Osimertinib-resistant Cells Research Articles

AX-0085, a novel AXL kinase inhibitor, and effects on osimertinib-resistance in non–small-cell lung cancer.

e15121 Background: Osimertinib is a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) having high efficacy in treating patients with advanced non-small cell lung cancer (NSCLC) with EGFR activating mutations and EGFR T70M mutations. Although, osimertinib is a frontline anticancer agent for treating NSCLC, many patients inevitably develop osimertinib-resistance tumor recurrence. The activation of AXL was reported to be a major factor driving osimertinib-resistance in NSCLC. Thus, AXL is a promising therapeutic target for the treatment of osimertinib-resistant NSCLC, and we developed a new small-molecule AXL inhibitor, AX-0085. Methods: We established osimertinib-resistant cell lines from EGFR-mutated NSCLC cell lines, HCC827 and H1975, after high dose exposure and stepwise exposure to osimertinib in culture. We investigated the cell viability of AX-0085 and other kinase inhibitors, and the anti-tumor activity of AX-0085 on the proliferation, migration, apoptosis, and epithelial-mesenchymal transition (EMT) in osimertinib-resistant cells. Results: Compared to the parental cells, IC50 of resistant cell to osimertinib was significantly increased and osimertinib-resistant cells showed remarkably increased expression of AXL/pAXL and p-SRC as compared to the parental HCC827 cell. AX-0085 was completely blocked the AXL and SRC activation but EGFR inhibitors (gefitinib and osimertinib) did not inhibit the activation of AXL and SRC in the osimertinib-resistant cell line. AX-0085 (IC50: 4.4nM for AXL kinase in cell-based kinase assay) was one of the most potent AXL inhibitors and showed the strongest cytotoxicity against osimertinib-resistant cells compared to other kinase inhibitors. AX-0085 effectively down-regulated mRNA level of AXL and AXL regulating transcription factors in NSCLC cell lines such as HCC827 and H1975. AX-0085 treatment effectively inhibited the activation of AXL in acquired osimertinib-resistant cells and decreased the mRNA level of AXL and AXL regulating transcription factors. AX-0085 significantly inhibited the cell proliferation, apoptosis, migration, and EMT in acquired osimertinib-resistant cells. Conclusions: Our results showed that AX-0085 selectively inhibits the activation of AXL to overcome acquired resistance to osimertinib, suggesting an effective AXL-based therapy for patients with osimertinib-resistant tumors. Currently, AX-0085 is undergoing non-clinical trials.

Biological Electric Fields Guide Directional Migration and Promote Epithelial–Mesenchymal Transition in Lung Cancer

Background: Endogenous direct-current electric fields (dcEFs), as one of the essential biophysical signals that naturally occur in the tumor microenvironment, were previously demonstrated to suppress the cytotoxicity of the third-generation tyrosine kinase inhibitor osimertinib in epidermal growth factor receptor (EGFR)-mutant lung cancer. Materials and Methods: In the current study, we further investigated the electrotactic response of EGFR-mutant lung cancer with different osimertinib sensitivity, including osimertinib-sensitive PC-9GR cells and osimertinib-resistant PC-9GROR cells. Results: Firstly, in murine subcutaneous xenografts, robust endogenous electric currents were detected at the surface of tumors derived from osimertinib-resistant cells with a highly sensitive vibrating probe. Next, the electrotactic responses of two cell lines under EFs of different intensities were studied. Both PC-9GR and PC-9GROR cells exhibited directionally cathodal migration in a voltage-dependent manner, and osimertinib-resistant PC-9GROR cells displayed higher migration speeds. Epithelial-mesenchymal transition (EMT), which was previously reported to be closely related to tumor invasion and metastasis and could be suppressed by osimertinib, was enhanced under EF stimulation as reflected by increased vimentin and decreased E-cadherin in PC-9GR cells via western blotting and immunofluorescent staining regardless of osimertinib treatment. Additionally, pharmacological inhibition of phosphoinositide 3-kinase/protein kinase B (AKT) signals reduced electrotaxis and EMT. Conclusion: Taken together, these results suggested that activation of AKT pathway may play an important role in electrotaxis and EMT of EGFR-mutant lung cancer.

Abstract 428: The role of sphingosine kinase 2 in overcoming EGFR-tyrosine kinase inhibitor resistance, EMT and NSCLC tumor progression

