Conventional real-time PCR-based detection of T790M using tumor tissue or blood in patients with EGFR TKI-resistant NSCLC

Liquid Biopsy as a Tool for the Characterisation and Early Detection of the Field Cancerization Effect in Patients with Oral Cavity Carcinoma

Oral squamous cell carcinoma (OSCC) constitutes approximately 25% of all head and neck cancer, for which the consumption of tobacco and alcohol are the main associated risk factors. The field cancerization effect of OSCC is one of the main reasons for the poor survival rates associated with this disease. Despite some advances, its ccharacterization and early diagnosis continue to challenge modern oncology, and the goal of improving the prognosis remains to be achieved. Among new early diagnostic tools for OSCC that have been proposed, liquid biopsy appears to be an ideal candidate, as studies have shown that the analysis of blood and saliva provides promising data for the early detection of relapses or second tumours.

Impact of detecting plasma EGFR mutations with ultrasensitive liquid biopsy in outcomes of NSCLC patients treated with first- or second-generation EGFR-TKIs

BACKGROUND

Few trials have evaluated the utility of liquid biopsies to detect epidermal growth factor receptor mutations (EGFRm) at the time of response evaluation and its association with the clinical characteristics and outcomes of non-small-cell lung cancer (NSCLC) patients.

OBJECTIVE

This study aimed to evaluate, in a real-world clinical setting, the prevalence of plasma EGFRm and its association with the clinical characteristics, response and survival outcomes of NSCLC patients under treatment with EGFR-tyrosine kinase inhibitors (EGFR-TKIs).

METHODS

This observational study enrolled advanced or metastatic NSCLC patients, with confirmed tumor EGFRm, receiving treatment with first- or second-generation EGFR-TKIs. Blood samples for the detection of plasma EGFRm were collected at the time of response evaluation and processed using the Target Selector™ assay. The main outcomes were the detection rate of plasma EGFRm, median Progression-Free Survival (PFS) and Overall Survival (OS) according to plasma EGFR mutational status.

RESULTS

Of 84 patients, 50 (59.5%) had an EGFRm detected in plasma. After a median follow-up of 21.1 months, 63 patients (75%) had disease progression. The detection rate of plasma EGFRm was significantly higher in patients with disease progression than in patients with partial response or stable disease (68.3% versus 33.3%; P< 0.01). PFS and OS were significantly longer in patients without plasma EGFRm than among patients with plasma EGFRm (14.3 months [95% CI, 9.25-19.39] vs 11.0 months [95% CI, 8.61-13.46]; P= 0.034) and (67.8 months [95% CI, 39.80-95.94] vs 32.0 months [95% CI, 17.12-46.93]; P= 0.006), respectively. A positive finding in LB was associated with the presence of ⩾ 3 more metastatic sites (P= 0.028), elevated serum carcinoembryonic (CEA) at disease progression (P= 0.015), and an increase in CEA with respect to baseline levels (P= 0.038).

CONCLUSIONS

In NSCLC patients receiving EGFR-TKIs, the detection of plasma EGFRm at the time of tumor response evaluation is associated with poor clinical outcomes.

The Validity and Predictive Value of Blood-Based Biomarkers in Prediction of Response in the Treatment of Metastatic Non-Small Cell Lung Cancer: A Systematic Review

With the introduction of targeted therapies and immunotherapy, molecular diagnostics gained a more profound role in the management of non-small cell lung cancer (NSCLC). This study aimed to systematically search for studies reporting on the use of liquid biopsies (LB), the correlation between LBs and tissue biopsies, and finally the predictive value in the management of NSCLC. A systematic literature search was performed, including results published after 1 January 2014. Articles studying the predictive value or validity of a LB were included. The search (up to 1 September 2019) retrieved 1704 articles, 1323 articles were excluded after title and abstract screening. Remaining articles were assessed for eligibility by full-text review. After full-text review, 64 articles investigating the predictive value and 78 articles describing the validity were included. The majority of studies investigated the predictive value of LBs in relation to therapies targeting the epidermal growth factor receptor (EGFR) or anaplastic lymphoma kinase (ALK) receptor (n = 38). Of studies describing the validity of a biomarker, 55 articles report on one or more EGFR mutations. Although a variety of blood-based biomarkers are currently under investigation, most studies evaluated the validity of LBs to determine EGFR mutation status and the subsequent targeting of EGFR tyrosine kinase inhibitors based on the mutation status found in LBs of NSCLC patients.

