex14 skipping in all three patients carrying these variants. Conclusion: This study reveals two non-canonical MET splice variants that cause exon 14 skipping, concurrently also proposes a clinical workflow for the classification of such non-canonical splicing site variants detected by routine DNA-based NGS test. It shows the usefulness of in silico prediction to identify potential METex14 driver mutation and exemplifies the opportunity of routine cytology slides for RNA-based testing.

e20530 Background: Increasing efforts have been invested in elucidating the resistance mechanisms to osimertinib. Major resistance mechanisms include but not limited to acquired EGFR mutations, predominantly C797, mutations in bypass pathways and small cell lung cancer (SCLC) transformation. However, no study has comprehensively investigated clinical outcomes of various mechanisms of resistance. Methods: 103 T790M positive advanced Chinese non-small cell lung cancer (NSCLC) patients who progressed on 1st generation EGFR-TKI were enrolled. Targeted sequencing, using a panel consisting of 168 lung cancer related genes, was performed on paired plasma samples collected prior to osimertinib and after the development of disease progression (PD) to profile mutation spectrum. 7 patients with no mutation detected at PD were excluded from analyses. Results: Major acquired mutations included 25% EGFR mutations, predominantly C797 and L792, 16% MET amplification, 8% TP53 mutations, 4% KRAS mutations, 4% RET fusions, 4% ERBB2 amplification and 6.25% RB1 mutations. Acquired RB1 mutation may indicate the possibility of SCLC transformation. Approximately, 30% of patients with no known resistance mechanisms at PD. In this cohort, we had 61 patients with 19 deletion and 35 patients with EGFR L858R prior to the initiation of osimertinib. We revealed patients with 19del acquired more mutations ( p= 0.014) and were more likely to acquire mutations in MAP/PI3Kpathway ( p= 0.04) and TP53 at PD ( p= 0.021). On the other hand, acquired ERBB2 amplifications were only detected in L858R-mutant patients ( p= 0.047). Furthermore, 36 patients preserved T790M and 60 patients lost T790M at PD. Our data revealed patients retaining T790M, often associated with activation of bypass signaling pathways or continued EGFR activation through tertiary mutations, had a longer progression-free survival (PFS) ( p= 0.047) and overall survival (OS) ( p= 0.04) comparing to patients with T790M loss, often with diverse and EGFR-independent mechanisms. We also show that patients with acquired C797S had significantly longer PFS ( p= 0.031), while patients with acquired MET amplifications had significantly shorter PFS ( p= 0.033). Conclusions: Collectively, we revealed differential clinical outcomes associated with various resistance mechanisms, representing an important step in advancing the understanding of resistance mechanisms of osimertinib.

In brain metastases, radiation necrosis (RN) is a complication that arises after single or multiple fractionated stereotactic radiosurgery (SRS/FSRS), which is challenging to distinguish from local recurrence (LR). Studies have shown increased RN incidence rates in non-small cell lung cancer (NSCLC) patients with oncogenic driver mutations (ODMs) or receiving tyrosine kinase inhibitors (TKIs). This study investigated enlarging brain lesions following SRS/FSRS, for which additional surgeries were performed to distinguish between RN and LR. We investigated seven NSCLC patients with ODMs undergoing SRS/FSRS for BM and undergoing surgery for suspicion of LR on MRI imaging. Descriptive statistics were performed. Among the seven patients, six were EGFR+, while one was ALK+. The median irradiation dose was 30 Gy (range, 20-35 Gy). The median time to develop RN after SRS/FSRS was 11.1 months (range: 6.3-31.2 months). Moreover, gradually enlarging lesions were found in all patients after 6 months post-SRS/FSR. Brain radiation necrosis was pathologically confirmed in all the patients. RN should be suspected in NSCLC patients when lesions keep enlarging after 6 months post-SRS/FSRS, especially for patients with ODMs and receiving TKIs. Further, this case series indicates that further dose reduction might be necessary to avoid RN for such patients.

