Experimental Therapeutics, BC Cancer Research Centre, Vancouver, BC, Canada; Department of Chemistry, University of British Columbia, Vancouver, BC, Canada; Cuprous Pharmaceuticals Inc., Vancouver, BC, Canada; Nanomedicine Innovation Network, University of British Columbia, Vancouver, BC, Canada.
Experimental Therapeutics, BC Cancer Research Centre, Vancouver, BC, Canada; The Interdisciplinary Oncology Program, University of British Columbia, Vancouver, BC, Canada; Nanomedicine Innovation Network, University of British Columbia, Vancouver, BC, Canada.
J Control Release. 2022 May;345:75-90. doi: 10.1016/j.jconrel.2022.03.004. Epub 2022 Mar 5.
CX5461, a compound initially identified as an RNA polymerase inhibitor and more recently as a G-quadruplex binder, binds copper to form a complex. Our previous publication showed that the complexation reaction can be leveraged to formulate copper-CX5461 inside liposomes, improving the apparent solubility of CX5461 by over 500-fold and reducing the elimination of CX5461 from the plasma compartment following intravenous administration. In mouse models of acute myeloid leukemia, the resulting formulation was more effective than the free drug solution of CX5461 (pH 3.5) currently used in clinical trials. However, the gains observed with the liposomal formulation were minimal, despite significant increases in circulation half-life. Since the formulation technology used relied on liposomes and the fate of most compounds associated with liposomes is dependent on liposomal lipid composition, the studies described here were designed to evaluate how simple changes in lipid composition could affect therapeutic activity. The previously reported formulation method was simplified to ensure an easy scale-up process. In the modified method, pre-measured solid CX5461 was added to copper-containing liposomes prior to an incubation at 60 °C, which enabled copper-CX5461 complexation inside DSPC/Chol or DMPC/Chol liposomes. Efficacy was determined in BRCA-normal (BxPC3) and BRCA-deficient (Capan-1) models of pancreatic cancer. Both liposomal formulations enhanced the circulation lifetime of CX5461 compared to the free drug solution (pH 3.5). Unlike most compounds that are loaded using a transmembrane pH-gradient, the dissociation of CX5461 from liposomes prepared using the copper complexation method were comparable for DSPC/Chol and DMPC/Chol liposomes, in vitro and in vivo. Nonetheless, copper CX5461 prepared using DMPC/Chol liposomes exhibited superior efficacy. The reason for the improved activity of DMPC/Chol copper-CX5461 was not readily explained by the release data and may be due to the fact that DMPC/Chol liposomes are less stable following localization in the tumor. The results indicate that the therapeutic effects of copper-CX5461 will be dependent on liposomal lipid composition and that liposomal CX5461 should exhibit superior benefits when used to treat BRCA-deficient cancers.
CX5461 最初被鉴定为 RNA 聚合酶抑制剂，最近又被鉴定为 G-四链体结合物，能与铜形成复合物。我们之前的研究表明，该络合反应可用于在脂质体中形成铜-CX5461，使 CX5461 的表观溶解度提高 500 多倍，并减少静脉注射后 CX5461 从血浆隔室中的消除。在急性髓细胞白血病的小鼠模型中，与目前临床试验中使用的 CX5461 游离药物溶液（pH3.5）相比，该制剂更为有效。然而，尽管循环半衰期显著延长，但脂质体制剂的效果却很微小。由于所使用的制剂技术依赖于脂质体，并且与脂质体相关的大多数化合物的命运都取决于脂质体的脂质组成，因此，这里描述的研究旨在评估简单改变脂质组成如何影响治疗活性。简化了先前报道的制剂方法，以确保易于放大过程。在改良方法中，将预先测量的固态 CX5461 添加到含铜脂质体中，然后在 60°C 下孵育，从而使 CX5461 与 DSPC/Chol 或 DMPC/Chol 脂质体中的铜络合。在 BRCA 正常（BxPC3）和 BRCA 缺失（Capan-1）的胰腺癌模型中测定疗效。与游离药物溶液（pH3.5）相比，两种脂质体制剂均延长了 CX5461 的循环半衰期。与大多数使用跨膜 pH 梯度加载的化合物不同，从使用铜络合方法制备的脂质体中解离 CX5461 的情况，DSPC/Chol 和 DMPC/Chol 脂质体的体外和体内情况相当。尽管如此，使用 DMPC/Chol 脂质体制备的铜 CX5461 表现出更好的疗效。DMPC/Chol 铜-CX5461 活性提高的原因不能仅用释放数据来解释，这可能是由于 DMPC/Chol 脂质体在肿瘤定位后不太稳定。结果表明，铜-CX5461 的治疗效果将取决于脂质体的脂质组成，并且当用于治疗 BRCA 缺失的癌症时，脂质体 CX5461 应该具有更好的益处。
