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PubMed2006

Increased antitumor activity, intratumor paclitaxel concentrations, and endothelial cell transport of cremophor-free, albumin-bound paclitaxel, ABI-007, compared with cremophor-based paclitaxel.

ABI-007, an albumin-bound, 130-nm particle form of paclitaxel, was developed to avoid Cremophor/ethanol-associated toxicities in Cremophor-based paclitaxel (Taxol) and to exploit albumin receptor-mediated endothelial transport. We studied the antitumor activity, intratumoral paclitaxel accumulation, and endothelial transport for ABI-007 and Cremophor-based paclitaxel. Antitumor activity and mortality were assessed in nude mice bearing human tumor xenografts [lung (H522), breast (MX-1), ovarian (SK-OV-3), prostate (PC-3), and colon (HT29)] treated with ABI-007 or Cremophor-based paclitaxel. Intratumoral paclitaxel concentrations (MX-1-tumored mice) were compared for radiolabeled ABI-007 and Cremophor-based paclitaxel. In vitro endothelial transcytosis and Cremophor inhibition of paclitaxel binding to cells and albumin was compared for ABI-007 and Cremophor-based paclitaxel. Both ABI-007 and Cremophor-based paclitaxel caused tumor regression and prolonged survival; the order of sensitivity was lung > breast congruent with ovary > prostate > colon. The LD(50) and maximum tolerated dose for ABI-007 and Cremophor-based paclitaxel were 47 and 30 mg/kg/d and 30 and 13.4 mg/kg/d, respectively. At equitoxic dose, the ABI-007-treated groups showed more complete regressions, longer time to recurrence, longer doubling time, and prolonged survival. At equal dose, tumor paclitaxel area under the curve was 33% higher for ABI-007 versus Cremophor-based paclitaxel, indicating more effective intratumoral accumulation of ABI-007. Endothelial binding and transcytosis of paclitaxel were markedly higher for ABI-007 versus Cremophor-based paclitaxel, and this difference was abrogated by a known inhibitor of endothelial gp60 receptor/caveolar transport. In addition, Cremophor was found to inhibit binding of paclitaxel to endothelial cells and albumin. Enhanced endothelial cell binding and transcytosis for ABI-007 and inhibition by Cremophor in Cremophor-based paclitaxel may account in part for the greater efficacy and intratumor delivery of ABI-007.

Albumin-Bound Paclitaxel↗

PubMed1997

The microtubule-stabilizing agent discodermolide competitively inhibits the binding of paclitaxel (Taxol) to tubulin polymers, enhances tubulin nucleation reactions more potently than paclitaxel, and inhibits the growth of paclitaxel-resistant cells.

The lactone-bearing polyhydroxylated alkatetraene (+)-discodermolide, which was isolated from the sponge Discodermia dissoluta, induces the polymerization of purified tubulin with and without microtubule-associated proteins or GTP, and the polymers formed are stable to cold and calcium. These effects are similar to those of paclitaxel (Taxol), but discodermolide is more potent. We confirmed that these properties represent hypernucleation phenomena; we obtained lower tubulin critical concentrations and shorter polymers with discodermolide than paclitaxel under a variety of reaction conditions. Furthermore, we demonstrated that discodermolide is a competitive inhibitor with [3H]paclitaxel in binding to tubulin polymer, with an apparent Ki value of 0.4 microM. Multidrug-resistant human colon and ovarian carcinoma cells overexpressing P-glycoprotein, which are 900- and 2800-fold resistant to paclitaxel, respectively, relative to the parental lines, retained significant sensitivity to discodermolide (25- and 89-fold more resistant relative to the parental lines). Ovarian carcinoma cells that are 20-30-fold more resistant to paclitaxel than the parental line on the basis of expression of altered beta-tubulin polypeptides retained nearly complete sensitivity to discodermolide. The effects of discodermolide on the reorganization of the microtubules of Potorous tridactylis kidney epithelial cells were examined at different times. Intracellular microtubules were reorganized into bundles in interphase cells much more rapidly after discodermolide treatment compared with paclitaxel treatment. A variety of spindle aberrations were observed after treatment with both drugs. The proportions of the different types of aberration were different for the two drugs and changed with the length of drug treatment.

Alkanes↗

PubMed2000

Oral paclitaxel and concurrent cyclosporin A: targeting clinically relevant systemic exposure to paclitaxel.

