Overcoming AZD9291 Resistance and Metastasis of NSCLC via Ferroptosis and Multitarget Interference by Nanocatalytic Sensitizer Plus AHP-DRI-12.

The acquired resistance to Osimertinib (AZD9291) greatly limits the clinical benefit of patients with non-small cell lung cancer (NSCLC), whereas AZD9291-resistant NSCLCs are prone to metastasis. It's challenging to overcome AZD9291 resistance and suppress metastasis of NSCLC simultaneously. Here, a nanocatalytic sensitizer (VF/S/A@CaP) is proposed to deliver Vitamin c (Vc)-Fe(II), si-OTUB2, ASO-MALAT1, resulting in efficient inhibition of tumor growth and metastasis of NSCLC by synergizing with AHP-DRI-12, an anti-hematogenous metastasis inhibitor by blocking the amyloid precursor protein (APP)/death receptor 6 (DR6) interaction designed by our lab. Fe2+ released from Vc-Fe(II) generates cytotoxic hydroxyl radicals (•OH) through Fenton reaction. Subsequently, glutathione peroxidase 4 (GPX4) is consumed to sensitize AZD9291-resistant NSCLCs with high mesenchymal state to ferroptosis due to the glutathione (GSH) depletion caused by Vc/dehydroascorbic acid (DHA) conversion. By screening NSCLC patients' samples, metastasis-related targets (OTUB2, LncRNA MALAT1) are confirmed. Accordingly, the dual-target knockdown plus AHP-DRI-12 significantly suppresses the metastasis of AZD9291-resistant NSCLC. Such modality leads to 91.39% tumor inhibition rate in patient-derived xenograft (PDX) models. Collectively, this study highlights the vulnerability to ferroptosis of AZD9291-resistant tumors and confirms the potential of this nanocatalytic-medicine-based modality to overcome critical AZD9291 resistance and inhibit metastasis of NSCLC simultaneously.

Dual blockade of EGFR and PI3K signaling pathways offers a therapeutic strategy for glioblastoma.

BACKGROUND: Glioblastoma multiforme (GBM) is a devastating disease that lacks effective drugs for targeted therapy. Previously, we found that the third-generation epidermal growth factor receptor (EGFR) inhibitor AZD-9291 persistently blocked the activation of the ERK pathway but had no inhibitory effect on the phosphoinositide 3-kinase (PI3K)/Akt pathway. Given that the PI3K inhibitor GDC-0084 is being evaluated in phase I/II clinical trials of GBM treatment, we hypothesized that combined inhibition of the EGFR/ERK and PI3K/Akt pathways may have a synergistic effect in the treatment of GBM. METHODS: The synergistic effects of cotreatment with AZD-9291 and GDC-0084 were validated using cell viability assays in GBM and primary GBM cell lines. Moreover, the underlying inhibitory mechanisms were assessed through colony formation, EdU proliferation, and cell cycle assays, as well as RNA-seq analyses and western blot. The therapeutic effects of the drug combination on tumor growth and survival were investigated in mice bearing tumors using subcutaneously or intracranially injected LN229 xenografts. RESULTS: Combined treatment with AZD-9291 and GDC-0084 synergistically inhibited the proliferation and clonogenic survival, as well as induced cell cycle arrest of GBM cells and primary GBM cells, compared to monotherapy. Moreover, AZD-9291 plus GDC-0084 combination therapy significantly inhibited the growth of subcutaneous tumors and orthotopic brain tumor xenografts, thus prolonging the survival of tumor-bearing mice. More importantly, the combination of AZD-9291 and GDC-0084 simultaneously blocked the activation of the EGFR/MEK/ERK and PI3K/AKT/mTOR signaling pathways, thereby exerting significant antitumor activity. CONCLUSION: Our findings demonstrate that the combined blockade of the EGFR/MEK/ERK and PI3K/AKT/mTOR pathways is more effective against GBM than inhibition of each pathway alone, both in vitro and in vivo. Our results suggest that AZD-9291 combined with GDC-0084 may be considered as a potential treatment strategy in future clinical trials. Video Abstract.

