T790M Testing Research Articles

The Perceived Value of Liquid Biopsy: Results From a Canadian Validation Study of Circulating Tumor DNA T790M Testing—Patient’s Willingness-to-Pay: A Brief Report

IntroductionLiquid biopsy is recommended to diagnose molecular resistance to targeted therapy in patients with lung cancer. Nevertheless, not all jurisdictions provide funding and patient access. We report patients’ perceived value of liquid biopsy in targeted therapy resistance. MethodsCanadian patients participating in a national EGFR T790M liquid biopsy validation study completed structured interviews measuring perceived value and willingness-to-pay for plasma circulating tumor DNA testing as an alternative to tumor biopsy using open-ended and iterative bidding approaches. ResultsA total of 60 patients with advanced lung cancer participated with a median age of 64 years (range: 31–87 y); 69% were Asian and 45% female. All had received prior EGFR tyrosine kinase inhibitor; 17% also received chemotherapy. All patients preferred to have plasma testing over repeat tumor biopsy. In the context of the Canadian publicly funded system, patients estimated that a median of 300 (interquartile range: 150–800) Canadian dollars was a reasonable price to pay for liquid biopsy. Patients were personally willing to pay a median 100 (interquartile range: 33–350) Canadian dollars. ConclusionsIn a system that covers the cost of standard diagnostic tests, patients with lung cancer indicated high willingness-to-pay out-of-pocket for liquid biopsy in the setting of acquired targeted therapy resistance. Patients have high perceived value of plasma genotyping and prefer it to repeat tumor biopsy.

A Phase II Study of Osimertinib in Patients with Advanced-Stage Non-Small Cell Lung Cancer following Prior Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor (EGFR TKI) Therapy with EGFR and T790M Mutations Detected in Plasma Circulating Tumour DNA (PLASMA Study).

Epidermal growth factor receptor (EGFR) T790M mutations drive resistance in 50% of patients with advanced non-small cell lung cancer (NSCLC) who progress on first/second generation (1G/2G) EGFR tyrosine kinase inhibitors (TKIs) and are sensitive to Osimertinib. Tissue sampling is the gold-standard modality of T790M testing, but it is invasive. We evaluated the efficacy of Osimertinib in patients with EGFR mutant NSCLC and T790M in circulating tumour DNA (ctDNA). PLASMA is a prospective, open-label, multicentre single-arm Phase II study. Patients with advanced NSCLC harbouring sensitizing EGFR and T790M mutations in plasma at progression from ≥one 1G/2G TKI were treated with 80 mg of Osimertinib daily until progression. The primary endpoint was the objective response rate (ORR); the secondary endpoints included progression-free survival (PFS), overall survival (OS), disease control rate (DCR) and toxicities. Plasma next-generation sequencing was performed to determine Osimertinib resistance mechanisms and assess serial ctDNA. A total of 110 patients from eight centres in five countries were enrolled from 2017 to 2019. The median follow-up duration was 2.64 (IQR 2.44-3.12) years. The ORR was 50.9% (95% CI 41.2-60.6) and the DCR was 84.5% (95% CI 76.4-90.7). Median PFS was 7.4 (95% CI 6.0-9.3) months; median OS was 1.63 (95% CI 1.35-2.16) years. Of all of the patients, 76% had treatment-related adverse events (TRAEs), most commonly paronychia (22.7%); 11% experienced ≥ Grade 3 TRAEs. The ctDNA baseline load and dynamics were prognostic. Osimertinib is active in NSCLC harbouring sensitizing EGFR and T790M mutations in ctDNA testing post 1G/2G TKIs.

Epidermal Growth Factor Receptor T790M Mutation Testing in Non-Small Cell Lung Cancer: An International Collaborative Study to Assess Molecular EGFR T790M Testing in Liquid Biopsy.

