Esophageal cancer (EC) is a highly aggressive cancer with poor outcomes under current treatment regimens. More recent findings suggest stroma elements, specifically cancer-associated fibroblasts (CAFs), play a role in disease occurrence and progression. Cancer-associated fibroblasts are largely the product of converted fibroblasts, but a variety of other local cell types including epithelial cells, endothelial cells, and mesenchymal cells have also been shown to transform to CAFs under the correct conditions. Cancer-associated fibroblasts primarily function in the communication between the tumor microenvironment and cancer cells via cytokine and chemokine secretions that accentuate immunosuppression and cancer growth. Cancer-associated fibroblasts also pose issues for EC treatment by contributing to resistance of current chemotherapeutics like cisplatin. Targeting this cell type directly proves difficult given the heterogeneity between CAFs subpopulations, but emerging research provides hope that treatment is on the horizon. This review aims to unravel some of the complexities surrounding CAFs’ impact on EC growth and therapy.

Tumors with elevated c-Myc expression often exhibit a highly aggressive phenotype, and c-Myc amplification has been shown to be frequent in esophageal cancer. Emerging data suggests that synthetic lethal interactions between c-Myc pathway activation and small molecules inhibition involved in cell cycle signaling can be therapeutically exploited to preferentially kill tumor cells. We therefore investigated whether exploiting elevated c-Myc expression is effective in treating esophageal cancer with the CDK inhibitor flavopiridol. We found frequent overexpression of c-Myc in human esophageal cancer cell lines and tissues. c-Myc overexpression correlated with accelerated esophageal cancer subcutaneous xenograft tumor growth. Esophageal cancer cells with elevated c-Myc expression were found preferentially more sensitive to induction of apoptosis by the CDK inhibition flavopiridol compared to esophageal cancer cells with lower c-Myc expression. In addition, we observed that flavopiridol alone or in combination with the chemotherapeutic agent nanoparticle albumin-bound paclitaxel (NPT) or in combinations with the targeted agent BMS-754807 significantly inhibited esophageal cancer cell proliferation and subcutaneous xenograft tumor growth while significantly enhancing overall mice survival. These results indicate that aggressive esophageal cancer cells with elevated c-Myc expression are sensitive to the CDK inhibitor flavopiridol, and that flavopiridol alone or in combination can be a potential therapy for c-Myc overexpressing esophageal cancer.

Introduction: Esophageal adenocarcinoma (EAC) is one of the fastest growing cancers in the Western world and the overall 5-year survival rate of EAC is below 20 percent. Epidemiological studies have linked obesity with EAC. Insulin-like growth factor (IGF) signaling is an important mediator in obesity-associated EAC. Paclitaxel (PT) has been used in combination with carboplatin as a standard combination therapy for advanced EAC. PT required emulsification with solvents which have resulted in serious adverse effects in patients. Nanoparticle albumin-bound paclitaxel (nab-paclitaxel) is an albumin-stabilized, cremophor-free and water-soluble nanoparticle formulation of PT. Nab-paclitaxel has recently shown greater efficacy over PT in EAC. In this study, we evaluated the potential of targeting IGF signaling and improvement in nab-paclitaxel response by the addition of BMS-754807 in experimental EAC. Methods: We first evaluated the phosphorylation status of IGF-1R/IR protein by Western blot in a panel of EAC cell lines. BMS-754807 and nab-paclitaxel, alone or in combination were tested for effects on cell growth, cell apoptosis, cell migration and cell cycle analyses of EAC cell lines detected respectively by WST-1 assay, Western blotting, would healing scratch assay and propidium iodide flow cytometry. We then explored the antitumor efficacy of BMS-754807 and nab-paclitaxel monotherapy and in combination in murine subcutaneous xenograft and peritoneal metastatic survival models of human EAC. Results: BMS-754807 dose-dependently inhibited in-vitro cell proliferation of EAC cell lines having phosphorylation of IGF-1R/IR protein. The co-administration of BMS-754807 and nab-paclitaxel effectively enhanced cell growth inhibition, cleavage of caspase-3 and PARP, in-vitro wound healing inhibition and cell cycle arrest at sub G0/G1 phase. BMS-754807 in combination with nab-paclitaxel treatment resulted in significantly higher antitumor efficacy by increasing intratumoral apoptosis and survival benefit compared with BMS-754807 or nab-paclitaxel treatment alone. In subcutaneous xenografts using OE19 cells, average net tumor growth after two weeks in different therapy groups was 558.67 mm3 in control, 208.47 mm3 after BMS-754807 (p=0.043), 104.60 mm3 after nab-paclitaxel (p=0.013), and 14.30 mm3 after BMS-754807 plus nab-paclitaxel (p=0.0005). There was a significant increase in median animal survival after BMS-754807 plus nab-paclitaxel treatment (85 days) compared to control (47 days, p=0.0034), BMS-754807 monotherapy (57 days, p=0.0021) or nab-paclitaxel (68 days, p=0.0339) monotherapy. Conclusion: These results support the potential of BMS-754807 in combination with nab-paclitaxel as an effective option for EAC therapy. Citation Format: Md Sazzad Hassan, Nicholas Cwidak, Chloe Johnson, Saisantosh Ponna, Niranjan Awasthi, Urs von Holzen. BMS-754807, a small-molecule inhibitor of insulin-like growth factor-1 receptor/insulin receptor is cytotoxic to esophageal adenocarcinoma cells and enhances nab-paclitaxel response in experimental esophageal 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 1066.

