Frequency of EGFR T790M mutation and multimutational profiles of rebiopsy samples from non-small cell lung cancer developing acquired resistance to EGFR tyrosine kinase inhibitors in Japanese patients

Real-world data on efficacy and safety of osimertinib in non-small cell lung cancer patients with EGFR T790M mutation detected by first and repeat rebiopsy

BACKGROUND

Osimertinib could effectively target epidermal growth factor receptor (EGFR) T790M resistance mutations in non-small cell lung cancer (NSCLC), indicating that rebiopsy may be particularly important. However, the clinical benefit of repeat rebiopsy in T790M-negative patients with NSCLC detected by the first rebiopsy is still unclear, and data on the efficacy and safety of osimertinib in patients with NSCLC who are T790M-positive patients on a repeat rebiopsy remain rare.

METHODS

We retrospectively collected the clinical data of advanced NSCLC patients with common EGFR mutation who were treated with 1/2-generation (1/2G) EGFR-tyrosine kinase inhibitors (TKIs) in first-line therapy in our center from January 2018 to December 2020. The detection rate of T790M by first and repeat rebiopsy was recorded, and we also analyzed the efficacy and safety of osimertinib for T790M-positive patients.

RESULTS

Among 190 common EGFR-mutant patients who received 1/2G EGFR-TKIs with advanced NSCLC in the first-line treatment, 141 patients developed progressive disease. In total, 110 of 141 accepted the first rebiopsy, with a T790M prevalence of 50.9% (56/110). In total, 43 T790M-positive patients who received osimertinib were included in first rebiopsy group. Of 54 T790M-negative patients detected by the first rebiopsy, 28 underwent repeated rebiopsy in subsequent clinical treatment, and 10 (35.7%) T790M-positive cases were confirmed. In total, eight T790M-positive patients treated with osimertinib were included in repeat rebiopsy group. Overall, 66 (60%) of 110 patients acquired a T790M mutation. In patients with the T790M mutation discovered by the first and repeat rebiopsy, osimertinib resulted in median progression-free survival of 7 (95% confidence interval [CI]: 5.3-8.7) and 6 (95% CI: 4.7-7.3) months, respectively (p = .656). The median overall survival since osimertinib initiation for T790M-positive patients at first rebiopsy was 20 (95% CI: 15.1-24.9) months and 19 (95% CI: 16.9-21.1) months, for those at repeated rebiopsy (p = .888). Adverse events of grade 3 or higher were similar in the two groups (25.6% vs. 12.5%, p = .616). There was no treatment-related death in the two groups.

CONCLUSIONS

Repeat rebiopsy can increase the T790M mutation positivity rate. Osimertinib showed similar efficacy and safety in T790M-positive patients whether detected by the first or repeat rebiopsy.

Changes in HER3 expression profiles between primary and recurrent gynecological cancers

BACKGROUND

Human epidermal growth factor receptor-3 (HER3) is a member of the epidermal growth factor receptor family of receptor tyrosine kinases, and its overexpression is associated with inferior prognosis in several cancers. However, it is unclear whether HER3 expression status changes in tumor tissue at recurrence. Therefore, this study aimed to evaluate the changes in HER3 expression between primary and recurrent status in gynecological cancers.

METHODS

This retrospective study used matched-pair tissues of gynecological cancer patients at initial diagnosis and at recurrence. Immunohistochemical (IHC) scores of 3 + or 2 + were termed "HER3-high", while IHC scores of 1 + or 0 were designated as "HER3-low/zero".

RESULTS

A total of 86 patients (40 with ovarian cancers, 32 with endometrial cancers, and 14 with cervical cancers) were included in this study. In ovarian cancer, 67.5% and 80.0% of the patients received a HER3-high at initial and recurrent diagnosis, respectively. The H-score was significantly increased at recurrence (p = 0.004). The proportion of HER3-high endometrial cancer patients increased from 46.9% at initial diagnosis to 68.8% at recurrence, and the H-score tended to increase at recurrence (p = 0.08). The fraction of HER3-high-rated cervical cancer patients remained unchanged at 85.7% both at initial and recurrent diagnosis. The discordance rate of HER3 expression detection in initial and recurrent diagnosis samples was 27.5%, 53.1%, and 14.3% for ovarian, endometrial, and cervical cancers, respectively. Ovarian and endometrial cancers with a HER3-high recurrent score tended to show shorter median survival time than those with a HER3-low/zero recurrent rating.

CONCLUSION

Our findings suggest that, in main types of gynecological cancers, the proportion of patients having a HER3-high score increased from initial to recurrent diagnosis.

Clinical correlations with EGFR circulating tumor DNA testing in all-stage lung adenocarcinoma

BACKGROUND

Information on genetic alterations, notably EGFR mutations, is important for guiding non-small-cell lung cancer (NSCLC) treatment. Circulating tumor DNA (ctDNA) analysis represents a less invasive alternative to tissue biopsy for analyzing mutation status, but its clinical value may vary across disease stages.

OBJECTIVE

To explore clinical correlates of ctDNA and tissue/plasma-based EGFR mutation (EGFRm) status across all NSCLC stages.

METHODS

Ninety patients were analyzed, representing three cohorts: newly-diagnosed early-stage, advanced-stage, and recurrent NSCLC. Relationships among clinical/surgical parameters, ctDNA, EGFRm status, and survival outcomes were analyzed.

RESULTS

Plasma/tissue EGFRm concordance was lower in early-stage (58.6%) than in advanced-stage patients (87.5%). In early-stage patients, ctDNA levels were variable and not significantly associated with clinical/surgical parameters. In advanced-stage patients, time to EGFR-TKI treatment failure (TTF), but not overall survival (OS), was significantly longer in EGFRm-positive vs. EGFRm-negative patients. In patients with recurrent disease, 40% of plasma samples were EGFRT790M-positive at recurrence. In T790M-positive patients, we noted slight trends toward longer OS with vs. without osimertinib treatment and longer OS and TTF with second-line vs. later-line osimertinib.

CONCLUSIONS

Our results affirm the use of ctDNA testing in advanced-stage and recurrent NSCLC. Further studies on osimertinib as early-line therapy, clinical correlates and the utility of plasma-based testing in early-stage NSCLC are warranted.

Optimizing Patient Outcomes Through Sequential EGFR TKI Treatment in Asian Patients With EGFR Mutation-Positive NSCLC

Patients from Asia with non-small-cell lung cancer (NSCLC) often have mutations in the epidermal growth factor receptor (EGFR) gene. While an increasing number of EGFR tyrosine kinase inhibitors (TKIs) are now available for patients with EGFR mutation-positive NSCLC, most patients inevitably develop resistance to the treatment. Evidence from clinical studies suggests that treatment outcomes and resistance mechanisms vary depending on the choice of TKI therapy in the first-line setting. Hence, it is important to develop optimal treatment sequencing strategies that can provide maximum survival benefit for the patient. In this review we present clinical evidence in Asian patients with NSCLC for various EGFR TKIs, with the goal of supporting the optimization of treatment sequencing.