肺癌是全球癌症相关死亡的主要原因。非小细胞肺癌（non-small cell lung cancer, NSCLC）占所有肺癌患者中的80%-85%，大多数肺癌患者在确诊时已处于晚期阶段。目前，基于驱动基因的靶向治疗的发展改变了晚期NSCLC患者的治疗模式。在NSCLC中，表皮生长因子受体突变（epidermal growth factor receptor, EGFR）和棘皮动物微管相关蛋白和间变性淋巴瘤激酶（echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase, EML4-ALK）融合已被验证为强大的生物标志物。众所周知KRAS也是NSCLC中最常见的突变致癌基因之一，尽管20多年前在NSCLC中发现了KRAS突变，迄今为止用于治疗KRAS突变的NSCLC患者的药物有很多，但目前还没有针对直接消除KRAS活性的选择性和特异性抑制剂。此外具有KRAS突变的NSCLC患者对大多数系统性治疗的反应性差。然而使用靶向药物针对活化的信号通路个体化治疗对KRAS突变的NSCLC患者的预后有很好疗效。此外KRAS突变在NSCLC中的预后和预测作用尚不清楚。在这篇综述中，我们重点讨论了KRAS突变的NSCLC的研究进展，包括分子生物学、临床病理特征、KRAS突变的预后和预测等方面，进而有助于提高临床工作者对KRAS突变的NSCLC的认知。。

e21578 Background: Programmed cell death 1 (PD-L1) is the first FDA-approved predictive biomarker for non-small cell lung cancer (NSCLC) patients treated with PD-(L)1 blockade therapy. Herein, we aim to identify potential anti-PD-L1 treatment-related biomarkers through evaluating the correlation between the PD-L1 expression level, clinical characteristics, and the mutational profile of a large Chinese NSCLC cohort. Methods: Genomic profiling of tumor biopsies from a total of 808 Chinese NSCLC patients, including 651 adenocarcinomas (ADCs) and 157 squamous cell carcinomas (SCCs), was performed using next-generation sequencing by targeting 425 cancer-relevant genes. Immunohistochemical analysis was used to evaluate PD-L1 protein expression using PD-L1 antibodies including DAKO 22C3 ( N= 695) and DAKO 28-8 ( N= 113), respectively. Results: The PD-L1 positive ( &gt; 1%) rate was 49.2% in ADCs and 52.9% in SCCs, respectively. PD-L1 expression (22C3) was associated with the male gender( p&lt; 0.01) and lymph node metastasis ( p= 0.048) in ADCs but not in SCC patients. PD-L1 expression (22C3) was inversely correlated with KRAS wildtype ( p&lt; 0.001) and EGFR exon 19 deletion( p&lt; 0.01) in ADC, while it was negatively associated with TP53 oncogenic mutations ( p= 0.049) in SCC. Copy number variation analysis revealed that MDM2 amplification ( p= 0.027), 1q gain ( p= 0.012), and 5q deletion ( p&lt; 0.01) negatively correlated with PD-L1 expression, whereas PD-L1 and PD-L2 amplification ( p&lt; 0.001 and p&lt; 0.0001) were positively associated with PD-L1 expression in ADCs. In SCCs, PD-L1 expression (22C3) was negatively associated with copy number gain in EGFR ( p= 0.040), MDM2 ( p= 0.044), 14q ( p= 0.032), and 20q ( p= 0.026), along with PTPRD loss (p = 0.015) and 19p deletion (p = 0.025). However, it was positively associated with 9p amplification ( p&lt; 0.01) and 13q deletion ( p= 0.019). Plus, KIF5B- RET ( p= 0.006) appeared to be inversely related to the PD-L1 expression levels (22C3) in ADCs alone. In addition, these predicted biomarkers were used to delineate the receiver operating characteristic (ROC) calculation to discriminate between PD-L1 low and high (22C3, 50%) with an AUC score of 0.779. Lastly, PD-L1 expression (28-8) did not show significant correlation with any detected oncogenic mutations, but negatively correlated with NKX2-1 gain ( p= 0.0379) and 9q deletion ( p= 0.0379) in ADCs. Conclusions: This study revealed the correlation between PD-L1 protein expression, clinical features, and mutational traits in NSCLC patients, and provided a classifier for PD-L1 expression prediction.