Design, synthesis and biological evaluation of novel tumor hypoxia-activated EGFR tyrosine kinase inhibitors.

Hypoxia is widespread in solid tumors, such as NSCLC, and has become a very attractive target. On the basis of AZD9291 scaffold, novel hypoxia-targeted EGFR inhibitors without the acrylamide warhead but containing hypoxic reductive activation groups were described. Among them, compound JT21 exhibited impressive inhibitory activity (IC50 = 23 nM) against EGFRL858R/T790M and displayed about 21-fold inhibitory activity decrease against EGFRwt. Under hypoxia, JT21 exhibited more significant proliferation inhibitory activities against H1975 cells (IC50 = 7.39 ± 2.20 nM) and HCC827 cells (IC50 = 5.88 ± 0.85 nM) than that of AZD9291, which was about 5 times more effective than normoxia activities. Meanwhile, the weak inhibition effects on A549 and BEAS-2B cells suggested JT21 might be a selective inhibitor for EGFR mutations with low toxicity. Furthermore, JT21 could induce apoptosis of H1975 cells under hypoxia and showed good bio-reductive property.

Elevated exosome-derived miRNAs predict osimertinib resistance in non-small cell lung cancer.

BACKGROUND: Non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutations will inevitably develop drug resistance after being treated with the third-generation EGFR-tyrosine kinase inhibitor (TKI), osimertinib. Recently, the drug resistance information transmitted by exosomal miRNAs has attracted much attention. However, the mechanism of exosome-derived miRNAs in osimertinib resistance remains unexplored. METHODS: We extracted and sequenced exosomes from the supernatant of the osimertinib-resistant cell line, H1975-OR, and the sensitive cell line, H1975. The results were compared with plasma exosome sequencing before and after the appearance of drug resistance in three NSCLC clinical patients treated with oral osimertinib. Exosome-derived miRNAs that had significantly increased expression levels after osimertinib resistance were screened for expanded validation in other 64 NSCLC patients. RESULTS: Cluster analysis of the target genes revealed that exosomal miRNAs participate in osimertinib resistance mechanisms through the activation of bypass pathways (RAS-MAPK pathway abnormality and PI3K pathway activation). Exosome-derived miR-184 and miR-3913-5p expression levels increased significantly after the onset of osimertinib resistance. Exosomal miR-3913-5p was associated with TNM stage, platelet count, tumor marker carcinoembryonic antigen, and distant metastases. In patients with EGFR exon 21 L858R mutation, the increased expression levels of miR-184 and miR-3913-5p derived from serum exosomes indicated osimertinib resistance. Similarly, for T790M-positive patients, the level of exosome-derived miR-3913-5p can be used as a predictive marker for osimertinib resistance. CONCLUSIONS: The expression levels of miR-184 and miR-3913-5p derived from exosomes in the peripheral blood of NSCLC patients could be used as biomarkers to indicate osimertinib resistance.

AZD9291 promotes autophagy and inhibits PI3K/Akt pathway in NSCLC cancer cells.

AZD9291, a third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), is highly selective against EGFR T790M-mutant non-small cell lung cancer (NSCLC). On investigating the growth inhibitory effects of AZD9291 on NSCLC and the underlying mechanism, we found that AZD9291 can trigger autophagy-mediated cell death in both A549 and H1975 cells by increasing the expression of phosphatidylethanolamine-modified microtubule-associated protein light-chain 3 (LC3) and decreasing the expression of p62. In the presence of the autophagy inhibitor chloroquine, the AZD9291-induced increase in LC3 level was further augmented. AZD9291 decreased the levels of phosphoinositide-3 kinase (PI3K), protein kinase B (Akt), and phosphorylated Akt. AZD9291-induced cell death was enhanced by Akt knockdown, and the levels of both EGFR and phosphorylated EGFR were decreased by AZD9291. AZD9291 was also found to significantly suppress the tumor growth in H1975 xenograft nude mice. Thus, AZD9291 was found to induce autophagy, decrease in EGFR levels, and show a strong inhibitory effect on NSCLC both in vitro and in vivo. Furthermore, the PI3K/Akt signaling pathway was found to play a critical role in AZD9291-induced cell death.

