Epidermal Growth Factor Receptor Copy Number Research Articles

The association of EGFR amplification with aberrant exon 20 insertion report using the cobas EGFR Mutation Test v2.

Determining the exact type of epidermal growth factor receptor (EGFR) exon 20 insertion (ex20ins) mutation in lung cancer has become important. We found that not all ex20ins mutations reported by cobas EGFR test v2 could be validated by Sanger sequencing even using surgical specimens with high tumor contents. This study aimed to validate the ex20ins results reported by the cobas test and to determine whether there were clinicopathological factors associated with aberrant cobas ex20ins report. In total, 123 cobas-reported cases with ex20ins were retrospectively collected and validated by Sanger sequencing and Idylla assay. Clinicopathological features between ex20ins cobas+/Sanger+ group (n = 71) and cobas+/Sanger- group (n = 52) were compared. The Idylla assay detected ex20ins in 82.6% of cobas+/Sanger+ cases but only in 4.9% of cobas+/Sanger- cases. The cobas+/Sanger- group was significantly associated with higher tumor contents, poorly differentiated patterns, tumor necrosis, and a lower internal control cycle threshold value reported by the Idylla which suggesting the presence of increased EGFR gene copy numbers. EGFR fluorescence in situ hybridization (FISH) revealed the majority of cobas+/Sanger- group had EGFR high copy number gain (16%) or amplification (76%) according to the Colorado criteria. Among cases reported to have concomitant classic EGFR and ex20ins mutations by the cobas, the classic EGFR mutations were all detected by Sanger sequencing and Idylla, while the ex20ins mutations were undetected by Sanger sequencing (0%) or rarely reported by Idylla assay (3%). FISH revealed high EGFR copy number gain (17.9%) and amplification (79.5%) in cases reported having concomitant classic EGFR and ex20ins mutations by the cobas. This study demonstrated an unusually high frequency of EGFR amplification in cases with aberrant cobas ex20ins report which could not be validated by Sanger sequencing or Idylla assay. Ex20ins reported by the cobas test should be validated using other methods especially those reported having concomitant ex20ins and classic EGFR mutations.

Abstract CT126: A Phase 0 Study of EGF-Depleting Therapy CIMAvax-EGF in Combination With Standard Therapy for RAS- and BRAF Wild-Type Metastatic Colorectal Cancer

Abstract Background: Colorectal Cancer (CRC) is the 3rd most common cancer in the US and a leading cause of cancer-related death. The epidermal growth factor receptor (EGFR) is overexpressed by immunohistochemistry (IHC) in up to 60% of CRC and is a relevant target for treatment. Monoclonal antibodies targeting the EGFR (cetuximab, panitumumab) have been in clinical use since 2004 as single agents as well as in combination with chemotherapeutics for patients with metastatic CRC, however primary and secondary resistance is very common. CIMAvax-EGF® (CIMAvax) vaccinates against one of the main EGFR ligands: the epidermal growth factor (EGF) protein. The vaccine is based on active immunotherapy where an individual’s immune response is manipulated to release its own effector antibodies against circulating EGF. We hypothesize that adding CIMAvax-EGF to standard chemotherapy has the potential to elicit an immune response against EGF for RAS- and BRAF wild-type metastatic CRC. Methods: This is a phase 0 study to evaluate CIMAvax in combination with standard therapy for RAS- and BRAF wild-type metastatic CRC. Patients will be treated with chemotherapy/biologic agent plus CIMAvax 2.4 mg (DL 1); DL -1 is 1.2 mg. The starting dose is the dose currently established as recommended dose in combination with immunotherapy in patients with non-small cell lung cancer. Cohorts A, B1 and B2 will enroll each 6-12 patients. Based on the known CIMAvax safety profile, we expect to enroll 18-20 patients in these cohorts. Cohort C will enroll 4-6 patients. Cohort A will enroll patients who have not received prior therapy for advanced disease. Patients in Cohort A will be treated with mFOLFOX6/Bevacizumab/CIMAvax at present. Cohort B will enroll patients who have received at least one but no more than 2 prior therapies for advanced disease. Cohort B is comprised of 2 sub-Cohorts. The standard therapy backbone in Cohort B1 will be FOLFIRI/anti-EGFR therapy, and in Cohort B2 mFOLFOX6/anti-EGFR therapy. Cohort C will enroll patients who have not received prior therapy for advanced disease and are candidates for liver metastasectomy. Cohort C will start accruing after the safety run-in phase in Cohorts A, and B2 are completed. The primary objective of this study is to determine the immunogenicity of CIMAvax in the 1st and 2nd/3rd line setting. Secondary objectives include determining the safety and efficacy of these combinations in this patient population and PFS. Exploratory objectives include evaluation of immunomodulation in the tumor microenvironment in patients undergoing metastasectomy of liver metastases, predictive/prognostic role of EGFR ligands (such as EGF, epiregulin, and amphiregulin), somatic mutation profile, EGFR expression by IHC and EGFR copy number alterations/mRNA expression. This trial is currently open for accrual. Clinicaltrials.gov number NCT06011772 Citation Format: Deepak Vadehra, Cayla Janes, Rachel Frascati, Mary Reid, Tania C. Ramos, Sarbajit Mukherjee, Kalet L. Monzón, Patricia L. Alvárez, Orestes S. Morales, Circe M. Pardillo, Christos Fountzilas. A Phase 0 Study of EGF-Depleting Therapy CIMAvax-EGF in Combination With Standard Therapy for RAS- and BRAF Wild-Type Metastatic Colorectal Cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT126.