Oral paclitaxel is not inherently bioavailable because of the overexpression of P-glycoprotein by intestinal cells and the significant first-pass extraction by cytochrome P450-dependent processes. This study sought to simulate the toxicological and pharmacological profile of a clinically relevant schedule of paclitaxel administered on clinically relevant i.v. dosing schedules in patients with advanced solid malignancies using oral paclitaxel administered with cyclosporin A, an inhibitor of both P-glycoprotein and P450 CYP3A. Nine patients were treated with a single course of oral paclitaxel in its parenteral formulation at a paclitaxel dose level of 180, 360, or 540 mg. Cyclosporin A was administered at a dose of 5 mg/kg p.o. 1 h before and concurrently with oral paclitaxel. Blood sampling was performed to evaluate the pharmacokinetics of paclitaxel, 6-alpha-hydroxypaclitaxel, 3-p-hydroxypaclitaxel, and cyclosporin A. The pharmacokinetic behavior of paclitaxel was characterized using both compartmental and noncompartmental methods. Model-estimated parameters were used to simulate paclitaxel concentrations after once daily and twice daily oral administration of paclitaxel and cyclosporin A. Aside from an unpleasant taste, the oral regimen was well tolerated, and there were no grade 3 or 4 drug-related toxicities. The systemic exposure to paclitaxel, as assessed by maximum plasma concentration (Cmax) and area under the plasma concentration versus time curve (AUC) values, did not increase as the dose of paclitaxel was increased from 180 to 540 mg, and there was substantial interindividual variability (4-6-fold) at each dose level. Mean paclitaxel Cmax values approached plasma concentrations achieved with clinically relevant parenteral dose schedules, averaging 268+/-164 ng/ml. AUC values averaged 3306+/-1977 ng x h/ ml, which was significantly lower than AUC values achieved with clinically relevant i.v. paclitaxel dose schedules. However, computer simulations using pharmacokinetic parameters derived from the present study demonstrated that pharmacodynamically relevant steady-state plasma paclitaxel concentrations of at least 0.06 microM would be achieved after protracted once daily and twice daily dosing with oral paclitaxel and cyclosporin A. Paclitaxel metabolites were detectable in three patients, and the 6-alpha-hydroxypaclitaxel: paclitaxel and 3-p-hydroxypaclitaxel:paclitaxel AUC ratios averaged 0.63 and 0.86, respectively; these values were substantially higher than values reported in patients treated with i.v. paclitaxel. Oral paclitaxel was bioavailable in humans when administered in combination with oral cyclosporin A 5 mg/kg 1 h before and concurrently with paclitaxel treatment, and plasma paclitaxel concentrations achieved with this schedule were biologically relevant and approached concentrations attained with clinically relevant parenteral dose schedules. However, treatment of patients with oral paclitaxel using a single oral dose administration schedule failed to achieve sufficiently high systemic drug exposure and pharmacodynamic effects. In contrast, computer simulations demonstrated that clinically relevant pharmacodynamic effects are likely to be achieved with multiple once daily and twice daily oral paclitaxel-cyclosporin A dosing schedules.

Administration, Oral↗

PubMed2004

Enhanced paclitaxel bioavailability after oral administration of pegylated paclitaxel prodrug for oral delivery in rats.

The bioavailability and pharmacokinetic parameters of paclitaxel in a PEGylated paclitaxel prodrug were studied after the oral administration of paclitaxel (25, 50, 100 mg/kg) and prodrug (87.5, 175, 350 mg/kg) in rats. The area under the plasma concentration-time curve (AUC) of paclitaxel by oral paclitaxel were 836, 1,602 and 3,076 ng/mlh, which increased dose-dependently (P < 0.006, r = 0.9996). The AUCs of paclitaxel by the oral paclitaxel prodrug were 1,646, 3,079 and 5,998 ng/mlh, also increased dose-dependently (P < 0.003, r = 0.9999). The AUC of paclitaxel by the intravenous administration of paclitaxel (2 mg/kg) was 3,992 ng/mlh. The mean absolute bioavailability (AB%) of paclitaxel was 1.6% by the oral administration of paclitaxel. The mean AB% of paclitaxel by the prodrug was 6.3%, which was 3.94-fold higher than the oral paclitaxel. The peak concentration of paclitaxel (C(max)) in the dose of 350 mg/kg (50 mg/kg as paclitaxel) of prodrug was 339 ng/ml, which was significantly higher (P < 0.01) than the dose of 50 mg/kg of paclitaxel (104 ng/ml). At the same dose of paclitaxel, the AUC of paclitaxel in the prodrug resulted in a remarkable increase, approximately four-fold compared to the oral paclitaxel. It might be considered that the significantly enhanced bioavailability of paclitaxel by the prodrug, which is water-soluble and easy to permeat through the intestinal mucosa, is due to the avoidance of being inhibited by p-glycoprotein efflux pump in the intestinal mucosa and reduction of metabolism by cytochrome-p-450 (CYP3A) in epitherial cells of small intestine. It appears that the development of oral paclitaxel preparations as a prodrug is possible, which will be more convenient than the IV dosage form.

