Clinical Validation of Coexisting Activating Mutations Within EGFR, Mitogen-Activated Protein Kinase, and Phosphatidylinositol 3-Kinase Pathways in Lung Cancers

Robust Performance of the Novel Research-Use-Only Idylla GeneFusion Assay Using a Diverse Set of Pathological Samples with a Proposed 1-Day Workflow for Advanced NSCLC Evaluation

A range of different techniques are available for predictive biomarker testing for non-small-cell lung cancer (NSCLC) clinical management. International guidelines suggest next-generation sequencing (NGS) as the preferred procedure, but other reverse transcriptase-polymerase chain reaction (RT-PCR)-based methods are rapidly evolving. In this study, we evaluated the reliability and accuracy of the Idylla^TM GeneFusion assay, a rapid and fully automated platform able to simultaneously detect ALK, ROS1, RET and NTRK1/2/3 and MET ex14 skipping mutations and compared its performance with routine reference methods. The cohort included thirty-seven NSCLCs plus two parotid gland carcinomas, previously characterized for the above alterations through either IHC, FISH, RT-PCR or NGS. In 36 of 39 cases, the Idylla GeneFusion assay and the reference methods were concordant (overall agreement: 92.3%). Tumor sections stored at room temperature for up to 60 days and 17 cases older than 2 years were successfully characterized. Our results suggest that the Idylla GeneFusion assay is a reliable tool to define gene fusion status and may be a valuable stand-alone diagnostic test when time efficiency is needed or NGS is not feasible.

Double PIK3CA Alterations and Parallel Evolution in Colorectal Cancers

OBJECTIVES

To demonstrate clinicopathologic features and evaluate the clonality of double PIK3CA alterations in colorectal cancers (CRCs).

METHODS

Clonality was examined in 13 CRCs with double PIK3CA alterations (1.7% of CRCs or 9.6% of PIK3CA-mutated CRCs). Multiregional analyses were performed to confirm subclonal PIK3CA alterations.

RESULTS

PIK3CA alterations were detected within exon 9 (51%), exon 20 (23%), exon 1 (15%), and exon 7 (6.0%). CRCs with exon 7 alterations showed a significantly higher incidence of double PIK3CA alterations. Most double PIK3CA alterations consisted of a hotpsot alteration and an uncommon alteration; they were often clonal and present within a single tumor population. Multiregional analyses of CRCs with predicted subclonal double-alterations revealed multiclonal CRCs with divergent PIK3CA variant status originating from a common APC- and KRAS-mutated founder lineage of adenoma.

CONCLUSIONS

The findings supported multiclonal CRCs resulting from parallel evolution during the progression from adenoma to adenocarcinoma within the mitogen-activated protein kinase pathway, as previously demonstrated, or the mammalian target of rapamycin pathway. Further studies are warranted to elucidate clinical significance and potential targeted therapy for CRC patients with double PIK3CA alterations and impacts on clinical decision-making in patients with multiclonal CRCs harboring divergent PIK3CA mutational status.

A case of advanced adenocarcinoma genetically confirmed with EGFR/BRAF co-mutation in both primary and metastatic lesions

Driver mutations in lung cancer have been generally considered mutually exclusive; however, multiple gene screenings have recently become mainstream. Therefore, it is not uncommon to identify two or more mutations at first diagnosis, making it difficult to determine which tyrosine kinase inhibitor to administer. A 69-year-old woman complaining of back pain was diagnosed with adenocarcinoma T4N3M1c, stage IVB. Although PCR mutation test detected exon21 L858R point mutation by bronchoscopic sample, the therapeutic effect of afatinib was poor. Subsequently, next-generation sequencing (NGS) panel test of a metastasized bone specimen confirmed BRAF V600E. Furthermore, high sensitivity NGS panel system found the gene mutation allele frequency was higher for BRAF V600E than EGFR exon21 L858R for both primary lung tissue and the metastasized specimen. Subsequent BRAF/MEK inhibitor administration showed a remarkable treatment effect. When two or more driver mutations are detected in lung cancer, confirming the allelic frequency of the mutant gene might be useful in selecting more effective agents for front-line treatment.

IDH1 and IDH2 Mutations in Colorectal Cancers

OBJECTIVES

To elucidate clinicopathologic and molecular characteristics of IDH1 and IDH2 (IDH1/2) mutations in colorectal cancers (CRCs).

METHODS

We evaluated IDH1/2 mutations in 1,623 CRCs using a next-generation sequencing assay.