Genomic characterisation of de novo EGFR copy number gain and its impact on the efficacy of first-line EGFR-tyrosine kinase inhibitors for EGFR mutated non-small cell lung cancer

BackgroundNon-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutation generally respond well to epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs). However, genomic characterisation of de novo EGFR copy number gain (CNG) and its impact on the efficacy of first-line EGFR-TKIs remains unclear. MethodsThis multicenter, retrospective and real-world study included two cohorts that enroled EGFR mutant NSCLC patients. EGFR CNG was tested by next-generation sequencing of untreated tissue specimens. Cohort 1 detected the impact of EGFR CNG on first-line EGFR-TKIs treatment, and cohort 2 explored the genomic characterisation. ResultsCohort 1 enroled 355 patients from four cancer centres between January 2013 and March 2022. The patients were divided into three groups, included the EGFR non-CNG, EGFR CNG, and EGFR uncertain-CNG. No significant difference in progression-free survival (PFS) was found between the three groups (10.0 months vs. 10.8 months vs. 9.9 months, respectively, p = 0.384). Furthermore, the overall response rate was not statistically significant in the EGFR CNG group compared to the EGFR non-CNG or uncertain arm (70.3% vs. 63.2% vs. 54.5%, respectively, p = 0.154). Cohort 2 included 7876 NSCLC patients with 16.4% showing EGFR CNG. Gene mutations such as TP53, IKZF1, RAC1, MYC, MET, CDKN2A/B and alterations of the metabolic-related and ERK signalling pathway were significantly associated with patients with EGFR CNG compared to those without. ConclusionsDe novo EGFR CNG had no effect on the efficacy of first-line EGFR-TKI treatment in EGFR mutant NSCLC patients, and tumours with EGFR CNG had more complex genomic profiles than those without.

Tenascin-C affects invasiveness of EGFR-mutated lung adenocarcinoma through a putative paracrine loop

Tenascin C (TNC) is an extracellular matrix (ECM) protein and a potential biomarker affecting progression of different tumor types, such as pancreatic and lung cancer. Alternative splicing variants of TNC are known to have an impact on interaction partners like other ECM proteins or cell surface receptors, including epidermal growth factor receptor (EGFR), leading to numerous and sometimes opposite roles of TNC in tumor cell dissemination and proliferation. Only little is known about the impact of TNC on biologic characteristics of lung cancer, such as invasion and metastatic potential. In the present study, we could link an increased expression of TNC in lung adenocarcinoma (LUAD) tissues with an unfavorable clinical outcome of patients. Furthermore, we investigated the functional role of TNC in LUAD. Immunohistochemical staining of TNC revealed a significant increase of TNC levels in primary tumours and metastases compared to normal lung tissue. Additionally, a significant correlation between TNC mRNA expression and EGFR copy number and protein expression levels has been determined. Moreover, inhibition of TNC in lung fibroblasts led to reduced invasiveness of LUAD cells harboring EGFR-activating mutations and to a shorter lamellipodia perimeter and a reduced lamellipodia area on the surface of LUAD cells. This study provides the evidence that TNC expression might be a biological relevant factor in LUAD progression in an EGFR-dependent manner and that it regulates tumor cell invasion by rearrangement of the actin cytoskeleton, especially affecting lamellipodia formation.

Correlation between PD-L1 high-expression and EGFR variants in non-small cell lung cancer.

e21062 Background: In previous studies, researchers have demonstrated that activation of the epidermal growth factor receptor (EGFR)-mutant pathway induced PD-L1 expression. In this study, we explored the correlation between PD-L1 expressions and EGFR variations. Methods: This study enrolled 2417 non-small cell lung cancer(NSCLC) patients harboring diverse EGFR mutations, including exon 19 deletions(19del)(n = 1045), L858R(n = 906), G719X(n = 176), S768I(n = 62), L861Q(n = 89) and exon 20 insertions(20ins)(n = 139). The stages range from I through IV, the majority were female(n = 1452, 60.07%) and adenocarcinoma(n = 1788, 73.98%), median age was 62(range 24-92). In this study, we retrospectively analyzed variants using next-generation sequencing(NGS). PD-L1 status was determined by VENTANA PD-L1 (SP263) Assay, TPS≥50% and TPS＜1% was the cut-off value for PD-L1 high-expression and negative separately. The 95% confidence interval (CI) was used to estimate the precision of the odds ratio (OR). Results: 1) Even though we observed subtle differences of PD-L1 high-expression ratio among various subtypes(19del：9.57%, L858R: 9.27%, G719X: 12.50%, S768I: 11.29%, L861Q: 7.87%, exon 20ins: 12.23%) in total patients, that PD-L1 high-expression was more likely to shown with G719X/S768I/exon 20ins than with 19del/L858R/L861Q, there was no statistically significant between 19del and other mutation：L858R(p = 0.8224), G719X (p = 0.2319), S768I(p = 0.6563), L861Q(p = 0.5982), exon 20ins(P = 0.3247). 2)We analyzed 742 treatment-naive EGFR-mutant NSCLC patients (PD-L1 negative, n = 624; high-expression, n = 118), PD-L1 high-expression group come with higher frequency of EGFR copy number variation(CNV)(OR = 2.2364, 95%CI, 1.4576-3.4312, p = 0.0002). Importantly, the ratio of high-level EGFR CNV(CN≥6) was higher in PD-L1 high-expression group than that in the negative group(OR = 3.0668, 95% CI, 1.3745-6.8427, p = 0.0062). Conclusions: In the newly diagnosed EGFR-mutant NSCLC patients, PD-L1 high-expression patients come with more frequent high-level EGFR CNV. There is no statistical significance between PD-L1 high-expression and EGFR mutation subtypes. As for how the EGFR signal affects PD-L1 expression, the mechanism needs to be further explored. The association between driver genes and immune checkpoints is a definite interest of future investigations.