The detection of the EGFR T790M (T790M) mutation in non-small cell lung cancer (NSCLC) patients who progressed under treatment with first- or second-generation EGFR-tyrosine kinase inhibitors (TKIs) is important to offer a subsequent therapy with a third-generation EGFR-TKI. Liquid biopsy is a powerful tool to determine the T790M mutation status. Several liquid biopsy platforms with varying degrees of accuracy are available to test for T790M mutations, and sensitivities may differ among these methods. As no standard exists for the testing of T790M mutation in liquid biopsy, we performed a collaborative study to describe and compare the sensitivity of different in-house liquid biopsy platforms for the detection of the T790M mutation, EGFR exon 19 deletion (del19) and EGFR L858R mutation (L858R) across multiple participating laboratories in seven Central and Eastern European countries. Of the 25 invited laboratories across Central and Eastern Europe, 21 centers participated and received 10 plasma samples spiked with cell-line DNA containing the T790M, del19, or L858R mutation in different concentrations. In-house PCR-based and NGS-based methods were used accordingly, and results were reported as in routine clinical practice. Two laboratories, which used the AmoyDx® EGFR 29 Mutations Detection Kit (AmoyDx) with Cobas® cfDNA Sample Preparation Kit and QX200 Droplet Digital PCR (ddPCR) with the QIAamp Circulating Nucleic Acid Kit identified all ten samples correctly. Cobas® EGFR Mutation Test v2 (Cobas), the NGS methods, and the IdyllaTM detection method used in this study performed within the known sensitivity range of each detection method. If a negative result was obtained from methods with lower sensitivity (e.g., Cobas), repeated liquid biopsy testing and/or tissue biopsy analysis should be performed whenever possible, to identify T790M-positive patients to allow them to receive the optimal second-line treatment with a third-generation EGFR TKI.

Best practices in epidermal growth factor receptor T790M testing for advanced non-small-cell lung cancer in Hong Kong.

The T790M mutation in the epidermal growth factor receptor gene causes most acquired resistance to firstor second-line epidermal growth factor receptor-tyrosine kinase inhibitors in advanced non-small-cell lung cancer. The results of T790M testing can guide subsequent treatment. Despite the availability of guidelines from international organisations, T790M testing practices in Hong Kong must be streamlined and adapted to the Hospital Authority setting. To address this issue, a panel of experts in oncology and pathology met for discussion of key topics regarding T790M testing practices in Hong Kong, including the appropriate timing of testing and re-testing, as well as optimal testing methods. All panel members voted on the results of the discussion to achieve consensus. Items supported by a majority vote were adopted as consensus statements regarding current best practices for T790M testing in Hong Kong. Among the topics discussed, the panel agreed that T790M testing should be initiated upon radiological progression, including symptomatic disease progression or central nervous system-only progression. The experts also preferred initial testing with liquid biopsy, using the widely available digital polymerase chain reaction platform. This document provides the final consensus statements, as well as a testing and treatment workflow, for clinicians in Hong Kong to use as guidance in T790M testing.

Real world efficacy of osimertinib in second line/beyond in patients with metastatic EGFR+ non-small cell lung cancer and role of paired tumour-plasma T790M testing at tyrosine kinase inhibitor resistance.

Osimertinib is a third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) approved for use in EGFR-mutant lung cancer. We examined its performance in the second/subsequent line after resistance to first- and second-generation (1/2G) EGFR-TKI. We reviewed electronic records of 202 patients who received osimertinib from July 2015 to January 2019 in the second/subsequent line after progression on prior EGFR-TKI. Of these, complete data from 193 patients were available. Clinical data including patient characteristics, primary EGFR mutation, T790M mutation status, presence of baseline brain metastases (BM), first-line EGFR-TKI use, and survival outcomes were extracted, and results retrospectively analyzed. Of 193 evaluable patients, 151 (78.2%) were T790M+ (T790M positive) with 96 (49.2%) tissue confirmed; 52% of patients received osimertinib in the second line setting. After median follow up of 37 months, median progression-free survival (PFS) of the entire cohort was 10.3 [95% confidence interval (CI): 8.64-11.50] months and median overall survival (OS) was 20 (95% CI: 15.61-23.13) months. Overall response rate (ORR) to osimertinib was 43% (95% CI: 35.9-50.3%); 48.3% in T790M+ vs. 20% in T790M- (T790M negative) patients. OS in T790M+ patients was 22.6 vs. 7.9 months in T790M- patients (HR 0.43, P=0.001), and PFS was 11.2 vs. 3.1 months respectively (HR 0.52, P=0.01). Tumour T790M+ was significantly associated with longer PFS (P=0.007) and OS (P=0.01) compared to tumour T790M- patients, however this association was not seen with plasma T790M+. Of the 22 patients with paired tumor/plasma T790M testing, response rate (RR) to osimertinib was 30% for those plasma T790M+/tumour T790M-, compared to 63% and 67% for those who were plasma T790M+/tumour T790M+ and plasma T790M-/tumour T790M+, respectively. By multivariable analysis (MVA), Eastern Cooperative Oncology Group (ECOG) performance status ≥2 was associated with shorter OS (HR 2.53, P<0.001) and PFS (HR 2.10, P<0.001), whereas presence of T790M+ was associated with longer OS (HR 0.50, P=0.008) and PFS (HR 0.57, P=0.027). This cohort demonstrated the efficacy of osimertinib in second line/beyond for EGFR+ (EGFR mutation-positive) non-small cell lung cancer (NSCLC). Tissue T790M result appeared more predictive of osimertinib efficacy compared to plasma, highlighting potential T790M heterogeneity and the advantage with paired tumor-plasma T790M testing at TKI resistance. T790M- disease at resistance remains an unmet treatment need.