RESULTS

IDH1/2 mutations, predominantly IDH1 p.R132C, were detected in 15 (0.9%) CRCs and in 5 (3.0%) of 167 BRAF p.V600E-mutated CRCs. Three IDH1/2-mutated CRCs were associated with inflammatory bowel disease. They were significantly associated with old age, mucinous or signet ring cell adenocarcinoma, and high-grade histomorphology. Concordance of variant allele frequency between IDH1/2 mutants and other trunk drivers in CRCs and presence of IDH1/2 mutation in the adenoma and early adenocarcinoma indicated IDH1/2 mutations could be trunk drivers suitable for targeted therapy.

CONCLUSIONS

IDH1/2 mutations in CRCs were uncommon but enriched in BRAF p.V600E-mutated CRCs and perhaps colitis-associated CRCs. Further studies on IDH1/2-mutated CRCs are needed to clarify their clinicopathologic features and implications for targeted therapy.

FSCN1 Promotes Radiation Resistance in Patients With PIK3CA Gene Alteration

Radiotherapy is one of the standard treatments for cervical cancer and head and neck cancer. However, the clinical efficacy of this treatment is limited by radioresistance. The discovery of effective prognostic biomarkers and the identification of new therapeutic targets have helped to overcome the problem of radioresistance. In this study, we show that in the context of PIK3CA mutation or amplification, high expression of fascin actin-bundling protein 1 (FSCN1) (using the median as the cut-off value) is associated with poor prognosis and radiotherapy response in cancer patients. Silencing FSCN1 enhances radiosensitivity and promotes apoptosis in cancer cells with PIK3CA alterations, and this process may be associated with the downregulation of YWHAZ. These results reveal that FSCN1 may be a key regulator of radioresistance and could be a potential target for improving radiotherapy efficacy in cervical cancer and head and neck cancer patients with PIK3CA alterations.

Non-Small Cell Lung Cancer Harboring Concurrent EGFR Genomic Alterations: A Systematic Review and Critical Appraisal of the Double Dilemma

The molecular pathways which promote lung cancer cell features have been broadly explored, leading to significant improvement in prognostic and diagnostic strategies. Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have dramatically altered the treatment approach for patients with metastatic non-small cell lung cancer (NSCLC). Latest investigations by using next-generation sequencing (NGS) have shown that other oncogenic driver mutations, believed mutually exclusive for decades, could coexist in EGFR-mutated NSCLC patients. However, the exact clinical and pathological role of concomitant genomic aberrations needs to be investigated. In this systematic review, we aimed to summarize the recent data on the oncogenic role of concurrent genomic alterations, by specifically evaluating the characteristics, the pathological significance, and their potential impact on the treatment approach.

Phase I results of S49076 plus gefitinib in patients with EGFR TKI-resistant non-small cell lung cancer harbouring MET/AXL dysregulation

BACKGROUND

MET and AXL dysregulation is reported as a bypass mechanism driving tumour progression in non-small cell lung cancer (NSCLC) with acquired resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI). This non-comparative phase I study investigated the combination of gefitinib with S49076, a MET/AXL inhibitor, in advanced EGFR TKI-resistant NSCLC patients with MET and/or AXL dysregulation.

METHODS

Patients received S49076 at escalating doses of 500 or 600 mg with a fixed dose of 250 mg gefitinib orally once daily in continuous 28day cycles. MET and AXL dysregulation and EGFR/T790M mutation status were centrally assessed in tumour biopsies at screening. Tumour response was evaluated using Response Evaluation Criteria in Solid Tumors (RECIST). EGFR TKI resistance mechanisms were analysed by next-generation sequencing. The clonal evolution of tumours was monitored with the analysis of circulating tumour DNA.

RESULTS

Of 92 pre-screened patients, 22 met the molecular inclusion criteria and 14 were included. The recommended dose was 600 mg daily S49076. Best overall responses were 2 partial responses (1 patient with MET dysregulation only, 1 MET and AXL co-dysregulation) and 8 patients with stable disease. Other potential concomitant mechanisms of resistance to EGFR TKI were identified in more than half of the included patients.

CONCLUSIONS

S49076 plus gefitinib demonstrated a good tolerability with limited anti-tumour activity. Due to the low number of eligible patients, no tendency in term of activity appeared in any specific molecular subset and the data did not allow for identification of AXL overexpression as an oncogenic driver.

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

BACKGROUND

The 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.

OBJECTIVE

We aimed to estimate EGFR copy number gain using amplicon-based next generation sequencing data and explored its prognostic value.

PATIENTS AND METHODS

Next 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.

RESULTS

Specificity 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.

CONCLUSIONS

Pre-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.

