Targeted Therapy in Mesotheliomas: Uphill All the Way.

Mesothelioma (MM) is an aggressive and lethal disease with few therapeutic opportunities. Platinum-pemetrexed chemotherapy is the backbone of first-line treatment for MM. The introduction of immunotherapy (IO) has been the only novelty of the last decades, allowing an increase in survival compared to standard chemotherapy (CT). However, IO is not approved for epithelioid histology in many countries. Therefore, therapy for relapsed MM remains an unmet clinical need, and the prognosis of MM remains poor, with an average survival of only 18 months. Increasing evidence reveals MM complexity and heterogeneity, of which histological classification fails to explain. Thus, scientific focus on possibly new molecular markers or cellular targets is increasing, together with the search for target therapies directed towards them. The molecular landscape of MM is characterized by inactivating tumor suppressor alterations, the most common of which is found in CDKN2A, BAP1, MTAP, and NF2. In addition, cellular targets such as mesothelin or metabolic enzymes such as ASS1 could be potentially amenable to specific therapies. This review examines the major targets and relative attempts of therapeutic approaches to provide an overview of the potential prospects for treating this rare neoplasm.

Osimertinib in Patients With Treatment-Naive EGFR-Mutant Non-small Cell Lung Cancer: Overall Survival, Post-progression Management and Budget Impact Analysis in Real-World.

INTRODUCTION: The observational multicenter prospective FLOWER study (NCT04965701) confirmed effectiveness and safety of osimertinib in the real-world (RW) management of untreated EGFR-mutant advanced non-small cell lung cancer (aNSCLC) patients. METHODS: Herein, we report updated survival data, post-progression management, cost/effectiveness and budget impact (BI) of osimertinib compared with a RW population receiving gefitinib or erlotinib. RESULTS: Overall, 189 Caucasian patients receiving first-line osimertinib were included. After a follow-up of 20.7 months, 74(39.2%) patients discontinued osimertinib, median time-to-treatment discontinuation (mTTD) was 27.9 months, overall survival 36.8 months. At progression, tissue biopsy was performed in 29 (56.9%), liquid biopsy in 15 (29.4%) and both in 7 (13.7%) cases. The most frequent resistant mechanism was MET amplification (N = 14, 29.8%). At data cutoff, 13 (6.9%) patients were continuing osimertinib beyond progression; 52 (67.5%) received second-line treatment; no further treatments were administered in 25 (32.5%) cases. Thirty-three (63.4%) patients received chemotherapy, 12(23.1%) TKIs combination. Cost-effectiveness analysis showed a total cost per patient based on RW mTTD of 98,957.34€, 21,726.28€ and 19,637.83€ for osimertinib, erlotinib and gefitinib, respectively. The incremental cost-effectiveness ratio (ICER)/month for osimertinib was 359,806.0€/life-year-gained (LYG) and 197,789.77€/LYG compared to erlotinib and gefitinib. For osimertinib, the BI-gap between RW-TTD and theoretical-TTD was 16,501.0€ per patient. CONCLUSIONS: This updated analysis confirms the effectiveness of osimertinib in RW. Although the ICER of osimertinib seems not cost-effective, additional costs for the management of disease progression to old generation TKIs were not considered in this study. The BI-gap suggests RW mTTD as a more reliable measure for expense estimation.

Case report: First evidence of impressive efficacy of modulated dose selpercatinib in a young Caucasian with ANK3-RET fusion-positive NSCLC.

Over the past decade, molecular characterization has led to change the management of advanced non-small cell lung cancer (NSCLC) harboring driver mutations. Rearranged during transfection (RET) gene fusions, occurring in 1% to 2% of NSCLC, have emerged as an oncogenic druggable target. Systemic targeted therapies with highly selective RET inhibitors (RETi), selpercatinib and pralsetinib, represent a recent clinical breakthrough. While the development of RETi has improved survival, with their increasing use, it is crucial to be aware of the risks of rare but serious adverse events (AEs). A particular challenge for clinicians in applying targeted therapies is not only diagnosing but also interpreting rare mutations. Herein, we report a case of a 43-year-old Caucasian advanced NSCLC patient diagnosed with a rare RET gene fusion, ANK3::RET, identified with Next Generation Sequencing (NGS). Selpercatinib has been initiated at the recommended initial dose after one incomplete chemotherapy cycle due to a severe infusion reaction, but it subsequently required a dose adjustment following grade 3 (G3) AEs. During treatment, we used a particular selpercatinib dosage (160 mg in the morning and 80 mg in the evening) with good tolerance and without compromising effectiveness. Our finding broadens the range of RET fusion types in not-Asian NSCLC. To the best of our knowledge, our case demonstrates, for the first time, a clinical and radiological response to frontline highly selective RETi selpercatinib, expanding the spectrum of potential oncogenic RET fusion partners in newly diagnosed NSCLC patients. Furthermore, to our knowledge, this is the first case describing a RET fusion-positive (RET+) NSCLC patient treated with a modified selpercatinib dosage outside the drug data sheet and demonstrating a safe and effective use.

