Intratumoral Injection of Anlotinib Hydrogel Combined With Radiotherapy Reduces Hypoxia in Lewis Lung Carcinoma Xenografts: Assessment by Micro Fluorine-18-fluoromisonidazole Positron Emission Tomography/Computed Tomography Hypoxia Imaging.

Qin Gao,Hui Chen,Xiaojie Li,Yue Chen,Han Chen,Shaozhi Fu,Yiqing Jiang,Shan Tang,Sheng Lin,Xiangxiang Shi

doi:10.3389/fonc.2021.628895

Qin Gao, Hui Chen + Show 8 more

Open Access

https://doi.org/10.3389/fonc.2021.628895

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Abstract

Hypoxia is a common feature of solid tumors that increases tumor invasiveness and resistance to radiotherapy (RT) and chemotherapy. Local application of anlotinib (AL) might increase the regulation of new blood vessel growth and improve tumor hypoxia in RT. Therefore, it is essential to fully understand the drug delivery system of AL. Herein, we applied hypoxia imaging using micro fluorine-18-fluoromisonidazole positron emission tomography/computed tomography (micro 18F-FMISO PET/CT) to assess responses to intratumoral injections of an AL hydrogel (AL-HA-Tyr) combined with RT in mice bearing Lewis lung carcinoma (LLC). We formed AL-HA-Tyr by encapsulating AL with hyaluronic acid-tyramine (HA-Tyr) conjugates via the oxidative coupling of tyramine moieties catalyzed by H2O2 and horseradish peroxidase. AL-HA-Tyr restrained the proliferation of human umbilical endothelial cells (HUVECs) in colony formation assays in vitro (p < 0.001). We established a subcutaneous LLC xenograft model using C57BL/6J mice that were randomly assigned to six groups that were treated with AL, HA-Tyr, AL-HA-Tyr, RT, and RT+AL-HA-Tyr, or untreated (controls). Tumor volume and weight were dynamically measured. Post treatment changes in hypoxia were assessed in some mice using micro 18F-FMISO PET/CT, and survival was assessed in others. We histopathologically examined toxicity in visceral tissues and Ki-67, VEGF-A, γ-H2AX, and HIF-1α expression using immunohistochemistry. Direct intratumoral injections of AL-HA-Tyr exerted anti-tumor effects and improved hypoxia like orally administered AL (p > 0.05), but reduced visceral toxicity and prolonged survival. The uptake of 18F-FMISO did not significantly differ among the AL, AL-HA-Tyr, and RT+AL-HA-Tyr treated groups. Compared with the other agents, RT+AL-HA-Tyr decreased HIF-1α, Ki67, and VEGF-A expression, and increased γ-H2AX levels in tumor cells. Overall, compared with AL and AL-HA-Tyr, RT+AL-HA-Tyr improved tumor hypoxia, enhanced anti-tumor effects, and prolonged the survival of mice bearing LLC.

Highlights

Lung cancer accounts for the highest morbidity worldwide
AL-HA-Tyr hydrogel was formed following oxidative coupling of tyramine moieties catalyzed by H2O2 and HRP (Figure 1B)
We found that, compared with AL, AL-HA-Tyr decreased the expression of vascular endothelial growth factor (VEGF)-A; compared with RT, RT+AL-HA-Tyr combined therapy could significantly reduce the proportion of VEGF-A positive cells

Summary

Introduction

75% patients are diagnosed in the middle and advanced stages, which seriously hampers treatment [1, 2]. RT is the primary treatment option for patients with locally advanced (stage III) lung cancer [4]. Anlotinib (AL) hydrochloride is a new and promising antiangiogenesis drug, which has broad anti-tumor capacity showing significant therapeutic effect on several kinds of solid tumors [5,6,7,8,9]. Being an anti-vascular drug, many elderly patients cannot tolerate AL, due to side effects such as hypertension and hyperlipidemia. Local application of AL might downregulate the angiogenesis and tumor hypoxia during RT. The effects AL-HA-Tyr on angiogenesis, tumors, and hypoxia should be fully understood in the context of RT

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