7593 Background: ALK gene rearrangement is a recently identified molecular alteration in the tumors of a small proportion of NSCLC patients. Previous reports have shown that the rate of EGFR gene mutations may vary in NSCLC patients of different ethnic background. It is unclear if similar differences exist with regards to ALK positivity. We analyzed ALK expression in tumors of AA NSCLC patients and also assessed the epidemiologic features and outcomes of these patients, as well as the occurrence of known oncogene mutations. Methods: We identified 260 tumor tissues of AA NSCLC patients, enrolled on several epidemiologic studies conducted at our institution. Immunohistochemistry, using the anti-Alk D5F3 antibody (Cell Signaling Technology) was used to visualize ALK expression. Fifty-three of these tumors also underwent mutation analysis using the OncoCarta Panel V1 (Sequenom) to evaluate 238 mutations in 19 oncogenes. Results: Of the 260 tumors analyzed, 6 (2.3%, 95% CI- 0.5-4.1%) were ALK positive. All ALK positive patients had adenocarcinoma histology (6/157) while no patients with other NSCLC histologies were ALK positive, p=0.04. There was no difference in the rate of positivity based on sex, 1% (1/99) in males versus 3.1% (5/161) in females, p=0.27. Consistent with prior studies, patients with ALK positive tumors were slightly younger (median age 56 years vs 61 years, p = 0.27) and the positive rate was higher in never smokers 11% (2/18) than in ever smokers 1.6%, p=0.06. There was no correlation of ALK positivity with the stage of the disease at diagnosis. The survival of ALK positive and negative patients, adjusted for age, sex and stage, was similar (HR=0.77; 95% CI 0.19-3.13). Fifty-three tumors have been assessed for oncogene mutations in addition to ALK expression. Of these, 2 (3.8%) were ALK positive and neither of these tumors carried other tested mutations such as EGFR, Kras, PIK3 or AKT. Conclusions: The rate of ALK positive tumors among African-American NSCLC patients is similar to the general population and the demographic features of ALK positive AA patients is also similar to the general ALK positive NSCLC patient population.

e21608 Background: EGFR is the most commonly altered biomarker in East Asian NSCLC patients. Common driver mutations (L858R or exon 19 deletions (del)) are the focus of conventional hotspot testing which may overlook less common activating alterations such as single nucleotide variants (SNVs) in the tyrosine kinase or extracellular domain as well as exon 20 insertions (ins). We investigated the prevalence of uncommon EGFR mutations in ctDNA from NSCLC patients in East Asia tested by a commercially available comprehensive next generation sequencing (NGS) assay (Guardant360). This assay identifies SNVs, ins and del, fusions, and amplifications (amp), with complete exon sequencing of EGFR. Methods: Guardant360 test results from Hong Kong, Korea, Japan, Taiwan, and Southeast Asia were reviewed (cut-off December 2019). We identified cases with a diagnosis of “lung cancer,” excluding pure squamous, small cell, neuroendocrine, carcinoid and sarcomatoid histology. Patients enrolled in certain prospective clinical trials were excluded at the investigators’ request. Clinically relevant biomarkers were mutations in EGFR, BRAF (V600E), ERBB2, or KRAS; MET amp or exon 14 skipping; and ALK, ROS1, or RET fusions. Uncommon EGFR mutations were defined as those other than L858R, exon 19 del, or resistance SNV in codons 790-797; synonymous mutations and amp were excluded. Results: Plasma from 820 non-squamous NSCLC patients was tested. Samples came from 436 women and 384 men, median age 61 years. ctDNA was identified in samples from 701 patients (85% detection rate). Alterations in at least one clinically relevant gene were detected in 75% of the ctDNA positive cases: EGFR (54%), KRAS (8%), ALK (5%), ERBB2 (5%), RET (2%), MET (2%), BRAF (1%), ROS1 ( &lt; 1%). Uncommon EGFR alterations were found in 115 samples (16%), with 63 (9%) potentially actionable (exon 19 ins (1); exon 20 ins (22); activating SNV (40), some with multiple mutations, including L718Q (6), L718V (5), G719A (5), L861Q (5), S768I (4), and others) and 52 (7%) variants of unknown significance. Uncommon EGFR mutations were the only clinically relevant biomarker in 53 samples (8%). Conclusions: Uncommon, potentially actionable EGFR mutations were found in 9% of plasma samples from East Asian NSCLC patients. In this clinical practice dataset, uncommon EGFR mutations were more prevalent than actionable biomarkers in other genes. These data support the use of NGS testing methods to identify NSCLC patients for appropriate EGFR-targeted therapy.