PD-L1 expression, tumor-infiltrating lymphocytes, mismatch repair deficiency, EGFR alteration and HPV infection in sinonasal squamous cell carcinoma

The antitumor efficacies of immune checkpoint inhibitors (ICIs) and the usefulness of potential predictive markers such as programmed death-ligand 1 (PD-L1) expression, density of tumor-infiltrating lymphocytes (TILs) and microsatellite instability (MSI) in sinonasal squamous cell carcinoma (SNSCC) have not been fully elucidated. We retrospectively analyzed 131 SNSCCs with immunohistochemistry for PD-L1 expression, TIL subpopulations and loss of mismatch repair (MMR) proteins as a surrogate for MSI-high. We also comprehensively evaluated the mutual relationships among these immuno-markers, high-risk human papillomavirus (HPV) infection, epidermal growth factor receptor (EGFR) gene status, and KRAS mutation. PD-L1 expression (tumor proportion score ≥ 1%) was detected in 60 (45.8%) SNSCC cases and was significantly associated with worse overall survival (OS) (p = 0.0240). High density of cluster of differentiation 8 (CD8)-positive TILs was significantly associated with better progression-free survival (PFS) (p = 0.0368), and high density of forkhead box protein P3-positive TILs was significantly associated with better PFS and OS (p = 0.0007 and 0.0143, respectively). With respect to the combination of CD8 + TIL and PD-L1 expression, the high-CD8/PD-L1-negative group showed the most favorable prognosis, whereas the low-CD8/PD-L1-positive group showed the worst prognosis. MMR loss was detected in 3 (2.3%) of the 131 cases. HPV infection (6.1%), EGFR mutation (14.5%), EGFR copy number gain (26%), and MMR loss were essentially mutually exclusive; patients in these molecular groups showed significant differences in prognosis but not in the degree of PD-L1 expression or TILs. Among the nine ICI-treated patients, three (33.3%) were responders, and the EGFR-wild type cases (n = 7) showed better clinical responses to an ICI compared to the EGFR-mutant cases (n = 2). Among the patients with residual/recurrent EGFR-wild type tumors (n = 43), ICI treatment significantly improved OS (p = 0.0281). The results suggest that the evaluation of immuno-markers and molecular subclassification may be helpful for prognostic prediction and selecting an individualized therapeutic strategy for patients with SNSCC.

P13.18 Inhibition of epidermal growth factor receptor and platelet-derived growth factor receptor-alpha exerts synergistic efficacy in glioblastoma

Abstract BACKGROUND Despite our understanding of the genetic changes that precipitate gliomagenesis, targeted therapy has failed in glioblastoma (GBM) with median survival not significantly improved over the past two decades. Epidermal growth factor receptor (EGFR) alterations, including amplification and activating mutations, are among the most common genetic changes in GBM, occurring in more than half of cases. EGFR is located on Chr. 7, and Chr. 7 gain is one of the earliest events precipitating gliomagenesis. Various EGFR inhibitors, including tyrosine kinase inhibitors, monoclonal antibodies, vaccines, and CAR-T cells have failed in GBM due to intrinsic heterogeneity and receptor tyrosine kinase bypass pathways that mediate therapeutic resistance. New targeted therapeutic approaches to leverage synergistic combinations are desperately needed to improve GBM prognosis. Using the TCGA and other GBM databases, we have previously demonstrated that the presence of PDGFRAamplification in patients with EGFR-amplified GBM carries significantly worse survival. EGFR and PDGFRA co-expression occur in more than one-third of GBM patients. The PDGFRA ligand PDGFA is also located on Chr. 7, and its expression is significantly increased with Chr. 7 gain and EGFR copy number increase. Therefore, Chr. 7 gain inherently leads to co-activation of both EGFR and PDGFRA signaling pathways. MATERIALS AND METHODS We used models of patient-derived glioblastoma cells to test combined inhibition of epidermal growth factor receptor and platelet-derived growth factor receptor-alpha in vitro. RESULTS Using patient-derived GBM models with Chr. 7 gain, we found that combined inhibition of both EGFR and PDGFRA using a variety of FDA-approved EGFR-targeted agents (Erlotinib, Gefitinib, Dacomitinib, Neratinib, and Osimertinib) and Crenolanib, respectively, leads to synergistic cytotoxicity in vitro. We found that inhibition of either EGFR or PDGFRA alone led to receptor cross-activation, and EGF and PDGF-AA-induced receptor tyrosine kinase activation was blocked by Neratinib and Crenolanib. Immunoprecipitation experiments and proximity ligation assays demonstrated that combined inhibition prevents EGFR and PDGFRA heterodimerization and pathways of therapeutic resistance. This combined inhibition led to decreased activation of downstream signaling pathways, including phosphatidylinositol 3-kinase and mitogen-activated protein kinase. CONCLUSIONS We show that combined inhibition of EGFR and PDGFRA exerts synergistic cytotoxicity in GBM and prevents resistance pathways that emerge during single-agent targeted therapy against these receptor tyrosine kinases. These pathways are targetable with FDA-approved agents that could be used in patients with GBM with Chr. 7 gain.