Abstract Background: Tyrosine Kinase Inhibitors (TKIs) such as Erlotinib (ER) and Osimertinib (OR) are being used to treat lung cancer patients with EGFR mutations; however, patients develop resistance to these drugs within 10-18 months. EGFR-TKI resistance may be mediated by epithelial-mesenchymal transition (EMT), which causes a motile and invasive phenotype similar to mesenchymal cells. Sphingosine kinase 2 (SphK2), which is upregulated in Non-Small Cell Lung Cancer (NSCLC), phosphorylates sphingosine to sphingosine-1-phosphate (S1P) and increases cell proliferation, tumor survival and cell migration. The sphingolipid rheostat controls the cell fate by maintaining a balance between pro-survival and pro-apoptotic sphingolipids, which is regulated by SphK2. However, the role of SphK2 in TKI resistance and EMT is not well understood. Hypothesis: We hypothesize that the inhibition/downregulation of SphK2 will reverse EMT, reduce tumorigenicity and overcome ER and OR resistance. Study design and Results: We studied expression of SphK2 in both drug resistant (OR and ER) and drug sensitive (parental) H358, H2170, H3255 and PC9 NSCLC cell lines. In drug resistant cells, qPCR and immunoblotting studies showed that SphK2 was upregulated by 1.5-1.7 and 1.5-3.3 fold in ER and OR resistant cell lines respectively compared to parental cells. 48 hours after SphK2 knockdown with siRNA treatment, SphK2 was downregulated by 4.6-fold and EMT mediator E-cadherin expression was upregulated by 2.9-fold. EMT proteins Vimentin and N-cadherin were downregulated by 3.8 and 2.2 fold respectively (p≤0.01). Using an MTT assay, differences in percentage viability of cells with different treatments were calculated with respect to their viability in the presence of OR. We found that 81.43% of H358OR and 76.35% of the H3255OR cells were inhibited by a combination of Opaganib, a Sphk2 inhibitor, and OR, this is 27.74% and 12.28% higher compared to the additive effect of drug and inhibitor in H358OR and H3255 cells respectively. Furthermore, transwell migration assays, wound healing assays and spheroid assays were performed in OR resistant cells and the results indicated inhibition of the above assays by 94.97%, 82.36%, 88.67% respectively when treated with a combination of Opaganib and OR as compared to the diluent. This indicates the potential of SphK2 inhibition to overcome TKI resistance and EMT. To analyze the role of SphK2 expression in cancer progression, IHC was performed on 63 early and 48 late-stage lung cancer patient sections. We observed upregulation of SphK2 in late-stage lung cancer (p≤0.05), indicating its role in cancer progression. Conclusion: In this study, SphK2 was shown to decrease tumor survival, cancer cell proliferation, and expression of EMT markers. Thus, SphK2 may be a promising clinical target for overcoming EGFR-TKI resistance and NSCLC tumor progression. Citation Format: S M Nasifuzzaman, Namrata Dube, Katie Lam, Robert J. Hillwig, Neelu Puri. The role of sphingosine kinase 2 in overcoming EGFR-tyrosine kinase inhibitor resistance, EMT and NSCLC tumor progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 428.

Abstract 1582: Inhibition of autophagy by CAGE targeting peptide retard tumor growth in non-small cell lung cancer of EGFR TKI resistance

Abstract Epidermal growth factor receptor tyrosine kinase inhibitor (EGFR TKI) is the standard of care as 1st-line treatment for NSCLC patients with activating EGFR mutations (exon 19 deletion or L858R mutation). However, EGFR-TKI therapy eventually leads to acquired drug resistance approximately 1-2 years from the beginning of treatment. Multiple acquired resistance mechanisms including on-target EGFR mutations, phenotype transformation, and activation of bypass signaling molecules have been identified, but over 35% still remains unknown. CAGE, a cancer/testis antigen, was originally isolated from the sera of patients with gastric cancer and is known to regulate the autophagic flux in acquired resistance to EGFR TKI in NSCLC. Herein, the expression of CAGE was found in more than 50% of NSCLC patients using immunohistochemistry (IHC). Interestingly, the expression level was increased especially for the patients acquiring resistance to EGFR-TKIs. In addition, both PC-9/ER (Erlotinib-resistance cells) and H1975/OR (Osimertinib-resistant cells) cells demonstrated increased CAGE expression and autophagic flux, when compared with their parental cells. Thus, we developed the peptide drugs targeting the DEAD box domain of CAGE. This novel peptide effectively inhibited tumor cell proliferation in EGFR-TKI resistant cell line. Moreover, in Erlotinib-resistant patient-derived xenograft (PDX) mice, the peptide drug retarded tumor growth and enhanced anti-tumor efficacy. Collectively, our data suggest that CAGE plays a crucial role in the tumor progression and acquired resistance of EGFR TKI by the modulation of autophagic flux. Furthermore, we provided evidence that the inhibition of autophagy through CAGE- derived peptide could overcome the acquired resistance to EGFR TKIs in advanced/metastatic NSCLC patients. Citation Format: Jung-Young Shin, Min-Young Kim, Mi-Ran Lee, Hankyu Lee, Doyong Jeon, Seung Ryel Baek, Kim Joo Il, Jaemoon Koh, Dooil Jeoung, Jin Hyoung Kang. Inhibition of autophagy by CAGE targeting peptide retard tumor growth in non-small cell lung cancer of EGFR TKI resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1582.

A phosphoglycerate mutase 1 allosteric inhibitor overcomes drug resistance to EGFR-targeted therapy via disrupting IL-6/JAK2/STAT3 signaling pathway in lung adenocarcinoma

Resistance to epidermal growth factor receptor (EGFR) inhibitors, from the first-generation erlotinib to the third generation osimertinib, is a clinical challenge in the treatment of patients with EGFR-mutant lung adenocarcinoma. Our previous work found that a novel allosteric inhibitor of phosphoglycerate mutase 1 (PGAM1), HKB99, restrains erlotinib resistance in lung adenocarcinoma cells. However, the role of HKB99 in osimertinib resistance and its underlying molecular mechanism remains to be elucidated. Herein, we found that IL-6/JAK2/STAT3 signaling pathway is aberrantly activated in both erlotinib and osimertinib resistant cells. Importantly, HKB99 significantly blocks the interaction of PGAM1 with JAK2 and STAT3 via the allosteric sites of PGAM1, which leads to inactivation of JAK2/STAT3 and thereby disrupts IL-6/JAK2/STAT3 signaling pathway. Consequently, HKB99 remarkably restores EGFR inhibitor sensitivity and exerts synergistic tumoricidal effect. Additionally, HKB99 alone or in combination with osimertinib down-regulated the level of p-STAT3 in xenograft tumor models. Collectively, this study identifies PGAM1 as a key regulator in IL-6/JAK2/STAT3 axis in the development of resistance to EGFR inhibitors, which could serve as a therapeutic target in lung adenocarcinoma with acquired resistance to EGFR inhibitors.