Administration, Oral↗

PubMed1998

A phase I/II trial of paclitaxel for non-Hodgkin's lymphoma followed by paclitaxel plus quinine in drug-resistant disease.

Patients with non-Hodgkin's lymphoma (NHL) recurrent after chemotherapy exhibit clinical characteristics compatible with the phenomenon of multidrug resistance (MDR) and frequently have detectable levels of P-glycoprotein (P-gp). Paclitaxel has been used in recurrent NHL with limited success. To test whether clinical resistance to paclitaxel can be reversed, we treated patients having paclitaxel-resistant NHL with paclitaxel plus quinine and measured the effects of quinine on paclitaxel pharmacokinetics. Eligible patients had recurrent and measurable NHL. Patients initially received paclitaxel, 120 mg/m2 (dose determined by a phase I trial of paclitaxel plus quinine), as a 20-24 h infusion every 3 weeks until there was evidence of clinical resistance. Patients then received paclitaxel at the same dose rate plus oral quinine at a fixed dose rate of 400 mg three times each day. Paclitaxel pharmacokinetics were studied in each patient using paired samples from plasma obtained at the end of the 24 h paclitaxel infusion as an estimate of the steady-state drug level. Of 14 patients treated with paclitaxel alone, one patient obtained a partial response (7%). At the time of disease progression, one patient (same patient) obtained a partial response with paclitaxel plus quinine (7%). Steady-state paclitaxel levels were obtained in 12 patients. In 11 of 12 patients the steady-state paclitaxel level was substantially lower with the addition of quinine. The average ratio of end of infusion plasma levels (paclitaxel alone/paclitaxel plus quinine) was 0.6 (range 0.31-0.97) indicating a 40% decrease in paclitaxel levels with the addition of quinine (p=0.001). We conclude that paclitaxel given by this dose and schedule has modest activity in recurrent NHL. The addition of quinine to paclitaxel also has limited activity, but the combination did reverse paclitaxel resistance in one patient, adding support to the hypothesis that clinical drug resistance can be overcome with chemosensitizers in individual patients. Pharmacokinetic studies indicate that the reversal of drug resistance in this study cannot be attributed to changes in clearance of paclitaxel (which appears to increase with quinine), but more likely to the sensitization of lymphoma cells.

Adolescent↗

PubMed2002

Paclitaxel delivery systems: the use of amino acid linkers in the conjugation of paclitaxel with carboxymethyldextran to create prodrugs.

Paclitaxel was bound via its hydroxyl group to carboxymethyldextran (CMDex, 150 kDa) by means of an amino acid linker; the linker was introduced into the 2'- or 7-hydroxyl group of the paclitaxel through an ester bond. These conjugates--CMDex-2'-paclitaxel and CMDex-7-paclitaxel--were designed to be water-soluble with a paclitaxel content between 6-8% (w/w) with a degree of subsititution (DS) of the CM groups at 0.6 per sugar residue. The release of the paclitaxel from the conjugates was influenced by the hydroxyl group (2'- or 7-) of paclitaxel to which the amino acid linker was introduced, and by what amino acid was used as the linker. In mouse plasma incubated at 37 degrees C for 72 h, the most paclitaxel was released using CMDex-paclitaxel conjugate with 2'gly followed by, in descending order, 2'-ala, 2'-leu, 2'-ile, and 7-gly as the amino linkers. Colon 26, a Taxol resistant cancer, was introduced into mice and the conjugates were intravenously administered by bolus injection for a tumor distribution study, and intermittently intravenously administered for a tumor growth regression study. In both studies the highest amount of paclitaxel release was found in the CMDex-2'-gly-paclitaxel followed by CMDex-2'-ala-paclitaxel, CMDex-2'-leu-paclitaxel and paclitaxel. There was a direct correlation between the amount of paclitaxel released and the observed efficacy. CMDex-2'-ile-paclitaxel and CMDex-7-gly-paclitaxel did not show any anti-tumor activity. These results clearly demonstrate that a CMDex-paclitaxel with an appropriate amino acid linker has significant anti-tumor activity against colon 26, and that these anti-tumor effects appear to correlate with the amounts of paclitaxel released in the tumor.

