AT-101 enhances gefitinib sensitivity in non-small cell lung cancer with EGFR T790M mutations

Non-small cell lung cancer cells with uncommon EGFR exon 19delins variants respond poorly to third-generation EGFR inhibitors

BACKGROUND

This study compared the clinical efficacy of first-, second-, and third-generation tyrosine kinase inhibitors (TKIs) in previously untreated non-small cell lung cancer (NSCLC) patients harboring uncommon epidermal growth factor receptor (EGFR) exon 19delins variants.

METHODS

We retrospectively analyzed the clinical outcomes of NSCLC patients with EGFR exon 19delins mutations who were treated with third- and first-generation EGFR TKIs. In vitro and in vivo studies were conducted to verify the sensitivity of these mutations to distinct generations of TKIs. Molecular simulation was used to investigate the structural characteristics of the EGFR mutant molecules.

RESULTS

In a multicenter cohort of 1,526 patients, 37 (2.4 %) had uncommon EGFR 19delins mutations. Twenty-four patients were treated with first-generation EGFR TKIs, and third-generation TKIs were administered to ten patients as frontline therapy. Patients carrying EGFR exon 19delins mutations who were given third-generation TKIs exhibited comparatively shorter progression-free survival (PFS) and overall survival (OS) in relation to those who received first-generation EGFR inhibitors; median PFS: 6.9 months vs. 19.1 months (p < 0.001), Median OS: 19.1 months vs. 32.6 months (p < 0.001). In vivo and in vitro studies revealed that uncommon EGFR 19delins variants exhibit limited sensitivity to third-generation EGFR inhibitors in contrast to first- and second-generation EGFR inhibitors. The molecular binding affinity of third-generation EGFR TKIs toward uncommon EGFR 19delins mutations was less than that of first- and second-generation EGFR inhibitors.

CONCLUSIONS

Uncommon EGFR 19delins variants respond poorly to third-generation EGFR inhibitors in NSCLC. Uncommon EGFR 19delins mutations may serve as an unfavorable predictive factor for the efficacy of third-generation EGFR TKI therapy, offering potential guidance for future clinical decision-making.

DoubleSG-DTA: Deep Learning for Drug Discovery: Case Study on the Non-Small Cell Lung Cancer with EGFRT790M Mutation

Drug-targeted therapies are promising approaches to treating tumors, and research on receptor-ligand interactions for discovering high-affinity targeted drugs has been accelerating drug development. This study presents a mechanism-driven deep learning-based computational model to learn double drug sequences, protein sequences, and drug graphs to project drug-target affinities (DTAs), which was termed the DoubleSG-DTA. We deployed lightweight graph isomorphism networks to aggregate drug graph representations and discriminate between molecular structures, and stacked multilayer squeeze-and-excitation networks to selectively enhance spatial features of drug and protein sequences. What is more, cross-multi-head attentions were constructed to further model the non-covalent molecular docking behavior. The multiple cross-validation experimental evaluations on various datasets indicated that DoubleSG-DTA consistently outperformed all previously reported works. To showcase the value of DoubleSG-DTA, we applied it to generate promising hit compounds of Non-Small Cell Lung Cancer harboring EGFRT790M mutation from natural products, which were consistent with reported laboratory studies. Afterward, we further investigated the interpretability of the graph-based "black box" model and highlighted the active structures that contributed the most. DoubleSG-DTA thus provides a powerful and interpretable framework that extrapolates for potential chemicals to modulate the systemic response to disease.

