Therapeutic advances for osteosarcoma have stagnated over the past several decades, leading to an unmet clinical need for patients. The purpose of this study was to develop a novel therapy for osteosarcoma by reformulating and validating niclosamide, an established anthelminthic agent, as a niclosamide stearate prodrug therapeutic (NSPT). We sought to improve the low and inefficient clinical bioavailability of oral dosing, especially for the relatively hydrophobic classes of anticancer drugs. Nanoparticles were fabricated by rapid solvent shifting and verified using dynamic light scattering and UV-vis spectrophotometry. NSPT efficacy was then studied in vitro for cell viability, cell proliferation, and intracellular signaling by Western blot analysis; ex vivo pulmonary metastatic assay model; and in vivo pharmacokinetic and lung mouse metastatic model of osteosarcoma. NSPT formulation stabilizes niclosamide stearate against hydrolysis and delays enzymolysis; increases circulation in vivo with t1/2 approximately 5 hours; reduces cell viability and cell proliferation in human and canine osteosarcoma cells in vitro at 0.2–2 μmol/L IC50; inhibits recognized growth pathways and induces apoptosis at 20 μmol/L; eliminates metastatic lesions in the ex vivo lung metastatic model; and when injected intravenously at 50 mg/kg weekly, it prevents metastatic spread in the lungs in a mouse model of osteosarcoma over 30 days. In conclusion, niclosamide was optimized for preclinical drug delivery as a unique prodrug nanoparticle injected intravenously at 50 mg/kg (1.9 mmol/L). This increased bioavailability of niclosamide in the blood stream prevented metastatic disease in the mouse. This chemotherapeutic strategy is now ready for canine trials, and if successful, will be targeted for human trials in patients with osteosarcoma.

中文翻译：

---

新型硬脂酸氯硝柳胺前药治疗 (NSPT) 的临床前测试显示对骨肉瘤有效

在过去的几十年里，骨肉瘤的治疗进展停滞不前，导致患者的临床需求未得到满足。本研究的目的是通过重新配制和验证氯硝柳胺（一种已建立的驱虫药）作为硬脂酸氯硝柳胺前药治疗剂 (NSPT)，开发一种新的骨肉瘤疗法。我们试图改善口服给药的低且低效的临床生物利用度，特别是对于相对疏水的抗癌药物类别。纳米颗粒是通过快速溶剂转移制造的，并使用动态光散射和紫外可见分光光度法进行验证。然后通过蛋白质印迹分析在体外研究 NSPT 功效的细胞活力、细胞增殖和细胞内信号传导；离体肺转移测定模型；骨肉瘤的体内药代动力学和肺小鼠转移模型。NSPT 配方可稳定氯硝柳胺硬脂酸盐以防止水解并延迟酶解；以 t1/2 约 5 小时增加体内循环；在体外以 0.2–2 μmol/L IC50 降低人和犬骨肉瘤细胞的细胞活力和细胞增殖；在 20 μmol/L 时抑制公认的生长途径并诱导细胞凋亡；消除离体肺转移模型中的转移病灶；当以每周 50 毫克/千克的剂量静脉内注射时，它可以防止骨肉瘤小鼠模型在 30 天内发生肺部转移性扩散。总之，氯硝柳胺作为一种独特的前药纳米颗粒以 50 mg/kg (1.9 mmol/L) 静脉注射，针对临床前药物递送进行了优化。这种增加的氯硝柳胺在血流中的生物利用度预防了小鼠的转移性疾病。这种化疗策略现已准备好用于犬类试验，如果成功，将用于骨肉瘤患者的人体试验。