Comparison of T790M Acquisition After Treatment With First- and Second-Generation Tyrosine-Kinase Inhibitors: A Systematic Review and Network Meta-Analysis

Background

Lung adenocarcinoma is a common disease with a high mortality rate. Epidermal growth factor receptor (EGFR) mutations are found in adenocarcinomas, and oral EGFR-tyrosine kinase inhibitors (EGFR-TKIs) show good responses. EGFR-TKI therapy eventually results in resistance, with the most common being T790M. T790M is also a biomarker for predicting resistance to first- and second-generation EGFR-TKIs and is sensitive to osimertinib. The prognosis was better for patients with acquired T790M who were treated with osimertinib than for those treated with chemotherapy. Therefore, T790M mutation is important for deciding further treatment and prognosis. Previous studies based on small sample sizes have reported very different T790 mutation rates. We conducted a meta-analysis to evaluate the T790M mutation rate after EGFR-TKI treatment.

Methods

We systematic reviewed the electronic databases to evaluate the T790M mutation rate after treatment with first-generation (gefitinib, erlotinib, and icotinib) and second-generation (afatinib and dacomitinib) EGFR-TKIs. Random-effects network meta-analysis and single-arm meta-analysis were conducted to estimate the T790M mutation rate of the target EGFR-TKIs.

Results

A total of 518 studies were identified, of which 29 were included. Compared with afatinib, a higher odds ratio (OR) of the T790M mutation rate was observed after erlotinib [OR = 1.48; 95% confidence interval (CI):1.09–2.00] and gefitinib (OR = 1.45; 95% CI: 1.11–1.90) treatments. An even OR of the T790M mutation rate was noted after icotinib treatment (OR = 0.91, 95% CI: 0.46–1.79) compared with that after afatinib. The T790M mutation rate was significantly lower with afatinib (33%) than that with gefitinib (49%) and erlotinib treatments (47%) (p < 0.001). The acquired T790M mutation rate in all participants was slightly lower in Asians (43%) than that in Caucasians (47%).

Conclusions

Erlotinib and gefitinib had a higher OR for the T790M mutation than afatinib. The T790M mutation rate was significantly lower in afatinib than in gefitinib and erlotinib. T790M is of great significance because osimertinib shows a good prognosis in patients with T790M mutation.

Systematic Review Registration

PROSPERO, identifier CRD42021257824.

Effectiveness and Safety of EGFR-TKI Rechallenge Treatment in Elderly Patients with Advanced Non-Small-Cell Lung Cancer Harboring Drug-Sensitive EGFR Mutations

Background and Objectives: Epidermal growth factor receptor–tyrosine kinase inhibitors (EGFR-TKIs) are effective first-line chemotherapeutic agents for patients with advanced non-small-cell lung cancer (NSCLC) harboring drug-sensitive EGFR mutations. However, the effectiveness of EGFR-TKI rechallenge after first-line EGFR-TKI treatment is not sufficient in elderly patients (over 75 years of age) harboring drug-sensitive EGFR mutations. Therefore, we investigated the effectiveness and safety of EGFR-TKI rechallenge after first-line EGFR-TKI treatment in elderly patients with advanced NSCLC harboring drug-sensitive EGFR mutations. Materials and Methods: Between April 2008 and December 2015, we analyzed 78 elderly patients with advanced NSCLC harboring drug-sensitive EGFR mutations with first-line EGFR-TKI treatment at four Japanese institutions. We retrospectively evaluated the clinical effectiveness and safety profiles of EGFR-TKI rechallenge after first-line EGFR-TKI treatment in elderly patients with advanced NSCLC harboring drug-sensitive EGFR mutations (exon 19 deletion/exon 21 L858R mutation). Results: Twenty-two patients in the cohort were rechallenged with EGFR-TKI. The median age was 79.5 years (range 75–87 years). Despite the fact that it was a retrospective analysis, even with EGFR-TKI rechallenge treatment the response rate was 23%, progression-free survival was 5.3 months, and overall survival was 14.4 months. Common adverse events included rash acneiform, paronychia, diarrhea, and anorexia. There were no treatment-related deaths. Due to the occurrence of adverse events of grade 2 or more, dose reduction was performed in 15 (68.2%) of 22 cases. Conclusions: EGFR-TKI rechallenge treatment after first-line EGFR-TKI treatment in elderly patients with advanced NSCLC harboring drug-sensitive EGFR mutations was one of the limited, safe and effective treatment options for elderly EGFR-positive lung cancer patients.

Hope and Worry: An Interpretative Phenomenological Analysis of Psychological Experiences Associated With Targeted Drug Therapy Among Patients With Advanced Non-Small-Cell Lung Cancer

BACKGROUND

With the rapid development of precision medicine, targeted therapy has brought new hope for patients with advanced lung cancer. However, because of the high specificity of targeted therapy, individual differences in treatment have occurred, and drug resistance has led to treatment failure, or unpredictable serious side effects have resulted in reducing or stopping treatment. Such outcomes reduce hope.

OBJECTIVE

The aim of this study was to understand the phenomena of existential worry and hope in patients with advanced non-small-cell lung cancer (NSCLC) who are receiving targeted therapies.

METHODS

The interpretative phenomenological analysis method was used in this study. Semistructured interviews were conducted with patients with advanced NSCLC who had received targeted drug therapy at a public cancer hospital in China.

RESULTS

Four themes emerged from the descriptions of 16 patients regarding their psychological experiences of undergoing targeted therapy: wishes and concerns, hopes and fears, expectations and worry, and desires and anxiety.

CONCLUSIONS

Non-small-cell lung cancer patients experience positive emotions, such as hope and expectation, as well as negative emotions, such as worry and anxiety, while receiving targeted drug therapy. These different emotions can be experienced concurrently.

IMPLICATIONS FOR PRACTICE

Our findings illuminate NSCLC patients' psychological perceptions while undergoing targeted drug therapy. Supportive care resources and interventions are required to enhance patients' positive feelings and reduce their worry during targeted therapy. Patients also require better preparation and information to enable them to improve their quality of life and remain safe after undergoing treatment.

A Real-World, Observational, Prospective Study to Assess the Molecular Epidemiology of Epidermal Growth Factor Receptor (EGFR) Mutations upon Progression on or after First-Line Therapy with a First- or Second-Generation EGFR Tyrosine Kinase Inhibitor in EGFR Mutation-Positive Locally Advanced or Metastatic Non-Small Cell Lung Cancer: The 'LUNGFUL' Study

Simple Summary

Non-small cell lung cancer (NSCLC) accounts for approximately 85% of lung cancer cases, with few patients carrying driver mutations in the gene encoding for epidermal growth factor receptor (EGFR). Advances in translational research have established EGFR tyrosine kinase inhibitors (TKIs) as the standard first-line therapy for NSCLC patients with activating EGFR mutations. The aim of our observational study was to assess the frequency of T790M acquired resistance and predictors of its presence, in patients with EGFR-mutated locally advanced or metastatic NSCLC who have progressed in the first-line EGFR-TKI treatment setting with first- or second-generation TKIs and have undergone molecular testing in tissue and/or plasma biopsy. The study highlights the challenges of performing tissue re-biopsy in routine care settings, which can lead to patients considered non-eligible for certain therapies from which they can benefit, and merits further actions from the healthcare community, in order to establish re-biopsy as a standard procedure.