Amino Acids↗

PubMed2002

Short versus long duration infusions of paclitaxel for any adenocarcinoma.

BACKGROUND: Paclitaxel has become a standard drug used in a number of common cancers. At first long infusions were used to reduce the rate of inflow of the drug and as a result reduce the occurrence of hypersensitivity types of allergic reactions. Trials with shorter durations of infusion, and using a cocktail of anti-allergic drugs to prevent hypersensitivity reactions, some randomised, were begun. These were interpreted as showing that effectiveness of treatment was not lessened by a short infusion time. These studies also appeared to show that some important toxicities were less common with short infusions and that they were more convenient for the patient and the hospital. OBJECTIVES: To assess the effect of varying the duration of infusion of paclitaxel on its anti-cancer effectiveness and side-effects. SEARCH STRATEGY: Electronic searches of the Cochrane Gynaecological Cancer CRG, the Cochrane Register of Controlled Trials, MEDLINE, EmBase, CANCERLIT, PDQ, Meta-register (mRCT) and the M.D. Anderson Cancer Centre, GOG were carried out. Information from the manufacturer and authors of reports of studies was also acquired. SELECTION CRITERIA: The review was restricted to randomised controlled trials of single agent paclitaxel or paclitaxel with other drugs, where the only variable was the duration of paclitaxel infusion. The review only included patients with advanced adenocarcinoma. DATA COLLECTION AND ANALYSIS: Data was extracted by two independent reviewers and where there was disagreement this was resolved by discussion. Where possible the data was synthesised in a meta-analysis. MAIN RESULTS: Three hour paclitaxel infusions appear to result in a smaller fall in white blood cell count, less fever, infection and sore mouth than 24 hour infusions. In contrast, 24 hour infusions cause less nerve toxicity. Other side-effects are not dependent on the duration of infusion. Evidence from individual trials suggesting efficacy may be slightly greater with 24 hour infusions is inconclusive. Combination of data from trials of different cancer sites in a meta-analysis must be considered speculative, but the combined data also suggest that 24 hour infusions of paclitaxel may be slightly more effective. REVIEWER'S CONCLUSIONS: This review confirms that, apart from neurological effects, three hour infusion of paclitaxel causes significantly less side effects than 24 hour infusion. Insufficient data exists to state whether varying the duration of infusion has a significant effect on its anti-cancer effectiveness. Further study would be required to establish whether there genuinely is a significant difference in efficacy according to the duration of infusion of paclitaxel.

Adenocarcinoma↗

PubMed2004

Enhanced paclitaxel bioavailability after oral administration of paclitaxel or prodrug to rats pretreated with quercetin.

The aim of this study was to investigate the effect of quercetin on the bioavailability of paclitaxel after the oral administration of paclitaxel or a prodrug to rats pretreated with quercetin. Paclitaxel (40 mg/kg) and prodrug (280 mg/kg, 40 mg/kg as the paclitaxel) were administered orally to rats pretreated with quercetin (2, 10, 20 mg/kg). The plasma concentrations of paclitaxel pretreated with quercetin were increased significantly (P < 0.01 for paclitaxel; P < 0.05 for prodrug) compared to the control. The areas under the plasma concentration-time curve (AUC) and the peak concentrations (Cmax) of paclitaxel pretreated with quercetin were significantly higher (P < 0.01) than the control. The half-life (t(1/2)) and mean residence times were significantly (P < 0.05) longer compared to the control. The absolute bioavailability (AB%) of paclitaxel pretreated with quercetin was significantly higher (P < 0.01) than the control. The AUC of paclitaxel after administration of the prodrug to rats pretreated with quercetin was significantly (P < 0.05) higher than the prodrug control. The relative bioavailability of paclitaxel after administration of the prodrug to rats pretreated with quercetin was 1.25- to 2.02-fold higher than the prodrug control. The AB% of paclitaxel was increased significantly (P < 0.05) by quercetin from 8.0 to 10.1 and 16.2%. The bioavailability of paclitaxel administered as a prodrug with or without pretreatment of quercetin was remarkably higher than the control. AUC, AB% and Cmax of paclitaxel after administration of the paclitaxel or prodrug pretreated with quercetin for 3 days were much higher than those administered after 20 min. It might have resulted from the physicochemical properties of the prodrug, which is a water-soluble compound and passes through the gastrointestinal mucosa more easily than paclitaxel without obstruction of P-gp and cytochrome P-450 in the gastrointestinal mucosa. It seems that the development of oral paclitaxel preparations as a prodrug or with quercetin is feasible, which is more convenient than the i.v. dosage forms.

