Combination of Vandetanib, Radiotherapy, and Irinotecan in the LoVo Human Colorectal Cancer Xenograft Model

Novel biomarkers used for early diagnosis and tyrosine kinase inhibitors as targeted therapies in colorectal cancer

Colorectal cancer (CRC) is the third most common and second most lethal type of cancer worldwide, presenting major health risks as well as economic costs to both people and society. CRC survival chances are significantly higher if the cancer is diagnosed and treated early. With the development of molecular biology, numerous initiatives have been undertaken to identify novel biomarkers for the early diagnosis of CRC. Pathological disorders can be diagnosed at a lower cost with the help of biomarkers, which can be detected in stool, blood, and tissue samples. Several lines of evidence suggest that the gut microbiota could be used as a biomarker for CRC screening and treatment. CRC treatment choices include surgical resection, chemotherapy, immunotherapy, gene therapy, and combination therapies. Targeted therapies are a relatively new and promising modality of treatment that has been shown to increase patients' overall survival (OS) rates and can inhibit cancer cell development. Several small-molecule tyrosine kinase inhibitors (TKIs) are being investigated as potential treatments due to our increasing awareness of CRC's molecular causes and oncogenic signaling. These compounds may inhibit critical enzymes in controlling signaling pathways, which are crucial for CRC cells' development, differentiation, proliferation, and survival. On the other hand, only one of the approximately 42 TKIs that demonstrated anti-tumor effects in pre-clinical studies has been licensed for clinical usage in CRC. A significant knowledge gap exists when bringing these tailored medicines into the clinic. As a result, the emphasis of this review is placed on recently discovered biomarkers for early diagnosis as well as tyrosine kinase inhibitors as possible therapy options for CRC.

Targeting the Extra-Cellular Matrix-Tumor Cell Crosstalk for Anti-Cancer Therapy: Emerging Alternatives to Integrin Inhibitors

The extracellular matrix (ECM) is a complex network composed of a multitude of different macromolecules. ECM components typically provide a supportive structure to the tissue and engender positional information and crosstalk with neighboring cells in a dynamic reciprocal manner, thereby regulating tissue development and homeostasis. During tumor progression, tumor cells commonly modify and hijack the surrounding ECM to sustain anchorage-dependent growth and survival, guide migration, store pro-tumorigenic cell-derived molecules and present them to enhance receptor activation. Thereby, ECM potentially supports tumor progression at various steps from initiation, to local growth, invasion, and systemic dissemination and ECM-tumor cells interactions have long been considered promising targets for cancer therapy. Integrins represent key surface receptors for the tumor cell to sense and interact with the ECM. Yet, attempts to therapeutically impinge on these interactions using integrin inhibitors have failed to deliver anticipated results, and integrin inhibitors are still missing in the emerging arsenal of drugs for targeted therapies. This paradox situation should urge the field to reconsider the role of integrins in cancer and their targeting, but also to envisage alternative strategies. Here, we review the therapeutic targets implicated in tumor cell adhesion to the ECM, whose inhibitors are currently in clinical trials and may offer alternatives to integrin inhibition.

Radiosensitisation of Hepatocellular Carcinoma Cells by Vandetanib

Hepatocellular Carcinoma (HCC) is increasing in incidence worldwide and requires new approaches to therapy. The combination of anti-angiogenic drug therapy and radiotherapy is one promising new approach. The anti-angiogenic drug vandetanib is a tyrosine kinase inhibitor of vascular endothelial growth factor receptor-2 (VEGFR-2) and RET proto-oncogene with radio-enhancement potential. To explore the benefit of combined vandetanib and radiotherapy treatment for HCC, we studied outcomes following combined treatment in pre-clinical models. Methods: Vandetanib and radiation treatment were combined in HCC cell lines grown in vitro and in vivo. In addition to 2D migration and clonogenic assays, the combination was studied in 3D spheroids and a syngeneic mouse model of HCC. Results: Vandetanib IC50s were measured in 20 cell lines and the drug was found to significantly enhance radiation cell kill and to inhibit both cell migration and invasion in vitro. In vivo, combination therapy significantly reduced cancer growth and improved overall survival, an effect that persisted for the duration of vandetanib treatment. Conclusion: In 2D and 3D studies in vitro and in a syngeneic model in vivo, the combination of vandetanib plus radiotherapy was more efficacious than either treatment alone. This new combination therapy for HCC merits evaluation in clinical trials.

