Nab-Paclitaxel (albumin-bound paclitaxel)

Tubulin/microtubule

紫杉烷是多种恶性肿瘤的关键化疗成分，包括转移性乳腺癌症（MBC）、癌症和晚期癌症（NSCLC）。尽管溶剂型（sb）紫杉烷类药物具有临床益处，但这些药物可能与严重的毒性有关。白蛋白结合的紫杉醇（Abraxane；nab®-紫杉醇）是一种新型的无溶剂紫杉醇，与基于溶剂的制剂相比，在晚期MBC和NSCLC患者中显示出更高的反应率和更好的耐受性。用于制备nab-紫杉醇的技术利用白蛋白递送紫杉醇，从而产生有利的药代动力学（PK）特征。本综述讨论了nab紫杉醇的递送机制，包括对相对于sb-紫杉醇而言，利用白蛋白转运的假设能力更强的检查。有利的PK特征和基于白蛋白的转运的更有效使用可能有助于临床前发现，nab-紫杉醇的肿瘤摄取量比sb-紫杉醇高33%。另一个可能导致nab-紫杉醇肿瘤积聚的因素是白蛋白与富含半胱氨酸的酸性分泌蛋白（SPARC）的结合，尽管支持SPARC和nab-紫杉酚之间这种关系的数据在这一点上仍然具有很大的相关性。最近的数据还表明，在用这两种药物治疗的癌症中，nab-paclitaxel可能增强吉西他滨的肿瘤积聚。此外，nab紫杉醇和卡培他滨之间可能存在的机制协同作用被引用为将这两种药物联合用于MBC治疗的理论基础。因此，nab-紫杉醇似乎以许多有趣但尚未完全理解的方式与肿瘤相互作用。有必要对一系列肿瘤类型进行持续的临床前和临床研究，以回答关于nab-紫杉醇递送机制和抗肿瘤活性的问题[1]。

关于药物分布的经典思想认为，药物的自由或未结合部分是活性部分，因为与蛋白质或其他大分子结合的药物可能无法穿过细胞膜。在临床研究中，sb-紫杉醇已被证明在血浆中高度结合蛋白质，Cremophor-EL进一步降低了药物的游离/未结合部分。为了研究该制剂对紫杉醇药代动力学（PK）的影响，在癌症患者中进行了一项随机交叉PK研究，患者接受3小时输注175 mg/m2 q3w的sb-paclitaxel或30分钟输注260 mg/m2 q3 w的nab-paclitassel。在这项研究中，质谱用于鉴定循环紫杉醇是否游离/未结合。在本报告中，与Cremophor EL相关的紫杉醇不会被确定为未结合药物。该研究的关键发现是，与sb紫杉醇相比，nab紫杉醇的制剂允许nab紫杉酚的未结合紫杉醇分数高得多（6.3%对2.4%，p<0.001）。此外，nab紫杉醇的未结合紫杉醇的最大浓度约为10倍（1284 ng/mL vs.122 ng/mL，p<0.000001），nab-紫杉醇的非结合紫杉醇全身暴露量（AUCINF）约为3倍（1159 h*ng/mL vs 410 h*ng/mL，p<0.00005）。这些差异的一个可能解释是紫杉醇在溶剂型紫杉醇制剂中的Cremophor EL胶束中的包封。与胶束包埋对紫杉醇分布的影响一致，Sparreboom等人发现，在临床前研究中，nab-紫杉醇比sb-紫杉醇具有更高的血浆清除率和更大的分布体积。有人认为胶束包埋会影响sb-紫杉醇的PK线性。表3列出了sb-紫杉醇和nab-紫杉醇的选定PK研究，并给出了作者对这两种药物PK线性的描述。[1]

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尽管对未结合药物分布的研究很重要，但同样重要的是要考虑到在人体血液中，紫杉醇与蛋白质和其他生物分子高度结合。如前所述，Kumar等人证明，当sb-紫杉醇施用于人体时，大约95%的紫杉醇会与其他分子结合。白蛋白和α-1-酸糖蛋白对这种结合的贡献相同，紫杉醇的一小部分与脂蛋白结合。此外，众所周知，白蛋白是血液中无处不在的生物分子载体，这促使人们考虑白蛋白如何影响nab-紫杉醇向肿瘤的转运。循环白蛋白必须穿过内皮细胞才能到达肿瘤，据报道，白蛋白至少通过两种方式实现这一点（图1）：受体介导的转胞作用和增强的渗透和保留（EPR）效应。有人假设nab-紫杉醇可能利用这些机制中的每一种到达肿瘤微环境[1]。

