Phase I Study of Paclitaxel by Three-hour Infusion: Hypotension Just after Infusion Is One of the Major Dose-limiting Toxicities

The primary objectives of this study were to determine the maximum tolerated dose (MTD) of paclitaxel administered by 3-h infusion to patients with solid tumors, and to characterize the pharmacokinetics of a 3-h infusion in comparison with those of a 24-h infusion. Twenty-seven patients each received one of six levels of paclitaxel, 105, 135, 180, 210, 240 and 270 mg/m², with premedication. Two patients given 240 mg/m² and one patient given 270 mg/m² unexpectedly had grade 3/4 hypotension just after finishing the paclitaxel infusion. Peripheral neuropathy was also dose-limiting at 270 mg/m². Although granulocytopenia was significantly less severe than with a 24-h infusion, more than half of the patients experienced grade 4 toxicity at doses of 240 or 270 mg/m². Severe hypersensitivity reactions (HSRs) were not observed. Pharmacokinetic studies using high performance liquid chromatography demonstrated proportionally greater increases in the peak plasma concentration and area under the curve, and decreases in clearance and volume of distribution with increasing dose, suggesting non-linear pharmacokinetics of paclitaxel when given by 3-h infusion. The MTD of paclitaxel given as a 3-h infusion was determined to be 240 mg/m² with dose-limiting toxicities of granulocytopenia, peripheral neuropathy and hypotension. Hypotension just after infusion, induced by 3-h infusion of paclitaxel, is a new observation which has not been reported previously. The recommended dose for phase II study is 210 mg/m². Although hypotension was observed as an unexpected toxic effect, paclitaxel could be administered safely over 3 h with premedication and proper monitoring, resulting in reduced myelotoxicity and with no increase in the incidence of HSRs as compared with a 24-h infusion.     

Isolation,purification, and biological activity of mono- and dihydroxylated paclitaxel metabolites from human feces

Three metabolites of the cytotoxic drug paclitaxel (Taxol) were isolated and purified from the feces of cancer patients receiving the agent as an intravenous infusion. The procedures involved sample homogenization in water followed by liquid-liquid extraction with diethyl ether and high-performance liquid chromatography (HPLC). Approximately 1–3.5 mg of each metabolite was obtained from 100 g of feces. As judged from the chromatographic traces of analytical HPLC with ultraviolet (UV) detection at 227 nm, the purity of each compound was >97%. On-line photodiode-array detection demonstrated that the UV spectrum of the isolated compounds closely resembles that of the parent drug. Mass spectrometry provided evidence that these metabolites are mono- and dihydroxy-substituted derivatives, namely, 6-hydroxypaclitaxel, 3-p-hydroxypaclitaxel, and 6,3-p-dihydroxypaclitaxel. The two 6-hydroxy-substituted metabolites were shown to have lost their cytotoxicity in in vitro clonogenic assays using the A2780 human ovarian carcinoma and the CC531 rat colon-carcinoma tumor cell lines. In addition, the metabolites showed reduced myelotoxic effects as compared with paclitaxel in an in vitro hemopoietic progenitor toxicity assay. Our procedure for the isolation and purification of paclitaxel metabolites in milligram quantities should be useful for testing the biological activities of these compounds and for the preparation of calibration standards essential for pharmockinetics studies.     

Enhancement of Radiation Response by Paclitaxel in Mice According to Different Treatment Schedules

Purpose: The aim of our study was to determine if paclitaxel could be used as a radiosensitizer in vivo.

Materials and methods: Paclitaxel was tested as a single agent and combined with an X-ray treatment. Paclitaxel was administered i.p. in doses from 30 to 120 mg/kg b.w. to (C3D2F1) mice bearing spontaneous mammary carcinoma. Tumor growth delay (TGD) or tumor control dose (TCD₅₀, radiation dose needed to induce local tumor control in 50% of irradiated animals) and moist desquamation dose (MDD₅₀, radiation dose needed to induce serious moist desquamation in 50% of the non-tumor-bearing feet) were the endpoints. DNA flow cytometric analysis was performed.

