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Epidermal growth factor receptor (EGFR)-mutant non-small-cell lung cancer (NSCLC) patients treated with EGFR–tyrosine kinase inhibitors (TKIs) inevitably develop resistance through several biological mechanisms. However, little is known on the molecular mechanisms underlying acquired resistance to suboptimal EGFR-TKI doses, due to pharmacodynamics leading to inadequate drug exposure. To evaluate the effects of suboptimal EGFR-TKI exposure on resistance in NSCLC, we obtained HCC827 and PC9 cell lines resistant to suboptimal fixed and intermittent doses of gefitinib and compared them to cells exposed to higher doses of the drug. We analyzed the differences in terms of EGFR signaling activation and the expression of epithelial–mesenchymal transition (EMT) markers, whole transcriptomes byRNA sequencing, and cell motility. We observed that the exposure to low doses of gefitinib more frequently induced a partial EMT associated with an induced migratory ability, and an enhanced transcription of cancer stem cell markers, particularly in the HCC827 gefitinib-resistant cells. Finally, the HCC827 gefitinib-resistant cells showed increased secretion of the EMT inducer transforming growth factor (TGF)-β1, whose inhibition was able to partially restore gefitinib sensitivity. These data provide evidence that different levels of exposure to EGFR-TKIs in tumor masses might promote different mechanisms of acquired resistance. [ABSTRACT FROM AUTHOR]

Increasing evidence suggests that liquid biopsy might play a relevant role in the management of metastatic non-small cell lung cancer (NSCLC) patients. Here, we show how the Molecular Tumor Board (MTB) in our cancer center employed liquid biopsy to support therapeutic decisions in a patient with NSCLC carrying a rare EGFR mutation. A 44-year-old woman, never-smoker with an EGFR, ALK, and ROS1-negative lung adenocarcinoma and multiple brain metastases received systemic therapy and surgery before being referred to our Institute. The MTB suggested NGS testing of tumor biopsy that revealed a rare exon-20 EGFR insertion (p.His773dup; c.2315_2316insCCA) and EGFR amplification. The MTB recommended treatment with erlotinib and follow-up with liquid biopsy, by using both cell-free DNA (cfDNA) and circulating tumor cells (CTCs). An increase of EGFR mutation levels in cfDNA revealed resistance to treatment about 6 months before clinical progression. Extremely low levels of EGFR p.T790M were detected at progression. Based on preclinical data suggesting activity of osimertinib against EGFR exon-20 insertions, the MTB recommended treatment with brain and bone radiotherapy and osimertinib. A dramatic reduction of EGFR mutation levels in the cfDNA was observed after 4 weeks of treatment. The PET scan demonstrated a metabolic partial remission that was maintained for 9 months. This case supports the evidence that liquid biopsy can aid in the management of metastatic NSCLC. It also suggests that treatment with osimertinib might be a therapeutic option in patients with EGFR exon-20 insertions when a clinical trial is not available. [ABSTRACT FROM AUTHOR]

Identification of driver mutations in lung adenocarcinoma has led to development of targeted agents that are already approved for clinical use or are in clinical trials. Therefore, the number of biomarkers that will be needed to assess is expected to rapidly increase. This calls for the implementation of methods probing the mutational status of multiple genes for inoperable cases, for which limited cytological or bioptic material is available. Cytology specimens from 38 lung adenocarcinomas were subjected to the simultaneous assessment of 504 mutational hotspots of 22 lung cancer-associated genes using 10 nanograms of DNA and Ion Torrent PGM next-generation sequencing. Thirty-six cases were successfully sequenced (95%). In 24/36 cases (67%) at least one mutated gene was observed, including EGFR, KRAS, PIK3CA, BRAF, TP53, PTEN, MET, SMAD4, FGFR3, STK11, MAP2K1. EGFR and KRAS mutations, respectively found in 6/36 (16%) and 10/36 (28%) cases, were mutually exclusive. Nine samples (25%) showed concurrent alterations in different genes. The next-generation sequencing test used is superior to current standard methodologies, as it interrogates multiple genes and requires limited amounts of DNA. Its applicability to routine cytology samples might allow a significant increase in the fraction of lung cancer patients eligible for personalized therapy. [ABSTRACT FROM AUTHOR]