Interaction and molecular dynamics simulation study of Osimertinib (AstraZeneca 9291) anticancer drug with the EGFR kinase domain in native protein and mutated L844V and C797S.

BACKGROUND: Targeted therapy is a novel, promising approach to anticancer treatment that endeavors to overcome drug resistance to traditional chemotherapies. Patients with the L858R mutation in epidermal growth factor receptor (EGFR) respond to the first generation tyrosine kinase inhibitors (TKIs); however, after one year of treatment, they may become resistant. The T790M mutation is the most probable cause for drug resistance. Third generation drugs, including Osimertinib (AZD9291), are more effective against T790M and other sensitive mutations. Osimertinib is effective against the L844V mutation, has conditional effectiveness for the L718Q mutation, and is ineffective for the Cys797Ser (C797S) mutation. Cells that have both the T790M and C797 mutations are more resistant to third generation drugs. Although research has shown that Osimertinib is an effective treatment for EGFR L844V cells, this has not been shown for cells that have the C797S mutation. This molecular mechanism has not been well-studied. METHODS: In the present study, we used the GROMACS software for molecular dynamics simulation to identify interactions between Osimertinib and the kinase part of EGFR in L844V and C797S mutants. RESULTS: We evaluated native EGFR protein and the L844V and C797S mutations' docking and binding energy, kI, intermolecular, internal, and torsional energy parameters. Osimertinib was effective for the EGFR L844V mutation, but not for EGFR C797S. All simulations were validated by root-mean-square deviation (RMSD), root-mean square fluctuation (RMSF), and radius of gyration (ROG). CONCLUSION: According to our computational simulation, the results supported the experimental models and, therefore, could confirm and predict the molecular mechanism of drug efficacy.

SHR-A1403, a novel c-mesenchymal-epithelial transition factor (c-Met) antibody-drug conjugate, overcomes AZD9291 resistance in non-small cell lung cancer cells overexpressing c-Met.

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI) have been used as the first-line treatment of non-small cell lung cancers (NSCLC) harboring EGFR-activating mutations, but acquired resistance is ubiquitous and needs to be solved urgently. Here, we introduce an effective approach for overcoming resistance to the EGFR-TKI, AZD9291, in NSCLC cells using SHR-A1403, a novel c-mesenchymal-epithelial transition factor (c-Met)-targeting antibody-drug conjugate (ADC) consisting of an anti-c-Met monoclonal antibody (c-Met mAb) conjugated to a microtubule inhibitor. Resistant cells were established by exposing HCC827 to increasing concentrations of EGFR-TKI. c-Met was found to be overexpressed in most resistant cells. AZD9291 resistance was partially restored by combination of AZD9291 and crizotinib only in resistant cells overexpressing phospho-c-Met, which synergistically inhibited c-Met-mediated phosphorylation of the downstream targets ERK1/2 and AKT. In resistant cells overexpressing c-Met, neither crizotinib nor c-Met mAb was able to overcome AZD9291 resistance. In contrast, SHR-A1403 strongly inhibited proliferation of AZD9291-resistant HCC827 overexpressing c-Met, regardless of the levels of c-Met phosphorylation. SHR-A1403 bound to resistant cells overexpressing c-Met was internalized into cells and released associated microtubule inhibitor, resulting in cell-killing activity that was dependent on c-Met expression levels only, irrespective of the involvement of c-Met or EGFR signaling in AZD9291 resistance. Consistent with its activity in vitro, SHR-A1403 significantly inhibited the growth of AZD9291-resistant HCC827 tumors and caused tumor regression in vivo. Thus, our findings show that SHR-A1403 efficiently overcomes AZD9291 resistance in cells overexpressing c-Met, and further indicate that c-Met expression level is a biomarker predictive of SHR-A1403 efficacy.

