Ultra-sensitive EGFR T790M Detection as an Independent Prognostic Marker for Lung Cancer Patients Harboring EGFR del19 Mutations and Treated with First-generation TKIs

Significance of micro-EGFR T790M mutations on EGFR-tyrosine kinase inhibitor efficacy in non-small cell lung cancer

Small amounts of epidermal growth factor receptor (EGFR) T790M mutation (micro-T790M), which is detected using droplet digital PCR (ddPCR) but not conventional PCR, in formalin-fixed and paraffin-embedded (FFPE) samples have been investigated as a predictive factor for the efficacy of EGFR-tyrosine kinase inhibitors (TKIs). However, the predictive value of micro-T790M remains controversial, possibly owing to the failure to examine artificial T790M in FFPE specimens. Therefore, we examined the predictive value of micro-T790M in first-generation (1G), second-generation (2G), and third-generation (3G) EGFR-TKI efficacy using a new method to exclude FFPE-derived artificial mutations in our retrospective cohort. The primary objective was time to treatment failure (TTF) of 1G, 2G, and 3G EGFR-TKIs according to micro-T790M status. In total, 315 patients with EGFR-positive non-small cell lung cancer treated with 1G, 2G, and 3G EGFR-TKIs were included in this study. The proportion of patients positive for micro-T790M in the 1G, 2G, and 3G EGFR-TKI groups was 48.2%, 47.1%, and 47.6%, respectively. In the micro-T790M-positive group, the TTF was significantly longer in the 2G and 3G EGFR-TKI groups than in the 1G TKI group. No differences in the micro-T790M-negative group were observed. Micro-T790M status detected using ddPCR, eliminating false positives, may be a valuable predictor of EGFR-TKI efficacy.

Circulating tumor DNA minimal residual disease in clinical practice of non-small cell lung cancer

INTRODUCTION

The advance of diagnostics and treatments has greatly improved the prognosis of non-small cell lung cancer (NSCLC) patients. However, relapse and metastasis are still common problems encountered by NSCLC patients who have achieved complete remission. Therefore, overcoming the challenge of relapse and metastasis is particularly important for improving the prognosis of NSCLC patients. Research has shown that minimal residual disease (MRD) was a potential source of tumor relapse and metastasis, and circulating tumor DNA (ctDNA) MRD has obvious advantages in predicting the relapse and metastasis of NSCLC and evaluating treatment effectiveness. Therefore, dynamic monitoring of MRD is of great significance for NSCLC patient management strategies.

AREAS COVERED

We have reviewed articles related to NSCLC MRD included in PubMed and describes the biological significance and historical context of MRD research, reasons for using ctDNA to evaluate MRD, and potential value and challenges of ctDNA MRD in assessing relapse and metastasis of NSCLC, ultimately guiding clinical therapeutic strategies and management.

EXPERT OPINION

The standardized scope of ctDNA MRD detection for NSCLC requires more clinical research evidence to minimize study differences, making it possible to include in the clinical staging as a reliable indicator.

Case report: Liquid biopsy, the sooner the better?

The detection of circulating tumor DNA (ctDNA) by liquid biopsy is taking an increasing role in thoracic oncology management due to its predictive and prognostic value. For non-small cell lung cancer, it allows the detection of molecular mutations that can be targeted with tyrosine kinase inhibitors (TKIs). We report the case of a patient with life-threatening hepatocellular failure and thrombotic microangiopathy at the diagnosis. A salvage chemotherapy was attempted, resulting in a major worsening of her general condition and the decision to stop all anti-cancer treatment. The liquid biopsy performed at the time of immunohistochemical non-small cell lung cancer diagnosis revealed within 7 days the presence of an epidermal growth factor receptor (EGFR) ^DEL19 activating mutation with 736,400 DNA copies/ml of plasma. It was finally decided to attempt a treatment with osimertinib (third generation anti-EGFR TKI) despite the fact that the patient was in a pre-mortem situation. Osimertinib led to a significant and prompt improvement of her performance status after only one week of treatment. The tumor tissue genotyping performed by next-generation sequencing (NGS) was available 10 days after starting TKI treatment. It revealed in addition to the EGFR ^DEL19 mutation, a JAK3 and EGFR amplification, highlighting the complex interactions between EGFR and the JAK/STAT signaling pathways. The first CT-scan performed after 2 months under osimertinib showed a tumor morphologic partial response. The biological assay showed a major decrease in the EGFR ^DEL19 mutation ctDNA levels (40.0 copies/ml). The liquid biopsy allowed an early implementation of a targeted therapy without which the patient would probably be dead. Testing for ctDNA should be discussed routinely at diagnosis in addition to tumor tissue genotyping for patient with metastatic non-small cell lung cancer that raise the clinical profile of oncogenic addiction.