Evaluating vandetanib in the treatment of medullary thyroid cancer: patient-reported outcomes

Medullary thyroid cancers (MTCs) are neuroendocrine tumors, which secrete calcitonin and carcinoembryonic antigen, both of which can serve as tumor markers. Extensive and accurate surgical resection is the primary treatment for MTC, whereas the use of external beam radiotherapy is limited. Moreover, since MTC is derived from thyroid parafollicular cells or C cells, it is not responsive to either radioiodine or thyroid-stimulating hormone suppression, and therefore, they cannot be considered as treatment strategies. Traditional therapies for advanced or metastatic progressive medullary thyroid cancer (pMTC) are poorly effective. Among the new approaches tested in clinical trials, targeted chemotherapies with tyrosine kinase inhibitors (TKIs) are now available and they represent effective interventions for progressive disease, with additional investigational options emerging. This paper reviews the efficacy and safety of vandetanib in patients with a pMTC, as it has been shown to improve progression-free survival (30.5 vs 19.3 months in controls). Vandetanib is approved by the FDA and EMA for symptomatic or progressive MTC in patients with unresectable locally advanced or metastatic disease in adults, adolescents, and children older than 5 years. The most common adverse events in vandetanib-treated patients are diarrhea, rash, folliculitis, nausea, QTc prolongation, hypertension, and fatigue. More data are required to deepen our knowledge on molecular biology of tumor and host defense, with the aim to achieve better prognosis and higher quality of life for affected patients.

TNF Signaling through RIP1 Kinase Enhances SN38-Induced Death in Colon Adenocarcinoma

Elucidation of TNF-directed mechanisms for cell death induction and maintenance of tumor growth has revealed a role for receptor-interacting protein kinases 1 and 3 (RIPK1/RIP1 and RIPK3/RIP3), components of the necrosome complex, as determinants of cell fate. Here, the participation of TNF signaling was analyzed with regard to the cytotoxic action of different DNA-damaging agents in a panel of colon cancer cells. While most of these cell lines were insensitive to TNF, combination with these drugs increased sensitivity by inducing cell death and DNA damage, especially in the case of the topoisomerase inhibitor SN38. Changes in levels of RIP1 and RIP3 occurred following monotherapy with SN38 or in combination with TNF. Downregulation of RIP1 resulted in increased resistance to SN38, implying a requirement for RIP1 in mediating cytotoxicity through the TNF/TNFR signaling pathway. Downregulation of RIP1 in a xenograft model impaired tumor growth inhibition from SN38 treatment, suggesting the potential of RIP1 to determine the clinical outcome of irinotecan treatment. These results indicate that TNF plays a key role in determining the cytotoxic effectiveness of SN38 in colorectal cancer and suggests a re-evaluation of TNF-based interventions to enhance therapeutic efficacy.Implications: The capacity of RIP1 to influence drug sensitivity suggests RIP1 may have biomarker potential. Mol Cancer Res; 15(4); 395-404. ©2017 AACR.

Recent Updates on the Management of Medullary Thyroid Carcinoma

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine tumor derived from the thyroid C cells producing calcitonin. MTC accounts for 0.6% of all thyroid cancers and incidence of MTC increased steadily between 1997 and 2011 in Korea. It occurs either sporadically or in a hereditary form based on germline rearranged during transfection (RET) mutations. MTC can be cured only by complete resection of the thyroid tumor and any loco-regional metastases. The most appropriate treatment is still less clear in patients with residual or recurrent disease after initial surgery or those with distant metastases because most patients even with metastatic disease have indolent courses with slow progression for several years and MTC is not responsive to either radioactive iodine therapy or thyroid-stimulating hormone suppression. Recently, two tyrosine kinase inhibitors (TKIs), vandetanib and cabozantinib, are approved for use in patients with advanced, metastatic or progressive MTC. In this review, we summarize the current approach according to revised American Thyroid Association guidelines and recent advances in systemic treatment such as TKIs for patients with persistent or recurrent MTC after surgery.

Selective use of vandetanib in the treatment of thyroid cancer

Vandetanib is a once-daily orally available tyrosine kinase inhibitor that works by blocking RET (REarranged during Transfection), vascular endothelial growth factor receptor (VEGFR-2, VEGFR-3), and epidermal growth factor receptor and to a lesser extent VEGFR-1, which are important targets in thyroid cancer (TC). It is emerging as a potentially effective option in the treatment of advanced medullary thyroid cancer (MTC) and in dedifferentiated papillary thyroid cancer not responsive to radioiodine. The most important effect of vandetanib in aggressive MTC is a prolongation of progression-free survival and a stabilization of the disease. Significant side effects have been observed with the vandetanib therapy (as fatigue, hypertension, QTc prolongation, cutaneous rash, hand-and-foot syndrome, diarrhea, etc), and severe side effects can require the suspension of the drug. Several studies are currently under way to evaluate the long-term efficacy and tolerability of vandetanib in MTC and in dedifferentiated papillary TC. The efficacy of vandetanib in patients with MTC in long-term treatments could be overcome by the resistance to the drug. However, the effectiveness of the treatment could be ameliorated by the molecular characterization of the tumor and by the possibility to test the sensitivity of primary TC cells from each subject to different tyrosine kinase inhibitor. Association studies are evaluating the effect of the association of vandetanib with other antineoplastic agents (such as irinotecan, bortezomib, etc). Further research is needed to determine the ideal therapy to obtain the best response in terms of survival and quality of life.