Oil and protein extraction from fruit seed and kernel by-products using a one pot enzymatic-assisted mild extraction.

This research evaluated the application of a one-pot enzymatic extraction by using a protease for the concomitant and sustainable extraction of oils and proteins from fruit seeds/kernels of different species of stone, citrus and exotic fruits. The proteolysis improved the oil solvent-extractability of seeds/kernels of some fruit species compared to the use of acid and/or organic solvents and led to directly recover fat (10-33%) from mango, lemon and pumpkin seeds. Good protein extraction yields were obtained compared to conventional solvent extractions and with a good hydrolysis degree (almost 10%) in the case of lemon and pumpkin seed protein hydrolysates. The nutritional quality of all the protein hydrolysates was quite low, because of their limiting amino acids (histidine, methionine and lysine). On the contrary, the fruit seed/kernel oils resulted with high nutritional value, as they were mostly rich in unsaturated fatty acids, primarily oleic acid (>25%) and linoleic acid (till 40%).

Therapeutical Options in ROS1-Rearranged Advanced Non Small Cell Lung Cancer.

ROS proto-oncogene 1 (ROS1) rearrangements occur in 0.9-2.6% of patients with non small cell lung cancer (NSCLC), conferring sensitivity to treatment with specific tyrosine-kinase inhibitors (TKI). Crizotinib, a first-generation TKI, was the first target-therapy approved for the first-line treatment of ROS1-positive NSCLC. Recently, entrectinib, a multitarget inhibitor with an anti-ROS1 activity 40 times more potent than crizotinib and better activity on the central nervous system (CNS), received approval for treatment-naive patients. After a median time-to-progression of 5.5-20 months, resistance mechanisms can occur, leading to tumor progression. Therefore, newer generation TKI with greater potency and brain penetration have been developed and are currently under investigation. This review summarizes the current knowledge on clinicopathological characteristics of ROS1-positive NSCLC and its therapeutic options.

Liquid Biopsy in NSCLC: An Investigation with Multiple Clinical Implications.

Tissue biopsy is essential for NSCLC diagnosis and treatment management. Over the past decades, liquid biopsy has proven to be a powerful tool in clinical oncology, isolating tumor-derived entities from the blood. Liquid biopsy permits several advantages over tissue biopsy: it is non-invasive, and it should provide a better view of tumor heterogeneity, gene alterations, and clonal evolution. Consequentially, liquid biopsy has gained attention as a cancer biomarker tool, with growing clinical applications in NSCLC. In the era of precision medicine based on molecular typing, non-invasive genotyping methods became increasingly important due to the great number of oncogene drivers and the small tissue specimen often available. In our work, we comprehensively reviewed established and emerging applications of liquid biopsy in NSCLC. We made an excursus on laboratory analysis methods and the applications of liquid biopsy either in early or metastatic NSCLC disease settings. We deeply reviewed current data and future perspectives regarding screening, minimal residual disease, micrometastasis detection, and their implication in adjuvant and neoadjuvant therapy management. Moreover, we reviewed liquid biopsy diagnostic utility in the absence of tissue biopsy and its role in monitoring treatment response and emerging resistance in metastatic NSCLC treated with target therapy and immuno-therapy.

A Web Tool to Help Counter the Spread of Misinformation and Fake News: Pre-Post Study Among Medical Students to Increase Digital Health Literacy.