Background: Cancer is one of the leading causes of death and one of the main barriers to increasing life expectancy worldwide. The development of therapeutic strategies directly targeting mutant oncogenes, such as EGFR and BRAF, has resulted in substantial benefits for patients with a variety of cancers. KRAS is one of the most frequently mutated oncogenes, however efforts to develop targeted therapies have been largely unsuccessful. Recently, two small-molecule inhibitors, AMG 510 and MRTX849, have shown promising activity in KRAS G12C-mutant solid tumors. The current study aims to assess the molecular profile of KRAS G12C in non-small-cell lung cancer (NSCLC) and colorectal cancer (CRC) from Brazilian patients tested in a clinically-certified laboratory. Methodology: 4,842 NSCLC patients were tested for KRAS, NRAS, EGFR and BRAF mutations by next generation sequencing (NGS), while 4,815 CRC patients were tested for KRAS and NRAS mutations, by pyrosequencing, between 2017 and 2019 Results and Discussion: From the 4,842 NSCLC samples tested, KRAS G12 mutations were identified in 1013 cases (20.9%) and, 336 of these (6.9% of total) were KRAS G12C. Additionally, from 4,815 CRC samples tested, KRAS G12 mutations were identified in 1633 cases (33.9%), and 166 of these (3.4% of total) were KRAS G12C. In the literature, KRAS G12C has been reported in 14 to 16% of all lung adenocarcinomas, and 5% of colorectal adenocarcinomas. Our data illustrate a relevance of this mutation in a significant number of patients and highlight an opportunity for targeted therapy. Some studies characterizing lung cancers have indicated that KRAS mutations, including KRAS G12C, are mutually exclusive with other known oncogenic driver mutations in NSCLC. However, in the current analysis, we identified 30 cases of NSCLC harboring multiple mutations, such as KRAS G12C mutations co-existing with EGFR, BRAF or NRAS mutations. This finding is probably due to the multiclonal presentation in selected cases. Conclusions: A relatively high number of patients may present with KRAS G12C-mutant cancers in Brazil, indicating the relevance of identifying such cases for targeted therapy. Further studies will deepen the analysis of clonality and heterogeneity in this cohort. Citation Format: Bianca Mendes Souza, Laura Rabelo Leite, Sabrina A. Parma, Natália P. Lopes, Frederico S. Malta, Luiz Henrique Araujo, Maíra C. Freire. Molecular profile of KRAS G12C-mutant non-small-cell lung cancer and colorectal cancer in Brazilian patients [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 4302.

11504 Background: PD-L1 can be induced by oncogenic signals or up-regulated via INFG in a STAT1- and NFκB-dependent manner. STAT3 opposes STAT1-mediated anti-tumor immune responses. I kappa B kinase epsilon (IKBKE) is an interferon signaling inducer. We explored whether INFG expression in pre-treatment tumors is associated with to the efficacy of ICB in NSCLC and melanoma patients. The role of inflammation-associated transcription factors STAT3, IKBKE and STAT1 was also examined. Methods: Total RNA from 17 NSCLC and 21 melanoma patients, was analyzed by qRT-PCR. INFG, STAT3, IKBKE, STAT1 and PD-L1 mRNA were examined. PD-L1 protein expression in tumor and immune cells was evaluated (Ventana SP142 assay). Progression free survival (PFS) and overall survival (OS) were estimated. Results: 17 previously treated NSCLC patients received nivolumab; 71% lung adenocarcinoma, 71% male, 53% smokers, 35% KRAS mutant, 88% EGFR wild-type (wt). 21 previously treated melanoma patients received pembrolizumab; 67% male, 67% BRAF wt. PFS to nivolumab was significantly longer in NSCLC patients with high vs. low INFG expression (5.12 vs. 2mo, p = 0.0124). PFS to pembrolizumab was significantly longer in melanoma patients with high vs. low INFG expression (4.99 vs. 1.86mo, p = 0.0099). Significantly longer OS was observed for melanoma patients with high vs. low INFG expression (not reached vs. 3.10mo p = 0.0183). There was a trend for longer OS for NSCLC patients with high vs. low INFG expression (10.15 vs. 4.86mo, p = 0.0687). The other gene levels and PD-L1 protein levels in tumor and immune cells did not affect the outcome to ICB. IKBKE was positively correlated with INFG and PD-L1 expression (NSCLC Spearman’s ρ = 0.58 and 0.65; melanoma Spearman’s ρ = 0.61 and 0.59), and STAT3 expression was loosely anticorrelated with PD-L1 expression (NSCLC Spearman’s ρ = −0.21; melanoma Pearson’s ρ = −0.01). Conclusions: INFG is an important marker for qRT-PCR mediated prediction of response to ICB in NSCLC and melanoma patients. Further research is warranted in order to validate that INFG is more accurate than PD-L1.