Clinical Outcomes, Treatment and Testing Patterns in Patients with Advanced Non-Small Lung Cell Cancer with Epidermal Growth Factor Receptor Mutations: Results of the Romanian Cohort From a Multi-national Retrospective Chart Review (REFLECT)

"Background: REFLECT was a retrospective, non-interventional study conducted in eight countries, including eleven sites from Romania, on patients with advanced stage non-small cell carcinoma (NSCLC). Aim: To characterize clinical outcomes, treatments and the proportion of T790M EGFR mutation testing in patients with advanced non-small cell lung cancer (NSCLC) receiving first- or second-generation (1G/2G) epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs ) as first-line (1L) treatment in the Romanian cohort of an international study. Methods: Comprehensive data were retrieved from the medical records of ninety patients with EGFR-mutated advanced NSCLC treated with 1G/2G EGFR TKIs between January 2015 and June 2018. All analyses are descriptive. Results: The median age at lung cancer diagnosis in the Romanian cohort was 67.5 years, with 68% females. The distribution of EGFR TKIs was 50% erlotinib, 31% afatinib, and 19% gefitinib. First line treatment was stopped in 76 (84%) patients due to progression (79%), toxicities (3%), the patient’s decision (1%) or surgery (1%). The median progression- free survival on 1L treatment was 12.0 months (95% CI 10.3-15.6), and the median overall survival from the start of first line therapy was 26.4 months (95% CI 22.4-34.2). EGFR T790M mutation testing was performed on 69% of patients at the time of progression on 1L therapy, with 57% of patients testing positive. Second-line (2L) therapy was started in 63% of patients discontinuing 1L therapy. Third-line treatment was started in 50% of patients discontinuing 2L treatment. Conclusion: Survival results mirrored those of randomized trials. The suboptimal T790M testing rate (69%) underlines the importance of reflex testing procedures, while attrition rates on 1L (26%) emphasize the need for an upfront selection of the most effective treatments."

EGFR T790M testing through repeated liquid biopsy over time: a real-world multicentric retrospective experience.

BackgroundAbout 15% of non-small cell lung cancers (NSCLCs) harbor epidermal growth factor receptor (EGFR) mutations. Upfront treatment with first and second generation EGFR tyrosine kinase inhibitors (1-2gen TKIs) is superior to chemotherapy. The most frequent resistance mechanism to 1-2gen TKIs is EGFR T790M mutation, which is targeted by osimertinib. T790M mutation can be revealed by liquid biopsy (LB) or by tissue rebiopsy (TB). LB is easily feasible but less sensitive than TB. We focused on repeated LBs and analyzed clinical features associated with EGFR T790M detection.MethodsThis is a retrospective multicenter observational study including EGFR-mutant NSCLC consecutive patients with disease progression (PD) after 1-2gen TKIs and with a first EGFR LB negative for T790M mutation, referred between 2016 and 2019. Aims of the study were to determine the prevalence of T790M mutation using LB in a real-life setting and the prevalence of T790M mutation by repeated LBs. We explored the association of T790M with clinical-pathological features and, through a survey, we evaluated the decision-making process behind LB request. Data on TBs were also collected.ResultsOne hundred and ten patients were included in the study, for a total of 326 LBs. Median number of LB per patient was 3.0. The T790M prevalence through LB was 34.5%. Over time, significantly more LBs were requested “at clinical and radiological PD” and “at radiological PD” compared to “arbitrarily”. The probability of finding the T790M mutation for a patient across each subsequent LB did not significantly change. Liver and lymph node PD were significantly correlated to T790M positivity. Notably, “at PD” compared to “arbitrarily” LB request and liver, bone or lymph node PD were correlated to the detection of any EGFR mutation in cfDNA. TB was performed in 59.7% of patients with a T790M negative LB and 18.8% of them were T790M positive. In most cases, TB was not feasible due to anatomical reasons. In our study population, the overall T790M prevalence—detected with both LB and TB—was 42.7%.ConclusionsRepeated LB testing can be useful in a real-life scenario to detect EGFR T790M mutation.

