Challenging BRAF/EGFR co-inhibition in NSCLC using sequential liquid biopsies

Liquid biopsy for the management of NSCLC patients under osimertinib treatment

Therapeutic management of NSCLC patients is quite challenging as they are mainly diagnosed at a late stage of disease, and they present a high heterogeneous molecular profile. Osimertinib changed the paradigm shift in treatment of EGFR mutant NSCLC patients achieving significantly better clinical outcomes. To date, osimertinib is successfully administered not only as first- or second-line treatment, but also as adjuvant treatment while its efficacy is currently investigated during neoadjuvant treatment or in stage III, unresectable EGFR mutant NSCLC patients. However, resistance to osimertinib may occur due to clonal evolution, under the pressure of the targeted therapy. The utilization of liquid biopsy as a minimally invasive tool provides insight into molecular heterogeneity of tumor clonal evolution and potent resistance mechanisms which may help to develop more suitable therapeutic approaches. Longitudinal monitoring of NSCLC patients through ctDNA or CTC analysis could reveal valuable information about clinical outcomes during osimertinib treatment. Therefore, several guidelines suggest that liquid biopsy in addition to tissue biopsy should be considered as a standard of care in the advanced NSCLC setting. This practice could significantly increase the number of NSCLC patients that will eventually benefit from targeted therapies, such as EGFR TKIs.

Pathways and targeting avenues of BRAF in non-small cell lung cancer

INTRODUCTION

BRAF is a serine-threonine kinase implicated in the regulation of MAPK signaling cascade. BRAF mutation-driven activation occurs in approximately 2-4% of treatment-naive non-small cell carcinomas (NSCLCs). BRAF upregulation is also often observed in tumors with acquired resistance to receptor tyrosine kinase inhibitors (TKIs).

AREAS COVERED

This review describes the spectrum of BRAF mutations and their functional roles, discusses treatment options available for BRAF p.V600 and non-V600 mutated NSCLCs, and identifies some gaps in the current knowledge.

EXPERT OPINION

Administration of combined BRAF/MEK inhibitors usually produces significant, although often a short-term, benefit to NSCLC patients with BRAF V600 (class 1) mutations. There are no established treatments for BRAF class 2 (L597, K601, G464, G469A/V/R/S, fusions, etc.) and class 3 (D594, G596, G466, etc.) mutants, which account for up to two-thirds of BRAF-driven NSCLCs. Many important issues related to the use of immune therapy for the management of BRAF-mutated NSCLC deserve further investigation. The rare occurrence of BRAF mutations in NSCLC is compensated by high overall incidence of lung cancer disease; therefore, clinical studies on BRAF-associated NSCLC are feasible.

Promising response of dabrafenib, trametinib, and osimertinib combination therapy for concomitant BRAF and EGFR-TKI resistance mutations

Despite the initial promise of epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) in effectively combating tumor growth, the majority of patients with advanced non-small cell lung cancers (NSCLCs) inevitably develop resistance to these treatments. An infrequent genetic mutation known as BRAFV600E has been identified as a contributing factor to the emergence of acquired resistance to EGFR-TKIs. Genetic alterations in BRAF, particularly V600E, contribute to resistance to osimertinib. However, a combination therapy involving osimertinib, dabrafenib (a BRAF inhibitor), and trametinib has shown effectiveness in overcoming BRAF V600E-mediated resistance in advanced lung adenocarcinoma. This treatment regimen holds promise for similar cases. In our case report, the combination of osimertinib, dabrafenib, and trametinib effectively overcame osimertinib resistance and resulted in sustained partial remission.