Effect of AKT1 (p. E17K) Hotspot Mutation on Malignant Tumorigenesis and Prognosis

The substitution of the seventeenth amino acid glutamate by lysine in the homologous structural domain of the Akt1 gene pleckstrin is a somatic cellular mutation found in breast, colorectal, and ovarian cancers, named p. Glu17Lys or E17K. In recent years, a growing number of studies have suggested that this mutation may play a unique role in the development of tumors. In this review article, we describe how AKT1(E17K) mutations stimulate downstream signals that cause cells to emerge transformed; we explore the differential regulation and function of E17K in different physiological and pathological settings; and we also describe the phenomenon that E17K impedes tumor growth by interfering with growth-promoting and chemotherapy-resistant AKT1^lowQCC generation, an intriguing finding that mutants may prolong tumor patient survival by activating feedback mechanisms and disrupting transcription. This review is intended to provide a better understanding of the role of AKT1(E17K) in cancer and to inform the development of AKT1(E17K)-based antitumor strategies.

IDH1 and IDH2 mutations in lung adenocarcinomas: Evidences of subclonal evolution

Background

Selective IDH1 and IDH2 inhibitors have been approved for targeted therapy of acute myeloid leukemia. Clinical trials for solid tumors with IDH1 and IDH2 (IDH1/2) mutations are ongoing. Reports of IDH1/2‐mutated non–small cell lung cancers (NSCLCs), however, are limited.

Methods

We evaluated IDH1/2 mutations in 1,924 NSCLC specimens (92% adenocarcinoma) using a next‐generation sequencing assay.

Results

Retrospective quality assessments identified false detection of IDH1 c.395G>A (p.R132H) resulting from cytosine deamination (C:G→T:A) artifact in one specimen. IDH1/2 mutations were detected in 9 (0.5%) adenocarcinomas taken by fine‐needle aspiration (n = 3), thoracentesis (n = 2) or core biopsy (n = 4). All nine adenocarcinomas showed high‐grade features. Extensive clear cell change, however, was not observed. High expression (50% or greater) of PD‐L1 was observed in two of five specimens examined. IDH1/2 mutations were associated with old age, smoking history, and coexisting KRAS mutation. Lower than expected variant allele frequency of IDH1/2 mutants and coexistence of IDH1/2 mutations with known trunk drivers in the BRAF, EGFR, and KRAS genes suggest they could be branching drivers leading to subclonal evolution in lung adenocarcinomas. Multiregional analysis of an adenocarcinoma harboring two IDH2 mutations revealed parallel evolution originating from a KRAS‐mutated lineage, further supporting subclonal evolution promoted by IDH1/2 mutations.

Conclusions

IDH1/2 mutations in NSCLCs are uncommon. They occur in adenocarcinomas with high‐grade features and may be branching drivers leading to subclonal evolution. Accumulation of more IDH1/2‐mutated NSCLCs is needed to clarify their clinicopathological characteristics and implications for targeted therapy.

Multiclonal colorectal cancers with divergent histomorphological features and RAS mutations: one cancer or separate cancers?

Detection of coexisting mutations within the same signal transduction pathway, which are expected to be mutually exclusive, raises a concern of laboratory errors. We have previously confirmed the presence of different RAS (KRAS and NRAS) mutations in the adenoma and/or adenocarcinoma subpopulations of colorectal cancers (CRCs). In this study, multiregional analyses by next-generation sequencing were conducted to elucidate the mechanisms underlying multiple RAS mutations seen in 5 CRC specimens. Multiregional analyses were initially conducted in a single tissue block originally submitted for mutational profiling. In 2 specimens, mutational status of the APC gene was not identical, indicating collisional adenoma and adenocarcinoma. In 3 specimens, the same APC mutation was present in different subpopulations with divergent RAS mutations, indicating a common clonal origin. Subsequent comprehensive multiregional analyses of additional adenoma and adenocarcinoma components revealed multiclonal CRCs with divergent histomorphological features and RAS mutations originating from a common APC-mutated founder lineage of adenoma, but from different RAS-mutated founder lineages of adenocarcinoma. These findings are consistent with the stepwise model of colorectal tumorigenesis along with parallel evolution, which affects RAS genes within the mitogen-activated protein kinase pathway and occurs during the progression from adenomas to adenocarcinomas. Evaluation of tumor subpopulations with divergent histomorphological features by pathologists may help identify multiclonal CRCs. Further studies are warranted to evaluate the incidence of multiclonality in CRCs and its impact on clinical outcomes. Perhaps, multiclonal CRCs originating from the same APC-mutated founder lineage of adenoma but from different RAS-mutated founder lineages of adenocarcinomas should be defined and managed as separate CRCs.

Clinical Validation of Discordant Trunk Driver Mutations in Paired Primary and Metastatic Lung Cancer Specimens

OBJECTIVES

To propose an operating procedure for validation of discordant trunk driver mutations.

METHODS

Concordance of trunk drivers was examined by next-generation sequencing in 15 patients with two to three metastatic lung cancers and 32 paired primary and metastatic lung cancers.

