Department of Micro- and Nanotechnology, Technical University of Denmark, Building 423, DK-2800 Kgs. Lyngby, Denmark; Centre for Nanomedicine and Theranostics, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark.
Department of Micro- and Nanotechnology, Technical University of Denmark, Building 423, DK-2800 Kgs. Lyngby, Denmark; Centre for Nanomedicine and Theranostics, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark; Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, Copenhagen University Hospital and Cluster for Molecular Imaging, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3B, DK-2200 Copenhagen, Denmark.
J Control Release. 2017 Sep 10;261:163-173. doi: 10.1016/j.jconrel.2017.06.024. Epub 2017 Jun 27.
The first developed secretory phospholipase A (sPLA) sensitive liposomal cisplatin formulation (LiPlaCis®) is currently undergoing clinical evaluation. In the present study we revisit and evaluate critical preclinical parameters important for the therapeutic potential and safety of platinum drugs, here oxaliplatin (L-OHP), formulated in sPLA sensitive liposomes. We show the mole percentage of negatively charged phospholipid needed to obtain enzyme-sensitivity for saturated systems is ≥25% for 16-carbon chain lipid membranes, and >40% for 18-chain lipid membranes, which was surprising as 25% is used clinically in LiPlaCis®. Efficient sPLA-dependent growth inhibition of colorectal cancer cells was demonstrated in vitro, where cell membrane degradation and cytolysis depends on the sensitivity of the formulation towards the enzyme and is governed by the amount of lysolipids generated and the presence of serum proteins. We found that serum proteins did not affect the lipase activity of the enzyme towards the membranes but instead sequester the lysolipid byproducts consequently inhibiting their detergent-like cytotoxic properties. In vivo therapeutic potential and safety of the liposomes was investigated in nude mice bearing sPLA-deficient FaDu squamous carcinoma and sPLA-expressing Colo205 colorectal adenocarcinoma. After intravenous injections, the tumor growth was suppressed for liposomal L-OHP relative to free drug, but only a weak response was observed for both slow- and fast-releasing sPLA-sensitive formulations compared to non-sensitive liposomes. Also, the mice did not show longer survival. In turn, for the highly sPLA-sensitive liposomes, multiple high doses caused petechial cutaneous hemorrhages, along with multifocal hepatonecrotic lesions, suggestive of premature activation in skin and liver irrespective of sPLA-status of the tumor engraft. These results indicate that although liposomal carriers can improve the antitumor efficacy of platinum drugs, sPLA-triggered release suffers from a narrow therapeutic index and has safety concerns.
首个开发的分泌型磷脂酶 A（sPLA）敏感脂质体顺铂制剂（LiPlaCis®）目前正在进行临床评估。在本研究中，我们重新审视并评估了对铂类药物治疗潜力和安全性至关重要的关键临床前参数，这里使用的是 sPLA 敏感脂质体包载的奥沙利铂（L-OHP）。我们发现，对于 16 碳链脂质膜，获得酶敏感性所需的带负电荷磷脂的摩尔百分比需要≥25%，而对于 18 碳链脂质膜，需要>40%，这令人惊讶，因为 LiPlaCis® 中临床使用的是 25%。我们证明了 sPLA 依赖性体外结肠直肠癌细胞生长抑制作用，其中细胞膜降解和细胞溶解依赖于制剂对酶的敏感性，并受生成的溶血磷脂的量和血清蛋白的存在影响。我们发现，血清蛋白不会影响酶对膜的脂肪酶活性，而是通过将溶血磷脂副产物隔离来抑制其去污剂样细胞毒性。我们在 FaDu 鳞状细胞癌和 Colo205 结肠直肠腺癌中 sPLA 缺陷裸鼠模型中研究了脂质体的体内治疗潜力和安全性。与游离药物相比，静脉注射脂质体 L-OHP 后肿瘤生长受到抑制，但与非敏感脂质体相比，两种缓慢和快速释放的 sPLA 敏感制剂的反应均较弱。此外，小鼠的存活时间也没有延长。相反，对于高度敏感的脂质体，多次高剂量会导致皮肤出现瘀点状出血，同时伴有多处肝坏死病变，提示无论肿瘤是否表达 sPLA，脂质体在皮肤和肝脏中均过早激活。这些结果表明，尽管脂质体载体可以提高铂类药物的抗肿瘤疗效，但 sPLA 触发的释放存在治疗指数较窄和安全性问题。