Osimertinib in patients with T790M mutation-positive, advanced non-small cell lung cancer: Long-term follow-up from a pooled analysis of 2 phase 2 studies.

BACKGROUND: Osimertinib is a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) that is selective for both EGFR-TKI-sensitizing and T790M (threonine-to-methionine substitution at codon 790)-resistance mutations. The authors present long-term follow-up data from a preplanned, pooled analysis of phase 2 studies, the AZD9291 First Time in Patients Ascending Dose Study (AURA) extension trial (clincialtrials.gov identifier NCT01802632) and the AURA2 trial (NCT02094261). METHODS: Patients with centrally confirmed, T790M mutation-positive, advanced non-small cell lung cancer received osimertinib 80 mg once daily until disease progression or study discontinuation. Response was assessed by a blinded, independent, central review using Response Evaluation Criteria in Solid Tumors, version 1.1. The primary endpoint was the objective response rate. RESULTS: In total, 411 patients received osimertinib (second line, 129 patients; third line or later, 282 patients). At the data cutoff date of November 1, 2016, the median treatment exposure was 16.4 months (range, 0-29.7 months), the objective response rate was 66% (95% confidence interval [CI], 61%-70%), the median response duration was 12.3 months (95% CI, 11.1-13.8 months), and the median progression-free survival was 9.9 months (95% CI, 9.5-12.3 months). At the data cutoff date of May 1, 2018, 271 patients (66%) had died, and 140 patients (34%) had discontinued before death. The median overall survival was 26.8 months (95% CI, 24.0-29.1 months); and the 12-month, 24-month, and 36-month survival rates were 80%, 55%, and 37%, respectively. Grade ≥3 possibly causally related (investigator assessed) adverse events were reported in 65 patients (16%), and the most common were rash (grouped terms; 42%; grade ≥3, 1%) and diarrhea (39%; <1%). CONCLUSIONS: This pooled analysis represents the most mature clinical trial data for osimertinib in patients with pretreated, T790M-positive, advanced non-small cell lung cancer, further establishing osimertinib as a standard of care for this patient population.

Role of osimertinib in the treatment of EGFR-mutation positive non-small-cell lung cancer.

Mutations in the EGFR occur in approximately 10-35% of non-small-cell lung cancer (NSCLC) patients. Osimertinib is a third-generation oral small molecule inhibitor of EGFR, active against the common targetable activating EGFR mutations in L858R and exon 19 deletion; it also inhibits the T790M mutation. It was initially developed and approved for the treatment of acquired resistance to EGFR inhibition mediated by the T790M pathway activation. Recently, the FLAURA trial showed significantly improved progression-free survival with osimertinib compared with the first generation EGFR tyrosine kinase inhibitors gefitinib or erlotinib; this has led to its approval by US FDA and European Medicines Agency (EMA) as frontline therapy. Ongoing studies will define the resistance mechanisms to osimertinib, novel combination approaches and role in earlier stages of NSCLC.

Identification of osimertinib (AZD9291) as a lysine specific demethylase 1 inhibitor.

Osimertinib (AZD9291) is a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) that has been approved for the treatment of EGFR-mutated non-small cell lung cancer (NSCLC). In this study, osimertinib was characterized as a LSD1 inhibitor for the first time with an IC50 of 3.98 ±â€¯0.3 µM and showed LSD1 inhibitory effect at cellular level. These findings provide new molecular skeleton for dual inhibitor for LSD1 and EGFR. Osimertinib could serve as a lead compound for further development for anti-NSCLC drug discovery with dual targeting.

AZD9291 inactivates the PRC2 complex to mediate tumor growth inhibition.