Studies have shown that a large fraction of injected albumin-conjugated molecules accumulate in proximity to tumors. As discussed above, albumin may reach tumors by receptor-mediated transport mechanisms or by the EPR effect. It has been hypothesized that cancer cells may consume albumin from the tumor microenvironment and then metabolize it, possibly enhancing tumor growth. Desai et al. conducted experiments in mice bearing xenograft tumors from injected human breast cancer cells to determine whether formulation played a role in the tumor uptake of paclitaxel. In these experiments, paclitaxel in both formulations was radioactively labeled and the amount of labeled paclitaxel that eventually reached tumors was quantified. When equal amounts were injected, the researchers found that a third more paclitaxel from the nab-paclitaxel formulation was taken up by tumors. The authors suggested that nab-paclitaxel reached a higher tumor accumulation vs. sb-paclitaxel due to both the lack of drug-sequestering solvent micelles and enhanced albumin-mediated transcytosis. A subsequent report of similar experiments suggested that nab-paclitaxel may achieve some degree of tumor selectivity relative to sb-paclitaxel, although the mechanisms responsible for this possibility were not characterized. [1]

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Another molecular mechanism proposed to play a potential role in the tumor accumulation of nab-paclitaxel is the prevalence of albumin-binding proteins such as secreted protein acidic and rich in cysteine (SPARC) in proximity to tumors. According to this theory, proteins such as SPARC may exist at higher-than-normal levels in the tumor interstitium. Thus, these proteins could sequester paclitaxel bound to albumin in tumors at levels higher than those in healthy tissues. High SPARC expression correlates with disease progression across a range of tumor types; however, some clinical data have suggested a correlation between SPARC expression in the tumor and/or tumor microenvironment and positive clinical outcomes in patients receiving nab-paclitaxel. Other studies have failed to show such a correlation. Thus, further studies delineating the molecular relationship between SPARC and nab-paclitaxel are warranted.[1]

[1]. Yardley DA. nab-Paclitaxel mechanisms of action and delivery. J Control Release. 2013 Sep 28;170(3):365-72.

nab-Paclitaxel was initially developed to avoid the toxicities typically associated with Cremophor EL in sb-paclitaxel. In contrast to sb-paclitaxel and docetaxel, nab-paclitaxel does not utilize non-ionic surfactants to solubilize paclitaxel, which are known to contribute to toxicity and entrap paclitaxel within solvent based micelles. nab-Paclitaxel is formulated with human serum albumin at a concentration similar to the concentration of albumin in the blood. Formulation of nab-paclitaxel takes place through high-pressure homogenization in which albumin and paclitaxel are combined to create particles with a mean diameter of 130 nm. This process does not covalently link albumin to paclitaxel. Upon injection, the nab-paclitaxel particles dissolve into soluble albumin–paclitaxel complexes, and paclitaxel may bind and unbind albumin (injected or endogenous) or other biomolecules, or it may exist in a free/unbound state (see Mechanism of Delivery section). Formulation with albumin allows nab-paclitaxel to be reconstituted with a simple saline solution. As such, nab-paclitaxel is administered without steroid or antihistamine prophylaxis for hypersensitivity reactions. Perhaps because nab-paclitaxel delivery is not complicated by solvents, a higher dose can be administered relative to sb-paclitaxel. In a pivotal phase III MBC trial of nab-paclitaxel and sb-paclitaxel at the label-indicated doses as ≥ first-line therapy in patients with MBC, the dose of paclitaxel delivered was 49% higher for patients receiving nab-paclitaxel vs sb-paclitaxel, suggesting that higher dose intensity is feasible with nab-paclitaxel [1].