Cediranib enhances control of wild type EGFR and EGFRvIII-expressing gliomas through potentiating temozolomide, but not through radiosensitization: implications for the clinic

Glioblastomas (GBM) frequently overexpress the epidermal growth factor receptor (wtEGFR) or its mutant, EGFRvIII, contributing to chemo- and radioresistance. The current standard of care is surgery followed by radiation therapy with concurrent temozolomide (TMZ) followed by adjuvant TMZ. New treatment strategies for GBM include blockade of EGFR signaling and angiogenesis. Cediranib is a highly potent receptor tyrosine kinase inhibitor that inhibits all three VEGF receptors. This study investigated the radiosensitizing potential of cediranib in combination with TMZ in U87 GBM xenografts expressing wtEGFR or EGFRvIII. U87 GBM cells stably transfected with either wtEGFR or EGFRvIII were injected into the hind limbs of nude mice. Cediranib was dosed at 3 mg/kg daily five times a week orally for 2 weeks. TMZ was dosed at 10 mg/kg once only on day 0. Radiotherapy (RT) consisted of 3 fractions of 5 Gy (days 0-2). Cediranib did not radiosensitize either tumor type; however, cediranib did enhance the effectiveness of TMZ in both transfectants. Our results suggest that combining cediranib with temozolomide in the clinic will lead to improved tumor control.

Vandetanib restores head and neck squamous cell carcinoma cells' sensitivity to cisplatin and radiation in vivo and in vitro

PURPOSE

We investigated whether vandetanib, an inhibitor of the tyrosine kinase activities of vascular endothelial growth factor receptor-2 (VEGFR-2), epidermal growth factor receptor (EGFR), and rearranged during transfection (RET), could augment the antitumor activity of radiation with or without cisplatin in preclinical in vitro and in vivo models of human head and neck squamous cell carcinoma (HNSCC).

EXPERIMENTAL DESIGN

OSC-19 and HN5 HNSCC cells that were cisplatin and radioresistant were treated with vandetanib, cisplatin, and radiation alone or in combination in vitro and in vivo using an orthotopic nude mouse model. Treatment effects were assessed using clonogenic survival assay, tumor volume, bioluminescence imaging, tumor growth delay, survival, microvessel density, tumor and endothelial cell apoptosis, and EGFR and Akt phosphorylation data.

RESULTS

Vandetanib plus cisplatin radiosensitized HNSCC cells in vitro and in vivo. The combination treatment with vandetanib, cisplatin, and radiation was superior to the rest of treatments (including the double combinations) in antitumoral effects, prolonging survival, decreasing cervical lymph node metastases in vivo. It also increased both tumor and tumor-associated endothelial cell apoptosis and decreased microvessel density in vivo. An analysis of tumor growth delay data revealed that vandetanib plus cisplatin enhanced radioresponse in vivo. All vandetanib-containing treatments inhibited EGFR and Akt phosphorylation in vitro and in vivo.

CONCLUSION

The addition of vandetanib to combination therapy with cisplatin and radiation was able to effectively overcome cisplatin and radioresistance in in vitro and in vivo models of HNSCC. Further study of this regimen in clinical trials may be warranted.

Epidermal growth factor receptor expression modulates antitumor efficacy of vandetanib or cediranib combined with radiotherapy in human glioblastoma xenografts

PURPOSE

The purpose of this study was to determine the ability of radiation therapy (RT) combined with the tyrosine kinase inhibitors (TKI) vandetanib (antiepidermal growth factor receptor [EGFR] plus antivascular endothelial growth factor receptor [anti-VEGFR]) and cediranib (anti-VEGFR) to inhibit glioblastoma multiforme (GBM) growth. A secondary aim was to investigate how this regimen is modulated by tumor EGFR expression.

METHODS AND MATERIALS

Radiosensitivity was assessed by clonogenic cell survival assay. VEGF secretion was quantified by enzyme-linked immunosorbent assay. GBM (U87MG wild-type EGFR [wtEGFR] and U87MG EGFR-null) xenografts were treated with vandetanib, cediranib, and RT, alone or in combinations. Excised tumor sections were stained for proliferative and survival biomarkers.

RESULTS

In vitro, U87MG wtEGFR and U87 EGFR-null cells had similar growth kinetics. Neither TKI affected clonogenic cell survival following RT. However, in vivo, exogenous overexpression of wtEGFR decreased tumor doubling time (T2x) in U87MG xenografts (2.70 vs. 4.41 days for U87MG wtEGFR vs. U87MG vector, respectively). In U87MG EGFR-null cells, TKI combined with radiation was no better than radiation therapy alone. In U87MG wtEGFR, RT in combination with vandetanib (but not with cediranib) significantly increased tumor T2x compared with RT alone (T2x, 10.4 days vs. 4.8 days; p < 0.001). In vivo, growth delay correlated with suppression of pAkt, survivin, and Ki67 expression in tumor samples. The presence of EGFR augmented RT-stimulated VEGF release; this effect was inhibited by vandetanib.

CONCLUSIONS

EGFR expression promoted tumor growth in vivo but not in vitro, suggesting a microenvironmental effect. GBM xenografts expressing EGFR exhibited greater sensitivity to both cediranib and vandetanib than EGFR-null tumors. Hence EGFR status plays a major role in determining a tumor's in vivo response to radiation combined with TKI, supporting a "personalized" approach to GBM management.