Adaptive therapy to circumvent drug resistance to tyrosine kinase inhibitors in cancer: is it clinically relevant?

INTRODUCTION

Cancer is highly adaptable and is constantly evolving against current targeted therapies such as tyrosine kinase inhibitors. Despite advances in recent decades, the emergence of drug resistance to tyrosine kinase inhibitors constantly hampers therapeutic efficacy of cancer treatment. Continuous therapy versus intermittent clinical regimen has been a debate in drug administration of cancer patients. An ecologically-inspired shift in cancer treatment known as 'adaptive therapy' intends to improve the drug administration of drugs to cancer patients that can delay emergence of drug resistance.

AREAS COVERED

We discuss improved understanding of the concept of drug resistance, the basis of continuous therapy, intermittent clinical regimens, and adaptive therapy will be reviewed. In addition, we discuss how adaptive therapy provides guidance for future cancer treatment.

EXPERT OPINION

The current understanding of drug resistance in cancer leads to poor prognosis and limited treatment options in patients. Fighting drug resistance mutants is constantly followed by new forms of resistance. In most reported cases, continuous therapy leads to drug resistance and an intermittent clinical regimen vaguely delays it. However, adaptive therapy, conceptually, exploits multiple parameters that can suppress the growth of drug resistance and provides safe treatment for cancer patients in the future.

Technical Validation and Clinical Implications of Ultrasensitive PCR Approaches for EGFR-Thr790Met Mutation Detection in Pretreatment FFPE Samples and in Liquid Biopsies from Non-Small Cell Lung Cancer Patients

In pretreatment tumor samples of EGFR-mutated non-small cell lung cancer (NSCLC) patients, EGFR-Thr790Met mutation has been detected in a variable prevalence by different ultrasensitive assays with controversial prognostic value. Furthermore, its detection in liquid biopsy (LB) samples remains challenging, being hampered by the shortage of circulating tumor DNA (ctDNA). Here, we describe the technical validation and clinical implications of a real-time PCR with peptide nucleic acid (PNA-Clamp) and digital droplet PCR (ddPCR) for EGFR-Thr790Met detection in diagnosis FFPE samples and in LB. Limit of blank (LOB) and limit of detection (LOD) were established by analyzing negative and low variant allele frequency (VAF) FFPE and LB specimens. In a cohort of 78 FFPE samples, both techniques showed an overall agreement (OA) of 94.20%. EGFR-Thr790Met was detected in 26.47% of cases and was associated with better progression-free survival (PFS) (16.83 ± 7.76 vs. 11.47 ± 1.83 months; p = 0.047). In LB, ddPCR was implemented in routine diagnostics under UNE-EN ISO 15189:2013 accreditation, increasing the detection rate of 32.43% by conventional methods up to 45.95%. During follow-up, ddPCR detected EGFR-Thr790Met up to 7 months before radiological progression. Extensively validated ultrasensitive assays might decipher the utility of pretreatment EGFR-Thr790Met and improve its detection rate in LB studies, even anticipating radiological progression.