Deregulated Polycomb repressive complex 2 (PRC2) is intimately involved in tumorigenesis and progression, making it an invaluable target for epigenetic cancer therapy. Disrupting the EZH2-EED interaction, which is required for PRC2 enzymatic activity, is a promising strategy for cancer treatment. However, this kind of inhibitors are still limited. The in-cell protein-protein interaction screening was conducted for approximately 1300 compounds by NanoBRET technology. Co-immunoprecipitation (Co-IP), protein thermal shift assay (PTSA), and cellular thermal shift assay (CETSA) were performed to investigate the regulation of PRC2 by AZD9291. The anti-tumor effects of AZD9291 on breast cancer (BC) cells and diffuse large B-cell lymphoma (DLBCL) cells were detected. MicroRNA array assay, luciferase reporter assay, and qRT-PCR were conducted to identify the interaction and regulation among AZD9291, EZH2, and miR-34a. We discovered that, AZD9291, a potent and selective EGFR inhibitor, disrupted the interaction of EZH2-EED, leading to impairment of PRC2 activity and downregulation of EZH2 protein. In addition, AZD9291 declined EZH2 mRNA expression via upregulating the expression of a tumor suppressor, miR-34a. Our results suggest that AZD9291 can serve as a lead compound for further development of antagonist of PRC2 protein-protein interactions and EZH2 mRNA may be a direct target of miR-34a through non-canonical base pairing.

Overcoming acquired resistance of gefitinib in lung cancer cells without T790M by AZD9291 or Twist1 knockdown in vitro and in vivo.

The T790M mutation is recognized as a typical mechanism of acquired resistance to first generation of epithermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) such as gefitinib in non-small cell lung cancer (NSCLC) patients who are commonly treated by third generation of EGFR-TKI AZD9291 (osimertinib). However, the therapeutic strategy for overcoming acquired resistance to EGFR-TKIs in NSCLC patients without T790M remains to be definitively determined. In the present study, gefitinib-resistant H1650 (H1650GR) or AZD9291-resistant H1975 (H1975AR) was generated by exposing NSCLC cell line H1650 or H1975 to progressively increased concentrations of gefitinib or AZD9291 over 11 months. The cytotoxic effects of gefitinib or AZD9291 in vitro were evaluated via the half maximal inhibitory concentrations (IC50s) determined by the MTT assay. IC50 of gefitinib in H1650GR (50.0 ± 3.0 µM) significantly increased compared with H1650 (31.0 ± 1.0 µM) (p < 0.05). Similarly, the IC50 of AZD9291 in H1975AR (10.3 ± 0.9 µM) significantly increased compared with H1975 (5.5 ± 0.6 µM) (p < 0.05). However, IC50 of AZD9291 on H1650GR (8.5 ± 0.5 µM) did not increase compared with H1650 (9.7 ± 0.7 µM). On the other hand, IC50 of AZD9291 on gefitinib-resistant A549 (A549GR established in our previous study) (12.7 ± 0.8 µM) was significantly increased compared with A549 (7.0 ± 1.0 µM) (p < 0.05). AZD9291 induced caspase 3/7 activation in A549, H1650, and H1650GR, but not in A549GR. Western blot analyses showed that p-Akt played a key role in determining the sensitivities of A549, A549GR, H1650, and H1650GR to gefitinib or AZD9291. Additionally, increased expression of Twist1 was observed in all cells with acquired EGFR-TKI resistance and knockdown of Twist1 by shRNA was found to significantly enhance the sensitivity of A549GR to gefitinib or AZD9291 via reversing epithelial-mesenchymal transition and downregulating p-Akt, but not of H1975AR to AZD9291. The enhanced cytotoxic effect of AZD9291 on A549GR by Twist1 knockdown in vitro was further validated by in vivo studies which showed that Twist1 knockdown could lead to significantly delayed tumor growth of A549GR xenograft with increased sensitivity to AZD9291 treatment in nude mice without any observed side toxic effects. In summary, our study demonstrated that the mechanisms of acquired resistance in different NSCLC cell lines treated by even the same EGFR-TKI might be quite different, which provide a rationale for adopting different therapeutic strategies for those NSCLC patients with acquired EGFR-TKI resistance based on different status of heterogeneous mutations.