e21173 Background: Immune checkpoint inhibitors (ICIs), such as PD-1/PD-L1 antibodies, are becoming standard of care for lung cancer treatment. However, low response rates to ICI antibodies and even hyperprogressive disease (HPD) have limited the clinical application of ICIs. Considering HPD for patients means shorter survival times and worse prognoses, valid biomarkers are in urgent demand to predict the occurrence of HPD and the efficacy of ICI. Here, we explored the genomic biomarkers of HPD in Chinese non-small cell lung cancer (NSCLC) patients. Methods: 749 NSCLC patients with both genomic information and PD-L1 expression data were screened from HapLab database. HaploX 605-gene panel sequencing, covering 1.31 MB genome, was performed to analyze the genomic data of patients. PDL-1 expression was detected by immunochemistry. Results: 15 genes related to HPD were detected altered in NSCLC patients. Collectively, 511 out of 749 patients (68.22%) had at least one alteration of HPD related genes. The frequent alterations were EGFR mutation (46.86%), ALK fusion (7.49%), MDM2 amplification (6.54%), KEAP1 mutation (5.34%), STK11 mutation (4.27%), FGF3/4 amplification (4.14%), DNMT3A mutation (2.14%) and MDM4 amplification (2.00%). While in EGFR wild-type and ALK-negative patients, the top 5 frequent alterations were KEAP1 mutation (8.96%), FGF3/4 amplification (7.00%), STK11 mutation (6.16%), PTEN mutation (5.32%) and MDM2 amplification (4.20%). Notably, EGFR mutation (49.27%, 68/138), ALK fusion (9.42%, 13/138) and MDM2 amplification (4.35%, 6/138) were also observed in PDL-1 positive (TPS≥1%) patients. Conclusions: It is urgent to identify specific biomarkers that could predict HPD and to develop effective methods to prevent HPD. Our study investigated the genomic alterations associated with HPD in Chinese NSCLC patients.

Little is known about the relationship between programmed cell death-ligand 1 (PD-L1) expression and histologic and genetic features in real-world Chinese non-small cell lung cancer patients. From November 2017 to June 2019, tumor tissues were collected from 2674 non-small cell lung cancer patients. PD-L1 expression was detected with immunohistochemistry using the 22C3 and SP263 antibodies, and patients were stratified into subgroups based on a tumor proportion score of 1%, 1% to 49%, and ≥ 50%. Genetic alterations were profiled using targeted next-generation sequencing. In the total population, 50.5% had negative PD-L1 expression (tumor proportion score < 1%), 32.0% had low-positive expression (1%-49%), and 17.5% had high-positive expression (≥50%). The PD-L1 positive rate was 39.0% in squamous cell carcinomas and 53.6% in adenocarcinomas. PD-L1 expression was higher in squamous cell carcinomas (P < .001) and lower in adenocarcinomas (P < .001). Of the overall patient population, 11.2% had Kirsten rat sarcoma viral oncogene (KRAS) mutations, 44.9% had epidermal growth factor receptor (EGFR) mutations, 2.1% had BRAF V600E mutations, 0.3% had MET exon 14 skipping mutations, 5.4% had anaplastic lymphoma kinase translocations, and 0.9% had ROS proto-oncogene 1 translocations. Patients carrying ROS proto-oncogene 1 translocations (P = .006), KRAS (P < .001), and MET (P = .023) mutations had significantly elevated expression of PD-L1, while those harboring EGFR (P < .001) mutations had lower PD-L1 expression. In our study, PD-L1 expression was significantly higher in squamous cell carcinomas and lower in adenocarcinomas, and was positively associated with MET and KRAS mutations, as well as the wild-type EGFR gene state. Nonetheless, additional studies are needed to further validate those associations and determine the clinical significance for immune checkpoint inhibitors of these factors.