The Presence of EGFR T790M in TKI-Naïve Lung Cancer Samples of Patients Who Developed a T790M-Positive Relapse on First or Second Generation TKI Is Rare

EGFR-mutated non-small cell lung cancer (NSCLC) patients can be effectively treated with tyrosine kinase inhibitors (TKI) but frequently present with an EGFR T790M resistance mutation at relapse. We aimed to screen for T790M in pre-treatment formalin-fixed and paraffin-embedded (FFPE) tissue samples of patients with a confirmed T790M mutation at progression. We analyzed 33 pre-treatment DNA samples of NSCLC patients who progressed upon TKI between 2013 to 2019. To establish storage-time dependent formalin fixation-induced background levels for C>T mutations, we analyzed DNA isolated from archival (stored >1 year, n = 22) and recently generated (stored <1 month, n = 11) FFPE samples and included DNA isolated from white blood cells (WBC) (n = 24) as controls. DNA samples were analyzed by droplet digital (dd)PCR, and positivity was defined by outlier detection according to Grubb’s criterion. The T790M background allele frequency levels were 0.160% in DNA isolated from archival-FFPE, 0.100% in fresh FFPE, and 0.035% in WBC. Progression-free survival (PFS) time of the single T790M positive patient was 9 months, while T790M negative patients had a median PFS of 10 months (range 2−27). Proper storage time matched FFPE control samples are essential for reliable detection of T790M mutation at low VAF. The presence of EGFR T790M mutations in pre-TKI samples is rare, even in patients who progressed with EGFR T790M mutations.

Prognostic impact of pretreatment T790M mutation on outcomes for patients with resected, EGFR-mutated, non-small cell lung cancer

Background

Many previous studies have demonstrated that minor-frequency pretreatment T790M mutation (preT790M) could be detected by ultrasensitive methods in a considerable number of treatment-naïve, epidermal growth factor receptor (EGFR)-mutated, non-small cell lung cancer (NSCLC) cases. However, the impact of preT790M in resected cases on prognosis remains unclear.

Methods

We previously reported that preT790M could be detected in 298 (79.9%) of 373 surgically resected, EGFR-mutated NSCLC patients. Therefore, we investigated the impact of preT790M on recurrence-free survival (RFS) and overall survival (OS) in this cohort by multivariate analysis. All patients were enrolled from July 2012 to December 2013, with follow-up until November 30, 2017.

Results

The median follow-up time was 48.6 months. Using a cutoff value of the median preT790M allele frequency, the high-preT790M group (n = 151) had significantly shorter RFS (hazard ratio [HR] = 1.51, 95% confidence interval [CI]: 1.01–2.25, P = 0.045) and a tendency for a shorter OS (HR = 1.87, 95% CI: 0.99–3.55, P = 0.055) than the low-preT790M group (n = 222). On multivariate analysis, higher preT790M was independently associated with shorter RFS (high vs low, HR = 1.56, 95% CI: 1.03–2.36, P = 0.035), irrespective of advanced stage, older age, and male sex, and was also associated with shorter OS (high vs low, HR = 2.16, 95% CI: 1.11–4.20, P = 0.024) irrespective of advanced stage, older age, EGFR mutation subtype, and history of adjuvant chemotherapy.

Conclusions

Minor-frequency, especially high-abundance of, preT790M was an independent factor associated with a poor prognosis in patients with surgically resected, EGFR-mutated NSCLC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09869-7.

Find the path of least resistance: Adaptive therapy to delay treatment failure and improve outcomes

Cytotoxic chemotherapy and targeted therapies help people with advanced cancers, but for most, treatment fails. Cancer heterogeneity is one cause of treatment failure, but also suggests an opportunity to improve outcomes; reconceptualising cancer therapy as an ecological problem offers the strategy of adaptive therapy. If an agent is active against a patient's cancer, instead of traditional continuous dosing at the maximum tolerated dose until treatment failure, the patient and their oncologist may instead choose to pause treatment as soon as the cancer responds. When tumour burden increases, the cancer is rechallenged with the same agent in hope of delivering another response, ideally before symptoms occur or quality-of-life is impacted. These 'loops' of 'pause/restart' allows an active treatment to be used strategically, to delay the development of evolutionary selection within the cancer, delaying the onset of treatment resistance, controlling the cancer for longer. Modelling predicts patients can navigate several 'loops', potentially increasing the utility of an active treatment by multiples, and early trials suggest at least doubling of progression-free survival. In this narrative review we confront how cancer heterogeneity limits treatment effectiveness, re-examine cancer as an ecological problem, review the data supporting adaptive therapy and outline the challenges and opportunities faced in clinical practice to implement this evolutionary concept. In an era where multiple novel active anti-neoplastic agents are being used with ancient inflexibile maximum tolerated dose for maximum duration approaches, adaptive dosing offers a personalised, n = 1 approach to cancer therapy selection.