Acquired resistance mechanisms to osimertinib: The constant battle

Lung cancer is the leading cause of cancer-related mortality worldwide. Detectable driver mutations have now changed the course of lung cancer treatment with the emergence of targeted therapy as a novel strategy that widely improved lung cancer prognosis, especially in metastatic patients. Osimertinib (AZD9291) is an irreversible third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) used to treat stage IV EGFR-mutated non-small-cell lung cancer. It was initially designed to target both EGFR-activating mutations and the EGFR T790M mutation as well, which is the most common resistance mechanism to first- and second-generation EGFR-TKIs. Following the FLAURA trial, osimertinib is now widely used in the first-line setting. However, resistance to osimertinib inevitably develops, with numerous mechanisms leading to its resistance, classified into two main categories: EGFR-dependent and EGFR-independent mechanisms. While EGFR-dependent mechanisms consist mainly of the C797S EGFR mutation, EGFR-independent mechanisms include bypass pathways, oncogenic fusions, and phenotypic transformation, among others. This review summarizes the molecular resistance mechanisms to osimertinib, with the aim of identifying novel therapeutic approaches to overcome osimertinib resistance and improve patient outcome.

Liquid Biopsy Analysis as a Tool for TKI-Based Treatment in Non-Small Cell Lung Cancer

The treatment of non-small cell lung cancer (NSCLC) has recently evolved with the introduction of targeted therapy based on the use of tyrosine kinase inhibitors (TKIs) in patients with certain gene alterations, including EGFR, ALK, ROS1, BRAF, and MET genes. Molecular targeted therapy based on TKIs has improved clinical outcomes in a large number of NSCLC patients with advanced disease, enabling significantly longer progression-free survival (PFS). Liquid biopsy is an increasingly popular diagnostic tool for treating TKI-based NSCLC. The studies presented in this article show that detection and analysis based on liquid biopsy elements such as circulating tumor cells (CTCs), cell-free DNA (cfDNA), exosomes, and/or tumor-educated platelets (TEPs) can contribute to the appropriate selection and monitoring of targeted therapy in NSCLC patients as complementary to invasive tissue biopsy. The detection of these elements, combined with their molecular analysis (using, e.g., digital PCR (dPCR), next generation sequencing (NGS), shallow whole genome sequencing (sWGS)), enables the detection of mutations, which are required for the TKI treatment. Despite such promising results obtained by many research teams, it is still necessary to carry out prospective studies on a larger group of patients in order to validate these methods before their application in clinical practice.

The Evolution of BRAF Activation in Non-Small-Cell Lung Cancer

Non-small-cell lung cancer (NSCLC) is the most common subtype of lung cancer, of which approximate 4% had BRAF activation, with an option for targeted therapy. BRAF activation comprises of V600 and non-V600 mutations, fusion, rearrangement, in-frame deletions, insertions, and co-mutations. In addition, BRAF primary activation and secondary activation presents with different biological phenotypes, medical senses and subsequent treatments. BRAF primary activation plays a critical role in proliferation and metastasis as a driver gene of NSCLC, while secondary activation mediates acquired resistance to other targeted therapy, especially for epidermal growth factor tyrosine kinase inhibitor (EGFR-TKI). Treatment options for different activation of BRAF are diverse. Targeted therapy, especially two-drug combination therapy, is an important option. Besides, immune checkpoint inhibitors (ICIs) would be another option since BRAF activation would be a positive biomarker of tumor response of ICIs therapy. To date, no high level evidences support targeted therapy or immunotherapy as prioritized recommendation. After targeted therapy, the evolution of BRAF includes the activation of the upstream, downstream and bypass pathways of BRAF. In this review, therapeutic modalities and post-therapeutic evolutionary pathways of BRAF are discussed, and future research directions are also provided.

Treatment outcomes and prognosis of patients with primary and acquired BRAF-mutated non-small cell lung cancer: a multicenter retrospective study

