探討奈米藥物結合超音波熱治療及熱手術對腫瘤之療效

Abstract

研究背景： 奈米抗癌藥物是透過腫瘤新生之微血管傳輸，從疏鬆的血管內皮孔洞滲漏出，當腫瘤體積較大時，內部血管發育不全，加上組織間質的壓力及血管間距增加，導致藥物無法有效輸送到整個腫瘤組織以達到全面的治療。 研究目標： 本研究之目的在於將奈米藥物結合超音波熱治療提升腫瘤外部血流灌注量來增加藥物之傳遞，再針對循環不佳部分進行超音波熱燒灼手術，以增進整體腫瘤治療效益。 材料與方法： 本實驗使用年齡4~8周，體重18~22公克之BALB/c母鼠，將10^6個小鼠乳癌細胞 4T1 植入小鼠右側背部皮下。使用物理治療用的1 MHz平面探頭進行熱治療，及0.47 MHz的聚焦型探頭進行熱燒灼手術。實驗組別依 PLD 劑量分為5 mg/kg 及3 mg/kg 兩大群；再依治療方式分為四組：Control 組、PLD 組、PLD 搭配熱治療(42°C 10 min)組、及PLD加上熱燒灼(56°C)搭配熱治療組。腫瘤在植入後每天利用電子式游標尺量測腫瘤體積並拍照記錄、及利用電子天平測量小鼠體重，於腫瘤長至 250-350 mm^3 開始進行第一次治療、隔五天後進行第二次治療，並持續觀察到第 12 天。在治療前、治療期間及治療後利用非侵入式活體分子影像系統(In Vivo Image System, IVIS)觀測腫瘤細胞數量變化，並在小鼠犧牲後進行腫瘤組織切片H&E染色分析。 結果： 施打PLD劑量為5 mg/kg 的三組腫瘤體積皆比Control組小且具有顯著差異，而PLD+熱治療組的腫瘤體積又比PLD組小，亦具有顯著差異。而在打入PLD後，針對腫瘤中心部分進行熱燒灼手術、再輔以熱治療的組別，其腫瘤體積外觀上則和PLD+熱治療組無顯著差異。若將PLD劑量減為3 mg/kg，則有施打PLD的三組腫瘤體積生長仍和Control組相比具有顯著差異，且PLD+熱治療組和PLD 組亦有顯著差異，PLD+熱燒灼+熱治療組和 PLD+熱治療組相比也有顯著差異。在活體分子影像部分，無論 PLD 劑量高低，Control組平均光子值皆比PLD組高，而PLD組別也比經過超音波治療的組別高，最後兩組之間差異並不明顯。從組織 H&E染色切片的結果也可看到，經過PLD加上熱治療的組織會聚集相當多單核球，胞外基質也較鬆散，而再加入熱燒灼手術的組別腫瘤組織則幾乎完全被破壞。 結論： 熱治療確實能提升PLD在腫瘤中累積的濃度並增加其治療效益，但在較高劑量藥物(5 mg/kg)施打下，由於藥物本身就具有優異療效，加入熱燒灼手術並不會和單給熱治療的組別有太大治療效益差別；不過在較低劑量藥物(3 mg/kg)施打下，輔以熱燒灼手術，就能顯著提升藥物及熱治療對腫瘤的療效。

Background: Anti-cancer nanodrugs can pass through leaky tumor vessels to achieve therapeutic purposes. When the tumor volume is large, the interior part forms coagulation necrosis, resulting in increased interstitial pressure and distance between blood vessels to hinder drug transport. Purpose: The purpose of this study is to combine nanodrug(PLD) with ultrasound hyperthermia to enhance the drug delivery in the peripheral region of tumors, and ultrasound ablation surgery for poor circulation region to achieve the overall treatment efficacy. Materials and methods: In this study, BALB/c female mice weighting from 18 to 22 g were used. Murine breast cancer cells 4T1(106 cells) were subcutaneously implanted into the mice's back. Hyperthermia was induced by a 1-MHz plane ultrasound transducer, and ablation surgery was conducted by a 0.47-MHz focus ultrasound transducer. Experimental groups were divided into two parts: 5 mg PLD/kg and 3 mg PLD/kg. Each part was divided into four groups: control group, PLD group, PLD+hyperthermia(42°C 10 min) group, and PLD+ablation(56°C)+hyperthermia group. When the tumor grew up to 250-350 mm3, the first treatment was conducted, and five days later for the second treatment. Body weight and tumor volume were measured every day. The tumor change was also quantified by In-Vivo Image System(IVIS) before and after the treatments. H&E histological staining was also used to analyze the tumor tissues. Results: The tumors treated with 5 mg PLD/kg were significantly smaller than the control group. The tumor size of the PLD+hyperthermia group was significantly smaller than the PLD group. However, there was no significant difference between the PLD+hyperthermia group and the PLD+ablation+hyperthermia group. When the PLD dose was reduced to 3 mg/kg, the tumors treated with PLD were smaller than the control group. The tumor size of the PLD+ablation+hyperthermia group was significantly smaller than the PLD+hyperthermia group. The result of IVIS image showed that both 5 mg PLD/kg and 3 mg PLD/kg resulted in lower photon signals than the control group. The groups conducted with additional ultrasound therapy showed lower photon signals than the PLD alone group. Nevertheless, there was no significant difference between the PLD+ablation+hyperthermia group and the PLD+hyperthermia group. The H&E tumor histological staining showed that hyperthermia could induce inflammation, and the ablated tumor tissues were seriously destroyed and looser than the other three groups. Conclusion: Hyperthermia could increase nanodrug accumulation in tumor tissues and improve therapeutic efficacy. When a high dose of nanodrug(5 mg/kg) was used, additional ablation could not significantly improve therapeutic results. On the other side, the combination of hyperthermia and ablation could significantly enhance the treatment efficacy for a low dose of nanodrug(3 mg/kg).