Clinical outcomes of patients taking first-generation EGFR-TKIs may predict the benefits afforded by osimertinib in EGFR T790M-mutant NSCLC patients

BACKGROUND

Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) are widely used to treat patients with EGFR-mutated non-small cell lung cancers (NSCLCs). The association between the clinical outcomes of patients on first-line EGFR-TKIs and the efficacy of osimertinib as second-line treatment has not been previously assessed. This is our topic here.

PATIENTS AND METHODS

We retrospectively analysed 67 patients with EGFR mutations on osimertinib after treatment with first-generation EGFR-TKIs. We evaluated patient characteristics, the EGFR T790M allele frequency in plasma samples and clinical outcomes.

RESULTS

When osimertinib was given as second-line treatment, the median progression-free survival (PFS) was 6.0 months, and the response rate and disease control rate were 32.8% and 91.0%, respectively. Correlation analysis showed that the female sex and isolated (not multiple) progression on first-line EGFR-TKIs were correlated with a superior response to osimertinib. Kaplan-Meier analysis showed that patients exhibiting a partial response, isolated progression, and longer PFS on first-line EGFR-TKIs experienced prolonged PFS on osimertinib. Univariate analysis indicated that the treatment response, PFS and progression when on first-line EGFR-TKIs affected the PFS on osimertinib. Multivariate analysis showed that progression when on first-line EGFR-TKIs was independently prognostic of a response to osimertinib. The median PFS of patients with isolated progressive disease PD alone who were receiving brain radiotherapy was significantly longer than that of patients with isolated progressive disease alone who did not receive brain radiotherapy as well as patients exhibiting multiple progression. A low frequency of the EGFR T790M allele in plasma tended to predict an inferior efficacy of osimertinib and shorter PFS.

CONCLUSION

We found that patients who benefited from first-line EGFR-TKIs may experience prolonged PFS and a higher response rate when subsequently given osimertinib. A low plasma frequency of the EGFR T790M allele may predict poor osimertinib efficacy and shorter PFS.

Development of hypoxia-activated PROTAC exerting a more potent effect in tumor hypoxia than in normoxia

Hypoxia is a hallmark of many solid tumors, and it causes the overexpression of a variety of proteins including the epidermal growth factor receptor (EGFR). Many antitumor prodrugs have been designed to target hypoxia. Here we report the identification of a kind of hypoxia-activated proteolysis targeting chimera (ha-PROTAC) by introducing the hypoxia-activated leaving group (1-methyl-2-nitro-1H-imidazol-5-yl)methyl or 4-nitrobenzyl into the structure of an EGFR^Del19-based PROTAC. Among the obtained molecules, ha-PROTAC 13 exhibits a more potent degradation activity for EGFR^Del19 in hypoxia than in normoxia in HCC4006 cells. This is the first example of identifying a PROTAC to selectively act on tumors utilizing the characteristic of tumor hypoxia and provides a new approach for PROTAC development.

An intelligent hypoxia-relieving chitosan-based nanoplatform for enhanced targeted chemo-sonodynamic combination therapy on lung cancer

The clinical efficacy of epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs)-based targeted molecular therapies (TMT) is inevitably hampered by the development of acquired drug resistance in non-small cell lung cancer (NSCLC) treatment. Sonodymanic therapy (SDT) is a promising new cancer treatment approach, but its effects are restricted by tumor hypoxia. Herein, a nanoplatform fabricated by erlotinib-modified chitosan loading sonosensitizer hematoporphyrin (HP) and oxygen-storing agent perfluorooctyl bromide (PFOB), namely CEPH, was developed to deliver HP to erlotinib-sensitive cells. CEPH with ultrasound could alleviate hypoxia inside the three-dimensional multicellular tumor spheroids, suppress NSCLC cell growth under normoxic or hypoxic condition, and enhance TMT/SDT synergistic effects through elevated production of reactive oxygen species, decrease of mitochondrial membrane potential, and down-regulation of the expression of the proteins EGFR, p-EGFR, and HIF-1α. Hence, CEPH could be a potential nanoplatform to improve the efficacy of oxygen-dependent SDT and overcome hypoxia-induced TMT resistance for enhanced synergistic TMT/SDT.