Cigarette Smoke Containing Acrolein Upregulates EGFR Signaling Contributing to Oral Tumorigenesis In Vitro and In Vivo.

Simple SummaryOral squamous cell carcinoma (OSCC) is one of the most common smoking-related cancer types in the world. Better understanding of the pathophysiology of OSCC would lead to the development of novel therapeutic options. The epidermal growth factor receptor (EGFR) pathway plays a crucial role in the development of OSCC, and aberrant EGFR expression levels have been associated with smoking. Cigarette smoke contains large amounts of aldehydes such as acrolein, which is a highly reactive environmental toxin. In this study, our results present that acrolein is important in oncogenic transformation through activating the EGFR signaling pathway, contributing to oral carcinogenesis. To the best of our knowledge, this is the first study to provide molecular evidence, showing that cigarette smoke containing acrolein contributes to EGFR amplification and activation of downstream signaling in OSCC. Thus, acrolein might be a novel target for early detection and prevention of oral cancer in the future.Oral squamous cell carcinoma (OSCC) accounts for 80–90% of all intraoral malignant neoplasms. The single greatest risk factor for oral cancer is tobacco use, including cigarettes, cigars, chewing tobacco, and snuff. Aberrations of the epidermal growth factor receptor (EGFR) pathway features prominently in oral tumorigenesis and progression. It was shown that cigarette smoking (CS) is associated with worse prognosis in OSCC patients and overexpression of EGFR in tumor tissue. However, the mechanism by which cigarette smoking induced EGFR pathway activation remains to be fully elucidated. Acrolein, an IARC group 2A carcinogen, is a highly reactive aldehyde found in CS. Here we report that acrolein is capable of inducing tumorigenic transformation in normal human oral keratinocytes (NOK). The acrolein-transformed NOK cells showed EGFR copy number amplification, increased EGFR expression, and activation of downstream ERK and AKT signaling pathway. No p53 mutations were observed in acrolein-transformed NOK cells. Inhibiting EGFR pathway using an anti-EGFR antibody, cetuximab, inhibits tumor growth. Furthermore, by examining tissue sample from patients, we found an increased EGFR copy number was positively associated with acrolein-induced DNA damages in OSCC patients. Taken together, our results indicate that acrolein is important in tumorigenic transformation through amplification of EGFR and activating the downstream signaling pathway, contributing to oral carcinogenesis. This is the first study to provide molecular evidence showing that CS containing acrolein contributes to EGFR amplification in OSCC.

Clinical Value of EGFR Copy Number Gain Determined by Amplicon-Based Targeted Next Generation Sequencing in Patients with EGFR-Mutated NSCLC.

BackgroundThe clinical relevance of epidermal growth factor receptor (EGFR) copy number gain in patients with EGFR mutated advanced non-small cell lung cancer on first-line tyrosine kinase inhibitor treatment has not been fully elucidated.ObjectiveWe aimed to estimate EGFR copy number gain using amplicon-based next generation sequencing data and explored its prognostic value.Patients and MethodsNext generation sequencing data were obtained for 1566 patients with non-small cell lung cancer. EGFR copy number gain was defined based on an increase in EGFR read counts relative to internal reference amplicons and normal controls in combination with a modified z-score ≥ 3.5. Clinical follow-up data were available for 60 patients treated with first-line EGFR-tyrosine kinase inhibitors.ResultsSpecificity and sensitivity of next generation sequencing-based EGFR copy number estimations were above 90%. EGFR copy number gain was observed in 27.9% of EGFR mutant cases and in 7.4% of EGFR wild-type cases. EGFR gain was not associated with progression-free survival but showed a significant effect on overall survival with an adjusted hazard ratio of 3.14 (95% confidence interval 1.46–6.78, p = 0.003). Besides EGFR copy number gain, osimertinib in second or subsequent lines of treatment and the presence of T790M at relapse revealed significant effects in a multivariate analysis with adjusted hazard ratio of 0.43 (95% confidence interval 0.20–0.91, p = 0.028) and 0.24 (95% confidence interval 0.1–0.59, p = 0.001), respectively.ConclusionsPre-treatment EGFR copy number gain determined by amplicon-based next generation sequencing data predicts worse overall survival in EGFR-mutated patients treated with first-line EGFR-tyrosine kinase inhibitors. T790M at relapse and subsequent treatment with osimertinib predict longer overall survival.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11523-021-00798-2.