Osimertinib induces autophagy and apoptosis via reactive oxygen species generation in non-small cell lung cancer cells.

Osimertinib (OSI), also known as AZD9291, is a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor that has been approved for the treatment of non-small cell lung cancer (NSCLC) patients harboring EGFR T790M mutation. Herein, we indicated for the first time that OSI increased the accumulations of cytoplasmic vacuoles, the expression of phosphatidylethanolamine-modified microtubule-associated protein light-chain 3 (LC3-II), and the formation of GFP-LC3 puncta in various cancer cells. The OSI-induced expression of LC3-II was further increased when combined treatment with chloroquine (CQ), an autophagy inhibitor, and the mRFP-EGFP-LC3 plasmid-transfected cells exposed to OSI led to the production of more red-fluorescent puncta than green-fluorescent puncta, indicating OSI induced autophagic flux in the NSCLC cells. Knockdown of EGFR showed no effect on the OSI-induced expression of LC3-II in NCI-H1975 cells. In addition, OSI increased reactive oxygen species (ROS) generation and scavenge of ROS via pretreatment with N-acetyl-l-cysteine (NAC), catalase (CAT), or vitamin E (Vita E) significantly inhibited OSI-induced the accumulations of cytoplasmic vacuoles, the expression of LC3-II, as well as the formation of GFP-LC3 puncta. Combinative treatment with CQ could not remarkably change the OSI-induced cell viability decrease, whereas the OSI-induced cell viability decrease and apoptosis could be reversed through pretreatment with NAC, CAT, and Vita E, respectively. Taken together, this is the first report that OSI induces an accompanied autophagy and the generation of ROS is critical for the OSI-induced autophagy, cell viability decrease, and apoptosis in NSCLC cells.

AZD9291 overcomes T790 M-mediated resistance through degradation of EGFR(L858R/T790M) in non-small cell lung cancer cells.

The discovery of activating mutations of epidermal growth factor receptor (EGFR) has resulted in the development of more effective treatments for non-small cell lung cancer (NSCLC). Although first-generation EGFR tyrosine kinase inhibitors (EGFR TKIs) provide significant clinical benefit, acquired resistance often occurs, most commonly (>50 %) via a T790 M resistance mutation. Although AZD9291 is selective for both T790 M and activating EGFR mutations over wild-type EGFR, it is highly active when T790 M is present, especially EGFR(L858R/T790M), and modestly active when T790 M is absent. The aim of this study was to elucidate the underlying mechanism of the high sensitivity of NSCLC cells harboring EGFR(L858R/T790M) to AZD9291. In H1975 cells harboring EGFR(L858R/T790M), AZD9291 potently inhibited cellular growth and EGFR signaling pathways together with depletion of mutant EGFR protein. AZD9291-induced depletion of EGFR(L858R/T790M) protein was abrogated through inhibition of the proteasome with MG132. However, AZD9291 had no effect on protein levels of EGFR(WT) and EGFR(L858R). In addition, AZD9291 induced apoptosis and caused expression changes in cell cycle-related genes. Moreover, oral administration of AZD9291 as a single agent induced tumor regression in vivo in a H1975 tumor xenograft model and reduced EGFR(L858R/T790M) protein levels in xenograft tumors. Taken together, our results provide a potential mechanism for the sensitivity of EGFR(L858R/T790M) cells to AZD9291 and suggest that AZD9291 may be effective in cases of T790 M-positive EGFR resistance.

Osimertinib (AZD9291) Attenuates the Function of Multidrug Resistance-Linked ATP-Binding Cassette Transporter ABCB1 in Vitro.