Abstract

Background: Real-world data on the molecular epidemiology of EGFR resistance mutations at or after progression with first- or second-generation EGFR-TKIs in patients with advanced NSCLC are lacking. Methods: This ongoing observational study was carried out by 23 hospital-based physicians in Greece. The decision to perform cobas^®EGFR Mutation Test v2 in tissue and/or plasma at disease progression was made before enrollment. For patients with negative/inconclusive T790M plasma-based results, tissue re-biopsy could be performed. Results: Ninety-six (96) eligible patients were consecutively enrolled (median age: 67.8 years) between July-2017 and September-2019. Of the patients, 98% were tested upon progression using plasma and 2% using tissue/cytology biopsy. The T790M mutation was detected in 16.0% of liquid biopsies. Tissue re-biopsy was performed in 22.8% of patients with a T790M-negative plasma result. In total, the T790M positivity rate was 21.9%, not differing between patients on first- or second-generation EGFR-TKI. Higher (≥2) ECOG performance status and longer (≥10 months) time to disease progression following EGFR-TKI treatment initiation were associated with T790M positivity. Conclusions: Results from plasma/tissue-cytology samples in a real-world setting, yielded a T790M positivity rate lower than previous reports. Fewer than one in four patients with negative plasma-based testing underwent tissue re-biopsy, indicating the challenges in routine care settings.

Higher osimertinib introduction rate achieved by multiple repeated rebiopsy after acquired resistance to first/second generation EGFR-TKIs

Background

Indication for treatment with osimertinib after first/second generation (1/2G) epidermal growth factor receptor‐tyrosine kinase inhibitor (EGFR‐TKI) resistance depends on T790M mutation detected by rebiopsy. The aim of our study was to analyze the data on clinical practice at our hospital where histological rebiopsy is actively carried out multiple times.

Methods

We retrospectively reviewed our electronic medical records of EGFR‐mutant non‐small cell lung cancer (NSCLC) patients to examine clinical rebiopsy situation, T790M detection rate, osimertinib introduction rate and associated outcomes.

Results

Among 95 patients with EGFR‐mutant NSCLC, 72 patients received 1/2G EGFR‐TKIs. Of 60 with progressive disease on 1/2G EGFR‐TKIs, 50 (83%) underwent rebiopsy. T790M was detected in 40 (80%) of 50, resulting in a 79% osimertinib introduction rate, as one patient refused osimertinib. T790M was detected by first rebiopsy in 18 (36%) of 50 patients, and by second or subsequent rebiopsy in 22 (44%). Median time to treatment failure of T790M‐positive patients at first rebiopsy was 22.6 (95% confidence interval [CI]: 10.2–32.8) months, and those at multiple repeated rebiopsy was 20.9 (95% CI: 8.6–not reached) months (p = 0.64). Median overall survival (OS) in osimertinib introduced group was 92.5 (95% CI: 62.9–not reached), while in nonosimertinib median OS was 39.0 months (95% CI: 22.2–not reached) (p = 0.04).

Conclusions

T790M detection rate was increased by multiple repeated rebiopsy, achieving a higher osimertinib introduction rate. This higher introduction rate could contribute to better prognosis of EGFR‐mutant NSCLC patients.

Exosome-based detection of EGFR T790M in plasma and pleural fluid of prospectively enrolled non-small cell lung cancer patients after first-line tyrosine kinase inhibitor therapy

Background

The exosomal nucleic acid (exoNA) from the plasma and pleural fluid can potentially provide means to identify genomic changes in non-small cell lung cancer (NSCLC) patients who develop resistance to targeted epidermal growth factor receptor (EGFR) inhibitor therapy.

Methods

We compared the performance of the following tools to detect EGFR mutations in 54 plasma samples and 13 pleural fluid using cfDNA, combined TNA (exoTNA + cfTNA), or total cellular DNA: droplet digital PCR (ddPCR), the Cobas® EGFR Mutation Test v2 (Cobas) and NGS with Oncomine Pan-Cancer Cell-Free Assay.

Results

All three of these platforms demonstrated 100% specificity in the detection of EGFR mutations in the plasma. In the detection of an activating mutation (exon 19 deletion and L858R), Cobas using cfDNA, ddPCR using combined TNA, and NGS using combined TNA showed a sensitivity of 93, 95.3, and 93.8%, respectively. For T790M mutation detection, the Cobas, ddPCR, and NGS showed a sensitivity of 64.7, 88.2, and 93.3%, respectively. Pleural fluid analysis revealed enrichment of the T790M mutant copies in the exosomes. ddPCR using exoTNA showed higher sensitivity than did total cellular DNA from the pleural fluid.

Conclusion

These results demonstrated that combined TNA in the plasma and exoTNA in the pleural fluid can be used to evaluate low-abundant EGFR mutant copies in NSCLC.

Real-World T790M Mutation Frequency and Impact of Rebiopsy in Patients With EGFR-Mutated Advanced Non-Small Cell Lung Cancer

Introduction

The T790M resistance mutation is present in about one-half of epidermal growth factor receptor (EGFR)-positive advanced non-small cell lung cancer (NSCLC) patients at disease progression. We aimed to assess the prevalence of this mutation in a real-world setting and the clinical impact of repeated biopsies in its detection.

Methods

This was a single-center retrospective cohort study of patients with EGFR-positive advanced NSCLC diagnosed between 2016 and 2018, who experienced radiographic disease progression during first-line treatment with first- or second-generation EGFR-tyrosine kinase inhibitor (TKI). The frequency of T790M detection and the number of rebiopsies were determined.

Results

A total of 88 patients were included, with a median age of 65 years (range: 38-84 years). The majority of the participants were females (63 (72%)) and non-smokers (70 (81%)). Upon disease progression, 80 (91%) patients were tested for T790M mutation, and the resistance mutation was detected in 57 (71%) cases (58% in plasma samples and 42% in tissue/cytology samples). In 14 (25%) cases, T790M mutation was only detected after rebiopsy (57% by liquid biopsy), which increased the rate of mutation detection in 17%. Subsequent treatment with third-generation EGFR-TKI was possible in 42 (74%) of T790M-positive cases. Detection of T790M mutation was more likely in patients who were less than 65 years old, with EGFR exon 19 deletions and duration of first-line treatment of more than 12 months (p < 0.05).