56P Simultaneous tissue and liquid next-generation sequencing after first-line EGFR tyrosine kinase inhibitors resistance in advanced non-small cell lung cancer

T790M testing is recommended after resistance to first or second-generation EGFR tyrosine kinase inhibitors (TKIs). However, the role of simultaneous tissue and liquid next-generation sequencing (NGS) after first-line EGFR TKI resistance is still unclear.

European and US Real-World Treatment Patterns in Patients with Epidermal Growth Factor Receptor Mutation-Positive Non-Small Cell Lung Cancer: A Retrospective Medical Record Review.

BackgroundEpidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are the preferred first-line (1L) therapy for EGFR mutation-positive (EGFRm) advanced/metastatic non-small cell lung cancer (NSCLC).ObjectiveOur objective was to describe real-world treatment patterns and T790M testing practices in patients with 1L disease progression (Europe/USA) following treatment with first- or second-generation EGFR-TKIs.MethodsThis was a retrospective, non-interventional medical record review of patients with EGFRm locally advanced/metastatic NSCLC from routine clinical practice (EGFR-TKI initiation: 1 January 2015 to 31 December 2017; follow-up: last available medical record). Endpoints were demographic/clinical characteristics, incidence of central nervous system (CNS) metastases/leptomeningeal disease, second-line (2L) treatment, T790M mutation testing, and osimertinib treatment prevalence.ResultsAmong 469 patients, 73% (n = 341/469) progressed on 1L EGFR-TKI treatment. Of those who progressed, 74% (n = 252/341) were tested for T790M, with 50% (n = 126/252) testing positive; 75% (n = 94/126) of T790M-positive patients received osimertinib (mostly 2L). Of the patients with progression, 24% (n = 83/341) did not receive 2L treatment, and 88% (n = 73/83) of these patients died. At diagnosis of advanced disease, 9% of patients (n = 41) had CNS metastases; at EGFR-TKI initiation, 14% of patients (n = 68) had CNS metastases. Over the study period, 11% of patients (n = 42) developed CNS metastases not detected at NSCLC diagnosis.ConclusionsRates of resistance mutation testing and subsequent utilization of recommended 2L therapies could be improved. As more targeted therapies are developed, it will be crucial to improve the molecular testing rates to ensure patients receive appropriate, effective, and timely treatment.Supplementary InformationThe online version contains supplementary material available at 10.1007/s40801-021-00261-8.

1244P Real-world EGFR and T790M testing patterns in patients from Central Eastern Europe with advanced non-small cell lung cancer: Results from a large retrospective study (REFLECT)

After an initial response to first- or second-generation (1G/2G) epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) roughly one-half of patients (pts) with advanced EGFR mutated (EGFRm) non-small cell lung cancer (NSCLC) develop resistance due to a secondary T790M mutation. REFLECT study (NCT04031898) explored EGFR/T790M testing and treatment patterns in EGFRm NSCLC pts receiving 1G/2G EGFR TKis in 8 countries. Pooled data from Central Eastern Europe (CEE) are presented here.

The correlation between the abundance of EGFR T790M mutation and osimertinib response in advanced non-small cell lung cancer.

BackgroundOsimertinib has been adopted as the standard therapy for T790M-mediated acquired resistance to first-line epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) in patients with non-small cell lung cancer (NSCLC). The detection of EGFR T790M can be evaluated using different methods. The association between baseline T790M abundance and osimertinib efficacy has not been fully determined.MethodsA total of 144 advanced NSCLC patients positive for T790M, at the time of progression, were retrospectively enrolled in this study. The effect of abundance of T790M mutation on the efficacy of osimertinib was explored.ResultsAmong the 144 patients receiving T790M testing, 20 (13.9%) had adopted amplification refractory mutation system (ARMS), 63 (43.8%) adopted droplet digital PCR (ddPCR), and 61 (42.4%) used next-generation sequencing (NGS). The objective response rate was 54.2%, the median progression-free survival was 12.0 months, and the overall survival was 23.0 months for the NSCLC patients treated with osimertinib. Three different technologies to assess T790M mutation (including ARMS, ddPCR, and NGS) could accurately predict the efficacy of osimertinib. There was no significant relationship between the abundance of T790M mutation and the efficacy of osimertinib.ConclusionsARMS, ddPCR, and NGS are reliable methods to evaluate EGFR T790M mutation. Osimertinib was equally effective for NSCLC patients with various abundance of T790M mutation.