Simultaneous detection of EGFR amplification and EGFRvIII variant using digital PCR-based method in glioblastoma

Epidermal growth factor receptor (EGFR) amplification and EGFR variant III (EGFRvIII, deletion of exons 2–7) are of clinical interest for glioblastoma. The aim was to develop a digital PCR (dPCR)-based method using locked nucleic acid (LNA)-based hydrolysis probes, allowing the simultaneous detection of the EGFR amplification and EGFRvIII variant. Sixty-two patients were included. An exploratory cohort (n = 19) was used to develop the dPCR assay using three selected amplicons within the EGFR gene, targeting intron 1 (EGFR1), junction of exon 3 and intron 3 (EGFR2) and intron 22 (EGFR3). The copy number of EGFR was estimated by the relative quantification of EGFR1, EGFR2 and EGFR3 amplicon droplets compared to the droplets of a reference gene. EGFRvIII was identified by comparing the copy number of the EGFR2 amplicon to either the EGFR1 or EGFR3 amplicon. dPCR results were compared to fluorescence in situ hybridization (FISH) and next-generation sequencing for amplification; and to RT-PCR-based method for EGFRvIII. The dPCR assay was then tested in a validation cohort (n = 43). A total of 8/19 EGFR-amplified and 5/19 EGFRvIII-positive tumors were identified in the exploratory cohort. Compared to FISH, the EGFR3 dPCR assay detected all EGFR-amplified tumors (8/8, 100%) and had the highest concordance with the copy number estimation by NGS. The concordance between RT-PCR and dPCR was also 100% for detecting EGFRvIII using an absolute difference of 10.8 for the copy number between EGFR2 and EGFR3 probes. In the validation cohort, the sensitivity and specificity of dPCR using EGFR3 probes were 100% for the EGFR amplification detection compared to FISH (19/19). EGFRvIII was detected by dPCR in 8 EGFR-amplified patients and confirmed by RT-PCR. Compared to FISH, the EGFR2/EGFR3 dPCR assay was estimated with a one-half cost value. These results highlight that dPCR allowed the simultaneous detection of EGFR amplification and EGFRvIII for glioblastoma.

Frequent EGFR expression/EGFR amplification and lack of activating mutation in testicular choriocarcinoma

Choriocarcinoma (CC) is the rarest but most aggressive histological component of adult testicular germ cell tumor (TGCT). Although we previously reported a putative role of epidermal growth factor receptor (EGFR) alterations in the progression of CC, little is known about the kinase-activating mutation status of EGFR, which predicts the response to EGFR-tyrosine kinase inhibitors. In this study, we clinicopathologically reviewed a total of 12 cases of mixed TGCTs with CC components. Immunohistochemistry, fluorescence in situ hybridization, and direct sequencing was performed to investigate EGFR expression, EGFR copy number alterations, and functional mutation of EGFR in these CC components, respectively. Four (33%) of 12 cases exhibited predominant CC components (>50%), and all these patients died due to disease within 62 months. Overexpression of EGFR, higher copy number of EGFR, and amplification of EGFR was observed in 12 (100%), 10 (83%), and 9 (75%) of 12 CC components, respectively. None of the cases showed any mutational events in exons 18 to 24, which encode the tyrosine kinase domain of EGFR. These results confirm an important role of EGFR in the tumor aggressiveness of testicular CCs and may suggest its possible innate resistance against conventional anti-EGFR therapies.

HPV-related Sinonasal Carcinoma: Clinicopathologic Features, Diagnostic Utility of p16 and Rb Immunohistochemistry, and EGFR Copy Number Alteration.

The prevalence and prognostic value of human papillomavirus (HPV) infection and epidermal growth factor receptor (EGFR) alteration in sinonasal squamous cell carcinoma (SNSCC) are not known. The reliability of p16 overexpression as a surrogate for HPV infection in SNSCC is also unclear. We investigated the prognostic and diagnostic significances of HPV infection, EGFR alteration, and p16 expression in SNSCC. We analyzed high-risk HPV infection by HPV-RNA in situ hybridization and EGFR gene copy number gain (CNG) by chromogenic in situ hybridization and by determining the protein expressions of p16, Rb, and EGFR by immunohistochemistry in 101 SNSCC cases. HPV infection (n=9, 8.9%) and p16 overexpression (n=15, 14.9%) were associated with better overall survival (P=0.0042 and 0.005, respectively). The HPV cases were located predominantly at the nasal cavity with nonkeratinizing histology and partial loss of Rb. Notably, 40% (6/15) of p16 SNSCCs were HPV. Two of these cases showed complete loss of Rb expression by immunohistochemistry, suggesting a reason for the above discrepancy. EGFR CNG, detected in 30.5% of the SNSCCs, was correlated with EGFR protein overexpression (P=0.0001). HPV infection and EGFR CNG were mutually exclusive. The HPV/EGFR CNG group had significantly better overall survival than the HPV/EGFR CNG and HPV/EGFR CNG groups (P=0.0471 and 0.0343, respectively). Our results suggest that HPV infection is a favorable prognostic marker in SNSCC, but p16 is not a perfect surrogate marker; the Rb expression pattern may improve the diagnostic accuracy. The molecular subclassification of SNSCCs based on HPV infection and EGFR copy number status might provide important information for therapeutic strategies.