BACKGROUND: The COVID-19 pandemic was accompanied by the spread of uncontrolled health information and fake news, which also quickly became an infodemic. Emergency communication is a challenge for public health institutions to engage the public during disease outbreaks. Health professionals need a high level of digital health literacy (DHL) to cope with difficulties; therefore, efforts should be made to address this issue starting from undergraduate medical students. OBJECTIVE: The aim of this study was to investigate the DHL skills of Italian medical students and the effectiveness of an informatics course offered by the University of Florence (Italy). This course focuses on assessing the quality of medical information using the "dottoremaeveroche" (DMEVC) web resource offered by the Italian National Federation of Orders of Surgeons and Dentists, and on health information management. METHODS: A pre-post study was conducted at the University of Florence between November and December 2020. First-year medical students participated in a web-based survey before and after attending the informatics course. The DHL level was self-assessed using the eHealth Literacy Scale for Italy (IT-eHEALS) tool and questions about the features and quality of the resources. All responses were rated on a 5-point Likert scale. Change in the perception of skills was assessed using the Wilcoxon test. RESULTS: A total of 341 students participated in the survey at the beginning of the informatics course (women: n=211, 61.9%; mean age 19.8, SD 2.0) and 217 of them (64.2%) completed the survey at the end of the course. At the first assessment, the DHL level was moderate, with a mean total score of the IT-eHEALS of 2.9 (SD 0.9). Students felt confident about finding health-related information on the internet (mean score of 3.4, SD 1.1), whereas they doubted the usefulness of the information they received (mean score of 2.0, SD 1.0). All scores improved significantly in the second assessment. The overall mean score of the IT-eHEALS significantly increased (P<.001) to 4.2 (SD 0.6). The item with the highest score related to recognizing the quality of health information (mean score of 4.5, SD 0.7), whereas confidence in the practical application of the information received remained the lowest (mean of 3.7, SD 1.1) despite improvement. Almost all students (94.5%) valued the DMEVC as an educational tool. CONCLUSIONS: The DMEVC tool was effective in improving medical students' DHL skills. Effective tools and resources such as the DMEVC website should be used in public health communication to facilitate access to validated evidence and understanding of health recommendations.

Selection Criteria and Treatment Outcome for Advanced Non-Small Cell Lung Cancer (NSCLC) Patients Unfit for Platinum-Based First-Line Therapy: Results of the MOON-OSS Observational Trial.

Limited evidence is available concerning the selection criteria and the outcomes of platinum unfit newly diagnosed advanced NSCLC patients receiving single-agent chemotherapy. We retrospectively collected data on consecutive, stage IIIB-IV, EGFR/ALK negative and PD-L1 < 50% NSCLC patients treated with first-line single agent chemotherapy. Baseline characteristics, outcome measures and toxicities were recorded, as well as criteria according to which treatment selection was made and what percentage of patients did not receive a first-line platinum-based chemotherapy. Two-hundred and twenty-one patients were included. Median age was 79 (range 56−92) years, M/F 165(74.6%)/56(25.4%), ECOG performance status (PS) 0/1/ ≥ 2 23(10.9%)/94(42.5%)/103(46.6%), with a median of two serious comorbidities. A median of 25% (range 10%-30%) of newly diagnosed NSCLC did not receive a first-line platinum combination. Clinical criteria according to which decision was made were older age (76.5%), comorbidities (72%), poor PS (55.2%) and familiar or social issues (10%). Single-agent treatment consisted of oral metronomic vinorelbine (MetV 78.6%), gemcitabine (Gem 10%), oral standard vinorelbine (Vin 8.2%) and other (O 3.2%). Median progression-free survival (PFS) and overall survival (OS) of single agent treatments ranged from 4.5 to 5 months and from 9 to 10.5 months, respectively. All grade toxicities did not differ among single agents, while grade 3−4 toxicities were less frequent with MetV. Up to 30% of newly diagnosed advanced EGFR/ALK negative and PD-L1 < 50% NSCLC patients do not receive a first-line platinum doublet. Main clinical selection criteria were older age (>70 years), comorbidities and poor PS. An oral treatment was frequently proposed with MetV being the most frequent choice according to its safety profile.

SARS-CoV-2 transmission by asymptomatic healthcare workers positive to screening swab: an Italian study.