Cell-Free Circulating Tumour DNA Blood Testing to Detect EGFR T790M Mutation in People With Advanced Non-Small Cell Lung Cancer: A Health Technology Assessment

BACKGROUND

Cell-free circulating tumour DNA blood testing (also called liquid biopsy) can determine if a person with advanced non-small cell lung cancer (NSCLC) whose disease is progressing has developed the epidermal growth factor receptor (EGFR) T790M resistance mutation. Identifying this resistance mutation can help physicians choose appropriate treatment (i.e., osimertinib if positive and chemotherapy if negative). Tissue biopsy is typically used to look for the resistance mutation, but this is an invasive test that might not be feasible if the patient is too ill. We conducted a health technology assessment of liquid biopsy for people with advanced NSCLC, which included an evaluation of the diagnostic accuracy, clinical utility, safety, cost-effectiveness, and the budget impact of publicly funding liquid biopsy, as well as an evaluation of patient preferences and values.

METHODS

We performed a systematic literature search of the clinical evidence. We assessed the risk of bias of each included study using Risk of Bias in Systematic Reviews (ROBIS), Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2), Risk of Bias Among Non-randomized Studies (RoBANS), and the Cochrane risk of bias (ROB) tool and assessed quality of evidence according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group criteria. We performed a systematic economic literature search and conducted short-term and long-term cost-effectiveness and cost-utility analyses comparing liquid biopsy as a triage test, liquid biopsy alone, and tissue biopsy alone from a public payer perspective. We also analyzed the budget impact of publicly funding liquid biopsy for people in Ontario with advanced NSCLC. To assess the potential value of liquid biopsy, we spoke with people with lung cancer and people with an understanding of the process of liquid biopsy.

RESULTS

We included 19 studies (within a published systematic review) to examine diagnostic test accuracy and 12 studies to examine clinical utility. In patients with advanced NSCLC, liquid biopsy to detect the EGFR T790M resistance mutation demonstrated a positive and negative predictive value of 89% and 61%, respectively, a sensitivity of 68%, and specificity of 86%. No studies examined the clinical utility of liquid biopsy as a triage test. When NSCLC was treated appropriately, progression-free survival was similar in patients with and without the resistance mutation, as ascertained by liquid biopsy.We estimated that it costs about $700 to conduct a liquid biopsy and $2,500 to conduct a tissue biopsy. Our analyses showed that, when considering costs and effects directly related to testing, liquid biopsy (as a triage test, which means patients who test negative undergo a follow-up tissue biopsy, or alone, which means using only liquid biopsy) was less costly than tissue biopsy alone and led to fewer tissue biopsies. Using liquid biopsy as a triage test produced the most correct treatment decisions and greatest number of people who were given osimertinib.When considering long-term costs (i.e., treatment and care) and effects (i.e., life-years and quality-adjusted life-years [QALYs]), liquid biopsy as a triage test was the most effective and most costly strategy followed by liquid biopsy alone. Tissue biopsy alone was the least effective and least costly strategy. The incremental cost-effectiveness ratios (ICERs) of liquid biopsy as a triage test compared with liquid biopsy alone and of liquid biopsy alone compared with tissue biopsy alone were greater than $100,000 per QALY. However, this result was largely driven by the cost of osimertinib, which was used more often when liquid biopsy was used as a triage test.We estimated that the total annual budget impact of publicly funding liquid biopsy as a triage test in Ontario over the next 5 years would range from approximateily $60,000 in year 1 to $3 million in year 5.People with lung cancer with whom we spoke said that liquid biopsy would likely be an appropriate test for people with NSCLC given their frail condition and because it would avoid the pain and anxiety associated with tissue biopsy.

CONCLUSIONS

As a minimally invasive test, liquid biopsy identifies a high proportion of people with the EGFR T790M resistance mutation. This identification could better guide treatment for people with advanced NSCLC. However, its relatively low negative predictive value means it is best used as a triage test (i.e., followed by tissue biopsy if the liquid biopsy does not identify a resistance mutation). Liquid biopsy as a triage test is likely more effective than tissue biopsy alone. However, owing to the high cost of treatment, liquid biopsy may not be cost-effective. We estimated that publicly funding liquid biopsy as a triage test in Ontario would result in additional costs (related to more patients being treated) of between $0.06 million and $3 million over the next 5 years.

The diagnostic value of circulating tumor cells and ctDNA for gene mutations in lung cancer

PURPOSE

Detecting gene mutations by two competing biomarkers, circulating tumor cells (CTCs) and ctDNA has gradually paved a new diagnostic avenue for personalized medicine. We performed a comprehensive analysis to compare the diagnostic value of CTCs and ctDNA for gene mutations in lung cancer.