Real-world Treatment Patterns in Patients with EGFR Mutation-positive NSCLC Receiving a First-Line, First- or Second-generation EGFR Tyrosine Kinase Inhibitor in South Korea and Taiwan

Introduction: The preferred first-line (1L) treatment for epidermal growth factor receptor (EGFR) mutation-positive (EGFRm) advanced/metastatic non-small lung cancer (NSCLC) are EGFR-tyrosine kinase inhibitors (TKIs). However, most patients treated with 1L first- or second-generation (1G/2G) EGFR-TKIs acquire resistance; the EGFR T790M mutation is observed in ~30–50% of patients. We report real-world NSCLC treatment and T790M testing patterns in South Korea and Taiwan. Methods: Retrospective medical record review of EGFRm advanced/metastatic NSCLC patients from routine practice. 1G/2G EGFR-TKI initiation 1 January 2015–31 December 2017 (follow-up end date: last available medical record or August 2019). Study measures: demographic/disease characteristics, 1L/2L treatment, T790M testing. Results: In South Korea, 70% (164/235) and in Taiwan 89% (89/100) experienced 1L disease progression (median [range] follow-up: 22 [2.3–50.7] months). Of those with disease progression, 68% (111/164) and 62% (55/89) had T790M testing in South Korea and Taiwan, respectively. In South Korea, 43% (48/111) were T790M-positive with 88% (n=42/48) receiving osimertinib (mostly 2L). In Taiwan, 18% (10/55) were T790M-positive; 100% received osimertinib. Overall, 73% (120/164) and 63% (63/100) in South Korea and Taiwan, respectively, received 2L therapy, predominantly pemetrexed-containing regimens. Among patients with disease progression, 9% (14/164) and 24% (21/89) died before receiving 2L therapy in South Korea and Taiwan, respectively. Conclusion: In both countries, &lt;70% with 1L disease progression were tested for T790M at any point from NSCLC diagnosis, suggesting resistance mutation testing could be improved. Treatment/testing patterns may have changed in both countries since study initiation due to osimertinib reimbursement changes beginning December 2017.

Real-world outcomes and clinical characteristics of patients with brain metastases from EGFR mutated non-small cell lung cancer: Data from a large retrospective study (REFLECT).

9086 Background: Brain metastases (BM) frequently occur in patients (pts) with epidermal growth factor receptor mutated non-small cell lung cancer (EGFRm NSCLC) and represent a poor prognostic marker. This study aimed to describe the clinical characteristics, treatment patterns and survival outcomes in EGFRm NSCLC pts treated with 1st or 2nd generation tyrosine-kinases inhibitors (TKIs) in first-line (1L). Methods: The retrospective real-world study REFLECT (NCT04031898) collected data from 896 pts initiating 1L TKI between 1 January 2015-30 June 2018 in Europe and Israel. Descriptive statistics were used to assess demographic and clinical characteristics in subgroups of patients with and without BM. Kaplan-Meier methods were used to estimate median real world progression free survival (mPFS) and overall survival (mOS) from start of 1L. Results: Out of 896 pts, 198 (22.1%) had BM at start of 1L, 134 (15%) developed BM later (any time), and 564 (62.9%) had no sign of BM at the time of data collection. Among pts who later developed BM the median time between the start of 1L and first diagnosis of BM was 13.5 months. Median duration of follow-up was 21.5 months. Of 332 pts with BM at any time 64.2% were female, similar to the ratio in pts without BM (64.0%). At diagnosis, median age was 65 years in pts with BM vs. 70 in those who never developed BM. Of pts with BM at any time, 50.9% had exon 19 deletion, 30.4% L858R point mutation and 18.7 % uncommon EGFR mutations at baseline, compared to 56.6%, 31.7% and 11.7% in pts without BM, respectively. At data collection, 94.9% of the pts with BM at diagnosis had progressed compared to 79.8% among those with no BM. Overall, whole brain radiation was the most frequently used treatment for BM (31.0%) followed by stereotactic radiosurgery (18.1%) and targeted therapies (13.3%). T790M testing rates were highest among pts developing BM later (85.7%) and lowest among those with BM from start (66.1%). The T790M positivity rate was highest in pts developing BM later (65.7%) and lowest among those with BM from start (50.4%). More pts received osimertinib in later lines among those with BM at any time compared to those without BM (51.3% vs 43.8%). Median real world PFS and OS (95% CI) were shorter among pts with BM at baseline compared to those never developing BM: 10.2 (8.8, 11.5) vs 15.2 (13.7, 16.1) months, and 19.4 (17.1, 22.1) vs 30.3 (27.1, 33.8) months, respectively. At the time of data collection, 77.3% of pts with BM at baseline were deceased compared to 52.5% pts with no BM. Conclusions: More than one third of pts included in REFLECT had BM at any time. Uncommon EGFR variants at baseline were observed more frequently in pts with BM. mPFS and mOS were shorter in pts with BM at baseline compared to those never developing BM. These data highlight the need for improved treatment and CNS control in pts with EGFRm NSCLC. Clinical trial information: NCT04031898.