Results: DNA analysis demonstrated a G2/M block of tumor cells and a depletion of cells in S phase, with a maximum at 24 h from paclitaxel administration. Administering paclitaxel, in graded doses, 15 min before a 10-Gy X-ray treatment resulted in a linear regression line, almost parallel to that with paclitaxel alone, with a growth delay of about 6 days. In contrast, varying the X-ray dose with a constant paclitaxel injection (45 mg/kg b.w.) treatment showed some degree of synergism as the linear regression curves diverged. Interval time and sequence between paclitaxel administration and a 10 Gy X-ray treatment did not influence TGD. Protocols with paclitaxel at 30, 45, or 60 mg/kg were combined with radiation treatments at various doses (from 10 to 65 Gy). Values of TCD50 varied from 50.8 Gy for X-ray alone to 31.8 Gy for paclitaxel 60 mg/kg + X-ray. No differences were observed among MDD of different protocols.

Conclusions: These results suggest that, under some conditions, paclitaxel combined with radiation can show superadditive effects and this result combined with the lack of severe normal tissue damage indicate that a favorable therapeutic gain can be obtained.     

Potentiation of Paclitaxel Cytotoxicity by Inostamycin in Human Small Cell Lung Carcinoma, Ms-1 Cells

In the present study, we found that inostamycin increased the ability of paclitaxel to induce apoptosis in Ms-1 cells. A considerably higher concentration of paclitaxel was required for the induction of apoptosis in Ms-1 cells than in other cell lines tested. Treatment of Ms-1 cells with inostamycin, an inhibitor of phosphatidylinositol (PI) synthesis, reduced the dosage of paclitaxel required to induce cell death by apoptosis. This effect of inostamycin is specific to Ms-1 cells, and inostamycin did not increase the cytotoxicity of other antitumor drugs such as adriamycin, vinblastine, methotrexate, cisplatin, etoposide, or camptothecin in Ms-1 cells. Addition of inostamycin to paclitaxel-treated cells caused a significant increase in the sub G1 peak, representing apoptosis, which was accompanied by a decrease in the G2/M peak seen in paclitaxel-treated Ms-1 cells, without affecting paclitaxel-inhibited tubulin depolymerization. Moreover, paclitaxel did not enhance inostamycin-inhibited PI synthesis. The expression levels of Bcl-2, Bax, and Bcl-X_L were not changed following the co-treatment with inostamycin plus paclitaxel, whereas the activated form of caspase-3 was markedly increased. Thus, inostamycin is a chemosensitizer of paclitaxel in small cell lung carcinoma Ms-1 cells.     

LHRHa靶向紫杉醇脂质体的制备及体外抗肿瘤作用

目的:制备促黄体激素释放激素类似物(Luteinizing hormone-releasing hormone analogues,LHRHa)靶向紫杉醇脂质体(Paclitaxel liposomes,PTX-Lipo),研究其在体外增强紫杉醇(Paclitaxel,PTX)对卵巢癌A2780/DDP细胞的抑制作用。方法:采用薄膜超声法制备PTX-Lipo与LHRHa靶向紫杉醇脂质体(LHRHa-Paclitaxel liposomes,LHRHa-PTX-Lipo),用透射电镜考察脂质体形态;高效液相色谱法测定2种PTX-Lipo的包封率;激光共聚焦法通过卵巢癌A2780/DDP细胞对4-氟-7-硝基-2,1,3-苯并氧杂恶二唑荧光素的摄取检测来反映细胞对NBD-Lipo与NBD-LHRHa-Lipo的摄取情况;MTT法及细胞克隆形成实验检测LHRHa-PTX-Lipo体外对卵巢癌细胞的生长抑制情况。结果:制备LHRHa-PTX-Lipo的平均粒径123.4 nm,包封率在90%以上;A2780/DDP细胞对NBD-LHRHa-Lipo组的荧光摄取明显高于NBD-Lipo组;LHRHa-PTX-Lipo对A2780/DDP细胞的生长及克隆形成抑制明显高于PTX组及PTX-Lipo组(P<0.05)。结论:采用薄膜超声法制备的LHRHa-PTX-Lipo可使药物在靶部位聚集,增强药物对卵巢癌细胞的抑制作用。     