Administration, Oral↗

PubMed2005

Enhanced paclitaxel bioavailability after oral coadministration of paclitaxel prodrug with naringin to rats.

The aim of this study was to investigate the effect of naringin on the bioavailability and pharmacokinetics of paclitaxel after oral administration of paclitaxel or its prodrug coadministered with naringin to rats. Paclitaxel (40 mg/kg) and prodrug (280, 40 mg/kg paclitaxel equivalent) were coadministered orally to rats with naringin (1, 3, 10 and 20 mg/kg). The plasma concentrations of paclitaxel coadministered with naringin increased significantly (p<0.01 at paclitaxel, p<0.05 at prodrug) compared to the control. The areas under the plasma concentration-time curve (AUC) and the peak concentrations (C(max)) of paclitaxel with naringin significantly higher (p<0.01) than the control. The half-life (t(1/2)) was significantly (p<0.05) longer than the control. The absolute bioavailability (AB, %) of paclitaxel with naringin was significantly higher (3.5-6.8%, p<0.01) than the control (2.2%). Absorption rate constant (K(a)) of paclitaxel with naringin increased, but not significantly. The AUC of paclitaxel after coadministration of prodrug with naringin to rats was significantly (p<0.05) higher than the prodrug control. The relative bioavailability (RB, %) of paclitaxel after coadministration of prodrug with naringin was 1.35-1.69-fold higher than prodrug control. The absolute bioavailability (AB, %) of paclitaxel after coadministration of prodrug with naringin increased significantly (p<0.05) from 6.6 to 9.0% and 11.2%. The bioavailability of paclitaxel coadministered as a prodrug with or without naringin was remarkably higher than the control. Paclitaxel prodrug, a water-soluble compound concerning with its physicochemical properties, passes through the gastrointestinal mucosa more easily than paclitaxel without obstruction of P-gp and cytochrome P-450 in the gastrointestinal mucosa. Oral paclitaxel preparations which is more convenient than the IV dosage forms could be developed with a prodrug form with naringin.

Absorption↗

PubMed1999

Evaluation of In-111 DTPA-paclitaxel scintigraphy to predict response on murine tumors to paclitaxel.

UNLABELLED: Our goal was to determine whether scintigraphy with 111In-DTPA-paclitaxel could predict the response to chemotherapy with paclitaxel. METHODS: Ovarian carcinoma (OCA 1), mammary carcinoma (MCA-4), fibrosarcoma (FSA) and squamous cell carcinoma (SCC VII) were inoculated into the thighs of female C3Hf/Kam mice. Mice bearing 8 mm tumors were treated with paclitaxel (40 mg/kg). The growth delay, which was defined as the time in days for tumors in the treated groups to grow from 8 to 12 mm in diameter minus the time in days for tumors in the untreated control group to reach the same size, was measured to determine the effect of paclitaxel on the tumors. Sequential scintigraphy in mice bearing 10 to 14 mm tumors was conducted at 5, 30, 60, 120, 240 min and 24 hrs postinjection of 111In-DTPA-paclitaxel (3.7MBq) or 111In-DTPA as a control tracer. The tumor uptakes (% injection dose/pixel) were determined. RESULTS: The growth delay of OCA 1, MCA-4, FSA and SCC VII tumors was 13.6, 4.0, -0.02 and -0.28 days, respectively. In other words, OCa 1 and MCA-4 were paclitaxel-sensitive tumors, whereas FSA and SCC VII were paclitaxel-resistant tumors. The tumor uptakes at 24 hrs postinjection of In-111 DTPA paclitaxel of OCA 1, MCA-4, FSA and SCC VII were 1.0 x 10(-3), 1.6 x 10(-3), 2.2 x 10(-3) and 9.0 x 10(-3) % injection dose/pixel, respectively. There was no correlation between the response to chemotherapy with paclitaxel and the tumor uptakes of 111In-DTPA-paclitaxel. CONCLUSIONS: Scintigraphy with 111In-DTPA-paclitaxel could not predict the response to paclitaxel chemotherapy. Although there was significant accumulation of the paclitaxel in the tumor cells, additional mechanisms must be operative for the agent to be effective against the neoplasm. 111In-DTPA-paclitaxel activity is apparently different from that of paclitaxel with Cremophor.