Conclusions

The frequency of T790M mutation in this study was higher than previously reported, suggesting that repeated biopsies after a negative result are beneficial. This allowed a greater percentage of patients to receive sequential osimertinib in our clinical practice.

Impact of the generation of EGFR-TKIs administered as prior therapy on the efficacy of osimertinib in patients with non-small cell lung cancer harboring EGFR T790M mutation

Background

There are few studies that directly compare the effects of osimertinib on patients with non‐small cell lung cancer (NSCLC) harboring epidermal growth factor receptor (EGFR) T790M mutation between the generation of prior EGFR tyrosine kinase inhibitors (TKIs).

Methods

We retrospectively reviewed clinical data from the medical records of consecutive patients with advanced NSCLC who had developed resistance to first‐ or second‐generation EGFR‐TKIs due to EGFR T790M mutation and were subsequently treated with osimertinib at Juntendo University Hospital. In patients with available tumor samples, target amplicon sequencing analyses were performed to explore the genetic biomarkers.

Results

A total of 38 patients with NSCLC harboring EGFR T790M mutation were treated with osimertinib. Eight patients were classified into group A (afatinib followed by osimertinib) and 30 patients were classified into group B (first‐generation EGFR‐TKI followed by osimertinib). Progression‐free survival (PFS) was significantly longer in group A than in group B (median PFS; not reached vs. 11.0 months, P = 0.018). Fourteen patients had available tissue samples collected before osimertinib treatment for target sequencing. In group A we found no additional mutations, other than EGFR T790M mutation. On the other hand, there were three samples in which other mutations emerged, in addition to EGFR T790M mutation, in group B.

Conclusions

PFS of osimertinib was significantly longer in patients with NSCLC harboring EGFR T790M mutation after treatment with afatinib than in patients after treatment with first generation EGFR‐TKIs. Additional mutations other than EGFR T790M may affect the efficacy of osimertinib treatment.

Key points

Significant findings of the study:

PFS of osimertinib was significantly longer in patients with NSCLC harboring EGFR T790M mutation after treatment with afatinib than in patients after treatment with first generation EGFR‐TKIs.

What this study adds:

Additional mutations other than EGFR T790M may affect the efficacy of osimertinib treatment.

Low T790M relative allele frequency indicates concurrent resistance mechanisms and poor responsiveness to osimertinib

Background

T790M relative allele frequency (RAF) in plasma, calculated by the ratio of T790M to epidermal growth factor receptor (EGFR)-sensitizing mutation allele frequencies (AF), is associated with osimertinib response in patients with progressive non-small cell lung cancer (NSCLC) post 1^st generation EGFR-tyrosine kinase inhibitor (TKI) treatment. However, which subgroup of patients carry concurrent resistance mechanisms and have poor responsiveness to osimertinib remains unknown.

Methods

Matched re-biopsy tissue and plasma samples obtained from 32 patients who had progression following 1^st generation EGFR-TKI treatment were genotyped using next-generation sequencing (NGS) to investigate which subgroup of patients, classified by plasma position 790 (T790M) RAF, were more likely to carry concurrent resistance mechanisms. In another independent cohort, consisting of 21 T790M-positive patients, we validated whether these patients had a poor response to osimertinib treatment.

Results

In the discovery cohort, patients with T790M RAF less than 20% were more likely to harbor concurrent resistance mechanisms (P=0.018), such as MET or ERBB2 amplification, and small cell lung cancer transformation. In the validation cohort, we found that patients with low T790M RAF (<20%) had significantly lower objective response rates (ORRs) (0 vs. 68.8%, P=0.03) and disease control rates (DCRs) (60% vs. 100%, P=0.048) in response to osimertinib compared to patients with high T790M RAF.

Conclusions

In patients with progressive NSCLC post 1^st generation EGFR-TKI treatment, plasma T790M RAFs of less than 20% can be used to identify patients who carry concurrent resistance mechanisms, and can predict a poorer response to osimertinib.

Trial registration

This study was registered on http://www.chictr.org.cn (registration number: ChiCTR-DDD-16007900).

The Role of Stereotactic Biopsy in Brain Metastases

Brain metastases (BrM) affect up to 20% of patients with cancer and represent an increasing portion of patients with surgical brain tumors owing to improving prognoses of cancer patients in general and in many cases even of those with brain metastases. With advances in molecular biology and targeted therapy, the indications for neurosurgical sampling and specifically stereotactic biopsy are likely to change in the future. In this review the authors address some of the scientific advances in BrM biology, the clinical rationale and range of techniques currently used to perform stereotactic biopsy, and how the advent of molecular interrogation may potentially alter the way patients with BrM are managed in the future.

Liquid biopsy mutation panel for non-small cell lung cancer: analytical validation and clinical concordance

Molecular testing for genomic variants is recommended in advanced non-small cell lung cancer (NSCLC). Standard tissue biopsy is sometimes infeasible, procedurally risky, or insufficient in tumor tissue quantity. We present the analytical validation and concordance study of EGFR variants using a new 17-gene liquid biopsy assay (NCT02762877). Of 144 patients enrolled with newly diagnosed or progressive stage IV nonsquamous NSCLC, 140 (97%) had liquid assay results, and 117 (81%) had both EGFR blood and tissue results. Alterations were detected in 58% of liquid samples. Overall tissue-liquid concordance for EGFR alterations was 94.0% (95% CI 88.1%, 97.6%) with positive percent agreement of 76.7% (57.7%, 90.1%) and negative percent agreement of 100% (95.8%, 100%). Concordance for ALK structural variants was 95.7% (90.1%, 98.6%). This assay detected alterations in other therapeutically relevant genes at a rate similar to tissue analysis. These results demonstrate the analytical and clinical validity of this 17-gene assay.

Molecular Analysis of Liquid-Based Cytological Specimen Using Virtually Positive Sputum with Adenocarcinoma Cells

Liquid-based cytology (LBC) analysis of sputum is a useful diagnostic and prognostic tool for detecting lung cancer. DNA and RNA derived from lung cancer cells can be used for this diagnosis. However, the quality of cytological material is not always adequate for molecular analysis due to the effect of formalin in the commercially available fixation kits. In this study, we examined DNA and RNA extraction methods for LBC analysis with formalin fixation, using lung carcinoma cell lines and sputum. The human non-small cell lung cancer cell lines were fixed with LBC fixation reagents, such as CytoRich red preservative. Quantification of thyroid transcription factor-1 (TTF-1) and actin mRNA, epidermal growth factor receptor (EGFR) DNA in HCC827, H1975, and H1299 cells, and mutation analysis of EGFR in HCC827 and H1975 cells were performed by quantitative PCR (qPCR) and fluorescence resonance energy transfer (FRET)-based preferential homoduplex formation assay (F-PHFA) method, respectively. mRNA and DNA extracted from cell lines using RNA and/or DNA extraction kits for formalin-fixed paraffin-embedded (FFPE) fixed with various LBC solutions were efficiently detected by qPCR. The detection limit of EGFR mutations was at a rate of 5% mutated positive cells in LBC. The detection limit of the EGFR exon 19 deletion in HCC827 was detected in more than 1.5% of the positive cells in sputum. In contrast, the detection limit of the T790M/L858R mutation in H1975 was detected in more than 13% of the positive cells. We also detected EGFR mutations using next generation sequencing (NGS). The detection limit of NGS for EGFR mutation was lower than that of the F-PHFA method. Furthermore, more than 0.1% of positive cells could be cytomorphologically detected. Our results demonstrate that LBC systems are powerful tools for cytopathological and genetic analyses. However, careful attention should be paid to the incidence of false negative results in the genetic analysis of EGFR mutations detected by LBC.