Real-world implementation of sequential targeted therapies for EGFR-mutated lung cancer.

Background:Epidermal growth factor receptor-mutated (EGFR+) non-small-cell lung cancer (NSCLC) patients failing tyrosine kinase inhibitors (TKI) can benefit from next-line targeted therapies, but implementation is challenging.Methods:EGFR+ NSCLC patients treated with first/second-generation (1G/2G) TKI at our institution with a last follow-up after osimertinib approval (February 2016), were analyzed retrospectively, and the results compared with published data under osimertinib.Results:A total of 207 patients received erlotinib (37%), gefitinib (16%) or afatinib (47%). The median age was 66 years, with a predominance of female (70%), never/light-smokers (69%). T790M testing was performed in 174/202 progressive cases (86%), positive in 93/174 (53%), and followed by osimertinib in 87/93 (94%). Among the 135 deceased patients, 94 (70%) received subsequent systemic treatment (43% chemotherapy, 39% osimertinib), while 30% died without, either before (4%) or after progression, due to rapid clinical deterioration (22%), patient refusal of further therapy (2%), or severe competing illness (2%). Lack of subsequent treatment was significantly (4.5x, p < 0.001) associated with lack of T790M testing, whose most frequent cause (in approximately 50% of cases) was also rapid clinical decline. Among the 127 consecutive patients with failure of 1G/2G TKI started after November 2015, 47 (37%) received osimertinib, with a median overall survival of 36 months versus 24 and 21 months for patients with alternative and no subsequent therapies (p = 0.003).Conclusion:Osimertinib after 1G/2G TKI failure prolongs survival, but approximately 15% and 30% of patients forego molecular retesting and subsequent treatment, respectively, mainly due to rapid clinical deterioration. This is an important remediable obstacle to sequential TKI treatment for EGFR+ NSCLC. It pertains also to other actionable resistance mechanisms emerging under 1G/2G inhibitors or osimertinib, whose rate for lack of next-line therapy is similar (approximately 35% in the FLAURA/AURA3 trials), and highlights the need for closer monitoring alongside broader profiling of TKI-treated EGFR+ NSCLC in the future.

Impact of epidermal growth factor receptor T790M testing in relapsed non-small cell lung cancer: A narrative review of the T790M reflex testing algorithm

Impact of epidermal growth factor receptor T790M testing in relapsed non-small cell lung cancer: A narrative review of the T790M reflex testing algorithm

Multicenter Validation Study to Implement Plasma Epidermal Growth Factor Receptor T790M Testing in Clinical Laboratories.