Molecular Mechanism of EGFR-TKI Resistance in EGFR-Mutated Non-Small Cell Lung Cancer: Application to Biological Diagnostic and Monitoring

Non-small cell lung cancer (NSCLC) is the most common cancer in the world. Activating epidermal growth factor receptor (EGFR) gene mutations are a positive predictive factor for EGFR tyrosine kinase inhibitors (TKIs). For common EGFR mutations (Del19, L858R), the standard first-line treatment is actually third-generation TKI, osimertinib. In the case of first-line treatment by first (erlotinib, gefitinib)- or second-generation (afatinib) TKIs, osimertinib is approved in second-line treatment for patients with T790M EGFR mutation. Despite the excellent disease control results with EGFR TKIs, acquired resistance inevitably occurs and remains a biological challenge. This leads to the discovery of novel biomarkers and possible drug targets, which vary among the generation/line of EGFR TKIs. Besides EGFR second/third mutations, alternative mechanisms could be involved, such as gene amplification or gene fusion, which could be detected by different molecular techniques on different types of biological samples. Histological transformation is another mechanism of resistance with some biological predictive factors that needs tumor biopsy. The place of liquid biopsy also depends on the generation/line of EGFR TKIs and should be a good candidate for molecular monitoring. This article is based on the literature and proposes actual and future directions in clinical and translational research.

Inhibitors Targeting CDK9 Show High Efficacy against Osimertinib and AMG510 Resistant Lung Adenocarcinoma Cells

Simple Summary

Non-small cell lung cancer accounts for 80% of all lung cancer cases. While a subset of non-small cell lung cancer patients respond to immunotherapy, those who are treated with chemotherapy or targeted therapy develop resistance to the drugs. Thus, novel therapeutic strategies are needed to combat this disease. Here we show that inhibitors of the cyclin-dependent kinase 9 are highly effective in preventing the growth of a variety of lung cancer cell lines and lung cancer organoids with high potency. These inhibitors suppressed the expression of several genes like Sox2, Sox9, and Mcl1 that promote tumor growth, facilitating growth arrest. Since inhibitors of cyclin-dependent kinase 9 are undergoing clinical trials for hematological malignancies, our studies suggest that these inhibitors would be attractive candidates to combat non-small cell lung cancer.

Abstract

Non-small cell lung cancer has a 5-year survival rate of less than 12–15%, calling for the development of additional therapeutic strategies to combat this disease. Here we tested the efficacy of inhibiting cyclin-dependent kinase 9 (CDK9) on lung cancer cell lines with K-Ras and EGFR mutations and on lung cancer organoids. Three different CDK9 inhibitors reduced the viability and anchorage-independent growth of lung cancer cell lines at very low nanomolar to micromolar concentrations. CDK9 inhibition suppressed the expression of the anti-apoptotic protein, Mcl1, as well as the embryonic stem cell transcription factors, Sox2 and Sox9, which are pro-tumorigenic. In contrast, treatment with CDK9 inhibitors increased the levels of WT p53 and its downstream target p21 in K-Ras mutant cell lines. Furthermore, the CDK9 inhibitors could markedly reduce the viability of Osimertinib-resistant PC9 and AMG510-resistant H23 and H358 cells with comparable efficacy as the parental cells. CDK9 inhibitors could also significantly reduce the growth and viability of lung cancer organoids with high potency. Taken together, the data presented here strongly suggest that CDK9 inhibitors would be efficacious against K-Ras mutant and EGFR mutant NSCLCs, including those that develop resistance to targeted therapies.