Spiral wire localization of lung nodules: procedure effectiveness and oncological usefulness

Background

In the last years, a large number of techniques and devices for localizing small pulmonary nodules prior to resection have been developed with the aim of facilitating minimally invasive surgery (VATS). However, each device presents pros and cons and there is no unanimous consensus. We report our experience with an uncommon wire system with spiral shape for percutaneous marking.

Methods

We recorded 102 consecutive CT-guided spiral wire localizations in our Institution, and we evaluated the efficacy of the method according to 4 success rates (SR): (I) successful targeting rate (SR-1): number of successful targeting procedures/number of all localizations; (II) successful localization in operative field (SR-2): (number of successful targeting procedures -number of dislodgements in operative field)/number of all localizations; (III) successful VATS rate (SR-3): number of successful VATS procedures/(number of localizations-number of thoracotomies not due to wire dislocation); (IV) successful curative rate (SR-4): number of neoplastic nodules resected with curative intent with free margins (R0) on definitive tissue diagnosis/number of neoplastic nodules resected with curative intent. Complications rate was recorded as well.

Results

SR-1: 100%, SR-2: 97.1%, SR-3: 100%, SR-4: 100%. Asymptomatic pneumothorax and minimal parenchymal hemorrhage were observed in 5 (4.9%) and 19 (18.6%) cases, respectively.

Conclusions

Spiral wire localization showed very good results in terms of feasibility, stability in operative field and contributed to effective use of VATS during wedge resection performed for malignant nodules. In the era of widespread radiological investigations (as it is happening in lung cancer screening) and evolutions in cancer treatments, this appears to be clinically relevant.

Clinical Features and Progression Pattern of Acquired T790M-positive Compared With T790M-negative EGFR Mutant Non-small-cell Lung Cancer: Catching Tumor and Clinical Heterogeneity Over Time Through Liquid Biopsy

BACKGROUND

Clinical-pathologic predictors of acquired T790M epidermal growth factor receptor (EGFR) mutation in Caucasian patients with non-small-cell lung cancer (NSCLC) progressing after first-/second-generation tyrosine kinase inhibitors (TKIs) is an open field for research. Similarly, the best time point for T790M detection by liquid or tissue biopsy after disease progression is currently matter of debate.

PATIENTS AND METHODS

This is an observational study at 7 Italian centers enrolling patients with EGFR-mutant NSCLC progressing after first-/second-generation EGFR TKIs, between 2014 and 2018, aiming at comparing baseline clinical-pathologic features and progression patterns in acquired T790M-positive compared with T790M-negative cases.

RESULTS

A total of 235 patients received first-line treatment with gefitinib (N = 126; 53%), erlotinib (N = 51; 22%), or afatinib (N = 58; 25%). In 120 (51%) cases, T790M was detected in liquid biopsy, tissue biopsy, or both. Age younger than 65 years (P = .037), the presence of common mutations (P = .004), and better response to first-line TKI (P = .023) were correlated with T790M positivity. T790M detection was associated with higher number of new progressing sites (P = .04), liver progression (P = .002), and a lower frequency of lung metastases (P = .027). When serial liquid biopsies were performed (N = 15), an oligoprogressive disease was correlated with a negative test outcome, whereas systemic progression was observed at the time of T790M positivity.

CONCLUSION

This study on a Caucasian population showed that age, type of EGFR mutation at diagnosis, response to first-line treatment, and peculiar progression pattern are associated with T790M status. Serial liquid biopsy might be useful for treatment selection, especially when tissue rebiopsy is not feasible.

Critical Assessment in Routine Clinical Practice of Liquid Biopsy for EGFR Status Testing in Non-Small-Cell Lung Cancer: A Single-Laboratory Experience (LPCE, Nice, France)

BACKGROUND

The introduction of liquid biopsy using PCR-based assays into routine practice has had a strong impact on the treatment of EGFR-mutated lung adenocarcinoma and is now commonly used for routine testing of EGFR mutations in certain clinical settings. To assess whether the claimed benefits of PCR-based assays hold true in daily practice at a multicenter clinical institution, we assessed how treatment decisions are affected by PCR-based assays for the analysis of EGFR mutations from plasma samples in a centralized laboratory (LPCE, Nice, France).

PATIENTS AND METHODS

A total of 345 samples were analyzed using the US Food and Drug Administration-approved Cobas EGFR Mutation Test v2 and 103 using the Therascreen EGFR Plasma RGQ PCR Kit over 3 years (395 samples from 324 patients). Eleven plasma samples were validated independently using Cobas at 3 institutions, and 130 samples were analyzed using Stilla digital PCR. Clinical data were collected for 175 (54%) of 324 patients.

RESULTS

Cobas was superior to the Therascreen assay and demonstrated 100% reproducibility. Digital PCR showed only 48%, 83%, and 58% concordance with Cobas for exon 19 deletions, L858R mutations, and T790M mutations, respectively. Liquid biopsies helped inform and change treatment when resistance occurred and enabled the detection of EGFR mutations in patients when biopsy tissue results were unavailable.

CONCLUSION

PCR-based assays are a fast and convenient test, allowing the detection of primary and secondary EGFR mutations from plasma. Cobas proved to be a reliable test, whereas digital PCR produced too many inconclusive results to be currently recommended as a principal testing device.

Analysis of Cell-Free DNA from 32,989 Advanced Cancers Reveals Novel Co-occurring Activating RET Alterations and Oncogenic Signaling Pathway Aberrations

PURPOSE

RET is an emerging oncogenic target showing promise in phase I/II clinical trials. An understudied aspect of RET-driven cancers is the extent to which co-occurring genomic alterations exist and how they may impact prognosis or therapeutic response.

EXPERIMENTAL DESIGN

Somatic activating RET alterations were identified among 32,989 consecutive patients with metastatic solid tumors tested with a clinical cell-free circulating tumor DNA (cfDNA) assay. This comprehensive next-generation sequencing (NGS) assay evaluates single-nucleotide variants, and select indels, fusions, and copy number gains in 68-73 clinically relevant cancer genes.

