搭載化學治療藥物之標靶性奈米傳輸系統於大腸直腸癌口服或腹膜轉移治療之開發與應用

Development of Targetable Nanoparticle-Based Drug Delivery Systems for Oral Chemotherapy for Colon Cancer and for Peritoneal Carcinomatosis

沈名吟(Ming-Yin Shen)

指導教授 ： 邱信程

國立清華大學/原子科學院/生醫工程與環境科學系/博士(2020年)

摘要

大腸直腸癌（Colorectal Cancer, CRC）是台灣最常見的癌症，在最近十年來，台灣每年診斷出超過一萬五千名大腸直腸癌患者。儘管超過一半以上的患者在治療後可以痊癒，但是仍有需多治療上的難題影響患者的生命與健康。在這些問題中，簡化化學治療從靜脈途徑到口服方式是一大難題，因為口服化學治療顯然可以減輕患者在治療過程中的痛苦並提高依從性。另一個主要問題是提高化學療法對大腸直腸癌腹膜轉移的效果，而目前常規化療無法有效控制疾病的惡化。
儘管臨床上已有大腸直腸癌化學治療的口服製劑，但是藥物吸收在腸道吸收後，仍不可避免地伴隨全身性副作用。因此我們期望開發出局部治療於腸道腫瘤的口服治療系統，其特徵在於高度選擇性地遞送至癌細胞，並最小化全身藥物吸收。我們的研究顯示，通過對葉酸（Folate, FA）和聚葡萄糖（dextran）進行分層靶向，可以將搭載艾黴素（doxorubicin）和超順磁奈米氧化鐵顆粒（superparamagnetic iron oxide nanoparticles）的固體脂質奈米顆粒（solid lipid nanoparticle, SLN）藥物傳遞系統，以順序逐層的方式有效的累積在腫瘤細胞及吸收，並應用於腫瘤的化學磁熱雙重治療。體外和體內實驗均強烈證實SLN表面上的聚葡萄糖殼不僅阻礙了小腸刷狀絨毛膜上的proton-coupled FA transporter對SLN的細胞轉運，而且因為與大腸腸道中的聚葡萄糖酶 （dextranase）的特異性結合，還增強了SLN在大腸腸道的停留時間。藉由酶分解除去SLN外層的聚葡萄糖塗層讓FA殘基的暴露，進一步以標靶受體媒介的細胞內嗜作用（receptor-mediated endocytosis）促進SLN的攝取。在體內實驗中，通過口服給藥對分級靶向的SLN治療系統的體內抗腫瘤功效的評估顯示，在腹水量，腫瘤結節數量和大小方面，有效抑制了原發性結腸腫瘤和腹膜轉移，並且沒有全身性副作用。
大腸直腸癌腹膜轉移（peritoneal carcinomatosis colorectal cancer, pcCRC）由於其侵襲性特徵和診斷局限性而成為臨床治療中最具挑戰性的病例之一，目前仍無法以現有的化學治療得到良好效果。在這項研究中，我們開發了 Poly(lactic-co-glycolic acid) nanoparticle (NP) 奈米藥物遞送系統，該系統能夠封裝治療效果極佳、但是臨床無法直接使用的化學藥物SN38，並增強轉移性腫瘤中的藥物累積，以治療pcCRC。搭載SN38 的奈米粒子（SN38 NP）直徑約160 nm，表面均經過N-acetyl histidine-modified D-α-tocopheryl polyethylene glycol succinate (TPGS) 和folate-TPGS修飾，在通過弱酸性腫瘤微環境條件下藉由表面電荷轉化，選擇性的靶向葉酸受體過度表達的結腸癌細胞，來增強藥物蓄積於腫瘤。體外實驗顯示這種分級靶向的藥物傳遞策略不僅改善了載藥NP的細胞攝取，而且改善了對CT26癌細胞的顯著抗癌作用。體內研究顯示，就腫瘤大小和結節數目的大幅度減少以及攜帶pcCRC的小鼠的生存時間延長而言，SN38 NPs對腫瘤具有良好的抑製作用，表明它們具有實用的pcCRC治療潛力。

