EGFR and Other Actionable Mutations in NSCLC

The growing number of approved targeted agents for metastatic non-small cell lung cancer (NSCLC) highlights the need for convenient, accurate, and reliable molecular testing to guide therapy selection. Approximately 60% of molecular alterations observed in advanced or metastatic lung adenocarcinoma can guide treatment.1-3 Epidermal growth factor receptor (EGFR) is one of the most common actionable mutations among patients with NSCLC adenocarcinomas.2-4 EGFR mutations may lead to unregulated proliferation and survival of tumor cells, making it a key driver of disease, regardless of stage.1,5 EGFR mutation prevalence appears to be consistent across all stages of NSCLC.1,6,7

Approximately 1 in 3 patients with adenocarcinoma has a potentially actionable biomarker1-3,a

Approximately 1 in 3 patients with adenocarcinoma has a potentially actionable biomarker
Approximately 1 in 3 patients with adenocarcinoma has a potentially actionable biomarker

ALK, anaplastic lymphoma kinase; BRAF, v-Raf murine sarcoma viral oncogene homolog B; KRAS, v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog; MET, mesenchymal-epithelial transition; NTRK, neurotrophic tyrosine receptor kinase; RET, rearranged during transfection; ROS1, ROS proto-oncogene 1, receptor tyrosine kinase.

aBased on 3 studies of patients with lung adenocarcinoma.1-3 Sholl et al, 2015 included 733 patients with lung adenocarcinoma but did not test patients for ROS1 rearrangements or NTRK fusions.1 Stransky et al, 2014 analyzed 513 samples from patients with lung adenocarcinoma.2 Bergethon et al, 2012 screened 694 patients with lung adenocarinoma for ROS1 rearrangement status.3 bPercentage adjusted based on aggregate of Sholl et al, Stransky et al, and Bergethon et al.

Importance of Testing for EGFR and Other Mutations

Why Test

Disease recurrence or death following surgery with or without chemotherapy remains high across disease stages in resectable NSCLC.8-10

Whom to Test

NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) recommendations for EGFR testing in NSCLC now include resectable Stages IB to IIIA.11

Molecular testing for EGFR mutations is recommended to ensure results are available for adjuvant treatment decisions for patients with resectable Stage IB to IIIA NSCLC.11

How to Test

In the resectable disease setting, using surgically resected tissue for EGFR testing is ideal.12 However, if presurgical biopsy tissue is available and sufficient, it can be tested and reflexed to surgical tissue, if needed.13-15

While liquid biopsy (along with tissue-based testing) is an indispensable tool in the metastatic setting, it has not yet been validated for molecular testing in resectable NSCLC.16,17 Circulating tumor DNA (ctDNA) technology is not currently validated in resectable NSCLC. The sensitivity of ctDNA analysis is reduced with lower tumor burden (and thus ctDNA shedding) in earlier disease stages compared to metastatic NSCLC.18

Why Test

NCCN Guidelines® recommend treatment selection for metastatic NSCLC be based on biomarker status.11

Whom to Test

NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) recommend molecular testing for certain patients with metastatic NSCLC.11

How to Test

  • Diagnostic and biomarker testing require a multidisciplinary approach, with appropriate sample acquisition and handling19,20
  • Histologic, cytologic, and liquid biopsy (plasma testing) specimens may be used for molecular testing11,21
  • When clinically feasible, know all biomarker test results for actionable biomarkers before initiating first-line treatment11

Testing for EGFR Mutations is a Critical Step Toward Optimizing Treatment Outcomes for Patients With NSCLC

How to Test: Sample Collection

Tumor IconIn the resectable disease setting, using surgically resected tissue for EGFR testing is ideal.12 However, if presurgical biopsy tissue is available and sufficient, it can be tested and reflexed to surgical tissue, if needed.13-15

Using Resected Tissue

Using surgically resected tissue can help ensure adequate samples for molecular testing.12

  • Molecular testing turnaround time is not typically a challenge in the adjuvant setting.12 Test results can be ready during surgical recovery time, allowing optimal treatment selection by the time appropriate patients can begin adjuvant therapy12,22,23

Using Diagnostic Biopsy

Presurgical diagnostic biopsy samples collected using fine-needle aspiration (FNA) or core needle biopsy (CNB) may be insufficient for both diagnosis and molecular testing.11

Various techniques may be utilized to help ensure adequacy of a tumor sample for molecular testing:

  • Rapid on-site evaluation of tissue quantity and quality can help ensure sample sufficiency for molecular testing24
  • Endobronchial ultrasound (EBUS)–guided transbronchial needle aspiration is a minimally invasive method that has substantially improved the ability to obtain material for diagnostic and molecular testing25
  • Mediastinoscopy may be available when minimally invasive techniques are not feasible; typically results in high tissue yield20,26
  • If diagnostic biopsy sample is insufficient for molecular testing, tissue from surgical resection can be used12,15

Exclamation IconTissue testing remains essential in both resectable and metastatic settings, while liquid biopsy is only clinically validated in the metastatic setting.20,21,27

Multiple methods are available for acquiring tumor samples for biomarker testing.20 Histologic, cytologic,a and liquid biopsy (plasma testing) may be used for molecular testing.21,28 The College of American Pathologists/International Association for the Study of Lung Cancer/Association for Molecular Pathology and NCCN Guidelines recommend liquid biopsy (plasma testing) in specific clinical situations to improve identification of actionable mutations.11,21 Concurrent tissue and liquid biopsy testing can help maximize the detection of therapeutically actionable mutations.16,29

aCytology-based samples have not yet been US Food and Drug Administration (FDA) approved for use in NSCLC companion diagnostics.