P14.54 Association of EGFR Expression and Copy Number with Outcome in Depatux-m (ABT-414) Randomized Phase II Study of the EORTC Brain Tumor Group

Abstract BACKGROUND Patients with glioblastoma (GBM) have a dismal prognosis and are in desperate need of better therapy than the standard of care (SOC). Epidermal growth factor receptor (EGFR) gene amplification is reported in more than 50% of GBMs as an important target for therapeutic intervention and as a potential predictive biomarker. Depatuxizumab mafodotin (depatux-m, ABT-414) is an antibody-drug conjugate that preferentially binds cells with EGFR active conformation, internalized and releases the cytotoxin, leading to cell death. In the primary analysis we reported a trend (in EORTC 1410; HR: 0.71, 95% CI [0.50–1.02], p = 0.06) at topline analysis which continued to improve with ad hoc follow up (HR of 0.66, 95%CI [0.47–0.93]; p = 0.016) was observed towards improved overall survival (OS) in patients with EGFR amplified (amp) recurrent glioblastoma treated with depatux-m in combination with temozolomide. OS was equivalent in the depatux-m monotherapy and chemotherapy control arms. Here, we evaluate the association of EGFR mRNA expression and EGFR copy number with outcome using the updated efficacy data. METHODS Eligible were patients with centrally confirmed EGFR amp GBM at first recurrence after temozolomide chemo-irradiation. Patients were randomized to either a) depatux-m 1.0–1.25 mg/kg combined with temozolomide 150–200 mg/m2 day 1–5 every 4 weeks, b) depatux-m 1.0–1.25 mg/kg monotherapy or c) either temozolomide or lomustine (TMZ/LOM) depending on the time of relapse. Primary endpoint was OS. Long-term follow-up data (24 months follow-up; 237 events) were utilized for this EGFR analysis. The expression level of EGFR was determined using RT-PCR. The absolute copy number of EGFR was determined using next generation sequencing. EGFR mRNA and EGFR copy number were treated as continuous variables and compared to OS using a generalized additive cox proportional hazards model. RESULTS The outcome of the long-term follow-up was that when used in combination with TMZ, depatux-m addition resulted in improved OS as compared to TMZ/ LOM control regardless of EGFR expression or absolute copy number of EGFR. In contrast, in depatux-m monotherapy, a trend was observed that depatux-m improved the outcome only at highest expression levels and highest absolute EGFR copy number. CONCLUSIONS The long-term follow-up trial results demonstrated that addition of depatux-m to SOC showed a trend to increased survival as compared to SOC alone in EGFR amp patients as determined using Fluorescent in situ hybridization (FISH) analysis. Further retrospective analysis supports this efficacy advantage is observed at all expression and amplification levels. When used in combination with SOC and regardless of the absolute copy number of EGFR, the trend for OS improvement was observed at all expression levels.

<p>Epidermal growth factor receptor (<em>EGFR</em>) gene alteration and protein overexpression in Malaysian triple-negative breast cancer (TNBC) cohort</p>

BackgroundEpidermal growth factor receptor (EGFR) is a member of the ErbB family of tyrosine kinase receptor proteins that plays important roles in tumour cell survival and proliferation. EGFR has been reported to be overexpressed in up to 78% of triple-negative breast cancer (TNBC) cases suggesting it as a potential therapeutic target. The clinical trials of anti-EGFR agents in breast cancer showed low response rates. However, a subgroup of patients demonstrated response to EGFR inhibitors highlighting the necessity to stratify patients, who might benefit from effective combination therapy that could include anti EGFR-agents. Population variability in EGFR expression warrants systematic evaluation in specific populations.PurposeTo study EGFR alterations and expressions in a multi ethnic Malaysian TNBC patient cohort to determine the possibility of using anti-EGFR combinatorial therapy for this population.Patients and methodsIn this study, we evaluated 58 cases of Malaysian TNBC patient samples for EGFR gene copy number alteration and EGFR protein overexpression using fluorescence in-situ hybridization (FISH) and immunohistochemistry (IHC) methods, respectively.ResultsEGFR protein overexpression was observed in about 30% while 15.5% displayed high EGFR copy number including 5.17% gene amplification and over 10% high polysomy. There is a positive correlation between EGFR protein overexpression and gene copy number and over expression of EGFR is observed in ten out of the 48 low copy number cases (20.9%) without gene amplification.ConclusionThis study provides the first glimpse of EGFR alterations and expressions in a multi ethnic Malaysian TNBC patient cohort emphasising the need for the nationwide large scale EGFR expression evaluation in Malaysia.

