EGFR x EGFR L858R x EGFR-Ex19del x EGFR T790M

Osimertinib is an irreversible EGFR tyrosine kinase inhibitor approved for the first-line treatment of patients with metastatic NSCLC harboring EGFR exon 19 deletions or L858R mutations. Patients treated with osimertinib invariably develop acquired resistance by mechanisms involving additional EGFR mutations, MET amplification and other pathways. There is no known involvement of the oncogenic MUC1-C protein in acquired osimertinib resistance.

H1975/EGFR(L858R/T790M) and patient-derived NSCLC cells with acquired osimertinib resistance were investigated for MUC1-C dependence in studies of EGFR pathway activation, clonogenicity and self-renewal capacity.

We demonstrate that MUC1-C is upregulated in H1975 osimertinib drug tolerant persister (DTP) cells and is necessary for activation of the EGFR pathway. H1975 cells selected for stable osimertinib resistance (H1975-OR) and MGH700-2D cells isolated from a patient with acquired osimertinib resistance are shown to be dependent on MUC1-C for induction of (i) p-EGFR, p-ERK and p-AKT, (ii) EMT, and (iii) the resistant phenotype. We report that MUC1-C is also required for p-EGFR, p-ERK and p-AKT activation and self-renewal capacity in acquired osimertinib-resistant (i) MET amplified MGH170-1D #2 cells, and (ii) MGH121 Res#2/EGFR(T790M/C797S) cells. Importantly, targeting MUC1-C in these diverse models reverses osimertinib resistance. In support of these results, high MUC1 mRNA and MUC1-C protein expression is associated with a poor prognosis for patients with EGFR mutant NSCLCs.

Our findings demonstrate that MUC1-C is a common effector of osimertinib resistance and is a potential target for the treatment of osimertinib resistant NSCLCs.

The detection of the EGFR T790M (T790M) mutation in non-small cell lung cancer (NSCLC) patients who progressed under treatment with first- or second-generation EGFR-tyrosine kinase inhibitors (TKIs) is important to offer a subsequent therapy with a third-generation EGFR-TKI. Liquid biopsy is a powerful tool to determine the T790M mutation status. Several liquid biopsy platforms with varying degrees of accuracy are available to test for T790M mutations, and sensitivities may differ among these methods.

As no standard exists for the testing of T790M mutation in liquid biopsy, we performed a collaborative study to describe and compare the sensitivity of different in-house liquid biopsy platforms for the detection of the T790M mutation, EGFR exon 19 deletion (del19) and EGFR L858R mutation (L858R) across multiple participating laboratories in seven Central and Eastern European countries.

Of the 25 invited laboratories across Central and Eastern Europe, 21 centers participated and received 10 plasma samples spiked with cell-line DNA containing the T790M, del19, or L858R mutation in different concentrations. In-house PCR-based and NGS-based methods were used accordingly, and results were reported as in routine clinical practice. Two laboratories, which used the AmoyDx^® EGFR 29 Mutations Detection Kit (AmoyDx) with Cobas^® cfDNA Sample Preparation Kit and QX200 Droplet Digital PCR (ddPCR) with the QIAamp Circulating Nucleic Acid Kit identified all ten samples correctly. Cobas^® EGFR Mutation Test v2 (Cobas), the NGS methods, and the Idylla^TM detection method used in this study performed within the known sensitivity range of each detection method.

If a negative result was obtained from methods with lower sensitivity (e.g., Cobas), repeated liquid biopsy testing and/or tissue biopsy analysis should be performed whenever possible, to identify T790M-positive patients to allow them to receive the optimal second-line treatment with a third-generation EGFR TKI.

In China, there has never been a comprehensive analysis of lung cancer-associated genetic mutations focused on ethnic minorities in the southwestern region. Our study aimed to provide valuable information on lung cancer-associated genetic alterations for cancer diagnosis and treatment, especially in ethnic minorities.

Retrospective data acquisition was conducted spanning 3 years (2016.01-2019.06) among all patients who were diagnosed with lung cancer at the Third Affiliated Hospital of Kunming Medical University Hospital. A total of 5,167 patients including 373 ethnic minorities were included in this study. Propensity score matching (PSM) was used to eliminate the bias between Han and other ethnic minorities, including gender, age, smoking history, metastasis status, clinical stage, histological type, sample type, region, and Xuanwei origin. All tests were two-tailed, and significance was defined as P less than 0.05.

In terms of the prevalence of EGFR, EGFR L858R, EGFR T790M, ROS1, RET, MET, BRAF, and ERBB2 mutations, there was no significant difference among ethnic groups in Yunnan Province (P>0.05). A higher proportion of EGFR 19 deletion was observed in Hui patients with lung cancer compared with patients of other ethnicities in Yunnan (P=0.048). The prevalence of KRAS mutations was higher in Hani (17.65%, 3/17) and Han patients (11.44%, 80/699) than that in other Yunnan ethnicities (6.04%, 9/149; P=0.07). In Hui patients, ALK fusion was correlated with a history of non-smoking and male gender. In Bai patients, BRAF mutation was also correlated with a history of non-smoking. In all ethnic groups, EGFR mutation was more frequent in women.

This study is the first in-depth large case-control study on genetic mutation profiles among multi-ethnic patients in southwestern China, especially focused on ethnic minorities in this area. Our study may facilitate the understanding of the etiology of this malignant disease and consequently help to reduce the incidence of lung cancer in Yunnan ethnic minority areas.