RESULTS

A total of 176 somatic activating RET alterations were detected in 170 patients (143 fusions and 33 missense mutations). Patients had non-small cell lung (NSCLC, n = 125), colorectal (n = 15), breast (n = 8), thyroid (n = 8), or other (n = 14) cancers. Alterations in other oncogenic signaling pathway genes were frequently identified in RET-positive samples and varied by specific RET fusion gene partner. RET fusions involving partners other than KIF5B were enriched for alterations in MAPK pathway genes and other bona fide oncogenic drivers of NSCLC, particularly EGFR. Molecular and clinical data revealed that these variants emerged later in the genomic evolution of the tumor as mechanisms of resistance to EGFR tyrosine kinase inhibitors.

CONCLUSIONS

In the largest cancer cohort with somatic activating RET alterations, we describe novel co-occurrences of oncogenic signaling pathway aberrations. We find that KIF5B-RET fusions are highly specific for NSCLC. In our study, only non-KIF5B-RET fusions contributed to anti-EGFR therapy resistance. Knowledge of specific RET fusion gene partner may have clinical significance.

Negative impact of malignant effusion on osimertinib treatment for non-small cell lung cancer harboring EGFR mutation

3rd-generation epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs), including osimertinib, have reasonable efficacy in non–small-cell lung cancers (NSCLC) with EGFR mutations. However, the efficacy of osimertinib in NSCLC patients with fluids, such as pleural, pericardial and abdominal effusions, is unclear. We evaluated the efficacy of osimertinib in this specific setting. NSCLC patients harboring EGFR T790 M mutations who experienced progressive disease after first EGFR-TKI treatment and started osimertinib treatment between April 2016 and August 2018 were retrospectively screened. In particular, we assessed the efficacy of osimertinib for NSCLC with EGFR T790 M mutations in patients who were diagnosed with EGFR T790 M mutation by malignant effusion. Among 90 patients with EGFR T790 M mutation who started osimertinib treatment after EGFR-TKI failure, 21 were diagnosed from malignant effusions excluding cerebrospinal fluid (F group) and 69 using other methods including tissue biopsies (NF group). Patient characteristics were well-balanced between the two groups. Overall response was 50%, and significantly worse in the F group (29%) than the NF group (57%; P = 0.025). Median progression-free survival with osimertinib treatment in the F group (7.1 months, 95% confidence interval [CI]: 2.3–14.0) was significantly shorter than that in the NF group (11.9 months, 95% CI: 9.5–16.0; P = 0.046)). Median drainage-free time was 10.9 months (95% CI: 1.4 months– not reached). The present study showed that the efficacy of osimertinib for NSCLC in which EGFR T790 M mutation is detected by malignant effusion may be less than in EGFR T790 M-mutated NSCLC detected by other methods.

Re-biopsy and liquid biopsy for patients with non-small cell lung cancer after EGFR-tyrosine kinase inhibitor failure

Background

Re‐biopsy is important for exploring resistance mechanisms, especially for non‐small cell lung cancer (NSCLC) patients who develop resistance to EGFR‐tyrosine kinase inhibitors (TKIs). Liquid biopsy using circulating tumor DNA has come into use for this purpose. This retrospective study investigated the status of re‐biopsy and liquid biopsy in NSCLC patients with EGFR mutations and evaluated their effect on clinical strategies and prognosis.

Methods

Five hundred fifty‐five NSCLC patients with resistance to EGFR‐TKIs were included and divided into three groups: re‐biopsy, liquid biopsy, and no re‐biopsy. Amplification refractory mutation system (ARMS) PCR or super ARMS PCR was used to detect EGFR mutations.

Results

Three hundred eight (55.5%) patients underwent re‐biopsy; 45.5% (140/308) were positive for T790M. The most common re‐biopsy procedure was computed tomography‐guided percutaneous core needle biopsy (60.1%), followed by effusion drainage (29.5%) and superficial lymph node biopsy (6.5%). One hundred eighteen (21.3%) patients underwent liquid biopsy; the T790M detection rate was 41.5% (49/118.) Of the 308 patients who underwent re‐biopsy, 69 were examined for EGFR mutations with plasma. The concordance rate of T790M detection between tissue and plasma was 66.7%. A statistical difference in further treatment after EGFR‐TKI failure was observed among all groups (P = 0.014). Patients in the biopsy groups were more likely to receive third‐generation EGFR‐TKIs. Multivariate analysis showed that re‐biopsy had a significant impact on overall survival (P < 0.001).

Conclusion

Re‐biopsy plays a pivotal role in the management of patients with NSCLC and resistance to EGFR‐TKIs. Liquid biopsy may be an alternative if difficulties performing re‐biopsy exist.

Advanced Non-Small Cell Lung Cancer with Activating Epidermal Growth Factor Receptor Mutation: First Line Treatment and Beyond

BACKGROUND

Lung cancer is the leading cause of cancer mortality, being responsible for more than 1.6 million deaths each year worldwide and non-small-cell lung cancer (NSCLC) accounts for approximately 85% of lung cancers; moreover, 10 to 15% of all NSCLCs harbor EGFR (epidermal growth factor receptor) activating mutations, being suitable for EGFR-Tyrosine Kinase Inhibitors (TKI) molecular targeted therapy. However, EGFR+ NSCLCs gain acquired resistance to these agents, representing one of the key challenges for modern precision oncology.

OBJECTIVE

Therefore, this paper aims to provide an extensive state of the art review, alongside with hints about future perspectives.

CONCLUSION

To date, in the light of the data from the FLAURA study, osimertinib represents the best first-line option in NSCLC patients with EGFR activating mutations; EGFR-TKI plus chemotherapy combination therapies, even though interesting, must still be considered investigational.

Transthoracic Rebiopsy for Mutation Analysis in Lung Adenocarcinoma: Outcomes and Risk Factors for the Acquisition of Nondiagnostic Specimens in 199 Patients

PURPOSE

To determine the outcomes of transthoracic rebiopsy for epidermal growth factor receptor (EGFR) mutation in patients with lung adenocarcinoma and to explore the clinical and procedure-related risk factors for the acquisition of nondiagnostic rebiopsy specimens.

PATIENTS AND METHODS

We retrospectively reviewed 367 patients with lung adenocarcinoma who underwent transthoracic core needle biopsy for mutation analysis from September 2011 to October 2016. Of these, 199 patients underwent rebiopsy. Patient characteristics, treatment history, target lesion characteristics, and procedure-related factors were evaluated. The adequacy rate of specimens for mutation analysis was evaluated. Univariable and multivariable analyses were performed to determine the independent predictors of nondiagnostic specimens.

RESULTS

Ninety percent of specimens (179 of 199) were adequate for mutation analysis. The EGFR mutation (exon 18-21) was 65% (117 of 179) and the EGFR T790M mutation 33% (59 of 179) of specimens. In univariable analysis, an internal low-attenuation area in the target lesion (P = .001) and pleural contact (P = .004) on computed tomography were significant risk factors for nondiagnostic specimens. In multivariable analysis, an internal low-attenuation area in the target lesion (odds ratio = 7.333; 95% confidence interval, 1.755-30.633; P = .006) was an independent predictor for acquisition of nondiagnostic specimens.