Systematic Review of Gossypol/AT-101 in Cancer Clinical Trials

The potential of gossypol and of its R-(−)-enantiomer (R-(−)-gossypol acetic acid, AT-101), has been evaluated for treatment of cancer as an independent agent and in combination with standard chemo-radiation-therapies, respectively. This review assesses the evidence for safety and clinical effectiveness of oral gossypol/AT-101 in treating various types of cancer. The databases PubMed, MEDLINE, Cochrane, and ClinicalTrials.gov were examined. Phase I and II trials as well as single arm and randomized trials were included in this review. Results were screened to determine if they met inclusion criteria and then summarized using a narrative approach. A total of 17 trials involving 759 patients met the inclusion criteria. Overall, orally applied gossypol/AT-101 at low doses (30 mg daily or lower) was determined as well tolerable either as monotherapy or in combination with chemo-radiation. Adverse events should be strictly monitored and were successfully managed by dose-reduction or treating symptoms. There are four randomized trials, two performed in patients with advanced non-small cell lung cancer, one in subjects with head and neck cancer, and one in patients with metastatic castration-resistant prostate cancer. Thereby, standard chemotherapy (either docetaxel (two trials) or docetaxel plus cisplatin or docetaxel plus prednisone) was tested with and without AT-101. Within these trials, a potential benefit was observed in high-risk patients or in some patients with prolongation in progression-free survival or in overall survival. Strikingly, the most recent clinical trial combined low dose AT-101 with docetaxel, fluorouracil, and radiation, achieving complete responses in 11 of 13 patients with gastroesophageal carcinoma (median duration of 12 months) and a median progression-free survival of 52 months. The promising results shown in subsets of patients supports the need of further specification of AT-101 sensitive cancers as well as for the establishment of effective AT-101-based therapy. In addition, the lowest recommended dose of gossypol and its precise toxicity profile need to be confirmed in further studies. Randomized placebo-controlled trials should be performed to validate these data in large cohorts.

Protease-activated receptor 2 stabilizes Bcl-xL and regulates EGFR-targeted therapy response in colorectal cancer

The Bcl-2 homolog Bcl-xL is emerging as a key factor in tumorigenesis due to its prominent pro-survival and cell death-independent functions. However, the regulation of Bcl-xL by microenvironment and its implication in cancer therapy of colorectal carcinoma (CRC) are unclear. Here, we demonstrated that Bcl-xL expression was positively associated with protease-activated receptor 2 (PAR2) in CRC. Activation of PAR2 stabilized Bcl-xL protein in a proteasome-dependent manner, whereas E3 ligase RING finger protein 152 (RNF152) accelerated the ubiquitination and degradation of Bcl-xL. RNF152 silencing by specific siRNAs rescued the expression of Bcl-xL in PAR2-deficient cells. Moreover, RNF152 physically interacted with Bcl-xL, which was disturbed by PAR2 activation. Further studies with serial mutation of Bcl-xL revealed that phosphorylation of Bcl-xL at S145 reduced its binding affinity for RNF152 and stabilized Bcl-xL. Importantly, inhibition of PAR2 signaling by its gene silencing or specific chemical inhibitors increased apoptosis induced by different EGFR-targeted therapies. In patient-derived xenograft model, inhibition of PAR2 increased the response of CRC to different EGFR-targeted therapies. These results indicate that PAR2 stabilizes Bcl-xL by altering RNF152 signaling and that PAR2 inhibition sensitizes CRC to EGFR-targeted therapies in vivo.

Targeted therapies for advanced non-small cell lung cancer

Lung cancer is a serious health problem and the leading cause of cancer death worldwide, due to its high incidence and mortality. 85% of lung cancers are represented by the non-small cell lung cancer (NSCLC). Traditional chemotherapy has been the main treatment option in NSCLC. However, it is often associated with limited efficacy and overall poor patient survival. In recent years, molecular targeting has achieved great progress in therapeutic treatment of cancer and plays a crucial role in the current clinical treatment of NSCLC, due to enhanced efficacy on cancer tissues and reduced toxicity for normal tissues. In this review, we summarize the current targeting treatment of NSCLC, including inhibition of the epidermal growth factor receptor (EGFR), phosphatidylinositol 3-kinase (PI3Ks), mechanistic target of rapamycin (mTOR), epidermal growth factor receptor 2 (ErbB2), vascular epidermal growth factor receptor (VEGFR), kirsten human rat sarcoma protein (KRAS), mesenchymal-epithelial transition factor or hepatocyte growth factor receptor (c-MET), anaplastic lymphoma kinase (ALK), v-Raf murine sarcoma viral oncogene homolog B (BRAF). This article may serve as a guide to clinicians and researchers alike by assisting in making therapeutic decisions. Challenges of acquired drug resistance targeted therapy and imminent newer treatment modalities against NSCLC are also discussed.