The incidence of primary and acquired BRAF mutations is low in non-small cell lung cancer (NSCLC), with limited demographic and treatment outcome data available for this patient population. We evaluated lung cancer samples with programmed cell death ligand 1 (PD-L1) information extracted from 12,051 cases (cohort A) of lung cancer from OncoPanscan^TM -based sequencing of tissue (Genetron Health) and conducted retrospective multicenter data analysis using the database of Zhejiang Cancer Hospital and four other centers (cohort B, including 73 primary BRAF mutation and 14 acquired BRAF mutation cases) to compare treatment outcomes of patient groups with primary and acquired BRAF mutations. In cohort A, after propensity score analysis, 165 samples of NSCLC with BRAF mutations were screened along with 165 paired non-BRAF mutation samples. We observed no significant differences in the proportion of samples with ≥1% PD-L1 between BRAF and non-BRAF mutant groups. The median progression-free survival (mPFS) period in 13 patients with primary BRAF mutations receiving BRAF tyrosine kinase inhibitors (BRAF-TKIs) was 7.0 months. The group with primary BRAF mutations receiving immune checkpoint inhibitor (ICI) combination chemotherapy had better PFS than those administered ICI monotherapy (14.77 months vs 5.0 months, P=0.025) and similar results were obtained for OS (unreached vs 20.3 months, P=0.013). For acquired BRAF mutations, mPFS of BRAF-TKI, ICI-based and chemotherapy-based regimens were 3.8, 1.5 and 1.9 months, respectively. Therefore, for patients with the primary BRAF V600E mutation, targeted therapy or immunochemotherapy could serve as effective treatment choices while for those with acquired BRAF V600E, targeted drug therapy may remain the preferred solution in China. This article is protected by copyright. All rights reserved.

Molecular Pathology of Lung Cancer

This overview of the molecular pathology of lung cancer includes a review of the most salient molecular alterations of the genome, transcriptome, and the epigenome. The insights provided by the growing use of next-generation sequencing (NGS) in lung cancer will be discussed, and interrelated concepts such as intertumor heterogeneity, intratumor heterogeneity, tumor mutational burden, and the advent of liquid biopsy will be explored. Moreover, this work describes how the evolving field of molecular pathology refines the understanding of different histologic phenotypes of non-small-cell lung cancer (NSCLC) and the underlying biology of small-cell lung cancer. This review will provide an appreciation for how ongoing scientific findings and technologic advances in molecular pathology are crucial for development of biomarkers, therapeutic agents, clinical trials, and ultimately improved patient care.

EGFR-dependent mechanisms of resistance to osimertinib determined by ctDNA NGS analysis identify patients with better outcome

Background

Osimertinib is an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) that is highly selective for EGFR^T790M subclones in patients with EGFR^sensitizing non-small cell lung cancer (NSCLC). Unfortunately, all patients develop resistance through EGFR-dependent or EGFR-independent pathways. Recently, circulating tumoral DNA (ctDNA) analysis has highlighted the usefulness of plasma genotyping for exploring patient survival outcomes after disease progression under osimertinib.

Methods

Plasma samples from patients treated with osimertinib as a second-line therapy were collected and the presence of molecular alterations of acquired resistance was evaluated after relapse under osimertinib using ctDNA molecular profiling by next-generation sequencing (NGS) assays. The clinical implications of these genomic alterations for the efficiency of the third-generation TKI were further assessed.

Results

Our ctDNA molecular profiling of plasma samples highlighted large number of actionable genomic alterations. According to ctDNA NGS results, patients were classified as having developed an EGFR-dependent or EGFR-independent mechanism of resistance. Thus, patients who developed an EGFR-dependent mechanism of resistance responded longer to osimertinib (13.8 vs. 4.6 months; P<10⁻⁴) and have a better post-osimertinib clinical outcome than EGFR-independent resistant patients. Moreover, the development of an EGFR-dependent mechanism of osimertinib resistance was identified as the best fit to determine patients’ clinical outcome compared with EGFR^T790M status alone (P=0.003).

Conclusions

Our study highlights the potential of ctDNA NGS to rapidly select the appropriate drug after osimertinib failure and to determine clinical outcomes of patients. We suggest that ctDNA NGS should be more intensively used in clinical practice to follow patients under third-generation TKIs.

Combined targeting of EGFR and BRAF triggers regression of osimertinib resistance by using osimertinib and vemurafenib concurrently in a patient with heterogeneity between different lesions

Acquired BRAF V600E mutation can occur in tumors with EGFR mutation and is suspected as a resistance mechanism to third‐generation EGFR‐tyrosine kinase inhibitors (TKIs). However, the treatment strategy for the coexistence of EGFR and acquired BRAF mutation with heterogeneity in lung cancer has not been systematically established. Here, we report a patient in whom BRAF V600E and EGFR 19del mutation in a metastatic lesion followed by disease progression on osimertinib was detected. Treatment with single‐agent vemurafenib was effective for treatment of the metastatic lesion in this patient but the primary lesion progressed. A concurrent combination of vemurafenib and osimertinib was therefore administered and a partial response of both primary and metastatic lesions was achieved with progression‐free survival (PFS) of 7 months. The concurrent combination treatment was well tolerated by the patient through dosing modification and supportive medical care. This case highlights the consideration of heterogeneity between different lesions and provides a successful example of the concurrent therapy with vemurafenib and osimertinib for triggering regression of osimertinb resistance induced by BRAF mutation.