CircRBM33 promotes migration, invasion and mediates osimertinib resistance in non-small cell lung cancer cell line.

It has been shown that circular RNAs (circRNAs) are involved in the pathogenesis of non-small cell lung cancer (NSCLC). However, the molecular mechanisms of circRNAs in tumor malignant progression and tyrosine kinase inhibitors (TKI) resistance remain undefined. Hereby, we explored the mechanisms by which circRBM33 promotes NSCLC progression and epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKI) resistance. Transcriptome sequencing (RNA-seq) was carried out to obtain the circRBM33 we investigated. Quantitative reverse transcriptase-polymerase chain reaction was performed to detect the expression of circRBM33. Cell counting kit-8 assay was performed to detect cell proliferation as well as flow cytometry to detect cell cycle and apoptosis. Transwell assay was performed to detect cell migration and invasion. In vivo tumourigenesis assays were performed to further validate the function of circRBM33. The transcriptome was sequenced after RNA-pulldown and knockdown of cirRBM33 to identify the proteins bound by cirRBM33 and the downstream mechanisms involved in the regulation of cirRBM33. The sequencing results revealed that cirRBM33 was highly expressed in the cell line of osimertinib resistant H1975. In vitro functional validation demonstrated that knockdown of circRBM33 inhibited H1975 proliferation, migration and invasion, changed cell cycle and promoted apoptosis. In vivo, knockdown of circRBM33 inhibited tumour growth. Mass spectrometry results and sequencing analysis of knockdown circRBM33 suggest that circRBM33 may mediate resistance to osimertinib in H1975-OR cells through regulate the DNMT1/interleukin-6 (IL-6) axis. CircRBM33 is upregulated in NSCLC and that knockdown of circRBM33 inhibits the progression of NSCLC. CircRBM33 may combine with DNMT1, and regulate the resistance of H1975 osimertinib-resistant cells to osimertinib that mediated by IL6. CircRBM33 is a promising diagnostic and prognostic marker to provide effective treatment strategies for NSCLC patients.

Lnc-TMEM132D-AS1 overexpression reduces sensitivity of non-small cell lung cancer cells to osimertinib

To screen the differentially expressed long non-coding RNAs (lncRNAs) in non-small cell lung cancer (NSCLC) cells with acquired resistance to osimertinib and explore their roles in drug resistance of the cells. The cell lines H1975_OR and HCC827_OR with acquired osimertinib resistance were derived from their osimertinib-sensitive parental NSCLC cell lines H1975 and HCC827, respectively, and their sensitivity to osimertinib was assessed with CCK-8 assay, clone formation assay and flow cytometry. RNA sequencing (RNA-seq) and real-time quantitative PCR (qPCR) were used to screen the differentially expressed lncRNAs in osimertinib-resistant cells. The role of the identified lncRNA in osimertinib resistance was explored using CCK-8, clone formation and Transwell assays, and its subcellular localization and downstream targets were analyzed by nucleoplasmic separation, bioinformatics analysis and qPCR. The resistance index of H1975_OR and HCC827_OR cells to osimertinib was 598.70 and 428.82, respectively (P < 0.001), and the two cell lines showed significantly increased proliferation and colony-forming abilities with decreased apoptosis (P < 0.01). RNA-seq identified 34 differentially expressed lncRNAs in osimertinib-resistant cells, and among them lnc-TMEM132D-AS1 showed the highest increase of expression after acquired osimertinib resistance (P < 0.01). Analysis of the TCGA database suggested that the level of lnc-TMEM132D-AS1 was significantly higher in NSCLC than in adjacent tissues (P < 0.001), and its high expression was associated with a poor prognosis of the patients. In osimertinib-sensitive cells, overexpression of Lnc-TMEM132D-AS1 obviously promoted cell proliferation, colony formation and migration (P < 0.05), while Lnc-TMEM132D-AS1 knockdown partially restored osimertinib sensitivity of the resistant cells (P < 0.01). Lnc-TMEM132D-AS1 was localized mainly in the cytoplasm, and bioinformatics analysis suggested that hsa-miR-766-5p was its candidate target, and their expression levels were inversely correlated. The target mRNAs of hsa-miR-766-5p were mainly enriched in the Ras signaling pathway. The expression of lnc-TMEM132D-AS1 is significantly upregulated in NSCLC cells with acquired osimertinib resistance, and may serve as a potential biomarker and therapeutic target for osimertinibresistant NSCLC.

Feiyiliu Mixture sensitizes EGFRDel19/T790M/C797S mutant non-small cell lung cancer to osimertinib by attenuating the PRC1/Wnt/EGFR pathway.