Tissue-Based Testing

Obtaining enough tissue at diagnosis for initial and downstream testing is important, with the adequacy of each sample ultimately affecting both histologic characterization and biomarker testing.20,30

Numerous tissue-based methods are available for acquiring tumor samples for biomarker testing30:

  • Bronchoscopy (+/- EBUS, endoscopic ultrasound)20
    • Endobronchial biopsy
    • Transbronchial biopsy
    • Brushing cytology
    • Washing cytology
    • FNA cytology
  • Surgical (eg, mediastinoscopy, thoracoscopy, resection)20,31
    • Surgical resection
  • Image guided (eg, transthoracic needle aspiration, thoracentesis)20,32
    • CNB
    • FNA cytology
    • Fluid cytology
    • Bone biopsy

However, not all patients can be tested via tissue-based testing due to challenges with obtaining sufficient tissue.33

Liquid Biopsy

Integrate liquid biopsy testing alongside tissue-based testing to improve patient identification for genetic alterations at diagnosis and minimize testing turnaround time.16,21,28,34,35

  • Liquid biopsy testing may be considered in all patients with metastatic NSCLC who need biomarker profiling but particularly when tumor tissue is scarce or unavailable or a significant delay (>2 weeks) is expected in obtaining tumor tissue28
  • A positive liquid biopsy result alone for an actionable mutation is sufficient to support initiation of targeted agents21,28; negative results require confirmation with tissue-based testing21

The detection of therapeutically actionable biomarkers improves with concurrent liquid and tissue testing, with 2 studies demonstrating that concurrent tissue and liquid biopsy testing can identify more patients with metastatic NSCLC with actionable alterations than either modality alone.16,29,a

aAggarwal et al, 2019 was a prospective study of 323 patients with metastatic NSCLC.16 Leighl et al, 2019 prospectively enrolled 282 patients with previously untreated metastatic NSCLC.29

Exclamation IconConcurrent tissue and liquid biopsy testing can help maximize the detection of therapeutically actionable mutations by increasing the number of patients identified with targetable alterations and improving testing turnaround time.28,29

Assays for EGFR Testing

A number of biomarker assays are available to help inform treatment selection decisions for patients with NSCLC.36 FDA approval of specific tests may vary by treatment setting. For the latest companion diagnostic tests available, visit fda.gov.

Sample Requirements for FDA-Approved NSCLC Companion Diagnostics Varya

Assay Intended Use for NSCLC Sample Requirements
cobas® EGFR Mutation Test v237
  • EGFR exon 19 deletions
  • EGFR exon 21 L858R mutations
  • EGFR exon 20 T790M mutations

4 unstained sections and 1 H&E-stained slide or FFPE block

OR

Plasma: 4 mLb

FoundationOne® CDx38,39
  • EGFR exon 19 deletions
  • EGFR exon 21 L858R mutations
  • EGFR exon 20 T790M mutations
  • ALK rearrangements
  • BRAF V600E mutations
  • MET exon 14 skipping mutation
  • NTRK1/2/3 fusionsc

10 unstained sections and 1 H&E slide

OR

FFPE block

FoundationOne® Liquid CDx40
  • EGFR exon 19 deletions
  • EGFR exon 21 L858R substitution

Blood: 2 tubes, 8.5 mL each

Guardant360® CDx41
  • EGFR exon 19 deletions
  • EGFR exon 21 L858R mutations
  • EGFR exon 20 T790M mutations

Blood: minimum of 5 mL

OncomineTM Dx Target42
  • EGFR exon 19 deletions and EGFR exon 21 L858R mutations
  • BRAF V600E mutations
  • ROS1 fusions

2 unstained sections (resection or surgical biopsies)

OR

9 unstained sections (core needle biopsies)

OR

FFPE block

therascreen® EGFR RGQ PCR43
  • EGFR exon 19 deletions
  • EGFR exon 21 L858R mutations

2 unstained sections and 1 H&E-stained slide

FFPE, formalin-fixed, paraffin-embedded; H&E, hematoxylin and eosin.

aThe table does not include all of the FDA-approved NSCLC companion diagnostics. bPlasma should be separated from blood within 8 hours of collection.41 cCompanion diagnostic indication for solid tumors.38

Exclamation IconTissue testing remains essential in both resectable and metastatic settings, while liquid biopsy is only clinically validated in the metastatic setting.20,21,27

Download an example EGFR test report

How to Interpret Biomarker Test Results

The American Society of Clinical Oncology has provided guidance on information to include for biomarker test reporting in cancer.44

Reports should include basic information about the test such as44:

EGFR Interpret Test Result – Limit of Detecting of the Test
EGFR Interpret Test Result – Limit of Detecting of the Test
EGFR Interpret Test Result – Genes and Gene Region Evaluated
EGFR Interpret Test Result – Genes and Gene Region Evaluated
EGFR Interpret Test Result – Types of Variants Detected
EGFR Interpret Test Result – Types of Variants Detected
EGFR Interpret Test Result – Types of Variants that may not be Detected
EGFR Interpret Test Result – Types of Variants that may not be Detected

Multidisciplinary Team Collaboration for EGFR Testing

A coordinated multidisciplinary approach is necessary to ensure quality biomarker testing.19,21,45,46 With increased understanding of the molecular pathways driving carcinogenesis, histologic and molecular subtyping and treatment with targeted agents have become part of the patient journey.47,48

All members of the multidisciplinary team should have a complete understanding of patient history and plans for all downstream testing prior to biopsy, in order to support the following47,49:

  • Adequate sample collection
  • Appropriate testing algorithm
  • Appropriate assay selection
  • Timely reporting of test results
  • Informed treatment decisions

MDT, multidisciplinary team.

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