Liquid biopsy = Individualized cancer management: Diagnosis, monitoring treatment and checking recurrence and metastasis

Traditional cancer-screening techniques such as imaging and protein biomarkers are not sufficient for early detection. Various forms of endoscopy and tumour biopsy are the current standard methods in diagnosing Head Neck Cancers. Liquid biopsy has been increasingly considered as an option for molecular characterization and detection of cancer as it can provide real-time information about cancer in a minimally invasive manner. Circulating tumor DNA (ctDNA), circulating tumor cells (CTCs), and exosomal miRNAs are emerging biomarkers that can be applied to cancer detection, treatment planning, and response monitoring. A 'liquid biopsy' presents an option where the disease can be tracked in a less-invasive, simple manner, allowing for serial sampling informing of the tumour heterogeneity, response to treatment and minimal residual disease.

Tumor response to EGFR/BRAF/MEK co-inhibition in a patient with EGFR mutated lung adenocarcinoma developing a BRAFV600 mutation as an acquired resistance mechanism

EGFR-mutant adenocarcinomas represent 12% of unselected lung adenocarcinomas and 44% of never smoker adenocarcinomas in the Caucasian population. Activating mutations like exon19 deletion or exon21 Leu858Arg point mutations are predictive of tumor response to EGFR tyrosine kinase inhibitors. Unfortunately, acquired resistance inevitably occurs by the development of novel EGFR mutations, mutations in other genes, gene amplification, gene fusion or tumor transformation. The management of tumors presenting multiple targetable mutations is unclear. We present the case of a patient developing a BRAF^V600 mutation as acquired resistance mechanism to osimertinib, who responded favorably to the combination of dabrafenib, trametinib and osimertinib.

Combination of tissue and liquid biopsy molecular profiling to detect transformation to small cell lung carcinoma during osimertinib treatment

Background:

Histological transformation of advanced non-small cell lung cancer (NSCLC) to small cell lung cancer (SCLC) is one of the mechanisms of resistance to third-generation tyrosine kinase inhibitors (TKIs), such as osimertinib. This acquired TKI resistance is linked to the high degree of tumor heterogeneity and adaptive cellular signaling pathways, including epidermal growth factor receptor (EGFR)-dependent pathways, observed in NSCLC.

Methods:

Here, we investigated a series of paired pre- and post-histological transformation biopsies obtained from three patients initially having a NSCLC with an EGFR^activating mutation treated with first-generation TKI, who then received osimertinib as second-line after EGFR^T790M resistance and, lastly, developed a histological transformation to SCLC. Both tissue and liquid biopsies were analyzed using large panel sequencing approaches at various time points to reconstruct the clonal evolutionary history of the tumor.

Results:

Our complementary analysis of tumor tissue and circulating tumor DNA samples allowed us to better characterize the histological and molecular alterations associated with resistance to osimertinib. SCLC transformation was linked to the presence of several concomitant gene alterations, including EGFR, TP53 and RB1, but also to specific signal bypass, such as EGFR and MET amplifications and activation of the PI3K/AKT/mTOR pathway.

Conclusion:

Our report emphasizes the mutational landscape of SCLC histological transformation and highlights the importance of combining tissue and liquid biopsy profiling before and during osimertinib treatment to predict such histological transformation.