Introduction: Osimertinib is a potent epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) for the treatment of patients with EGFR-mutant non-small cell lung cancer (NSCLC). However, the emergence of acquired resistance due to the EGFR-Del19/T790M/C797S mutation limits the clinical application of osimertinib. Feiyiliu Mixture (FYLM), a clinical experience formula of Chinese medicine, was used to treat lung cancer with good clinical efficacy. In this study, we aimed to investigate the mechanism by which Feiyiliu Mixture delays osimertinib resistance in EGFR-mutant cell lines and EGFR-mutant cell tumor-bearing mice. Methods: The osimertinib-resistant cell models were established in mouse Lewis lung carcinoma (LLC) cells transfected with EGFR-Del19/T790M/C797S mutant lentivirus. In cell experiments, after 48h of treatment with Feiyiliu Mixture-containing serum, MTT assay was used to detect the relative cell viability, and western blotting was used to detect EGFR protein phosphorylation expression. In animal experiments, C57BL/6J mice were subcutaneously injected with Lewis lung carcinoma cells stably expressing EGFR-Del19/T790M/C797S mutations to construct a xenograft model. After 2weeks of Feiyiliu Mixture and/or osimertinib treatment, the expression of proliferation-related, apoptosis-related and PRC1/Wnt/EGFR pathway markers was detected by real-time qPCR, western blotting and immunohistochemistry. Results: The results showed that when combined with osimertinib, Feiyiliu Mixture synergistically reduces proliferation and increases apoptosis to improve drug resistance. In vitro, Feiyiliu Mixture-containing serum reduced the EGFR phosphorylation. In vivo, Feiyiliu Mixture downregulated the expression of cyclin B1 and Bcl-2 while upregulating the level of cleaved Caspase-3 protein, indicating that Feiyiliu Mixture promotes apoptosis. Furthermore, Feiyiliu Mixture reduced the expression of p-EGFR, p-Akt, PRC1 and Wnt pathway-related proteins such as β-catenin, c-Myc and c-Jun. Conclusion: The present study identified that Feiyiliu Mixture inhibited PRC1/Wnt/EGFR pathway activation, reduced proliferation, and promoted apoptosis, thereby increasing the sensitivity of EGFR-mutant non-small cell lung cancer to osimertinib. Our study provided a new idea for Chinese medicine to play a role in enhancing efficacy and reducing toxicity in the treatment of non-small cell lung cancer.

Anlotinib combined with osimertinib reverses acquired osimertinib resistance in NSCLC by targeting the c-MET/MYC/AXL axis

Favorable clinical evidence suggests that the next trend in new treatments for advanced non-small cell lung cancer (NSCLC) will be combination therapies. However, inevitable epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) resistance greatly limits the clinical efficacy of patients carrying EGFR-activating mutants. In this study, we found a patient with clinical osimertinib resistance who regained a positive response after osimertinib plus anlotinib treatment. Two osimertinib-resistant cell lines were constructed, and AXL conferred resistance to osimertinib in NSCLC cell lines. The combined effects of anlotinib and osimertinib restored sensitivity to osimertinib in two osimertinib-resistant NSCLC cell lines and in xenografts. Moreover, anlotinib inhibits the phosphorylation of AXL in both resistant cell lines. Mechanistically, we confirmed that MYC binds to the promoter of AXL to promote its transcription in NSCLC cells, and we demonstrated that anlotinib combined with osimertinib treatment enhances the anti-tumor effect by inactivating the c-MET/MYC/AXL axis to reverse osimertinib resistance in NSCLC. In conclusion, our results provide strong support that this combination therapy may be effective in enhancing the efficacy of treatments in patients with advanced NSCLC.

YAP1 synergize with YY1 transcriptional co-repress DUSP1 to induce osimertinib resistant by activating the EGFR/MAPK pathway and abrogating autophagy in non-small cell lung cancer.

YAP1 is a well-known core effector of the Hippo pathway in tumors, but its potential role in osimertinib resistance remained unexplored. Our study provides evidence that YAP1 acts as a potent promoter of osimertinib resistance. By inhibiting YAP1 with a novel inhibitor, CA3, and combining it with osimertinib, we observed a significant suppression of cell proliferation and metastasis, induction of apoptosis and autophagy, and a delay in the emergence of osimertinib resistance. Interestingly, CA3 combined with osimertinib executed its anti-metastasis and pro-tumor apoptosis in part through autophagy. Mechanistically, we found that YAP1, in collaboration with YY1, transcriptionally represses DUSP1, leading to the dephosphorylation of the EGFR/MEK/ERK pathway and YAP1 phosphorylation in osimertinib-resistant cells. Our results also validate that CA3, in combination with osimertinib, executes its anti-metastasis and pro-tumor apoptosis partly through autophagy and the YAP1/DUSP1/EGFR/MEK/ERK regulatory feedback loop in osimertinib-resistant cells. Remarkably, our findings illustrate that YAP1 protein is upregulated in patients after osimertinib treatment and osimertinib resistance. Overall, our study confirms that the YAP1 inhibitor CA3 increases DUSP1 with concomitant activation of the EGFR/MAPK pathway and induces autophagy to enhance the efficacy of third-generation EGFR-TKI treatments for NSCLC patients.

Anti-EGF nanobodies enhance the antitumoral effect of osimertinib and overcome resistance in non-small cell lung cancer (NSCLC) cellular models.