CONCLUSION

Image-guided transthoracic rebiopsy to obtain specimens for mutation analysis in lung adenocarcinoma provides high diagnostic accuracy, with a low rate of nondiagnostic specimens. The presence of internal low-attenuation area in the target lesion on computed tomography was an independent predictor for acquiring nondiagnostic specimens.

An Acquired Epidermal Growth Factor Receptor T790M Mutation after the Addition of Bevacizumab to Preceding Erlotinib Monotherapy in a Lung Cancer Patient with Leptomeningeal Metastases

A 53-year-old man with advanced lung adenocarcinoma harboring epidermal growth factor receptor (EGFR) exon 19 deletion received erlotinib. After 12 months of disease control with erlotinib monotherapy, leptomeningeal metastases (LM) occurred. A cerebrospinal fluid examination demonstrated a pre-existing EGFR exon 19 deletion. Bevacizumab was combined with erlotinib, and the LM improved. After six months of combination therapy, however, the LM was exacerbated. A re-examination of the cerebrospinal fluid revealed a T790M mutation and exon 19 deletion. Osimertinib was administered, and the LM improved. The combination of bevacizumab and erlotinib was effective for erlotinib-resistant LM and resulted in the expression of a newly acquired T790M mutation, which enabled successful treatment with osimertinib.

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.

Chinese multidisciplinary expert consensus: Guidelines on percutaneous transthoracic needle biopsy

Biopsy has been used to diagnose thoracic diseases for more than a century. Percutaneous needle biopsy plays a crucial role in the diagnosis, staging, and treatment planning for tumors in the lungs, thoracic wall, hilum, and mediastinum. With the continuous improvement in imaging techniques, the range of clinical applications for percutaneous needle biopsy is also expanding. It has become important to improve Chinese professionals’ and technicians’ understanding of percutaneous transthoracic needle biopsy (PTNB) in order to standardize operating procedures and to strengthen perioperative management. However, there is currently no Chinese expert consensus that provides systematic standardization and guidance for PTNB in clinical practice. The Committee of Chinese Society of Interventional Oncology (CSIO) of the Chinese Anti‐Cancer Association (CACA) initiated a Chinese multidisciplinary expert consensus on PTNB. The consensus includes image‐guided methods, indications, contraindications, multidisciplinary team recommendations, biopsy procedures, daytime/outpatient biopsy, complications, pathological examination, and management of negative results.

Repeat biopsy in epidermal growth factor receptor mutation-positive nonsmall cell lung cancer: Feasibility, limitations, and clinical utility in Indian patients

INTRODUCTION

The feasibility and success rate of repeat biopsy for epidermal growth factor receptor (EGFR) mutation-positive lung cancers that have progressed on tyrosine kinase inhibitors (TKIs) are varied and merits further assessment.

MATERIALS AND METHODS

EGFR mutation-positive lung cancers were offered repeat biopsy upon progression on TKIs. Two groups of patients, first one on a clinical trial and second one from a database, were included for analysis. The feasibility to perform a repeat biopsy was analyzed in the first group. Success rate of biopsy and tissue adequacy for molecular testing was analyzed in both groups. Descriptive statistics were used for analyzing the demography, EGFR mutation type, tissue adequacy, and molecular profile at repeat biopsy. Kolmogorov-Smirnov test was used to assess normality of data. Two sample t-tests were used for comparison of proportions.

RESULTS

The feasibility of undergoing repeat biopsy was 77% (95% confidence interval [CI] of 69.4%-83.5%) in the first group (114/148 patients). Feasibility was not analyzed in the second group of patients. Out of 196 patients who underwent a repeat biopsy, 154 patients (78.6%; 95% CI: 72.2%-84.1%) had tumor tissue adequate for performing molecular testing. 27/196 (13.8%) patients did not have any evidence of malignancy on repeat biopsy whereas 15/196 (7.6%) patients had scanty tissue on repeat biopsy prohibiting molecular testing. Six patients (3.06%; 95% CI: 1.1%-6.5%) had small cell transformation. T790M mutation was detected in 12 out of the 42 patients (28.6%; 95% CI: 15.7-44.6) in whom EGFR testing was performed on repeat biopsy specimen.

CONCLUSION

Repeat biopsy was able to provide adequate tissue acquisition in only two-thirds of the patients. Liquid biopsy represents an important tool to bridge this gap.

Feasibility of re-biopsy and EGFR mutation analysis in patients with non-small cell lung cancer

Background

In cases of EGFR‐tyrosine kinase inhibitor (TKI) failure, re‐biopsy may be useful to understand resistance mechanisms and guide further treatment decisions. However, performing re‐biopsy is challenging because of several hurdles. We assessed the feasibility of re‐biopsy in advanced non‐small cell lung cancer (NSCLC) patients in real‐world clinical practice.

Methods

We retrospectively reviewed the clinical and pathologic data of advanced NSCLC patients who experienced disease progression after previous treatment with EGFR‐TKIs at a single tertiary hospital in Korea between January 2014 and December 2016. Re‐biopsy specimens included small biopsy, surgical tissue, or liquid‐based cytology. EGFR mutation was tested using peptide nucleic acid‐mediated clamping PCR.

Results

Of the 230 NSCLC patients that experienced progression after EGFR‐TKI therapy, 105 (45.7%) underwent re‐biopsy. Re‐biopsy was successfully performed in 94 (89.5%) patients, and 11 patients were diagnosed with no malignancy. The complication rate was 8.6%, including seven cases of pneumothorax. EGFR mutation testing was performed on 75 patients using re‐biopsy specimens. Of the 57 patients who had sensitizing mutations at diagnosis, T790M mutations were found in 19 (33.3%), while 38 (66.7%) had no T790M mutation. Multivariate analysis showed that the re‐biopsy group was younger (P = 0.002) and exhibited a previous response to EGFR‐TKIs (P < 0.001).

Conclusion

Re‐biopsy in advanced NSCLC is feasible in real world clinical practice, particularly in younger patients and those who achieved a previous response to EGFR‐TKIs.

The alteration of T790M between 19 del and L858R in NSCLC in the course of EGFR-TKIs therapy: a literature-based pooled analysis

Background

Treatment-naive epidermal growth factor receptor (EGFR) T790M mutation is more inclined to coexist with L858R than with 19 del in non-small cell lung cancer (NSCLC) patients. However, EGFR-tyrosine kinase inhibitors (EGFR-TKIs) might alter this status. We sought to compare the prevalence of T790M upon acquired resistance to EGFR-TKIs between 19 del and L858R by assembling all existing data.