RESULTS

Tissue identity was confirmed by genotyping 17 single-nucleotide polymorphisms within the panel. All except three pairs showed concordant trunk drivers. Quality assessment conducted in three primary and metastatic pairs with discordant trunk drivers indicates metastasis from a synchronous or remote lung primary in two patients. Review of literature revealed high discordant rates of EGFR and KRAS mutations, especially when Sanger sequencing was applied to examine primary and lymph node metastatic tumors.

CONCLUSIONS

Trunk driver mutations are highly concordant in primary and metastatic tumors. Discordance of trunk drivers, once confirmed, may suggest a second primary cancer. Guidelines are recommended to establish standard operating procedures for validation of discordant trunk drivers.

Targeted Gene Next-Generation Sequencing Panel in Patients with Advanced Lung Adenocarcinoma: Paving the Way for Clinical Implementation

Identification of targetable molecular changes is essential for selecting appropriate treatment in patients with advanced lung adenocarcinoma. Methods: In this study, a Sanger sequencing plus Fluorescence In Situ Hybridization (FISH) sequential approach was compared with a Next-Generation Sequencing (NGS)-based approach for the detection of actionable genomic mutations in an experimental cohort (EC) of 117 patients with advanced lung adenocarcinoma. Its applicability was assessed in small biopsies and cytology specimens previously tested for epidermal growth factor receptor (EGFR) and anaplastic lymphoma kinase (ALK) mutational status, comparing the molecular changes identified and the impact on clinical outcomes. Subsequently, an NGS-based approach was applied and tested in an implementation cohort (IC) in clinical practice. Using Sanger and FISH, patients were classified as EGFR-mutated (n = 22, 18.8%), ALK-mutated (n = 9, 7.7%), and unclassifiable (UC) (n = 86, 73.5%). Retesting the EC with NGS led to the identification of at least one gene variant in 56 (47.9%) patients, totaling 68 variants among all samples. Still, in the EC, combining NGS plus FISH for ALK, patients were classified as 23 (19.7%) EGFR; 20 (17.1%) KRAS; five (4.3%) B-Raf proto-oncogene (BRAF); one (0.9%) Erb-B2 Receptor Tyrosine Kinase 2 (ERBB2); one (0.9%) STK11; one (0.9%) TP53, and nine (7.7%) ALK mutated. Only 57 (48.7%) remained genomically UC, reducing the UC rate by 24.8%. Fourteen (12.0%) patients presented synchronous alterations. Concordance between NGS and Sanger for EGFR status was very high (κ = 0.972; 99.1%). In the IC, a combined DNA and RNA NGS panel was used in 123 patients. Genomic variants were found in 79 (64.2%). In addition, eight (6.3%) EML4-ALK, four (3.1%), KIF5B-RET, four (3.1%) CD74-ROS1, one (0.8%) TPM3-NTRK translocations and three (2.4%) exon 14 skipping MET Proto-Oncogene (MET) mutations were detected, and 36% were treatable alterations. Conclusions: This study supports the use of NGS as the first-line test for genomic profiling of patients with advanced lung adenocarcinoma.

Clinical validation of coexisting driver mutations in colorectal cancers

Mutational profiling is recommended for selecting targeted therapy and predicting prognosis of metastatic colorectal cancer (CRC). Detection of coexisting mutations within the same pathway, which are usually mutually exclusive, raises the concern for potential laboratory errors. In this retrospective study for quality assessment of a next-generation sequencing assay, we examined BRAF, KRAS, and NRAS genes within the mitogen-activated protein kinase (MAPK) pathway and the PIK3CA gene within the phosphatidylinositol 3-kinase (mTOR) pathway in 744 CRC specimens submitted to our clinical diagnostics laboratory. Although coexistence of mutations between the MAPK and mTOR pathways was observed, it rarely occurred within the MAPK pathway. Retrospective quality assessments identified false detection of coexisting activating KRAS and NRAS mutations in 1 specimen and confirmed 2 activating KRAS mutations in 2 specimens and coexisting activating KRAS and NRAS mutations in 2 specimens, but no coexisting activating RAS and BRAF mutations. There were 15 CRCs with a kinase-impaired BRAF mutation, including 3 with a coexisting activating KRAS mutation, which may have therapeutic implications. Multiregional analysis based on different histologic features demonstrated that coexisting KRAS and NRAS mutations may be present in the same or different tumor populations and showed that invasion of adenomas by synchronous adenocarcinomas of different clonal origin may result in detection of coexisting mutations within the MAPK pathway. In this study, we proposed an operating procedure for clinical validation of unexpected coexisting mutations. Further studies are warranted to elucidate the biological significance and clinical implications of coexisting mutations within the MAPK pathway.