Osimertinib is a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) that is effective against the EGFR T790M mutation in patients with advanced non-small-cell lung cancer (NSCLC). However, acquired resistance appears invariably due to several mechanisms. The strategy of using EGF-targeted nanobodies (Nbs) to block the initial step of the EGFR pathway constitutes a new research area. Nbs offer several advantages compared to traditional mAbs, such as their reduced size, increased stability, and tissue penetration, which provide key advantages for targeting soluble tumoral growth factors. In this study we investigated the efficacy of anti-EGF Nbs to reduce Osimertinib resistance. Two anti-EGF Nbs, generated in our laboratory, were shown to inhibit cell viability and colony formation in PC9 and PC9-derived osimertinib-resistant cell lines. The combination of these Nbs with osimertinib improved the antitumor efficacy of this EGFR-TKI in cell viability and colony formation experiments. In a mechanistic study of the EGFR pathway, the combination treatment dampened the activation of downstream proteins such as Akt and Erk1/2 MAP kinases. In addition, it increased cellular apoptosis and decreased the expression of Hes1, a cancer stem cell marker involved in metastasis and osimertinib resistance. We conclude that the addition of anti-EGF nanobodies enhances the antitumor properties of osimertinib, thus representing a potentially effective strategy for NSCLC patients.

P21-activated kinase 2-mediated β-catenin signaling promotes cancer stemness and osimertinib resistance in EGFR-mutant non-small-cell lung cancer.

Osimertinib (AZD9291) is a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), used for treating patients with advanced non-small-cell lung cancer (NSCLC) harboring EGFR-activating mutations or the resistant T790M mutation. However, acquired resistance to osimertinib is inevitable in EGFR-mutant NSCLC. By employing a global mass spectrometry-based phosphoproteomics approach, we identified that the activated p21-activated kinase 2 (PAK2)/β-catenin axis acts as a driver of osimertinib resistance. We found that PAK2 directly phosphorylates β-catenin and increases the nuclear localization of β-catenin, leading to the increased expression and transcriptional activity of β-catenin, which in turn enhances cancer stem-like properties and osimertinib resistance. Moreover, we revealed that HER3 as an upstream regulator of PAK2, drives the activation of PAK2/β-catenin pathways in osimertinib-resistant cells. The clinical relevance of these findings was further confirmed by examining tissue specimens from patients with EGFR-mutant NSCLC. The results demonstrated that the levels of HER3, phospho-PAK2 (p-PAK2) and β-catenin in the tissues from patients with EGFR-mutant NSCLC, that had relapsed after treatment with osimertinib, were elevated compared to those of the corresponding untreated tissues. Additionally, the high levels of HER3, p-PAK2 and β-catenin correlated with shorter progression-free survival (PFS) in patients with EGFR-TKI-treated NSCLC. We additionally observed that the suppression of PAK2 via knockdown or pharmacological targeting with PAK inhibitors markedly restored the response of osimertinib-resistant NSCLC cells to osimertinib both in vitro and in vivo. In conclusion, these results indicated that the PAK2-mediated activation of β-catenin is important for osimertinib resistance and targeting the HER3/PAK2/β-catenin pathway has potential therapeutic value in NSCLCs with acquired resistance to osimertinib.

SKLB-14b, a novel oral microtubule-destabilizing agent based on hydroxamic acid with potent anti-tumor and anti-multidrug resistance activities

A hydroxamic acid based microtubule-destabilizing agent (MDA) SKLB-14b was discovered in this study, which was derived from shortening the linker length of the HDAC6 and microtubule dual-target inhibitor SKLB-23bb. SKLB-14b exhibited low nanomolar IC50 values on a wide spectrum of human cancer cell lines including both sensitive and multidrug-resistant cell lines. Surprisingly, its anti-proliferative activity relied on the presence of the hydroxamic acid group but lost inhibitory activity against HDACs. SKLB-14b bound to the colchicine site of tubulin and could inhibit tubulin polymerization. It exhibited good metabolic stability in liver microsomes, no inhibitory effect on CYP450 isoenzymes and high oral bioavailability. In vivo experiments revealed that SKLB-14b was potent in both sensitive (A2780S, HCT116) and resistant (A2780/T) xenograft mice models. Furthermore, in the patient-derived tumor xenograft (PDX) models of osimertinib resistant non-small cell lung cancer (NSCLC), 50 mg/kg of SKLB-14b administered every twodays inhibited tumor growth by 70.6% without obvious toxicity, better than the 59.7% inhibition rate of paclitaxel. Mechanistically, we found that SKLB-14b exerted anti-tumor and anti-multidrug resistance effects in vitro and in vivo through cell cycle arrest and pro-apoptotic activities, as well as vascular disrupting activities. Therefore, we discovered that SKLB-14b, as a novel MDA based on hydroxamic acid, could serve as a potential drug candidate for cancer therapy which deserves further investigation.

Ras-Related Protein Rab-32 and Thrombospondin 1 Confer Resistance to the EGFR Tyrosine Kinase Inhibitor Osimertinib by Activating Focal Adhesion Kinase in Non-Small Cell Lung Cancer.