Effect of the BH3 Mimetic Polyphenol (-)-Gossypol (AT-101) on the in vitro and in vivo Growth of Malignant Mesothelioma

Malignant mesothelioma (MM) is a primary tumor arising from mesothelial cells. The survival of MM patients following traditional chemotherapy is poor, thus innovative treatments for MM are needed. (-)-gossypol (AT-101) is a BH3 mimetic compound which possesses anti-tumoral activity by targeting multiple signaling transduction pathways. Several clinical trials employing AT-101 have been performed and some of them are still ongoing. Accordingly, we investigated the in vitro effects of AT-101 on cell proliferation, cell cycle regulation, pro-survival signaling pathways, apoptosis and autophagy of human (MM-B1, H-Meso-1, and MM-F1) and mouse (#40a) MM cell lines. In addition, we explored the in vivo anti-tumor activities of AT-101 in a mouse model, in which the transplantation of MM cells induces ascites in the peritoneal space. AT-101 inhibited in vitro MM cells survival in a dose- and time-dependent manner and triggered autophagy, but the process was then blocked and was coincident with apoptosis activation. To confirm the effect of AT-101 in inducing the apoptosis of MM cells, MM cells were simultaneously treated with AT-101 and with the caspase inhibitor, Z-VAD-FMK. Z-VAD-FMK was able to significantly reduce the number of cells in the subG1 phase compared to the treatment with AT-101 alone. This result corroborates the induction of cell death by apoptosis following treatment with AT-101. Indeed, Western blotting results showed that AT-101 increases Bax/Bcl-2 ratio, modulates p53 expression, activates caspase 9 and the cleavage of PARP-1. In addition, the treatment with AT-101 was able to: (a) decrease the ErbB2 protein expression; (b) increase the EGFR protein expression; (c) affect the phosphorylation of ERK1/2, p38 and AKT; (d) stimulate JNK1/2 and c-jun phosphorylation. Our in vivo results showed that the intraperitoneal administration of AT-101 increased the median survival of C57BL/6 mice intraperitoneally transplanted with #40a cells and reduced the risk of developing tumors. Our findings may have important implications for the design of MM therapies by employing AT-101 as an anticancer agent in combination with standard therapies.

Leptomycin B reduces primary and acquired resistance of gefitinib in lung cancer cells

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) gefitinib has demonstrated dramatic clinical efficacy in non-small cell lung cancer (NSCLC) patients. However, its therapeutic efficacy is ultimately limited by the development of acquired drug resistance. The aim of this study was to explore the potential utility of chromosome region maintenance 1 (CRM1) inhibitor leptomycin B (LMB) in combination with gefitinib to overcome primary and acquired gefitinib resistance in NSCLC cells. The combinative effects of gefitinib and LMB were evaluated by MTT and its underlining mechanism was assessed by flow cytometry and Western blot. LMB displayed a synergistic effect on gefitinib-induced cytotoxicity in A549 (IC50: 25.0±2.1μM of gefitinib+LMB vs. 32.0±2.5μM of gefitinib alone, p<0.05). Gefitinib+LMB caused a significantly different cell cycle distribution and signaling pathways involved in EGFR/survivin/p21 compared with gefitinib. A549 cells then were treated with progressively increased concentrations of gefitinib (A549GR) or in combination with LMB (A549GLR) over 10months to generate gefitinib resistance. IC50 of gefitinib in A549GLR (37.0±2.8μM) was significantly lower than that in A549GR (53.0±3.0μM, p<0.05), which indicates that LMB could reverse gefitinib-induced resistance in A549. Further mechanism investigation revealed that the expression patterns of EGFR pathway and epithelial-mesenchymal transition (EMT) markers in A549, A549GR, and A549GLR were significantly different. In conclusion, LMB at a very low concentration (0.5nM) combined with gefitinib showed synergistic therapeutic effects and ameliorated the development of gefitinib-induced resistance in lung cancer cells.