A Self-Priming Microfluidic Chip with Cushion Chambers for Easy Digital PCR

A polydimethylsiloxane (PDMS)-based self-priming microfluidic chip with cushion chambers is presented in this study for robust and easy-operation digital polymerase chain reaction (dPCR). The chip has only one inlet and can partition samples autonomously through negative pressure, provided by a de-gassed PDMS layer with a multi-level vertical branching microchannel design. Meanwhile, cushion chambers make the chip capable of very robust use for sample partitioning. Finally, the proposed microfluidic chip showed excellent performance in the absolute quantification of a target gene by performing quantitative detection of a 10-fold serial dilution DNA template. Owing to its characteristics of easy operation, low cost, and high robustness, the proposed dPCR chip is expected to further promote the extensive application of digital PCR, especially in resource-limited settings.

Molecular testing and targeted therapy for non-small cell lung cancer: Current status and perspectives

Molecular testing has become a mandatory component of the non-small cell lung cancer (NSCLC) management. The detection of EGFR, BRAF and MET mutations as well as the analysis of ALK, ROS1, RET and NTRK translocations have already been incorporated in the NSCLC diagnostic standards, and the inhibitors of these kinases are in routine clinical use. There are emerging biomarkers, e.g., KRAS G12C substitutions and HER2 activating alterations, which are likely to enter NSCLC guidelines upon the approval of the corresponding drugs. In addition to genetic examination, NSCLCs are usually subjected to the analysis of PD-L1 protein expression in order to direct the use of immune checkpoint inhibitors. Comprehensive NSCLC testing for multiple predictive markers requires the analysis of distinct biological molecules (DNA, RNA, proteins) and, therefore, the involvement of different analytical platforms (PCR, DNA sequencing, immunohistochemistry, FISH). There are ongoing efforts aimed at the integration of multiple NSCLC molecular assays into a single diagnostic pipeline.

Establishment and validation of a novel droplet digital PCR assay for ultrasensitive detection and dynamic monitoring of EGFR mutations in peripheral blood samples of non-small-cell lung cancer patients

BACKGROUND

Droplet digital PCR (ddPCR)-based blood detection of EGFR mutations plays significant roles in the individualized therapy of non-small-cell lung cancer (NSCLC) patients. However, a standard assay that is approved by health authorities is still lacking. Additionally, the proper application of this method in clinical settings also needs further investigation.

METHODS

The performance of a newly established ddPCR assay was first evaluated using reference samples and then validated by comparing this method with the amplification refractory mutation system (ARMS) using cell-free DNA (cfDNA) in patients' peripheral blood. Further, the correlation between dynamic quantification of EGFR mutation in the patients and their clinical outcome of tyrosine kinase inhibitors (TKIs) therapy was investigated.

RESULTS

A total of 77 patients were included, with 50 in the test group and 27 in the validation group. According to the results of the reference samples and the blood samples in the test group, the cut-off value for patient detection was proposed as mutation rate ≥ 0.1% (total copy number of cfDNA ≥ 1000) or at least one copy of mutation DNA was detected (total copy number of cfDNA < 1000). With this criterion, superior sensitivity of our assay to that of ARMS was observed (P = 0.002 for Ex19Del & L858R and P < 0.001 for T790M). The dynamic quantification of EGFR mutations during TKI therapy indicated that an increase in mutation abundance was correlated with resistance, while a decline was associated with response. Notably, a rebound in mutation abundance during chemotherapy may indicate a desirable chance for TKI re-treatment.

CONCLUSION

The novel ddPCR assay showed superior sensitivity in the detection of EGFR mutation in blood. The dynamic quantification of EGFR mutations by this assay would greatly facilitate the administration of TKI therapy, including the monitoring of resistance and response, as well as cohort screening for retreatment.

Multiple low dose therapy as an effective strategy to treat EGFR inhibitor-resistant NSCLC tumours

Resistance to targeted cancer drugs is thought to result from selective pressure exerted by a high drug dose. Partial inhibition of multiple components in the same oncogenic signalling pathway may add up to complete pathway inhibition, while decreasing the selective pressure on each component to acquire a resistance mutation. We report here testing of this Multiple Low Dose (MLD) therapy model in EGFR mutant NSCLC. We show that as little as 20% of the individual effective drug doses is sufficient to completely block MAPK signalling and proliferation when used in 3D (RAF + MEK + ERK) or 4D (EGFR + RAF + MEK + ERK) inhibitor combinations. Importantly, EGFR mutant NSCLC cells treated with MLD therapy do not develop resistance. Using several animal models, we find durable responses to MLD therapy without associated toxicity. Our data support the notion that MLD therapy could deliver clinical benefit, even for those having acquired resistance to third generation EGFR inhibitor therapy.