關鍵字

階層式標靶 ； 硬脂質奈米粒子 ； 大腸癌腸道腫瘤治療 ； 口服劑型 ； 大腸直腸癌腹膜轉移 ； SN38奈米粒子 ； 靜脈注射治療

並列摘要

Colorectal cancer is the most common cancer in Taiwan and more than 15,000 colorectal cancer patients are diagnosed per year in recent decade. Although more than half of the patients could be cured after treatment, there are several major issues confronting us and affecting patient’s life. Among these issues, how to simplify chemotherapy administration from intravenous route to oral form is one of the majors, and it obviously reduce patients’ suffering during the treatment and increase their compliance. The other major problem is to improve the effect of chemotherapy on peritoneal carcinomatosis of colorectal cancer (pcCRC), which currently could not be efficiently treated by conventional chemotherapy.
Although oral formulations of anticancer chemotherapies are clinically available, the therapeutic action relies mostly on drug absorption, being inevitably accompanied with systemic side effects. It is thus desirable to develop oral therapy systems for the local treatment of colon cancers featured with highly selective delivery to cancer cells and minimized systemic drug absorption. Our study demonstrates the effective accumulation and cell uptake of the doxorubicin and superparamagnetic iron oxide nanoparticles-loaded solid lipid nanoparticle (SLN) delivery system for chemo/magnetothermal combination therapy at tumors by hierarchical targeting of folate (FA) and dextran coated on SLN surfaces in a sequential layer-by-layer manner. Both the in vitro and in vivo characterizations strongly confirmed that the dextran shells on SLN surfaces not only retarded the cellular transport of the FA-coated SLNs by the proton-coupled FA transporter on brush border membranes in small intestine, but also enhanced the particle residence in colon by specific association with dextranase. The enzymatic degradation and removal of dextran coating led to the exposure of the FA residues, thereby further facilitating the cellular-level targeting and uptake of the SLNs by the receptor-mediated endocytosis. The evaluation of the in vivo antitumor efficacy of the hierarchically targetable SLN therapy system by oral administration showed the effective inhibition of primary colon tumors and peritoneal metastasis in terms of the ascites volume and tumor nodule number and size, along with the absence of systemic side effects.
Peritoneal carcinomatosis colorectal cancer (pcCRC) is one of the most challenging cases in clinical treatment due to its aggressive characteristics and diagnostic limitations, impeding the therapeutic efficacy of chemotherapy. In our study, a poly(lactic-co-glycolic acid) nanoparticle (NP)-based drug delivery system capable of encapsulating the chemodrug, SN38, and enhancing drug accumulation in metastatic tumors was developed for the treatment of pcCRC. The SN38-loaded NPs with a diameter ca 160 nm were decorated with N-acetyl histidine-modified D-α-tocopheryl polyethylene glycol succinate (TPGS) and folate-TPGS on their surfaces for enhancing drug accumulation through surface charge conversion in a mildly acidic tumor microenvironment and further imparting the NPs to selectively target the folate receptor-overexpressed colon cancer cells. This hierarchically targeted drug delivery strategy improved not only the highly enhanced cellular uptake of drug-loaded NPs, but also the prominent anticancer effect against CT26 cancer cells in vitro. The in vivo studies demonstrated the sound tumor inhibition of the SN38-loaded NPs in terms of large reductions in both tumor size and nodule number and prolongation of survival time of pcCRC-bearing mice, indicating their high therapeutic potential for practical treatment of pcCRC.

並列關鍵字

Hierarchical targeting ； Solid lipid nanoparticles ； Local colon cancer treatment ； Oral formulations ； Peritoneal Carcinomatosis Colorectal Cancer ； SN38-loaded nanoparticles ； Intravenous formulations

參考文獻

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