Simple SummaryOsimertinib is a third-generation EGFR tyrosine kinase inhibitor and the standard of care therapy for non-small cell lung cancer patients harboring EGFR-activating mutations. However, even for patients treated with osimertinib, resistance inevitably occurs leading to disease progression. Here, we utilized two osimertinib-resistant cell lines and investigated their RNA profiles. We found that Ras-related protein Rab-32 (RAB32) and thrombospondin 1 (THBS1) were upregulated and associated with resistance in osimertinib-resistant cells as well as in liquid biopsies from patients with disease progression following osimertinib treatment. Moreover, we found RAB32 and THBS1 to be mechanistically linked to activation of the focal adhesion pathway where combination of osimertinib with a FAK inhibitor resulted in a synergistic suppression of viability of osimertinib-resistant cells. Our findings propose a potential therapeutic strategy for overcoming acquired resistance to osimertinib in non-small cell lung cancer.Treatment with the tyrosine kinase inhibitor (TKI) osimertinib is the standard of care for non-small cell lung cancer (NSCLC) patients with activating mutations in the epidermal growth factor receptor (EGFR). Osimertinib is also used in T790M-positive NSCLC that may occur de novo or be acquired following first-line treatment with other EGFR TKIs (i.e., gefitinib, erlotinib, afatinib, or dacomitinib). However, patients treated with osimertinib have a high risk of developing resistance to the treatment. A substantial fraction of the mechanisms for resistance is unknown and may involve RNA and/or protein alterations. In this study, we investigated the full transcriptome of parental and osimertinib-resistant cell lines, revealing 131 differentially expressed genes. Knockdown screening of the genes upregulated in resistant cell lines uncovered eight genes to partly confer resistance to osimertinib. Among them, we detected the expression of Ras-related protein Rab-32 (RAB32) and thrombospondin 1 (THBS1) in plasmas sampled at baseline and at disease progression from EGFR-positive NSCLC patients treated with osimertinib. Both genes were upregulated in progression samples. Moreover, we found that knockdown of RAB32 and THBS1 reduced the expression of phosphorylated focal adhesion kinase (FAK). Combination of osimertinib with a FAK inhibitor resulted in synergistic toxicity in osimertinib-resistant cells, suggesting a potential therapeutic drug combination for overcoming resistance to osimertinib in NSCLC patients.

Abstract 5459: Synergistic effects of WX-0593 in combination with panitumumab on osimertinib-resistant EGFR-mutantnon-small cell lung cancer in vitro and in vivo

Abstract Objective: To preliminarily demonstrate the synergistic effect of WX-0593 (anaplastic lymphoma kinase/ROS proto-oncogene 1 receptor tyrosine kinase [ALK/ROS1] tyrosine kinase inhibitor) in combination with panitumumab on osimertinib-resistant cis EGFR triple-mutant non-small cell lung cancer (NSCLC) both in vitro and in vivo. Methods: The tumor cell inhibition rates of WX-0593 and panitumumab alone or combined were assessed in osimertinib-resistant cis EGFR triple-mutant cell lines, including PC9 (EGFR Del19/T790M/C797S), NCI-H1975 (EGFR L858R/T790M/C797S), Ba/F3 (EGFR L858R/T790M/C797S and EGFR Del19/T790M/C797S). The in vivo tumor suppressive efficacy of single-agent WX-0593, panitumumab, and their combination was evaluated in H1975 (EGFR del19/T790M/C797S) and Ba/F3 (EGFR L858R/T790M/C797S) cell line-derived xenograft (CDX) models of BALB/c nude mice. The tolerability was also assessed. Results: In vitro studies showed that the combination of WX-0593 and panitumumab had a potent synergistic effect on proliferation inhibition in all the four cell lines with cis EGFR triple mutations resistant to osimertinib. WX-0593 in combination with panitumumab demonstrated a delaying effect on tumor growth without increasing drug toxicity in the H1975 CDX model. WX-0593 and panitumumab alone had tumor suppressive effects in the Ba/F3 CDX model. And WX-0593 plus panitumumab significantly enhanced the antitumor activity in the Ba/F3 model. Conclusion: The data from the study suggested that WX-0593 and panitumumab had a promising synergistic effect on osimertinib-resistant EGFR-mutant NSCLC both in vitro and in vivo. The combination regimen may have important clinical implications for the future treatment of patients with EGFR triple-mutant NSCLC resistant to osimertinib. Citation Format: Shansong Zheng, Qingmei Zheng, Dongmei Chen, Xinmei Wang, Xin Dong, Xin Zhang, Cuicui Ma, Huicheng Duan, Chenwei Zhang. Synergistic effects of WX-0593 in combination with panitumumab on osimertinib-resistant EGFR-mutantnon-small cell lung cancer in vitro and in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5459.

Abstract 428: Therapeutic potential of the novel SHP2 degrader, SHP2-D26, alone or in combination, in the treatment of lung cancer

Abstract Src homology 2 domain-containing phosphatase 2 (SHP2) functions as a protein tyrosine phosphatase and plays a critical role in the full activation of the Ras-MAPK signaling pathway downstream of cell surface tyrosine receptors (e.g., EGFR), which are frequently amplified or mutationally activated in human cancer. Therefore, SHP2 has emerged as an attractive therapeutic target for human cancers and other human diseases. While some allosteric inhibitors that are being tested in clinical trials, a few SHP2 degraders have been developed recently. However, their activities in human lung cancer have not been tested. The current study focused on evaluating the therapeutic potential of the novel SHP2 degrader, SHP2-D26 (D26), either alone or in combination, against non-small cell lung cancer cell (NSCLC). Most of tested NSCLC cell lines (12/14) were insensitive to the control small molecule SHP2 inhibitor with IC50s of far over 10 μM. However, all these cell lines responded to D26 with IC50s of &amp;lt; 8 μM. A few cell lines (4/14; e.g. HCC827, PC-9, H1792 and H1648) were much more sensitive than others with IC50s of &amp;lt; 3 μM. There was no clear association between basal levels of SHP2 and cell sensitivities to D26. Interestingly, D26 rapidly and potently decreased SHP2 levels in all the tested cell lines in a sustained way regardless cell sensitivities to D26, suggesting that there may be additional factors that impact cell response to D26. We noted that suppression of p70S6/S6, but not ERK1/2, was associated with cell responses to D26, warranting further study in this direction. In the sensitive cell lines, D26 effectively increased Bim levels while decreasing Mcl-1 levels likely through modulating their stability accompanied with induction of apoptosis. These events are all important for D26 to induce apoptosis. When combined with the third generation EGFR, osimertinib (AZD9291), synergistic effects on decreasing the survival of different osimertinib-resistant cell lines were observed. Moreover, the combination enhanced induction of apoptosis in these osimertinib-resistant cells. Although D26 alone exerted moderate effect on inhibiting the growth of NSCLC xenografts, the combination of osimertinib with D26 very effectively inhibited the growth of osimertinib-resistant xenografts, suggesting promising efficacy in overcoming acquired resistance to osimertinib. Our findings thus warrant further evaluation of the potential of D26 in overcoming acquired resistance to osimertinib in clinic. Citation Format: Yunful Deng, Guangzhi Ma, Karin A. Vallega, Dongsheng Wang, Mingliang Wang, Changwei Wang, Shaomeng Wang, Suresh S. Ramalingam, Shi-Yong Sun. Therapeutic potential of the novel SHP2 degrader, SHP2-D26, alone or in combination, in the treatment of lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 428.