A drug used at the maximum tolerated dose can exert a strong selective pressure on cancer cells leading to resistance. In this study, the authors demonstrate the efficacy of using low dose of multiple drugs for preventing and treating resistance to EGFR tyrosine kinase inhibitors in NSCLC cells.

Detection of Low-level EGFR c.2369 C > T (p.Thr790Met) Resistance Mutation in Pre-treatment Non-small Cell Lung Carcinomas Harboring Activating EGFR Mutations and Correlation with Clinical Outcomes

Increasing evidence points to the presence of low-level de novo T790M mutations in patients with non-small cell lung carcinoma (NSCLC) harboring activating EGFR mutations. We utilized digital PCR (dPCR), a highly sensitive gene mutation detection method, to detect pre-treatment T790M mutations in NSCLC tumor samples and correlated the T790M status with clinical features and patient outcomes. DNA extracted from pre-treatment NSCLC tumor tissue with known activating EGFR mutations, diagnosed between October 2010 and May 2017 at PathWest laboratory, was used to perform targeted dPCR for quantitative detection of T790M mutations. T790M was detected in 42 of 109 pre-treatment samples (38.5%). Median variant allele frequency was 0.14% (range 0.02-28.5%). Overall response rate to first generation EGFR tyrosine kinase inhibitors (TKI) was 67% regardless of T790M status. The median progression free survival was 10.7 (IQR 5.6-19.9) versus 6.7 (IQR 3.5-20.8) months in T790M negative and positive patients respectively. T790M positivity correlated with increased rate of early disease progression. It also correlated with increased mortality (HR 3.1 95%CI 1.2-8.1, p = 0.022) in patients who did not respond to TKI treatment. We detected a significant rate of low-level pre-treatment T790M mutations in NSCLC using highly sensitive dPCR. Low-level pre-treatment T790M did not impact treatment response rate or overall survival, but was associated with increased rate of early progression on TKI therapy.

Plasma screening for the T790M mutation of EGFR and phase 2 study of osimertinib efficacy in plasma T790M-positive non-small cell lung cancer: West Japan Oncology Group 8815L/LPS study

BACKGROUND

Liquid biopsy allows the identification of patients whose tumors harbor specific mutations in a minimally invasive manner. No prospective data have been available for the efficacy of osimertinib in patients with non-small cell lung cancer (NSCLC) who develop resistance to first- or second-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) and who test positive for the TKI resistance-conferring T790M mutation of EGFR by liquid biopsy. Therefore, a phase 2 study was conducted to assess the efficacy and safety of osimertinib in such patients.

METHODS

Eligible patients had advanced or recurrent NSCLC with known TKI-sensitizing mutations of EGFR, had documented disease progression after treatment with at least 1 first- or second-generation EGFR TKI, and were positive for the T790M mutation in plasma according to the Cobas EGFR Mutation Test v2 (Roche Diagnostics) or droplet digital polymerase chain reaction analysis. Patients were treated with osimertinib (80 mg/d) until disease progression. The primary endpoint was the overall response rate (ORR) in patients positive for T790M in plasma by the Cobas assay.

RESULTS

Between June 2016 and November 2017, 276 patients were screened for their T790M status with a liquid biopsy. Seventy-four patients were positive for T790M in plasma, and 53 of these individuals were enrolled in the study. The ORR for evaluable patients positive for T790M in plasma by the Cobas assay (n = 49) was 55.1% (95% confidence interval [CI], 40.2%-69.3%). The median progression-free survival for all evaluable patients (n = 52) was 8.3 months (95% CI, 6.9-12.6 months).

CONCLUSIONS

The results demonstrate the utility of liquid biopsy for the detection of T790M with the Cobas EGFR Mutation Test v2. Plasma genotyping with this assay is informative for treatment selection in clinical practice when tumor sampling is not feasible.