The effectiveness of cancer chemotherapy is often circumvented by multidrug resistance (MDR) caused by the overexpression of ATP-binding cassette (ABC) drug transporter ABCB1 (MDR1, P-glycoprotein). Several epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have been shown previously capable of modulating the function of ABCB1 and reversing ABCB1-mediated MDR in human cancer cells. Furthermore, some TKIs are transported by ABCB1, which results in low oral bioavailability, reduced distribution, and the development of acquired resistance to these TKIs. In this study, we investigated the interaction between ABCB1 and osimertinib, a novel selective, irreversible third-generation EGFR TKI that has recently been approved by the U.S. Food and Drug Administration. We also evaluated the potential impact of ABCB1 on the efficacy of osimertinib in cancer cells, which can present a therapeutic challenge to clinicians in the future. We revealed that although osimertinib stimulates the ATPase activity of ABCB1, overexpression of ABCB1 does not confer resistance to osimertinib. Our results suggest that it is unlikely that the overexpression of ABCB1 can be a major contributor to the development of osimertinib resistance in cancer patients. More significantly, we revealed an additional action of osimertinib that directly inhibits the function of ABCB1 without affecting the expression level of ABCB1, enhances drug-induced apoptosis, and reverses the MDR phenotype in ABCB1-overexpressing cancer cells. Considering that osimertinib is a clinically approved third-generation EGFR TKI, our findings suggest that a combination therapy with osimertinib and conventional anticancer drugs may be beneficial to patients with MDR tumors.

The next generation of epidermal growth factor receptor tyrosine kinase inhibitors in the treatment of lung cancer.

The discovery of "driver" genomic alterations in patients with non-small cell lung cancer (NSCLC) has dramatically changed the field of thoracic oncology in recent years. The best understood of these molecular drivers are those involving the epidermal growth factor receptor (EGFR), which when aberrantly activated are integral to the development of a subset of NSCLC tumors. First-generation and second-generation tyrosine kinase inhibitors (TKIs) specific to the activated EGFR have shown significant efficacy and have brought about the era of targeted therapy for NSCLC. The most common resistance mechanism is a threonine-to-methionine substitution (T790M) in exon 20 of the EGFR gene. Although the previous standard of care in patients with EGFR-mutated NSCLC that progressed on initial TKI therapy was chemotherapy, third-generation EGFR TKIs have now been developed and have yielded promising results for this population of patients with NSCLC. This article reviews the emerging data regarding third-generation agents in the treatment of patients with advanced NSCLC.

EGFR-independent mechanisms of acquired resistance to AZD9291 in EGFR T790M-positive NSCLC patients.

BACKGROUND: AZD9291 is an oral, irreversible, mutant-selective epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (EGFR-TKI), which specifically targets both sensitizing and resistant T790M mutations. This compound has shown outstanding activity, in a phase I/II (AURA) trial. However, despite impressive tumor responses in T790M-positive patients, acquired resistance to this drug limits the benefit of this compound. Mutations at the EGFR C797 codon, located within the kinase-binding site, were very recently reported to be a potential mechanism of resistance to AZD9291 in T790M-positive patients. PATIENTS AND METHODS: To identify potential mechanisms of resistance to AZD9291, we report here on two patients with resistant biopsy specimens that had been treated with AZD9291. RESULTS: We identified in two distinct cases, HER2 and MET amplification by FISH and CGH as a potential mechanism of acquired resistance to third-generation EGFR-TKI. Interestingly, this event occurred with complete loss of the T790M mutation. In one case, we observed a different molecular status at two biopsy sites (the T790M mutation at the primary site and wild-type T790M at the metastatic site with different pathways of acquired resistance to AZD9291). CONCLUSION: Our observations suggest that T790M-positive and wild-type T790M clones may coexist at baseline. AZD9291 efficiently suppresses the growth of T790M-positive cells, but a population of wild-type T790M cells at baseline will mediate the development of resistance, here via a by-pass pathway activating either HER2 or MET.

AZD9291 in EGFR-mutant advanced non-small-cell lung cancer patients.