P11.08 Defining EGFR amplification status for clinical trial inclusion

Abstract BACKGROUND Precision medicine trials targeting the epidermal growth factor receptor (EGFR) in glioblastoma patients require selection for EGFR-amplified tumors. However, there is currently no golden standard in determining the amplification status of EGFR or EGFRvIII expression. Here, we aimed to determine which technique and which cut-offs are suitable to determine EGFR amplification status. MATERIAL AND METHODS We compared fluorescent in-situ hybridization (FISH) and RT-qPCR data from patients screened for trial inclusion into the Intellance 2 clinical trial, with data from a panel-based next generation sequencing (NGS) platform (both DNA and RNA). RESULTS By using data from >1000 samples, we show which cut-offs are optimal to determine EGFR gene amplification by FISH. Our data also show that gene amplification (as determined by FISH) correlates with EGFR expression levels (as determined by RT-qPCR) with ROC analysis showing an under the curve area of up to 0.902. EGFR expression as assessed by RT-qPCR therefore may function as a surrogate marker for EGFR amplification. Our NGS data shows that EGFR copy numbers can strongly vary between tumors with levels ranging from 2 to more than 100 copies per cell. Levels exceeding 5 gene copies can be used to define EGFR-amplification by NGS; below this level FISH detects very few (if any) EGFR amplified nuclei and none of the samples express EGFRvIII. CONCLUSION Our data from central laboratories and diagnostic sequencing facilities, using material from patients eligible for clinical trial inclusion, help defining the optimal cut-off for various techniques to determine EGFR amplification for diagnostic purposes.

A phase 2 study of panitumumab with irinotecan as salvage therapy in chemorefractory KRAS exon 2 wild-type metastatic colorectal cancer patients

BackgroundTargeted agents are standard treatment for RAS wild-type metastatic colorectal cancer in the first- and second-line settings. This phase 2 study determined the benefit of targeting the epidermal growth factor receptor (EGFR) with panitumumab plus irinotecan in irinotecan-refractory patients.MethodsKRAS exon-2 wild-type patients failing prior irinotecan received panitumumab (6 mg/kg) and irinotecan (180 mg/m²) every 2 weeks. The primary endpoint was the overall response rate (ORR). Secondary endpoints included safety, progression-free survival (PFS) and overall survival (OS). KRAS exon-2 status was evaluated centrally, along with NRAS, BRAF mutations, epiregulin, amphiregulin, PTEN and EGFR copy number status, and correlated with efficacy.ResultsSixty-one patients were treated. Among the 46 wild-type RAS patients, the ORR was 15.2% (seven partial responses), with median PFS of 3.8 months (95% CI 2.7–4.3) and median OS of 12.5 months (95% CI 6.7–15.9). Wild-type BRAF patients showed a 13.0% response rate. No significant correlations between response and baseline biomarker expression were identified. Common grade 3–4 adverse events were diarrhoea and rash (18.0% each), hypomagnesaemia and asthenia (8.2% each).ConclusionsThe addition of panitumumab to irinotecan as salvage therapy is feasible but has limited activity in irinotecan-refractory metastatic colorectal cancer. No biomarkers predictive of response were identified.

Defining EGFR amplification status for clinical trial inclusion.

BackgroundPrecision medicine trials targeting the epidermal growth factor receptor (EGFR) in glioblastoma patients require selection for EGFR-amplified tumors. However, there is currently no gold standard in determining the amplification status of EGFR or variant III (EGFRvIII) expression. Here, we aimed to determine which technique and which cutoffs are suitable to determine EGFR amplification status. MethodsWe compared fluorescence in-situ hybridization (FISH) and real-time quantitative (RT-q)PCR data from patients screened for trial inclusion into the Intellance 2 clinical trial, with data from a panel-based next generation sequencing (NGS) platform (both DNA and RNA). ResultsBy using data from >1000 samples, we show that at least 50% of EGFR amplified nuclei should be present to define EGFR gene amplification by FISH. Gene amplification (as determined by FISH) correlates with EGFR expression levels (as determined by RT-qPCR) with receiver operating characteristics analysis showing an area under the curve of up to 0.902. EGFR expression as assessed by RT-qPCR therefore may function as a surrogate marker for EGFR amplification. Our NGS data show that EGFR copy numbers can strongly vary between tumors, with levels ranging from 2 to more than 100 copies per cell. Levels exceeding 5 gene copies can be used to define EGFR-amplification by NGS; below this level, FISH detects very few (if any) EGFR amplified nuclei and none of the samples express EGFRvIII. ConclusionOur data from central laboratories and diagnostic sequencing facilities, using material from patients eligible for clinical trial inclusion, help define the optimal cutoff for various techniques to determine EGFR amplification for diagnostic purposes.

A subset of esophageal squamous cell carcinoma patient-derived xenografts respond to cetuximab, which is predicted by high EGFR expression and amplification.

Epidermal growth factor receptor (EGFR) is reportedly overexpressed in most esophageal tumors, but most targeted therapies showed no efficacy in non-selected patients. This study aims at investigating the adaptive cetuximab subset in a cohort of esophageal squamous cell carcinoma (ESCC) patient-derived xenografts (PDXs). A large panel of ESCC PDXs has been established. The copy number, mRNA expression and immunohistochemistry (IHC) of key EGFR pathways have been examined along with cetuximab response. A preclinical trial on a randomly selected cohort of 16 ESCC PDXs was conducted, and the genomic annotations of these models were compared against the efficacy readout of the mouse trial. The trial identified that 7 of 16 (43.8%) responded to cetuximab (ΔT/ΔC <0 as responders). The gene amplification and expression analysis indicated that EGFR copy number ≥5 (P=0.035), high EGFR mRNA expression (P=0.001) and IHC score of 2-3 (P=0.034) are associated with tumor growth inhibition by cetuximab, suggesting EGFR may function as a single predictive biomarker for cetuximab response in ESCC. Overall, our results suggest that an ESCC subtype with EGFR amplification and overexpression benefits from cetuximab treatment, which warrants further clinical confirmation.

