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      PERK Inhibition by HC-5404 Sensitizes Renal Cell Carcinoma Tumor Models to Antiangiogenic Tyrosine Kinase Inhibitors


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          Tumors activate protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK, also called EIF2AK3) in response to hypoxia and nutrient deprivation as a stress-mitigation strategy. Here, we tested the hypothesis that inhibiting PERK with HC-5404 enhances the antitumor efficacy of standard-of-care VEGF receptor tyrosine kinase inhibitors (VEGFR-TKI).

          Experimental Design:

          HC-5404 was characterized as a potent and selective PERK inhibitor, with favorable in vivo properties. Multiple renal cell carcinoma (RCC) tumor models were then cotreated with both HC-5404 and VEGFR-TKI in vivo, measuring tumor volume across time and evaluating tumor response by protein analysis and IHC.


          VEGFR-TKI including axitinib, cabozantinib, lenvatinib, and sunitinib induce PERK activation in 786-O RCC xenografts. Cotreatment with HC-5404 inhibited PERK in tumors and significantly increased antitumor effects of VEGFR-TKI across multiple RCC models, resulting in tumor stasis or regression. Analysis of tumor sections revealed that HC-5404 enhanced the antiangiogenic effects of axitinib and lenvatinib by inhibiting both new vasculature and mature tumor blood vessels. Xenografts that progress on axitinib monotherapy remain sensitive to the combination treatment, resulting in ∼20% tumor regression in the combination group. When tested across a panel of 18 RCC patient-derived xenograft (PDX) models, the combination induced greater antitumor effects relative to monotherapies. In this single animal study, nine out of 18 models responded with ≥50% tumor regression from baseline in the combination group.


          By disrupting an adaptive stress response evoked by VEGFR-TKI, HC-5404 presents a clinical opportunity to improve the antitumor effects of well-established standard-of-care therapies in RCC.

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          Most cited references55

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          The integrated stress response.

          In response to diverse stress stimuli, eukaryotic cells activate a common adaptive pathway, termed the integrated stress response (ISR), to restore cellular homeostasis. The core event in this pathway is the phosphorylation of eukaryotic translation initiation factor 2 alpha (eIF2α) by one of four members of the eIF2α kinase family, which leads to a decrease in global protein synthesis and the induction of selected genes, including the transcription factor ATF4, that together promote cellular recovery. The gene expression program activated by the ISR optimizes the cellular response to stress and is dependent on the cellular context, as well as on the nature and intensity of the stress stimuli. Although the ISR is primarily a pro-survival, homeostatic program, exposure to severe stress can drive signaling toward cell death. Here, we review current understanding of the ISR signaling and how it regulates cell fate under diverse types of stress.
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            Is Open Access

            Comprehensive review of targeted therapy for colorectal cancer

            Colorectal cancer (CRC) is among the most lethal and prevalent malignancies in the world and was responsible for nearly 881,000 cancer-related deaths in 2018. Surgery and chemotherapy have long been the first choices for cancer patients. However, the prognosis of CRC has never been satisfying, especially for patients with metastatic lesions. Targeted therapy is a new optional approach that has successfully prolonged overall survival for CRC patients. Following successes with the anti-EGFR (epidermal growth factor receptor) agent cetuximab and the anti-angiogenesis agent bevacizumab, new agents blocking different critical pathways as well as immune checkpoints are emerging at an unprecedented rate. Guidelines worldwide are currently updating the recommended targeted drugs on the basis of the increasing number of high-quality clinical trials. This review provides an overview of existing CRC-targeted agents and their underlying mechanisms, as well as a discussion of their limitations and future trends.
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              Cabozantinib (XL184), a novel MET and VEGFR2 inhibitor, simultaneously suppresses metastasis, angiogenesis, and tumor growth.

              The signaling pathway of the receptor tyrosine kinase MET and its ligand hepatocyte growth factor (HGF) is important for cell growth, survival, and motility and is functionally linked to the signaling pathway of VEGF, which is widely recognized as a key effector in angiogenesis and cancer progression. Dysregulation of the MET/VEGF axis is found in a number of human malignancies and has been associated with tumorigenesis. Cabozantinib (XL184) is a small-molecule kinase inhibitor with potent activity toward MET and VEGF receptor 2 (VEGFR2), as well as a number of other receptor tyrosine kinases that have also been implicated in tumor pathobiology, including RET, KIT, AXL, and FLT3. Treatment with cabozantinib inhibited MET and VEGFR2 phosphorylation in vitro and in tumor models in vivo and led to significant reductions in cell invasion in vitro. In mouse models, cabozantinib dramatically altered tumor pathology, resulting in decreased tumor and endothelial cell proliferation coupled with increased apoptosis and dose-dependent inhibition of tumor growth in breast, lung, and glioma tumor models. Importantly, treatment with cabozantinib did not increase lung tumor burden in an experimental model of metastasis, which has been observed with inhibitors of VEGF signaling that do not target MET. Collectively, these data suggest that cabozantinib is a promising agent for inhibiting tumor angiogenesis and metastasis in cancers with dysregulated MET and VEGFR signaling.

                Author and article information

                Clin Cancer Res
                Clin Cancer Res
                Clinical Cancer Research
                American Association for Cancer Research
                01 December 2023
                21 September 2023
                : 29
                : 23
                : 4870-4882
                [1 ]HiberCell, Inc., New York City, New York.
                [2 ]Curia, Buffalo, New York.
                [3 ]Drug Discovery, Pharmaron UK Ltd., Hoddesdon, Herts, United Kingdom.
                [4 ]Indiana University School of Medicine, Indianapolis, Indiana.
                [5 ]Indiana University Melvin and Bren Simon Comprehensive Cancer Center, Indianapolis, Indiana.
                Author notes

                M.E. Stokes and V. Calvo contributed equally to this article.

                [* ] Corresponding Author: Michael E. Stokes, HiberCell, Inc., 619 West 54th Street, New York City, NY 10019. E-mail: mstokes@ 123456hibercell.com

                Clin Cancer Res 2023;29:4870–82

                Author information
                ©2023 The Authors; Published by the American Association for Cancer Research

                This open access article is distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) license.

                : 21 April 2023
                : 28 July 2023
                : 19 September 2023
                Page count
                Pages: 13
                Funded by: n/a, DOI 10.13039/;
                Angiogenesis Inhibitors & Stimulators
                Cellular Stress Responses
                Drug Targets
                Protein Kinase & Phosphatase Drug Targets
                Preclinical Models
                Xenograft Models
                Small Molecule Agents
                Kinase Inhibitors
                Translational Research
                Translational Cancer Mechanisms and Therapy


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