METHODS

Publications were electronically searched in PubMed, Embase, and Web of Science as of July 2018. Pooled sensitivity, specificity, and AUC, each with a 95% CI, were yielded. Subgroup analyses and sensitivity analyses were conducted. Quality assessment of included studies was also performed.

RESULTS

From 4,283 candidate articles, we identified 47 articles with a total of 7,244 patients for qualitative review and meta-analysis. When detecting EGFR, the CTC and ctDNA groups had pooled sensitivity of 75.4% (95% CI 0.683-0.817) and 67.1% (95% CI 0.647-0.695), respectively. When testing KRAS, pooled sensitivity was 38.7% (95% CI 0.266-0.519) in the CTC group and 65.1% (95% CI 0.558-0.736) in the ctDNA group. The diagnostic performance of ctDNA in testing ALK and BRAF was also evaluated. Heterogeneity among the 47 articles was acceptable.

CONCLUSION

ctDNA might be a more promising biomarker with equivalent performance to CTCs when detecting EGFR and its detailed subtypes, and superior diagnostic capacity when testing KRAS and ALK. In addition, the diagnostic performance of ctDNA and CTCs depends on the detection methods greatly, and this warrants further studies to explore more sensitive methods.

Thoracoscopic rebiopsy to detect the T790M mutation after postoperative recurrence

After pulmonary resection for non-small-cell lung cancer, some patients with postoperative recurrence and mutated epidermal growth factor receptor (EGFR) subsequently receive EGFR-tyrosine kinase inhibitors (EGFR-TKIs). Osimertinib may be efficacious if those patients become resistant to the 1st-line EGFR-TKI because of the T790M mutation. We recently performed thoracoscopic rebiopsy to detect the T790M mutation in 4 patients who became resistant to the 1st-line EGFR-TKI treatment for postoperative recurrence. Our limited experience suggests that thoracoscopic biopsy is associated with limited morbidity, can help detect the T790M mutation and may improve the management of select patients with acquired resistance to the 1st-line EGFR-TKIs.

The diagnostic accuracy of circulating tumor DNA for the detection of EGFR-T790M mutation in NSCLC: a systematic review and meta-analysis

This pooled analysis aims at evaluating the diagnostic accuracy of circulating tumor (ct) DNA for the detection of EGFR-T790M mutation in NSCLC patients who progressed after EGFR-TKIs. Data from all published studies, reporting both sensitivity and specificity of plasma-based EGFR-T790M mutation testing by ctDNA were collected by searching in PubMed, Cochrane Library, American Society of Clinical Oncology, European Society of Medical Oncology and World Conference of Lung Cancer meeting proceedings. A total of twenty-one studies, with 1639 patients, were eligible. The pooled sensitivity of ctDNA analysis was 0.67 (95% CI: 0.64–0.70) and the pooled specificity was 0.80 (95% CI: 0.77–0.83). The pooled positive predictive value (PPV) was 0.85 (95% CI: 0.82–0.87) and the pooled negative predictive value (NPV) was 0.60 (95% CI: 0.56–0.63). The positive likelihood ratio (PLR) and negative likelihood ratio (NLR) were 2.67 (95% CI: 1.86–3.82) and 0.46 (95% CI: 0.38–0.54), respectively. The pooled diagnostic odds ratio (DOR) was 7.27 (4.39–12.05) and the area under the curve (AUC) of the summary receiver operating characteristics (sROC) curve was 0.77. The ctDNA analysis represents a promising, non-invasive approach to detect and monitor the T790M mutation status in NSCLC patients. Development of standardized methodologies and clinical validation are recommended.

Evidence-based best practices for EGFR T790M testing in lung cancer in Canada

Epidermal growth factor receptor (egfr) tyrosine kinase inhibitors (tkis) are recommended as first-line systemic therapy for patients with non-small-cell lung cancer (nsclc) having mutations in the EGFR gene. Resistance to tkis eventually occurs in all nsclc patients treated with such drugs. In patients with resistance to tkis caused by the EGFR T790M mutation, the third-generation tki osimertinib is now the standard of care. For optimal patient management, accurate EGFR T790M testing is required. A multidisciplinary working group of pathologists, laboratory medicine specialists, medical oncologists, a respirologist, and a thoracic radiologist from across Canada was convened to discuss best practices for EGFR T790M mutation testing in Canada. The group made recommendations in the areas of the testing algorithm and the pre-analytic, analytic, and post-analytic aspects of clinical testing for both tissue testing and liquid biopsy circulating tumour dna testing. The recommendations aim to improve EGFR T790M testing in Canada and to thereby improve patient care.