Resistance to MET inhibition in MET-dependent NSCLC and therapeutic activity after switching from type I to type II MET inhibitors

OBJECTIVES

Resistance to MET inhibition occurs inevitably in MET-dependent non-small cell lung cancer and the underlying mechanisms are insufficiently understood. We describe resistance mechanisms in patients with MET exon 14 skipping mutation (METΔ^ex14), MET amplification, and MET fusion and report treatment outcomes after switching therapy from type I to type II MET inhibitors.

MATERIALS AND METHODS

Pre- and post-treatment biopsies were analysed by NGS (next generation sequencing), digital droplet PCR (polymerase chain reaction), and FISH (fluorescense in situ hybridization). A patient-derived xenograft model was generated in one case.

RESULTS

Of 26 patients with MET tyrosine kinase inhibitor treatment, eight had paired pre- and post-treatment biopsies (Three with MET amplification, three with METΔ^ex14, two with MET fusions (KIF5B-MET and PRKAR2B-MET).) In six patients, mechanisms of resistance were detected, whereas in two cases, the cause of resistance remained unclear. We found off-target resistance mechanisms in four cases with KRAS mutations and HER2 amplifications appearing. Two patients exhibited second-site MET mutations (p.D1246N and p. Y1248H). Three patients received type I and type II MET tyrosine kinase inhibitors sequentially. In two cases, further progressive disease was seen hereafter. The patient with KIF5B-MET fusion received three different MET inhibitors and showed long-lasting stable disease and a repeated response after switching therapy, respectively.

CONCLUSION

Resistance to MET inhibition is heterogeneous with on- and off-target mechanisms occurring regardless of the initial MET aberration. Switching therapy between different types of kinase inhibitors can lead to repeated responses in cases with second-site mutations. Controlled clinical trials in this setting with larger patient numbers are needed, as evidence to date is limited to preclinical data and case series.

CBDCA + Pemetrexed + Bevacizumab and Its Maintenance Chemotherapy in a Case of Solitary Breast Metastasis from a Lung Adenocarcinoma Resistant to Gefitinib

Based on the AVAPERL trial (36th ESMO 2011), CBDCA + pemetrexed + bevacizumab and its maintenance chemotherapy with pemetrexed + bevacizumab is a new promising regimen for the treatment of advanced non-small-cell lung adenocarcinoma. Herein, we report the rare case of a patient with solitary breast metastasis from a lung adenocarcinoma, which was effectively treated using CBDCA + pemetrexed + bevacizumab and its maintenance chemotherapy. A 57-year-old female was admitted to the hospital due to pleural effusion and cardiac tamponade caused by a lung adenocarcinoma possessing a mutation of the epidermal growth factor receptor (EGFR) gene (deletion of exon 19). The patient was treated by first-line chemotherapy (gefitinib 250 mg/body/day) which resulted in complete response. After 12 months, carcinoembryonic antigen was gradually increasing and she complained of a right breast mass. With a core-needle biopsy, the breast tumor was pathologically diagnosed as recurrence and solitary metastasis of a lung adenocarcinoma. Further study of the second mutation of EGFR revealed a T790M mutation. The patient was treated by second-line chemotherapy [CBDCA + pemetrexed + bevacizumab (AUC 6 + 500 mg/m² + 15 mg/kg)] and its maintenance chemotherapy (pemetrexed + bevacizumab). The cases of patients with breast metastasis from other organs are very rare. Immunohistopathological analysis is very useful to diagnose whether the malignancy is primary or not. In the case of a breast tumor with present or previous malignancy, a metastatic breast tumor should be considered. Furthermore, the biopsy of the breast metastasis also revealed the second mutation of resistance to gefitinib, T790M. Of note, according to our case, CBDCA + pemetrexed + bevacizumab and its maintenance chemotherapy is feasible and well tolerated for breast metastasis from a lung adenocarcinoma which is resistant to gefitinib and possesses the T790M mutation in the EGFR gene.

MET Fusions in NSCLC: Clinicopathologic Features and Response to MET Inhibition

INTRODUCTION

MET fusions have been described only rarely in NSCLC. Thus, data on patient characteristics and treatment response are limited. We here report histopathologic data, patient demographics, and treatment outcome including response to MET tyrosine kinase inhibitor (TKI) therapy in MET fusion-positive NSCLC.

METHODS

Patients with NSCLC and MET fusions were identified mostly by RNA sequencing within the routine molecular screening program of the national Network Genomic Medicine, Germany.

RESULTS

We describe a cohort of nine patients harboring MET fusions. Among these nine patients, two patients had been reported earlier. The overall frequency was 0.29% (95% confidence interval: 0.15-0.55). The tumors were exclusively adenocarcinoma. The cohort was heterogeneous in terms of age, sex, or smoking status. We saw five different fusion partner genes (KIF5B, TRIM4, ST7, PRKAR2B, and CAPZA2) and several different breakpoints. Four patients were treated with a MET TKI leading to two partial responses, one stable disease, and one progressive disease. One patient had a BRAF V600E mutation as acquired resistance mechanism.