White to off-white solid powder

Nanoparticle albumin-bound Paclitaxel; Nanoparticle albumin-bound ABI-007

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

注意: 如下所列的是一些常用的体内动物实验溶解配方，主要用于溶解难溶或不溶于水的产品（水溶度<1 mg/mL）。 建议您先取少量样品进行尝试，如该配方可行，再根据实验需求增加样品量。

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注射用配方1: DMSO : Tween 80： Saline = 10 : 5 : 85 (如： 100 μL DMSO → 50 μL Tween 80 → 850 μL Saline)
*生理盐水/Saline的制备：将0.9g氯化钠/NaCl溶解在100 mL ddH ₂ O中，得到澄清溶液。
注射用配方 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (如： 100 μL DMSO → 400 μL PEG300 → 50 μL Tween 80 → 450 μL Saline)
注射用配方 3: DMSO : Corn oil = 10 : 90 (如： 100 μL DMSO → 900 μL Corn oil)
示例: 以注射用配方 3 (DMSO : Corn oil = 10 : 90) 为例说明, 如果要配制 1 mL 2.5 mg/mL的工作液, 您可以取 100 μL 25 mg/mL 澄清的 DMSO 储备液，加到 900 μL Corn oil/玉米油中, 混合均匀。

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注射用配方 4: DMSO : 20% SBE-β-CD in Saline = 10 : 90 [如：100 μL DMSO → 900 μL (20% SBE-β-CD in Saline)]
*20% SBE-β-CD in Saline的制备（4°C，储存1周）：将2g SBE-β-CD (磺丁基-β-环糊精) 溶解于10mL生理盐水中，得到澄清溶液。
注射用配方 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (如： 500 μL 2-Hydroxypropyl-β-cyclodextrin (羟丙基环胡精)→ 500 μL Saline)
注射用配方 6: DMSO : PEG300 : Castor oil : Saline = 5 : 10 : 20 : 65 (如： 50 μL DMSO → 100 μL PEG300 → 200 μL Castor oil → 650 μL Saline)
注射用配方 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (如： 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
注射用配方 8: 溶解于Cremophor/Ethanol (50 : 50), 然后用生理盐水稀释。
注射用配方 9: EtOH : Corn oil = 10 : 90 (如： 100 μL EtOH → 900 μL Corn oil)
注射用配方 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (如： 100 μL EtOH → 400 μL PEG300 → 50 μL Tween 80 → 450 μL Saline)

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口服配方 1: 悬浮于0.5% CMC Na (羧甲基纤维素钠)
口服配方 2: 悬浮于0.5% Carboxymethyl cellulose (羧甲基纤维素)
示例: 以口服配方 1 (悬浮于 0.5% CMC Na)为例说明, 如果要配制 100 mL 2.5 mg/mL 的工作液, 您可以先取0.5g CMC Na并将其溶解于100mL ddH2O中，得到0.5%CMC-Na澄清溶液；然后将250 mg待测化合物加到100 mL前述 0.5%CMC Na溶液中，得到悬浮液。

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口服配方 3: 溶解于 PEG400 (聚乙二醇400)
口服配方 4: 悬浮于0.2% Carboxymethyl cellulose (羧甲基纤维素)
口服配方 5: 溶解于0.25% Tween 80 and 0.5% Carboxymethyl cellulose (羧甲基纤维素)
口服配方 6: 做成粉末与食物混合

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注意: 以上为较为常见方法，仅供参考， InvivoChem并未独立验证这些配方的准确性。具体溶剂的选择首先应参照文献已报道溶解方法、配方或剂型，对于某些尚未有文献报道溶解方法的化合物，需通过前期实验来确定（建议先取少量样品进行尝试），包括产品的溶解情况、梯度设置、动物的耐受性等。

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请根据您的实验动物和给药方式选择适当的溶解配方/方案：
1、请先配制澄清的储备液(如：用DMSO配置50 或 100 mg/mL母液(储备液));
2、取适量母液，按从左到右的顺序依次添加助溶剂，澄清后再加入下一助溶剂。以 下列配方为例说明 (注意此配方只用于说明，并不一定代表此产品 的实际溶解配方):
10% DMSO → 40% PEG300 → 5% Tween-80 → 45% ddH2O (或 saline);
假设最终工作液的体积为 1 mL, 浓度为5 mg/mL: 取 100 μL 50 mg/mL 的澄清 DMSO 储备液加到 400 μL PEG300 中，混合均匀/澄清；向上述体系中加入50 μL Tween-80，混合均匀/澄清；然后继续加入450 μL ddH2O (或 saline)定容至 1 mL；
3、溶剂前显示的百分比是指该溶剂在最终溶液/工作液中的体积所占比例;
4、 如产品在配制过程中出现沉淀/析出，可通过加热(≤50℃)或超声的方式助溶;
5、为保证最佳实验结果，工作液请现配现用！
6、如不确定怎么将母液配置成体内动物实验的工作液，请查看说明书或联系我们;
7、 以上所有助溶剂都可在 Invivochem.cn网站购买。