Methods

Electronic databases were comprehensively searched for eligible studies. The primary endpoint was the odds ratio (OR) of T790M mutation in NSCLC co-existing with L858R mutation and 19 del upon resistance to first-generation EGFR-TKIs. A random effects model was used. Stratified analysis was performed based on study type (retrospective and prospective), race (Asians and Caucasians) and sample type (tissue and plasma).

Results

A total of 25 studies involving 1,770 patients were included. The overall T790M existent rate was 45.25%. Post-resistance T790M was more frequent in 19 del than in L858R mutated patients (53% vs. 36%; OR 1.87; P<0.001). All outcomes of subgroup and overall analyses were similar. In contrast, we re-analyzed the previous meta-analysis, finding that the pooled rate of pretreatment T790M was 14% and 22% in 19 del and L858R respectively (OR 0.59; P<0.001). The increase of T790M rate was 2.79-fold in 19 del and only 0.63-fold in L858R in the course of EGFR-TKIs therapy.

Conclusions

Opposite to the situation of de novo T790M, it was observed that T790M was more frequent in exon 19 deletion than in L858R among patients with acquired resistance to EGFR-TKIs. The difference in T790M alteration between 19 del and L858R encourages development of detection or treatment strategies for the specific resistance mechanism.

Frequency of T790M mutations after progression on epidermal growth factor receptor tyrosine kinase inhibitor in metastatic non-small cell lung cancer in Indian patients: real-time data from tertiary cancer hospital

Aim

The aim of this study is to determine the incidence of T790M mutations after progression on epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI) and median duration on TKI before progression on TKI.

Methods

Records of Rajiv Gandhi Cancer Institute and Research Centre, of patients who were diagnosed with metastatic adenocarcinoma of the lung and progressed on oral EGFR TKIs and underwent T790M mutation analysis in the last 6 months were retrospectively reviewed. The incidence of T790M positivity, sites of progression, and median duration of TKI treatment before progression was calculated.

Results

Among 31 patients, 10 patients have undergone rebiopsy, and 24 patients had undergone liquid biopsy by Droplet Digital polymerase chain reaction (ddPCR), and three patients had undergone both tests. Among all, the rate of T790M positivity was 54.8%. Among these 17 patients positive for T790M, seven patients were positive by biopsy, and 11 patients were positive by ddPCR. Among three patients who underwent both, one was positive by both. The most common site of progression among all patients is pleura, and 10% of patients progressed in brain post-TKI. Median progression-free survival on TKI before progression is 289.7 days, highest being 1290 days, and lowest 45 days.

Conclusions

Exact incidence of T790M mutations after progression on TKI s in Asian population is not exactly known and requires large data, as incidence may be different than reported in the Western population. Rebiopsy and ddPCR help to determine the most common type of resistance after progression on TKI, for which effective targeted therapy is available.

Mechanisms of resistance to irreversible epidermal growth factor receptor tyrosine kinase inhibitors and therapeutic strategies in non-small cell lung cancer

Epidermal growth factor receptor (EGFR) T790M mutation is the most frequent mechanism which accounts for about 60% of acquired resistance to first-generation EGFR tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer (NSCLC) patients harboring EGFR activating mutations. Irreversible EGFR-TKIs which include the second-generation and third-generation EGFR-TKIs are developed to overcome T790M mediated resistance. The second-generation EGFR-TKIs inhibit the wide type (WT) EGFR combined with dose-limiting toxicity which limits its application in clinics, while the development of third-generation EGFR-TKIs brings inspiring efficacy either in vitro or in vivo. The acquired resistance, however, will also occur and limit their response. Understanding the mechanisms of resistance to irreversible EGFR-TKIs plays an important role in the choice of subsequent treatment. In this review, we show the currently known mechanisms of resistance which can be summarized as EGFR dependent and independent mechanisms and potential therapeutic strategies to irreversible EGFR-TKIs.

Clinical Factors Predicting Detection of T790M Mutation in Rebiopsy for EGFR-Mutant Non-small-cell Lung Cancer

BACKGROUND

T790M, a secondary epidermal growth factor receptor (EGFR) mutation, accounts for approximately 50% of acquired resistance to EGFR-tyrosine kinase inhibitors (TKIs). To facilitate the use of third-generation EGFR-TKIs to potentially overcome T790M-mediated resistance, we evaluated the clinical factors influencing the incidence of T790M mutation.

PATIENTS AND METHODS

We retrospectively screened patients with non-small-cell lung cancer harboring EGFR mutations with progressive disease who were rebiopsied between January 2013 and December 2016. Factors influencing T790M status were evaluated by univariate and multivariate analysis.

RESULTS

Among 131 rebiopsied patients for whom EGFR mutation status was available, 58 (44%) had T790M mutations. Patient characteristics at rebiopsy were not significantly different between T790M-positive and -negative groups, except for surgical history (postsurgery recurrence). Total duration of EGFR-TKI treatment before rebiopsy, TKI-free interval, EGFR-TKI treatment history immediately before rebiopsy, continuation of initial EGFR-TKI beyond progressive disease, progression-free survival after initial TKI treatment, and rebiopsy site (other than fluid samples) significantly influenced T790M status. The incidence of T790M mutation was shown by multivariate analysis to be significantly higher in patients with postsurgery recurrence and total duration of EGFR-TKI treatment ≥ 1 year before rebiopsy (odds ratio, 4.2; 95% confidence interval, 1.3-15.7 and odds ratio, 4.4; 95% confidence interval, 1.1-19.8, respectively).

CONCLUSION

Postsurgery recurrence and longer total duration of EGFR-TKI treatment before rebiopsy may represent useful predictive markers for T790M detection. In patients with these clinical factors, rebiopsies are more recommended to detect T790M mutation.

Prognostic value of plasma EGFR ctDNA in NSCLC patients treated with EGFR-TKIs

OBJECTIVE

Epidermal growth factor receptor (EGFR) specific mutations have been known to improve survival of patients with non-small-cell lung carcinoma (NSCLC). However, whether there are any changes of EGFR mutations after targeted therapy and its clinical significance is unclear. This study was to identify the status of EGFR mutations after targeted therapy and predict the prognostic significance for NSCLC patients.

METHODS

A total of forty-five (45) NSCLC patients who received EGFR-TKI therapy were enrolled. We identified the changes of EGFR mutations in plasma ctDNA by Amplification Refractory Mutation System (ARMS) PCR technology.

RESULTS

In the 45 cases of NSCLC with EGFR mutations, the EGFR mutation status changed in 26 cases, in which, 12 cases (26.7%) from positive to negative, and 14 cases (31.1%) from T790M mutation negative to positive after TKI targeted therapy. The T790M occurance group had a shorter Progression -Free-Survival (PFS) than the groups of EGFR mutation undetected and EGFR mutation turned out to have no change after EGFR-TKI therapy (p < 0.05).

CONCLUSIONS

According to this study, it's necessary to closely monitor EGFR mutations during follow-up to predict the prognosis of NSCLC patients who are to receive the TKI targeted therapy.