Abstract 5353: PIK3CA and PTEN mutations as drivers of osimertinib resistance in patients with NSCLC

Abstract Osimertinib is a third-generation EGFR-TKI approved for the first-line treatment of EGFR-driven lung adenocarcinomas. High response rates to osimertinib are observed in patients with activating EGFR mutations. However, there is variability in duration of response and patients eventually develop acquired resistance.Preclinical validation of potential acquired resistance mutations identified in relapsed patients treated with osimertinib is a key challenge to develop new strategies to improve outcomes for patients with EGFR mutation positive NSCLC. Tissue and ctDNA NGS analysis from relapsed patients treated first-line with osimertinib in the FLAURA and ORCHARD trials identified PIK3CA gain of function (GOF 11%) and PTEN loss of function (LOF 5%) mutations.To test whether PIK3CA activating mutations can drive resistance to osimertinib we introduced PIK3CA activating variants (PIK3CA-H1047R and PIK3CA-E453K) or knocked-out PTEN in NSCLC lung cancer cell lines harbouring EGFR activating mutations and WT PIK3CA/PTEN using CRISPR/Cas9 technology. Our results show that PIK3CA GOF and PTEN LOF mutations conferred resistance to osimertinib in vitro. Resistance was associated with increased EC50 for osimertinib and diminished apoptotic response in NSCLC PIK3CA GOF and PTEN LOF mutant CRISPR cell lines when compared to parental cells. Protein analysis by western blot also showed an increase in the basal and osimertinib treated levels of pAKT and pS6 in PIK3CA/PTEN CRISPR engineered cell lines, indicating activation of downstream PI3K/AKT and MAPK signalling pathways in the osimertinib-resistant cells. Importantly, our in vitro experiments from multiple cell line models indicated that PIK3CA-mediated resistance to osimertinib could be partially reversed by co-treatment with AKT (capivasertib, AstraZeneca) and PI3K alpha (alpelisib, Novartis) inhibitors; PTEN-mediated resistance could be rescued by co-treatment with capivasertib and PI3K beta (AZD8186, AstraZeneca) inhibitors. We next examined the in vivo efficacy of osimertinib + AKT/PI3K inhibitors therapies in NSCLC xenograft models. Our in vivo analysis show that PIK3CA GOF CRISPR engineered cells displayed diminished response to osimertinib when implanted in mice; importantly, combination with AKT (capivasertib) or PI3K alpha (alpelisib) inhibitors enhanced response on treatment and delayed outgrowth after withdrawal treatment. In addition, we observed that combination treatment with capivasertib induced tumour stasis in a PIK3CA-E454K and two PTENloss PDX models.Altogether our in vitro and in vivo data provide evidence of PIK3CA mutants and PTEN loss-driven mechanisms of resistance to osimertinib and offer possible therapeutic combination strategies for those patients that develop resistance or experience a sub-optimal response to osimertinib through PIK3CA/PTEN mutations Citation Format: Ursula Grazini, Daniel J. O'Neill, Matthew Martin, Chintia Xu, Nicolas Floch, Paul D. Smith, Emanuela Cuomo. PIK3CA and PTEN mutations as drivers of osimertinib resistance in patients with NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5353.

Abstract 1094: SMARCA4-mediated chromatin remodeling regulates osimertinib resistance in EGFR-mutant lung adenocarcinoma