BACKGROUND: SARS-CoV-2 spreads primarily through respiratory droplets of symptomatic individuals. With respect to asymptomatic individuals, there are conflicting results in the literature and a lack of studies specifically examining transmission in healthcare settings. METHODS: The aim of this retrospective study, conducted in a northeastern Italian region, was to estimate the contagiousness of asymptomatic healthcare workers (HCWs) who tested positive for SARS-CoV-2. Asymptomatic HCWs who tested positive for SARS-CoV-2 by real-time reverse transcription polymerase chain reaction (rRT-PCR) at a regular screening nasopharyngeal or oropharyngeal swab between 1 February 2020 and 15 September 2020 were considered index cases. Contacts who were at high risk of infection and had follow-up swabs were included. Contacts were considered infected if they had a positive follow-up swab and/or symptoms associated with COVID-19 confirmed by a positive test within 14 days of exposure. Information was taken from records previously collected to identify contacts. Infectivity was estimated using the attack rate (AR) with a 95% confidence interval (95% CI). RESULTS: Thirty-eight asymptomatic HCWs who were positive at the screening swab and 778 contacts were identified. Contacts included 63.8% of colleagues, 25.6% of patients, 7.7% of family members and 3.0% of other contacts. Seven contacts tested positive for SARS-CoV-2 (AR: 0.91%, 95% CI: 0.89-0.93). Five of them were family members (AR: 8.3%), one was a colleague (0.2%) and one was a contact of other type (4.2%). CONCLUSIONS: Viral spread by asymptomatic HCWs was less than in other settings. Identification of risk factors for transmission and reliable indicators of infectivity would be important to prioritize preventive measures.

Nature-Based Solutions for Restoring an Agricultural Area Contaminated by an Oil Spill.

A feasibility study is presented for a bioremediation intervention to restore agricultural activity in a field hit by a diesel oil spill from an oil pipeline. The analysis of the real contaminated soil was conducted following two approaches. The first concerned the assessment of the biodegradative capacity of the indigenous microbial community through laboratory-scale experimentation with different treatments (natural attenuation, landfarming, landfarming + bioaugmentation). The second consisted of testing the effectiveness of phytoremediation with three plant species: Zea mays (corn), Lupinus albus (lupine) and Medicago sativa (alfalfa). With the first approach, after 180 days, the different treatments led to biodegradation percentages between 83 and 96% for linear hydrocarbons and between 76 and 83% for branched ones. In case of contamination by petroleum products, the main action of plants is to favor the degradation of hydrocarbons in the soil by stimulating microbial activity thanks to root exudates. The results obtained in this experiment confirm that the presence of plants favors a decrease in the hydrocarbon content, resulting in an improved degradation of up to 18% compared with non-vegetated soils. The addition of plant growth-promoting bacteria (PGPB) isolated from the contaminated soil also promoted the growth of the tested plants. In particular, an increase in biomass of over 50% was found for lupine. Finally, the metagenomic analysis of the contaminated soil allowed for evaluating the evolution of the composition of the microbial communities during the experimentation, with a focus on hydrocarbon- oxidizing bacteria.

Detection of ALK fusion variants by RNA-based NGS and clinical outcome correlation in NSCLC patients treated with ALK-TKI sequences.

INTRODUCTION: Anaplastic lymphoma kinase (ALK) fusions identify a limited subset of non-small cell lung cancer (NSCLC) patients, whose therapeutic approach have been radically changed in recent years. However, diagnostic procedures and clinical-radiological responses to specific targeted therapies remain heterogeneous and intrinsically resistant or poor responder patients exist. METHODS: A total of 290 patients with advanced NSCLC defined as ALK+ by immunohistochemistry (IHC) and/or fluorescent in situ hybridisation (FISH) test and treated with single or sequential multiple ALK inhibitors (ALKi) from 2011 to 2017 have been retrospectively retrieved from a multicentre Italian cancer network database. In 55 patients with enough leftover tumour tissue, specimens were analysed with both targeted and customised next generation sequencing panels. Identified fusion variants have been correlated with clinical outcomes. RESULTS: Of the 55 patients, 24 received crizotinib as first-line therapy, 1 received ceritinib, while 30 received chemotherapy. Most of the patients (64%) received ALKi in sequence. An ALK fusion variant was identified in 73% of the cases, being V3 variant (E6A20) the most frequent, followed by V1 (E13A20) and more rare ones (e.g. E6A19). In three specimens, four new EML4-ALK fusion breakpoints have been reported. Neither fusion variants nor brain metastases were significantly associated with overall survival (OS), while it was predictably longer in patients receiving a sequence of ALKi. The presence of V1 variant was associated with progression-free survival (PFS) improvement when crizotinib was used (p = 0.0073), while it did not affect cumulative PFS to multiple ALKi. CONCLUSION: Outcomes to sequential ALKi administration were not influenced by fusion variants. Nevertheless, in V1+ patients a prolonged clinical benefit was observed. Fusion variant identification by NGS technology may add relevant information about rare chromosomal events that could be potentially correlated to worse outcomes.