CONCLUSIONS

MET fusions are very rare oncogenic driver events in NSCLC and predominantly seem in adenocarcinomas. They are heterogeneous in terms of fusion partners and breakpoints. Patients with MET fusion can benefit from MET TKI therapy.

CD44-hyaluronan mediating endocytosis of iron-platinum alloy nanoparticles induces ferroptotic cell death in mesenchymal-state lung cancer cells with tyrosine kinase inhibitor resistance

While tyrosine kinase inhibitor resistance in cancer is a critical issue in the medical field, it is important for clinical testing as well, since it affects the ultimate outcome of cancer therapy. Yet, no effective solutions have been implemented till date. Clinical observations after tyrosine kinase inhibitor treatment reveal that acquired resistance inevitably limits the curative effects of non-small cell lung cancer treatment because of mutations in the epidermal growth factor receptor gene, which are accompanied by epithelial-mesenchymal transition. Here, for the first time, we report that the transmembrane glycoprotein CD44, which is associated with epithelial-mesenchymal transition, chemoresistance, and cancer progression, mediates enhanced endocytosis of iron-platinum alloy nanoparticles (FePt NPs) in the mesenchymal-state gefitinib-resistant (GR+ and M6) cells, via the binding of the CD44 ligand, hyaluronan, to the surface-absorbed hyaluronan-binding protein 2. Upon treatment with FePt NPs, there was higher cellular uptake in mesenchymal-state GR+ and M6 cells, resulting from cell death through ferroptosis and mitochondrial dysfunction, as compared to that observed in the epithelial-state cells. Mechanistically, inactivation of dihydroorotate dehydrogenase elevated the production of mitochondrial lipid peroxidation, and enhanced the cell death in the epithelial-state HCC827 cells, thereby indicating its role in defense against FePt NPs-induced ferroptosis. Furthermore, induction of ferroptosis has been shown to specifically promote the cell death of drug-tolerant "persister" cells and reverse their resistance as well. Therefore, we concluded that FePt NPs preferentially target mesenchymal drug-tolerant "persister" cells and promote ferroptosis, to overcome their resistance. STATEMENT OF SIGNIFICANCE: In the present study, we identified FePt NPs as an innovative agent for cancer treatment, particularly in mesenchymal-state cells that exhibit TKI resistance. Mesenchymal-state cancer cells showed enhanced uptake of FePt NPs via CD44-HA-mediated endocytosis, accompanied by severe cell death and mitochondrial morphology alterations, in comparison to epithelial-state cells. We further elucidated the mechanism underlying FePt NPs-induced ferroptotic cell death as via a burst of mitochondrial LPO and DHODH protein inactivation. In addition, we found that FePt NPs inhibit tumor growth in TKI-resistant mesenchymal GR+ cell-bearing mice with better efficacy than the ferroptotic inducer RSL3. Our current findings on using FePt NPs to overcome TKI resistance through ferroptosis activation may offer a alternative strategy for improved cancer treatment.

ACTR10 Overexpression Facilitates the Progression and Tyrosine Kinase Inhibitor Resistance in Hepatocellular Carcinoma

Background

In the present day, hepatocellular carcinoma (HCC) remains a formidable threat to human health. Actin-related protein 10 (ACTR10) is related to tyrosine kinase inhibitor (TKI) resistance. A comprehensive analysis of ACTR10 in HCC will further our understanding of the molecular mechanisms underlying this resistance phenomenon, shedding light on potential therapeutic strategies for combating TKI resistance in HCC.

Methods

We conducted an integration of high-throughput datasets across various centers, analyzing ACTR10 expression using the Cancer Cell Line Encyclopedia (CCLE) and assessing its implications through clustered regularly interspaced short palindromic repeats (CRISPR) knockout screen. Pathogenic mechanisms were elucidated through enrichment analysis. Prognostic assessment utilized Kaplan-Meier survival and univariate Cox analyses. An integrated analysis of gene expression profiles related to TKI in HCC was conducted, and TKI resistance mechanisms were explored through enrichment analysis. Potential therapeutic drugs were identified using the Drug Gene Budger database and molecular docking techniques.

Results

The standardized mean difference (SMD) of 0.34 (95% confidence interval (CI): 0.22 - 0.45, P < 0.05) and ACTR10-dependent growth in HCC cells confirm its upregulation in HCC. The area under the summary receiver operating characteristic (sROC) curve was 0.69, indicating moderate discriminative ability of ACTR10 in HCC patients. ACTR10 exerts its pro-cancer effect by influencing RNA splicing, mRNA processing and nucleocytoplasmic transport. A hazard ratio of 2.19 (95% CI: 1.56 - 3.08, P < 0.05) identifies ACTR10 as an independent prognostic risk factor. Additionally, the SMD of 0.88 (95% CI: 0.01 - 0.76, P < 0.05) validates ACTR10 as a TKI-resistance gene, mediating resistance via enhanced exocytosis, autophagy, and apoptosis in HCC patients. Trichostatin A emerges as a prospective targeted agent for HCC.

Conclusion

The upregulation of ACTR10 accelerates HCC progression, promotes TKI resistance, and emerges as a prospective target for the treatment of HCC.