Frontiers of ctDNA, targeted therapies, and immunotherapy in non-small-cell lung cancer

Non-small-cell lung cancer (NSCLC), a main subtype of lung cancer, is one of the most common causes of cancer death in men and women worldwide. Circulating tumor DNA (ctDNA), tyrosine kinase inhibitors (TKIs) and immunotherapy have revolutionized both our understanding of NSCLC, from its diagnosis to targeted NSCLC therapies, and its treatment. ctDNA quantification confers convenience and precision to clinical decision making. Furthermore, the implementation of TKI-based targeted therapy and immunotherapy has significantly improved NSCLC patient quality of life. This review provides an update on the methods of ctDNA detection and its impact on therapeutic strategies; therapies that target epidermal growth factor receptor (EGFR) and anaplastic lymphoma kinase (ALK) using TKIs such as osimertinib and lorlatinib; the rise of various resistant mechanisms; and the control of programmed cell death-1 (PD-1), programmed cell death ligand-1 (PD-L1), and cytotoxic T-lymphocyte antigen-4 (CTLA-4) by immune checkpoint inhibitors (ICIs) in immunotherapy; blood tumor mutational burden (bTMB) calculated by ctDNA assay as a novel biomarker for immunotherapy. However, NSCLC patients still face many challenges. Further studies and trials are needed to develop more effective drugs or therapies to treat NSCLC.

Detection of EGFR T790M Mutation by Droplet Digital Polymerase Chain Reaction in Lung Carcinoma Cytology Samples

CONTEXT.—

Advanced-stage non-small cell lung carcinoma patients on EGFR-targeted tyrosine kinase inhibitors frequently present with an acquired EGFR T790M resistance mutation. Early detection using a high-sensitivity assay is critical to allow patients to switch to third-generation tyrosine kinase inhibitors. The detection of EGFR T790M mutation is often challenging because of low tumor fraction in posttreatment specimens. Because a large fraction of non-small cell lung carcinoma patients are given a diagnosis by cytology, evaluating a high-sensitivity technique for EGFR T790M detection in these specimens is essential.

OBJECTIVE.—

To evaluate a high-sensitivity droplet digital polymerase chain reaction (ddPCR) assay for EGFR T790M using different cytologic specimen preparations.

DESIGN.—

A total of 42 cytology samples, including smears and cell block preparation, were evaluated for EGFR T790M using ddPCR. The results of the mutation assay were compared to the patient's known EGFR T790M mutation status.

RESULTS.—

The ddPCR assay successfully determined the EGFR T790M mutation status in 36 of 42 samples (86%), including samples with low tumor fraction (≤20%). In 4 cases the results of the ddPCR assay could not be compared because the mutation status was unknown at the time of collection of the cytology sample. There was 1 false-positive result, with borderline positivity, and 1 false-negative result. Overall sensitivity and specificity of the ddPCR assay were 93% and 96%, respectively.

CONCLUSIONS.—

Our results indicate that EGFR T790M ddPCR is a highly sensitive and specific mutational assay that can be used reliably in cytologic specimens, including samples with low tumor fraction.

Tumor-educated platelet as liquid biopsy in lung cancer patients

Lung cancer is the most frequent cancer for males and third most frequent cancer for females. Targeted therapy drugs based on molecular alterations, such as angiogenesis inhibitors, epidermal growth factor receptor (EGFR) inhibitors, and anaplastic lymphoma kinase (ALK) inhibitors are important part of treatment of NSCLC. However, the quality of the available tumor biopsy and/or cytology material is sometimes not adequate to perform the necessary molecular testing, which has prompted the search for alternatives. This review examines the use of tumor-educated platelet (TEP) as a liquid biopsy in lung cancer patients. The development of sensitive and accurate techniques have made it possible to detect the specific genetic alterations for which targeted therapies are already available. Liquid biopsy offers opportunities to detect resistance mechanisms at an early stage. To conclude, tumor-educated platelet has the potential to be used as liquid biopsy for a variety of clinical and investigational applications.