Targeted Therapy and Immunotherapy in Early-Stage Non-Small Cell Lung Cancer: Current Evidence and Ongoing Trials.

The scenario of neoadjuvant and adjuvant settings in non-small cell lung cancer (NSCLC) is rapidly evolving. As already happened for the advanced disease, also early stages have entered the era of precision medicine, with molecular analysis and Programmed death-ligand 1 (PD-L1) evaluation that by now can be considered a routine assessment. New treatment options have been recently approved, with osimertinib now part of clinical practice for Epidermal Growth Factor Receptor mutated (EGFRm) patients, and immune checkpoint inhibitors (ICIs) available after FDA approval both in the adjuvant (atezolizumab) and neoadjuvant (nivolumab) setting. No mature data on overall survival benefits are available yet, though. Several clinical trials with specific-tyrosine kinase inhibitors (TKIs) and ICIs are currently ongoing, both with and without concomitant chemotherapy. As therapeutic strategies are rapidly expanding, quite a few questions remain unsettled, such as the optimal duration of adjuvant targeted therapy or the effective benefit of ICIs in early-stage EGFRm or ALK (Anaplastic Lymphoma Kinase) rearranged patients, or the possibility to individuate high-risk patients after surgical resection assessing minimal residual disease (MRD) by ctDNA evaluation. We hereby report already available literature data and summarize ongoing trials with targeted therapy and immunotherapy in early-stage NSCLC, focusing on practice-changing results and new perspectives for potentially cured patients.

The Change in Paradigm for NSCLC Patients with EML4-ALK Translocation.

The severe prognosis linked with a lung cancer diagnosis has changed with the discovery of oncogenic molecularly driven subgroups and the use of tailored treatment. ALK-translocated advanced lung cancer is the most interesting model, having achieved the longest overall survival. Here, we report the most important paradigmatic shifts in the prognosis and treatment for this subgroup population occurred among lung cancer.

Acquired Resistance to Osimertinib in EGFR-Mutated Non-Small Cell Lung Cancer: How Do We Overcome It?

Osimertinib is currently the preferred first-line therapy in patients with non-small cell lung cancer (NSCLC) with common epidermal growth factor receptor (EGFR) mutation and the standard second-line therapy in T790M-positive patients in progression to previous EGFR tyrosine kinase inhibitor. Osimertinib is a highly effective treatment that shows a high response rate and long-lasting disease control. However, a resistance to the treatment inevitably develops among patients. Understanding the secondary mechanisms of resistance and the possible therapeutic options available is crucial to define the best management of patients in progression to osimertinib. We provide a comprehensive review of the emerging molecular resistance mechanism in EGFR-mutated NSCLC pre-treated with osimertinib and its future treatment applications.

Brain Metastases Management in Oncogene-Addicted Non-Small Cell Lung Cancer in the Targeted Therapies Era.

The therapeutic landscape in patients with advanced non-small-cell lung cancer harboring oncogenic biomarkers has radically changed with the development of targeted therapies. Although lung cancers are known to frequently metastasize to the brain, oncogene-driven non-small-cell lung cancer patients show a higher incidence of both brain metastases at baseline and a further risk of central nervous system progression/relapse. Recently, a new generation of targeted agents, highly active in the central nervous system, has improved the control of intracranial disease. The intracranial activity of these drugs poses a crucial issue in determining the optimal management sequence in oncogene-addicted non-small-cell lung cancer patients with brain metastases, with a potential change of paradigm from primary brain irradiation to central nervous system penetrating targeted inhibitors.

NSCLC as the Paradigm of Precision Medicine at Its Finest: The Rise of New Druggable Molecular Targets for Advanced Disease.

Standard treatment for advanced non-small cell lung cancer (NSCLC) historically consisted of systemic cytotoxic chemotherapy until the early 2000s, when precision medicine led to a revolutionary change in the therapeutic scenario. The identification of oncogenic driver mutations in EGFR, ALK and ROS1 rearrangements identified a subset of patients who largely benefit from targeted agents. However, since the proportion of patients with druggable alterations represents a minority, the discovery of new potential driver mutations is still an urgent clinical need. We provide a comprehensive review of the emerging molecular targets in NSCLC and their applications in the advanced setting.