紫杉醇联合5-氟脲嘧啶持续输注治疗晚期胃癌的临床研究

目的 观察紫杉醇（PTX）联合5-氟脲嘧啶（5-Fu)持续静脉输注治疗晚期胃癌的疗效和毒性。方法 对30例晚期胃癌患者第1，第8，第15天使用PTX60mg/m^2，静脉滴注；第1-15天使用5-Fu0.25g/m^2,24h中心静脉持续输注。28天为1个周期，2个周期后评定疗效。平均3.43个周期。结果 28例可评价疗效。28例中完全缓解3例。部分缓解14例，总有效率为60.7%，中位缓解期为6.4个月。中位生存期为11.5个月。毒副作用主要为剂量限制性毒性，表现为骨髓抑制。结论 紫杉醇加5-氟脲嘧啶持续静脉输注是治疗晚期胃癌较好的化疗方案。     

Tau基因表达与紫杉醇治疗胃癌敏感性的研究

目的:探讨胃癌细胞的Tau基因表达丰度与紫杉醇治疗敏感性间的关系,并分析其可能的耐药机制。方法:通过实时定量PCR筛选出Tau基因高表达和低表达的胃癌细胞株各一,然后观察两细胞株对紫杉醇的反应;并应用细胞增殖实验(CCK8方法)、流式细胞技术(AnnexinⅤ标记)检测紫杉醇在体外对胃癌细胞增殖、凋亡和周期的影响。对于Tau基因高表达的胃癌细胞,通过小干扰RNA(small interfering RNA,siRNA)等技术,观察其敲低Tau基因表达后,对紫杉醇的敏感性有无变化。结果:体外增殖实验显示,紫杉醇对Tau表达低的胃癌细胞的增殖生长抑制作用更为明显(P0.05)。而体外凋亡实验显示,紫杉醇更能促进Tau基因低表达胃癌细胞的凋亡(P0.05),在整个细胞周期中以G2/M期为主。而应用siRNA技术将Tau基因高表达的胃癌细胞降为低基因表达后,紫杉醇对其增殖的抑制作用明显增高(P0.05),更能促进转染后细胞的凋亡(P0.05);且对整个细胞周期,以作用于G2/M期为主。结论:紫杉醇对Tau基因表达低的胃癌细胞具有更强的增殖抑制作用,且更能促进其凋亡。而对干扰后的胃癌细胞,紫杉醇具有更强的抑制增殖作用,且更能促进其凋亡。     

恩度联合特素和卡铂治疗卵巢癌临床分析

目的探讨恩度联合特素和卡铂治疗卵巢癌的疗效及不良反应。方法选择30例卵巢癌患者,采用恩度＋特素＋卡铂联合治疗,至少完成3个疗程,观察疗效及副作用。结果总有效率为80.0%（24/30）,主要副作用为骨髓抑制、脱发、恶心、呕吐,但均属轻微。结论恩度联合特素和卡铂应用于卵巢癌术后化疗,其疗效较佳,且不良反应少,值得推广应用。     

紫杉醇诱导神经病理性疼痛大鼠脊髓背角5-羟色胺含量变化

目的观察紫杉醇诱导神经病理性疼痛大鼠脊髓背角5-羟色胺(5-HT)含量变化。方法雄性SD大鼠54只,体重约300 g,随机均分为正常对照组(A组)、紫杉醇溶媒组(B组)和紫杉醇组(C组)。分别于腹腔注药前1 d、注药后3、5、7、9、11、14、18、21 d检测大鼠机械缩爪阈值。腹腔注药前1 d、注药后7、14、21 d每组各处死大鼠4只,取脊髓腰膨大背角组织,用高效液相色谱荧光法测定5-HT含量。腹腔注药后14 d取大鼠右侧坐骨神经,透射电镜观察神经病变情况。结果与注药前1 d比较,C组机械缩爪阈值从紫杉醇注射后7 d开始显著降低,并持续至注药后21 d达最低值(P<0.05),且显著低于A、B组(P<0.05)。坐骨神经超微结构C组纤维髓鞘板层结构松散,排列紊乱、肿胀变形、厚薄不均,A和B组大鼠坐骨神经未见异常。C组脊髓背角5-HT含量注药后7 d开始显著升高,并持续至注射后21 d达最高值(P<0.05),且显著高于A、B组(P<0.05)。C组大鼠脊髓背角5-HT含量与机械缩爪阈值呈显著线性负相关(r=-0.981,P<0.05)。结论紫杉醇诱导的神经病理性疼痛大鼠脊髓背角组织中5-HT含量表达上调,该变化可能参与了紫杉醇所致神经病理性疼痛的发病机制。