Plasma detection of EGFR T790M mutations is an emerging alternative to tumor rebiopsy in acquired epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor resistance. Validation of analytical sensitivity and clinical utility is required before routine diagnostic use in clinical laboratories. Sixty-three patients with advanced EGFR-mutant lung cancer at 7 Canadian centers, who were being screened for the ASTRIS trial (ClinicalTrials.gov identifier: NCT02474355), participated in this companion study. Plasma T790M mutation was detected using droplet digital polymerase chain reaction, Cobas (Roche Diagnostics, Indianapolis, IN), or next-generation sequencing in 4 laboratories. T790M concordance was assessed between plasma and tumor samples. Assessment of T790M in tumor biopsy tissue was successful in 81% of patients; 49% had confirmed T790M results (tumor or plasma) for ASTRIS. Plasma testing in this companion study yielded T790M results in 97% of patients; 62% had T790M-positive results, 36% had negative results, and 2% had indeterminate results. Of 38 patients with negative or indeterminate biopsy results, 55% had positive plasma T790M results, increasing the proportion with T790M-positive results to 73%. Sensitivity of plasma T790M testing was 75%. Overall concordance between tissue and plasma was 64%, and concordance among laboratories was 90.3%. Response to osimertinib and duration of therapy were similar irrespective of testing method (overall response rate, 62.5% for tissue, 66.7% for plasma, and 70.6% for both). This multicenter validation study demonstrates that plasma EGFR T790M testing can identify significantly more patients than biopsy alone who may benefit from targeted therapy.

An Observational Study of Acquired EGFR T790M-Dependent Resistance to EGFR-TKI Treatment in Lung Adenocarcinoma Patients in Taiwan.

In Taiwan, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (EGFR-TKIs), gefitinib, erlotinib, and afatinib are served as first-line therapy for non-small lung cell cancer (NSCLC) patients with EGFR sensitizing mutations. However, the majority of patients who initially respond to EGFR-TKIs, progress through acquiring EGFR T790M mutations (T790M), which is the most common resistant mechanism. Patients with T790M gain the opportunity of subsequent treatment with third-generation EGFR-TKI, osimertinib. This study aimed to evaluate the association between prior EGFR-TKI therapy and incidence of acquired T790M resistance in lung adenocarcinoma patients who have progressed on first/second-generation EGFR-TKI therapy. This retrospective study included lung adenocarcinoma patients who had a radiographically-confirmed progressive disease under EGFR-TKI treatment and had re-biopsy samples for T790M testing from seven medical centers in Taiwan from June 2013 to December 2018. Patients harboring de novo T790M or using more than one EGFR-TKI were excluded. Of the 407 patients enrolled, the overall T790M acquisition rate was 52.8%. The patients treated with gefitinib, erlotinib or afatinib had a statistically significant difference in the T790M rates (59.9, 45.5, and 52.7%, respectively; p = 0.037) after disease progression. Patients with common baseline EGFR mutations (Del-19 and L858R) (p = 0.005) and longer treatment duration with EGFR-TKIs (p < 0.001) had higher chances of T790M acquisition. Multivariate logistic regression analysis further showed that patients with common baseline EGFR mutations, gefitinib (compared to erlotinib) administration, and longer treatment duration with EGFR-TKIs had higher T790M incidence. There was no significant difference in the incidence of acquired T790M between different re-biopsy tissue samples or complications. In conclusion, this study showed that patients who progressed from gefitinib treatment, bearing common EGFR mutations, and with longer EGFR-TKI treatment duration had increased incidence of T790M acquisition and, therefore, were suitable for subsequent osimertinib treatment.

EGFR circulating tumour DNA testing: identification of predictors of ctDNA detection and implications for survival outcomes.

BackgroundEGFR T790M testing is the standard of care for activating EGFR mutation (EGFRm) non-small cell lung cancer (NSCLC) progressing on 1st/2nd generation TKIs to select patients for osimertinib. Despite sensitive assays, detection of circulating tumour deoxyribonucleic acid (ctDNA) is variable and influenced by clinical factors. The number and location of sites of progressive disease at time of testing were reviewed to explore the effect on EGFR ctDNA detection. The prognostic value of EGFR ctDNA detection on survival outcomes was assessed.MethodsFollowing extraction of cell-free DNA from plasma using the QIAamp Circulating Nucleic Acid Kit, custom droplet digital polymerase chair reaction (ddPCR) assays were used to assess EGFR ctDNA using the Bio-Rad QX200 system. The ddPCR assay has a limit of detection of ≤0.15% variant allele fraction. Baseline characteristics and imaging reports at time of EGFR ctDNA testing were reviewed retrospectively for a 1 year period.ResultsThe study included 177 patients who had an EGFR ctDNA test. Liver (aOR 3.13) or bone (aOR 2.76) progression or 3–5 sites of progression (aOR 2.22) were predictive of EGFR ctDNA detection. The median OS from first ctDNA test after multiple testing iterations was 12.3 m undetectable EGFR ctDNA, 7.6 m for original EGFR mutation only and 24.1 m with T790M (P=0.001).ConclusionsPatients with liver or bone progression and 3–5 progressing sites are more likely to have informative EGFR ctDNA testing. Detection of EGFR ctDNA is a negative prognostic indicator in the absence of a T790M resistance mutation, potentially reflecting the disease burden in the absence of targeted therapy options.