Abstract Targeted therapies have transformed the clinical management of many types of tumors, including EGFR-mutant lung adenocarcinomas. Although these treatments are highly beneficial for patient survival, acquired resistance almost inevitably occurs limiting cures with these agents. The tyrosine-kinase inhibitor (TKI) osimertinib is approved for the first-line treatment of EGFR-mutant lung tumors and leads to increased progression-free and overall survival compared to earlier generations of TKIs. However, acquired resistance to osimertinib frequently occurs and is mostly due to off-target mechanisms, many of which are not well-understood. Therefore, it is critical to understand the molecular processes behind these mechanisms of resistance. We generated osimertinib resistant cell lines and patient-derived models to identify and study novel mechanisms of osimertinib resistance. We found that, in some osimertinib resistant tumors, SMARCA4 is stabilized upon osimertinib treatment and knock-down of SMARCA4 re-sensitizes the resistant cells to osimertinib and globally alters their chromatin profile. ATAC-Seq and RNA-Seq studies revealed that SMARCA4 alters chromatin accessibility in resistant tumors to maintain the transcriptional activity of genes involved in cell proliferation. Furthermore, SMARCA4 enables access to NRF2 binding sites enhancing an antioxidant response necessary for cells to tolerate the increase in reactive oxygen species and oxidative stress created by osimertinib. These processes converge and lead to an increase in the amount of DNA damage that is repaired by ATR. Indeed, we found that these osimertinib resistant tumors are vulnerable to ATR inhibition. In summary, we have identified a new epigenetic mechanism of resistance to osimertinib driven by SMARCA4 that generates a vulnerability to ATR inhibition, offering new approaches to target TKI-resistant tumors. Citation Format: Fernando J. de Miguel, Wesley L. Cai, Mary Ann Melnick, Camila Robles-Oteiza, Anna Wurtz, Maria I. Toki, David L. Rimm, Robert Homer, Don X. Nguyen, Katerina A. Politi. SMARCA4-mediated chromatin remodeling regulates osimertinib resistance in EGFR-mutant lung adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1094.

Abstract 1041: HBI-2376, HUYABIO clinical stage SHP2 inhibitor, possess robust in vitro potency and in vivo efficacy in several preclinical tumor models carrying KrasG12C or EGFR mutations

Abstract SHP2 (Src homology region 2-containing protein tyrosine phosphatase 2) is an attractive target in oncology drug development due to its dual roles on the direct growth and proliferation of cancer cells and also acting as an immune checkpoint molecule to suppress tumor immunity. HBI-2376 is an orally bioavailable selective SHP2 inhibitor that is being developed for the treatment of solid tumors harboring KRAS or EGFR mutations, such as non-small cell lung cancer (NSCLC) and colorectal cancer (CRC). Additionally, HBI-2376 has the potential to suppress tumor growth via induction of the activity of immune infiltrating cells in the TME (tumor microenvironment). In a head-to-head comparison, in vitro studies showed greater potency of HBI-2376 to inhibit cell proliferation in a variety of cancer cell lines compared to other SHP2 inhibitors such as TNO-155 (Novartis AG) and RMC-4550 (Revolution Medicines). Consistently, HBI-2376 found to be more efficacious in tumor growth inhibition than TNO-155 and RMC-4550 in NCI-H1975L858R_T790M_C797S osimertinib-resistant cell line and other tumor models. In addition to xenograft models, we tested efficacy of HBI-2376 as single agent or in combination with anti-PD1 mAb in MC38 CRC syngeneic model. Consistent with xenograft data, HBI-2376 showed greater efficacy in tumor growth inhibition vs. TNO-155 and RMC-4550 both as single agent and in combination therapy. IHC data showed reduction in infiltration of M2 macrophages (F4/80+Arg1+) in the HBI-2376 treated tumors suggesting a MoA for its greater efficacy in MC38 model. Furthermore, Western blotting showed inhibition of p-ERK and DUSP6 in HBI-2376 treated cells indicative of a biomarker of response to the therapy. These findings, along with a positive safety profile led to HBI-2376 IND clearance by FDA and suggested promising responses in NSCLC or CRC patients in the forthcoming clinical studies. Citation Format: Farbod Shojaei, Farbod Shojaei, Jill M. Ricono, Che Fang, Fairooz Kabbinavar, Bob Goodenow, Mireille Gillings. HBI-2376, HUYABIO clinical stage SHP2 inhibitor, possess robust in vitro potency and in vivo efficacy in several preclinical tumor models carrying KrasG12C or EGFR mutations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1041.

Therapeutic efficacy of the novel SHP2 degrader SHP2-D26, alone or in combination, against lung cancer is associated with modulation of p70S6K/S6, Bim and Mcl-1.

SHP2, a protein tyrosine phosphatase, plays a critical role in fully activating oncogenic signaling pathways such as Ras/MAPK downstream of cell surface tyrosine receptors (e.g., EGFR), which are often activated in human cancers, and thus has emerged as an attractive cancer therapeutic target. This study focused on evaluating the therapeutic potential of the novel SHP2 degrader, SHP2-D26 (D26), either alone or in combination, against non-small cell lung cancer (NSCLC) cells. While all tested NSCLC cell lines responded to D26 with IC50s of < 8 μM, a few cell lines (4/14) were much more sensitive than others with IC50s of ≤ 4 μM. There was no clear association between basal levels of SHP2 and cell sensitivities to D26. Moreover, D26 rapidly and potently decreased SHP2 levels in different NSCLC cell lines in a sustained way regardless of cell sensitivities to D26, suggesting that additional factors may impact cell response to D26. We noted that suppression of p70S6K/S6, but not ERK1/2, was associated with cell responses to D26. In the sensitive cell lines, D26 effectively increased Bim levels while decreasing Mcl-1 levels accompanied with the induction of apoptosis. When combined with the third generation EGFR inhibitor, osimertinib (AZD9291), synergistic effects on decreasing the survival of different osimertinib-resistant cell lines were observed with enhanced induction of apoptosis. Although D26 alone exerted moderate inhibition of the growth of NSCLC xenografts, the combination of osimertinib and D26 effectively inhibited the growth of osimertinib-resistant xenografts, suggesting promising efficacy in overcoming acquired resistance to osimertinib.