Abstract 2571: An integral genomic/expression analysis reveals a cooperative role of APC and TP53 mutations in identifying cetuximab-sensitive colorectal cancer

Abstract The epidermal growth factor receptor (EGFR) is a major therapeutic target in metastatic colorectal cancer (CRC). Mutations in KRAS/NRAS have been identified as the resistance mechanisms to anti-EGFR antibody therapy (cetuximab/pantiumab). However, genomic understanding of the sensitivity to the EGFR-targeted therapy is lacking. A pre-specified, 203-gene cetuximab sensitivity (CTX-S) expression signature score was first validated on two previously published datasets: (1) 77 CTX-treated CRC tumors (progression free survival (PFS)&amp;gt;7 days), and (2) 147 in vitro CTX-treated CRC cell lines. The CTX-S signature was found to be consistently correlated with a newly developed 24-gene APC (truncating) mutations-specific Wnt/β-catenin score on four independent CRC datasets that also include Moffitt (n=468) and TCGA (n=624) CRC datasets. This promoted us to carry out a variety of analyses that revealed a cooperative role of mutant APC + mutant TP53 in identifying cetuximab sensitive subpopulations, which was further evidenced by additional validation analysis on two CRC PDX datasets (n=52 and n=98). While debating or inconclusive, other potential predictive markers of EGFRi therapies have been reported, including BRAF(V600E), PIK3CA mutations, loss of PTEN, and overexpression of HER2 as negative indicators, as well as increased EGFR copy number, and overexpression of EGFR ligands epiregulin and amphiregulin as positive indicators. Here, for the first time, we report that the mutant genes may cooperatively act as positive indicators of EGFRi response. Our study suggests that addition of the routine sequencing of APC and TP53 to extended RAS testing may refine the patient selection strategy to improve cetuximab/pantiumab response and potentially expand the therapeutic opportunity to previously-excluded mutant KRAS/NRAS patients who have “APC + TP53” mutations. Citation Format: Mingli Yang, Michael J. Schell, Andrey Loboda, Michael V. Nebozhyn, Jiannong Li, Jamie K. Teer, W. Jack Pledger, Timothy J. Yeatman. An integral genomic/expression analysis reveals a cooperative role of APC and TP53 mutations in identifying cetuximab-sensitive colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2571.

545P - Epidermal growth factor receptor (EGFR) copy number (CN) as a biomarker of prognosis and panitumumab (Pan) benefit in RAS-wt advanced colorectal cancer (aCRC)

Background: Whilst RAS mutations predict which aCRC patients (pts) will not benefit from anti-EGFR agents, RAS-wt status does not reliably predict who will. Several studies report that high EGFR ligand expression (EREG/AREG) is predictive of anti-EGFR agent benefit but progression towards clinical utility is limited by lack of consensus on a clinical dichotomisation point and additional tumor material required. Here we explore EGFR copy number as a biomarker of prognosis and predictor of Pan benefit in a randomised trial in aCRC. Methods: EGFR CN, EREG/AREG RNA expression, RAS/RAF mutations were assessed in tumor from 275 pts randomised to 2nd-line irinotecan (Ir) or IrPan (PICCOLO, Lancet Onc 14:749-59). EGFR CN status was measured by the Affymetrix OncoScan array, analysed using Biodiscovery Nexus software and defined as normal (2 copies) or gain (>2 copies). Prognostic analysis was in Ir alone pts. Predictive analysis, in the 234 RAS-wt pts, compared baseline values with outcomes using Cox proportional hazards models. Results: 196 (71.3%) pts were classified as EGFR gain and 79 (28.7%) as normal. EGFR gain was significantly associated with high EREG and AREG RNA expression (both p < 0.001). EGFR gain was not prognostic for OS (p = 0.97) or PFS (p = 0.98). However, it was predictive of Pan benefit: in RAS-wt pts with EGFR gain, median PFS was 5.7 mo (IrPan) vs 3.7 mo (Ir) (HR = 0.60[0.43-0.83], p = 0.002), but pts with normal EGFR had no benefit: 3.4 mo (IrPan) vs 2.9 mo (Ir) (HR = 1.23[0.72-2.08], p = 0.45); interaction p = 0.02. Significant PFS biomarker/treatment interaction was also seen in all 275 pts, including RAS or RAF mutants (p = 0.01). In RAS-wt pts EGFR gain was associated with higher response rates than normal with IrPan (45.3% vs 18.7%, p = 0.01) but not with Ir (13.3% vs 12.9%, p = 1.0). Interaction was not significant (p = 0.22) or for OS (p = 0.20). Conclusions: EGFR CN status may allow for further stratification for Pan benefit in RAS-wt patients. Normal EGFR CN status identified nearly 1/3 of pts without Pan benefit. This biomarker is consistent with EGFR ligand data, and is a DNA-based assay with a clearly definable dichotomised cut-point and therefore is of potential clinical utility.