Clinical implementation of plasma EGFR T790M testing using droplet digital PCR in TKI-resistant NSCLC patients

BackgroundMajority of non-small cell lung cancer (NSCLC) patients progressed on epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) due to acquired T790M mutation. Blood sample is increasingly used in clinical setting for EGFR T790M detection and our laboratory employed the droplet digital PCR (ddPCR) methodology for testing. This study investigated the positive rate, specimen type for rebiopsy and clinical impact of blood-based EGFR T790M testing. MethodsWe retrospectively evaluated clinical samples that underwent plasma EGFR T790M testing in TTSH Molecular Diagnostic Laboratory from August 2017 to September 2019. Data on diagnosis, EGFR activating and T790M mutations, and treatment strategies were recorded. ResultsA total of 104 progressive NSCLC cases were included in this study. Overall, 46 patients (44.2%) were tested T790M positive, and 47.8% of these tested positive had low levels (defined as ≤3% fractional abundance and <50 copies/mL plasma), which may be missed by the conventional methods with lower sensitivity. Of these tested with low T790M abundance, 77.3% subsequently received osimertinib. Activating mutations were not detected in 42 (40.4%) cases, indicating that the tumors were not actively shedding ctDNA. Among these, 24 patients underwent repeat testing with tissue or blood specimens. Thirteen patients were subsequently tested T790M positive and 12 of them switched treatment to osimertinib. The recommendation to repeat testing with a different biopsy or after a suitable interval increased the overall positive rate to 56.7% (59/104). ConclusionThe use of a highly sensitive platform such as ddPCR for the detection of low abundance T790M, and the approach of repeat testing in cases with insufficient ctDNA increased the positive rate. This in turn identified more patients who are eligible for targeted therapy.

Observational Study of Treatment Patterns in Patients with Epidermal Growth Factor Receptor (EGFR) Mutation-Positive Non-Small Cell Lung Cancer After First-Line EGFR-Tyrosine Kinase Inhibitors

Epidermal growth factor receptor (EGFR) mutations are observed in approximately 15% of patients with non-small cell lung cancer (NSCLC) in the USA. Little is known about treatment patterns in EGFR mutation-positive NSCLC following progression on or after first-line (1L) treatment with first- or second-generation EGFR tyrosine kinase inhibitors (EGFR-TKIs). Osimertinib, a third-generation EGFR-TKI, is a treatment option for patients with EGFR T790M-positive NSCLC following progression on 1L EGFR-TKIs. This study analyzed real-world treatment sequencing of EGFR-TKIs, EGFR T790M testing rates, and disposition of patients with EGFR mutations after 1L EGFR-TKI post-FDA approval of osimertinib in patients with EGFR mutation-positive NSCLC. Adult patients with stageIV NSCLC and documented EGFR mutation-positive status were identified between December 1, 2015 and May 31, 2017 from the US Oncology Network iKnowMed™ electronic health record (EHR). Data were abstracted from the EHR database and supplemented by chart review. Of 308 patients, 302 (98%) received an EGFR-TKI overall, and 246 patients (80%) received a 1L EGFR-TKI. The most common 1L EGFR-TKI was erlotinib (66%); the remaining 1L regimens were predominantly combination chemotherapies with or without an EGFR-TKI. Only 80 patients (26%) received any 2L therapy. The most common EGFR-TKIs used as 2L monotherapy in patients who received 1L EGFR-TKI were afatinib and osimertinib (n = 7 for both). Among all patients treated with 1L EGFR-TKI (n = 246), 47 (19%) were tested for EGFR T790M [16 patients (34%) were positive], 48 (20%) remained on 1L EGFR-TKI, 29 (12%) received subsequent therapy, 38 (15%) had died on or after their 1L EGFR-TKI therapy, and 131 (53%) stopped their EGFR-TKI with no recorded evidence of having received subsequent therapy at follow-up end. Following 1L EGFR-TKI treatment, 19% of patients were tested for EGFR T790M, and most (69%) had no record of receiving any subsequent therapy.