Non-small-cell lung cancer (NSCLC) patients whose tumors have an EGFR-activating mutation develop acquired resistance after a median of 9-11 months from the beginning of treatment with erlotinib, gefitinib and afatinib. T790M mutation is the cause of this resistance in approximately 60% of cases. AZD9291 is an oral, irreversible, mutant-selective EGF receptor (EGFR) tyrosine kinase inhibitor (TKI) developed to have potency against EGFR mutations, including T790M mutation, while sparing wild-type EGFR. A Phase I trial of AZD9291 in EGFR-mutant NSCLC patients, demonstrated high activity, essentially among T790M-mutant tumors, with a manageable tolerability profile. Ongoing Phase III trials are evaluating AZD9291 in EGFR-mutant patients as first-line treatment compared with erlotinib and gefitinib; and as second-line treatment compared with chemotherapy after progression on EGFR TKI in T790M-mutant tumors. Better identification of T790M-mutant tumors post EGFR TKI relapse and mechanisms of resistance to AZD9291 are the future challenges. This article reviews the emerging data regarding AZD9291 in the treatment of patients with advanced NSCLC.

Construction of chitooligosaccharide-based nanoparticles of pH/redox cascade responsive for co-loading cyclosporin A and AZD9291.

AZD9291 can prolong the survival of patients with non-small cell lung cancer. Unfortunately, resistance to AZD9291 is inevitable and hinders effectiveness. Studies showed the combination of Cyclosporin A (CsA) and AZD9291 could increase the efficacy of AZD9291, but the delivery efficiency of free drugs was limited. A chitooligosaccharide (COS) -based nanoparticle with enhanced delivery efficiency and endocytosis was constructed in this study. The results showed that this pH/redox cascade responsive nanoparticles improved therapeutic effect. The system is small and the surface charge changed from negative to positive according to the weakly acidic tumor microenvironment. After endocytosis, the nanoparticles decomposed and released AZD9291 and CsA in redox-rich cytoplasm. Experiments in vitro and in vivo proved that the nanoparticles overcame the biological barrier and significantly enhanced the anti-tumor effect of AZD9291. The novel multifunctional nanoparticle provides a way to overcome the drug resistance and the possibility of clinical application.

[AZD9291 suppresses proliferation and migration of nasopharyngeal carcinoma cells by inhibiting the PI3K-AKT-mTOR pathway].

OBJECTIVE: To investigate the effects of AZD9291 on the proliferation and migration of nasopharyngeal carcinoma cells. METHODS: Nasopharyngeal carcinoma HNE1 and CNE2Z cells were treated with AZD9291 at the doses of 0.5, 1, 2, 4, and 8 µmol/L and at the doses of 1, 2, 4, 8, and 16 µmol/L, respectively. Cell survival was measured using CCK8 assay, and proliferation inhibition of the cells after AZD9291 treatment was examined with colony-forming assay; the cell repair and migration abilities were determined using scratch assay and Transwell experiment. The expressions of EGFR-related signaling proteins and migration-related proteins were detected using Western blotting. RESULTS: The results of CCK8 assay and colonyforming assay showed that AZD9291 significantly inhibited the viability and proliferation of both HNE1 and CNE2Z cells (P < 0.01). AZD9291 treatment also attenuated the migration ability of HNE1 and CNE2Z cells (P < 0.01). Western blotting showed that, as the concentration of AZD9291 increased, the expression levels of the proteins involved in the PI3K-AKT-mTOR signaling pathway were lowered progressively (P < 0.01), resulting in inhibition of migration of HNE1 and CNE2Z cells (P < 0.01). CONCLUSION: AZD9291 suppresses proliferation and attenuates repair and migration capacities of nasopharyngeal carcinoma cells by inhibiting the EGFR/PI3K/AKT/mTOR signaling pathway, suggesting the potential value of AZD9291 in the treatment of nasopharyngeal carcinoma.