Bone Metastasis and Immune Checkpoint Inhibitors in Non-Small Cell Lung Cancer (NSCLC): Microenvironment and Possible Clinical Implications.

Patients with non-small cell lung cancer (NSCLC) develop bone metastasis (BoM) in more than 50% of cases during the course of the disease. This metastatic site can lead to the development of skeletal related events (SREs), such as severe pain, pathological fractures, spinal compression, and hypercalcemia, which reduce the patient's quality of life. Recently, the treatment of advanced NSCLC has radically changed due to the advent of immunotherapy. Immune checkpoint inhibitors (ICI) alone or in combination with chemotherapy have become the main therapeutic strategy for advanced or metastatic NSCLC without driver gene mutations. Since survival has increased, it has become even more important to treat bone metastasis to prevent SRE. We know that the presence of bone metastasis is a negative prognostic factor. The lower efficacy of immunotherapy treatments in BoM+ patients could be induced by the presence of a particular immunosuppressive tumor and bone microenvironment. This article reviews the most important pre-clinical and clinical scientific evidence on the reasons for this lower sensitivity to immunotherapy and the need to combine bone target therapies (BTT) with immunotherapy to improve patient outcome.

First-Line Osimertinib in Patients with EGFR-Mutant Advanced Non-Small Cell Lung Cancer: Outcome and Safety in the Real World: FLOWER Study.

BACKGROUND: Osimertinib became the standard treatment for patients with untreated EGFR-mutant advanced non-small cell lung cancer (aNSCLC) following results reported in the phase III randomized FLAURA trial. Because of strict exclusion criteria, patient populations included in pivotal trials are only partially representative of real-world patients. METHODS: We designed an observational, prospective, multicenter study enrolling patients with EGFR-mutant aNSCLC receiving first-line osimertinib to evaluate effectiveness, safety, and progression patterns in the real-world. RESULTS: At data cutoff, 126 White patients from nine oncology centers were included. At diagnosis, 16 patients (12.7%) had a performance status (PS) ≥2 and 38 (30.2%) had brain metastases. Overall response rate (ORR) was 73%, disease control rate (DCR) 96.0%. After a median follow-up of 12.3 months, median time to treatment discontinuation (mTTD) was 25.3 months, median progression-free-survival (mPFS) was 18.9 months and median overall survival (mOS) was not reached (NR). One hundred and ten patients (87%) experienced adverse events (AEs), 42 (33%) of grade 3-4, with venous thromboembolism (VTE) as the most common (n = 10, 7.9%). No difference in rates of VTE was reported according to age, PS, comorbidity, and tumor load. We observed longer mTTD in patients without symptoms (NR vs. 18.8 months) and with fewer than three metastatic sites at diagnosis (NR vs. 21.4 months). Patients without brain metastases experienced longer mPFS (NR vs. 13.3 months). No difference in survival outcome was observed according to age, comorbidity, and type of EGFR mutation. Isolated progression and progression in fewer than three sites were associated with longer time to treatment discontinuation (TTD). CONCLUSION: Osimertinib confirmed effectiveness and safety in the real world, although thromboembolism was more frequent than previously reported.

Acquired EGFR C797G Mutation Detected by Liquid Biopsy as Resistance Mechanism After Treatment With Osimertinib: A Case Report.

BACKGROUND: Osimertinib is a third-generation EGFR-tyrosine kinase inhibitor approved for the treatment of T790M-positive non-small-cell lung cancer. More recently, osimertinib demonstrated improved disease control compared to other EGFR-TKIs. Multiple mechanisms of resistance have been described in T790M-positive patients who experienced treatment failure with osimertinib. CASE REPORT: We report the case of a 78-year-old non-smoker woman with stage IV EGFR L858R-positive lung adenocarcinoma presented with T790M mutation after five years of treatment with gefitinib. The patient was started on osimertinib, but after two and a half years of treatment experienced disease progression. The analyses of circulating tumor DNA using next-generation sequencing showed, together with the pre-existing T790M and exon 21 L858R, the presence of the EGFR C797G resistance mutation. CONCLUSION: Our case report revealed a rare EGFR-dependent acquired resistance mutation to osimertinib in circulating tumor DNA. Liquid biopsy appears to be a promising resource to understand the biology of osimertinib resistance by clonal evolution monitoring and the identification of novel resistance mechanisms.