Simple Summary: Increasing evidence suggests that circulating cell-free DNA (cfDNA) testing might allow for monitoring the response to anti-EGFR monoclonal antibodies in patients with metastatic colorectal carcinoma (mCRC). However, few data are available in treatment-naïve patients. We tested cfDNA samples obtained from mCRC patients enrolled in a phase III trial of the anti-EGFR monoclonal antibody cetuximab plus chemotherapy as first-line treatment. Analysis of serial plasma samples revealed a complex dynamic of RAS/BRAF mutations in response to treatment, with transitory peaks of these mutations that were not associated with resistance to therapy. Overall, our findings suggest that early appearance of RAS/BRAF mutations in the plasma of patients receiving first-line anti-EGFR agents in combination with chemotherapy should not be considered as marker of resistance. Analysis of plasma-derived cell-free DNA (cfDNA) might allow for the early identification of resistance in metastatic colorectal carcinoma (mCRC) patients receiving anti-EGFR monoclonal antibodies. We tested plasma samples from the Erbitux Metastatic Colorectal Cancer Strategy (ERMES) phase III trial of FOLFIRI+Cetuximab in first-line treatment of RAS/BRAF wild-type mCRC. Samples were collected at baseline (n = 37), at 8 weeks of treatment (n = 32), progressive disease (PD; n = 36) and 3 months after PD (n = 21). cfDNA testing was performed using the Idylla™ ctKRAS and ctNRAS-BRAF tests and the Oncomine Pan-Cancer Cell-Free Assay. Analysis of basal samples revealed RAS/BRAF mutations in 6/37 cases. A transient RAS positivity not associated with PD was observed at 8 weeks in five cases that showed no mutations at baseline and PD. The frequency of mutant cases increased at PD (33.3%) and decreased again at 3 months after PD (9.5%). The median progression-free survival (mPFS) of patients RAS/BRAF mutant at PD was 7.13 months versus 7.71 months in wild-type patients (p = 0.3892). These data confirm that the occurrence of RAS/BRAF mutations in mCRC patients receiving anti-EGFR agents is relatively frequent. However, the cfDNA dynamics of RAS mutations in patients treated with anti-EGFR agents plus polychemotherapy are complex and might not be directly associated with resistance to treatment. [ABSTRACT FROM AUTHOR]

Background: Combination of chemotherapies (fluoropirimidines, oxaliplatin and irinotecan) with biologic drugs (bevacizumab, panitumumab, cetuximab) have improved clinical responses and survival of metastatic colorectal cancer (mCRC). However, patients' selection thorough the identification of predictive factors still represent a challange. Cetuximab (Erbitux®), a chimeric monoclonal antibody binding to the Epidermal Growth Factor Receptor (EGFR), belongs to the Immunoglobulins (Ig) grade 1 subclass able to elicite both in vitro and in vivo the Antibody-Dependent Cell-mediated Cytotoxicity (ADCC). ADCC is the cytotoxic killing of antibody-coated target cells by immunologic effectors. The effector cells express a receptor for the Fc portion of these antibodies (FcγR); genetic polymorphisms of FcγR modify the binding affinity with the Fc of IgG1. Interestingly, the high-affinity FcγRIIIa V/V is associated with increased ADCC in vitro and in vivo. Thus, ADCC could partially account for cetuximab activity.Methods/design: CIFRA is a single arm, open-label, phase II study assessing the activity of cetuximab in combination with irinotecan and fluorouracile in FcγRIIIa V/V patients with KRAS, NRAS, BRAF wild type mCRC. The study is designed with a two-stage Simon model based on a hypothetical higher response rate (+ 10%) of FcγRIIIa V/V patients as compared to previous trials (about 60%) assuming ADCC as one of the possible mechanisms of cetuximab action. The test power is 95%, the alpha value of the I-type error is 5%. With these assumptions the sample for passing the first stage is 14 patients with > 6 responses and the final sample is 34 patients with > 18 responses to draw positive conclusions. Secondary objectives include toxicity, responses' duration, progression-free and overall survival. Furthermore, an associated translational study will assess the patients' cetuximab-mediated ADCC and characterize the tumor microenvironment.Discussion: The CIFRA study will determine whether ADCC contributes to cetuximab activity in mCRC patients selected on an innovative immunological screening. Data from the translational study will support results' interpretation as well as provide new insights in host-tumor interactions and cetuximab activity.Trial Registration: The CIFRA trial (version 0.0, June 21, 2018) has been registered into the NIH-US National Library of Medicine, ClinicalTrials.gov database with the identifier number ( NCT03874062 ). [ABSTRACT FROM AUTHOR]