The Role of the Liquid Biopsy in Decision-Making for Patients with Non-Small Cell Lung Cancer

Liquid biopsy is a rapidly emerging tool of precision oncology enabling minimally invasive molecular diagnostics and longitudinal monitoring of treatment response. For the clinical management of advanced stage lung cancer patients, detection and quantification of circulating tumor DNA (ctDNA) is now widely adopted into clinical practice. Still, interpretation of results and validation of ctDNA-based treatment decisions remain challenging. We report here our experience implementing liquid biopsies into the clinical management of lung cancer. We discuss advantages and limitations of distinct ctDNA assay techniques and highlight our approach to the analysis of recurrent molecular alterations found in lung cancer. Moreover, we report three exemplary clinical cases illustrating the complexity of interpreting liquid biopsy results in clinical practice. These cases underscore the potential and current limitations of liquid biopsy, focusing on the difficulty of interpreting discordant findings. In our view, despite all current limitations, the analysis of ctDNA in lung cancer patients is an essential and highly versatile complementary diagnostic tool for the clinical management of lung cancer patients in the era of precision oncology.

Liquid biopsy and their application progress in head and neck cancer: focus on biomarkers CTCs, cfDNA, ctDNA and EVs

Head and neck cancer (HNC) is the sixth leading cause of cancer death worldwide. Due to the low early diagnosis rate of HNC, local recurrence and high distant metastasis rate are the main reasons for treatment failure. Therefore, it is important to establish a method of diagnosis and monitoring, which is convenient, safe, reproducible, sensitive and specific. Compared with tissue biopsy, liquid biopsy is an emerging biopsy technique, which has the advantages of re-sampling, noninvasive and cost-effectiveness, and has shown good diagnostic and prognostic value in studies for various types of malignant solid tumors. This review introduces liquid biopsy, its research progress and prospects in HNC including early diagnosis, staging, grading, prognosis assessment and disease surveillance.

Durable Clinical Response of Advanced Lung Adenocarcinoma Harboring EGFR-19del/T790M/BRAFV600E Mutations After Treating with Osimertinib and Dabrafenib Plus Trametinib: A Case Report

EGFR-T790M and BRAFV600E are the common resistance mechanisms to EGFR-tyrosine kinase inhibitors (TKIs). Standard treatment for the triple mutations of EGFR-19del, T790M, and BRAFV600E is still under debate. Herein, we present a case of therapeutic efficacy of osimertinib and dabrafenib plus trametinib on a 63-year-old man with advanced lung adenocarcinoma. This patient reached a remarkable progression-free survival of 9 months without any serious adverse reaction. At the progression of the disease, C797S mutation in cis was detected by liquid biopsy. Subsequently, brigatinib with cetuximab was administered but no curative effect was observed. Then, therapy was changed to apatinib combined with osimertinib. The subsequent CT scan showed that the lesions reached stable disease (SD), and the survival benefit has been evaluated. This case showed that the combination treatment of osimertinib and dabrafenib plus trametinib might be a great treatment option for NSCLC patients with triple mutations (EGFR-19del/T790M/BRAFV600E).

Combined osimertinib, dabrafenib and trametinib treatment for advanced non-small-cell lung cancer patients with an osimertinib-induced BRAF V600E mutation

INTRODUCTION

Previous studies have reported an acquiredBRAF V600E mutation as a potential resistance mechanism to osimertinib treatment in advanced NSCLC patients with an activating mutation in EGFR. However, the therapeutic effect of combining dabrafenib and trametinib with osimertinib remains unclear. Here we report treatment efficacy in two cases with acquired BRAF V600E mutations.

METHODS

Two patients with anEGFR exon 19 deletion and a T790 M mutation, both treated with osimertinib, acquired a BRAF V600E mutation at disease progression. Following the recommendation of the molecular tumor board, a concurrent combination of dabrafenib and trametinib plus osimertinib was administered.

RESULTS

Because of toxicity, one patient ultimately received a reduced dose of dabrafenib and trametinib combined with a normal dose of osimertinib. Clinical response in this patient lasted for 13.4 months. Re-biopsy upon tumor progression revealed loss ofBRAF V600E and emergence of EGFR C797S. The other patient, treated with full doses of the combined therapy, had progression with metastases in lung and brain one month after starting therapy.

CONCLUSION

BRAF V600E may be a resistance mechanism induced by osimertinib in EGFR-mutated advanced NSCLC. Combined treatment using dabrafenib/trametinib concurrently with osimertinib needs to be explored for osimertinib-induced BRAF V600E mutation.