Introduction: Esophageal adenocarcinoma (EAC) is an aggressive form of cancer with 5-year survival rates under 20%. The low survival rate is due largely to advanced stage upon diagnosis. Improved treatment options remain essential in combating the disease and bolstering patient outcomes. Nanoparticle albumin-bound paclitaxel (nab-paclitaxel) is a chemotherapeutic receiving attention for its potential in EAC treatment. The taxane has exhibited greater specificity for targeting cancer cells while decreasing cytotoxic effects to adjacent healthy populations. Unfortunately, chemoresistance remains an issue surrounding adequate treatment regimes. Epinephrine and its receptor, β2 adrenergic, have been shown to dysregulate various oncogenic pathways and reduce chemotherapeutics efficacy. Typically associated with pain management and addiction treatment, Methadone hydrochloride has been investigated for its potential to block the oncogenic effects of epinephrine and strengthen the impact of chemotherapeutics. In this study, we evaluated the enhancement of apoptosis by combination of nab-paclitaxel and methadone, and we demonstrated the ability of methadone to block epinephrine-induced chemoresistance. Method: We utilized PCR to elucidate EAC cell lines with the greatest expression of Mu opioid and β2 adrenergic receptors. Next, we investigated adequate dosages of methadone and epinephrine for the EAC cell lines by WST-1 assay. WST-1 assays were also utilized to determine cell growth under co-administration of nab-paclitaxel and methadone as well as methadone and epinephrine. Propidium iodine cell viability flow cytometry assay was used to detect cell death. Annexin V staining was utilized to further distinguish between apoptotic and necroptotic cells. Result: OE19 and OE33 cell lines showed increased expression of Mu and β2 adrenergic receptors, ensuring the cells were capable of binding to methadone or epinephrine. WST-1 assays established 100 nM of epinephrine and 200 nM of methadone as optimal dosages for both cell lines. Our previous studies demonstrated that about 5.85 uM of nab-paclitaxel (5ug/mL) induces apoptosis in OE19 and OE33. Propidium iodide staining showed the enhancement of cell death under combination treatment of nab-paclitaxel and methadone. Annexin V staining confirmed that the effect was via apoptosis. Conclusion: The current study demonstrated methadone’s ability to block epinephrine-induced cell proliferation and showed an enhanced effect on apoptosis when combining nab-paclitaxel with methadone in EAC treatment. Citation Format: Nicholas Cwidak, Sazzad Hassan, Chloe Johnson, Saisantosh Ponna, Niranjan Awasthi, Urs von Holzen. Methadone hydrochloride blocks epinephrine-induced proliferation and enhances apoptotic effects of nab-paclitaxel in esophageal 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 2624.

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