Animals↗

PubMed1999

Paclitaxel steady-state plasma concentration as a determinant of disease outcome and toxicity in lung cancer patients treated with paclitaxel and cisplatin.

The principal purpose of this study was to evaluate relationships between paclitaxel plasma steady-state concentration (Css) and both disease outcome and toxicity in patients with non-small cell lung cancer (NSCLC) treated with paclitaxel and cisplatin in an Eastern Cooperative Oncology Group (ECOG) Phase III study E5592. Chemotherapy-naive patients with stage IIIb and IV NSCLC were randomized to treatment with either 75 mg/m2 cisplatin i.v. on day 1 and 100 mg/m2 etoposide i.v. on days 1-3 (EC arm) or 75 mg/m2 cisplatin i.v. combined with either a low dose of paclitaxel (135 mg/m2, 24-h i.v. infusion; PC arm) or a higher dose of paclitaxel (250 mg/m2 i.v., 24-h i.v. infusion) with granulocyte colony-stimulating factor (PCG arm). End-of-24-h-infusion paclitaxel concentrations, which have been demonstrated to be nearly equal to CssS on this schedule, were obtained during the first and second courses in patients on the PC and PCG arms. Relationships between the average paclitaxel Css (Css,avg) and the best response to treatment, time to treatment failure (TTF), survival, and worst grade of leukopenia and neurotoxicity were evaluated by univariate analysis. A multivariate model was used to assess the influence of paclitaxel Css in conjunction with other potentially relevant patient variables that may affect disease outcome, including the paclitaxel treatment arm, age, sex, performance status, weight loss during the previous 6 months, and disease stage. Paclitaxel Css in both courses 1 and 2 were obtained in 71 patients treated with PC and 75 patients treated with PCG. Although Css,avgS in patients treated with PC and PCG were significantly different (median, 0.32 versus 0.81 micromol/liter; P < 0.0001), response rates were not (33.8 versus 26.7%; P = 0.3719). In addition, there were no differences between the PC and PCG arms in TTF (median, 5.1 versus 5.5 months, P = 0.6201) or survival (median, 11.6 versus 11.3 months, P = 0.7173). Combined analysis of paclitaxel concentrations from both treatment arms revealed no significant difference in paclitaxel Css,avg between responders and nonresponders [median, 0.40 (range, 0.16-1.6) micromol/liter versus 0.55 (range, 0.11-3.6)], and Css,avgS were similar in patients segregated according to whether they had a complete response, partial response, stable disease, or progressive disease as their best response to treatment (P = 0.7612). In addition, the relationship between Css,avg and TTF was weak (r2 = 0.00003, P = 0.94), as was the relationship between Css,avg and survival (P = 0.1267). With regard to the principal toxicities, neither the propensity to develop neuromuscular and neurosensory toxicity nor the worst grade of these adverse effects were related to Css,avg (P = 0.5000 and 0.2033, respectively); however, the relationship between Css,avg and the worst grade of leukopenia experienced was marginally significant (P = 0.0796). In a multivariate model, neither the combined effect of relevant demographic and stratification variables nor paclitaxel Css,avg predicted for either response (P = 0.1544) or TTF (P = 0.2574), whereas the combined effect of all covariates predicted for survival (P = 0.0249). With regard to individual covariates, a lower disease stage (stage IIIb) was the only significant positive determinant of response (P = 0.0173), female sex was the only significant favorable predictor for TTF (P = 0.0195), and a lower ECOG performance status (= 0) was the only significant positive determinant of survival (P = 0.0121) in the multivariate model. In summary, paclitaxel Css,avg was not a determinant of response, TTF, or survival in patients with advanced NSCLC treated with paclitaxel as a 24-h i.v. infusion combined with cisplatin. On the basis of both the clinical and pharmacodynamic results of E5592, there is no compelling reason to treat patients with advanced NSCLC with paclitaxel on a 24-h i.v. schedule at doses of > 135 mg/m2 in combination with cisplatin, although highe

Adult↗

PubMed2005

SRC tyrosine kinase and multidrug resistance protein-1 inhibitions act independently but cooperatively to restore paclitaxel sensitivity to paclitaxel-resistant ovarian cancer cells.

Src tyrosine kinase has been found to be overexpressed in both mouse and human ovarian cancer cells as well as in human primary ovarian cancers. Furthermore, Src inhibition sensitizes ovarian cancer cells to chemotherapeutic agents such as paclitaxel and cisplatin. Interestingly, Src inhibition has also been shown to resensitize paclitaxel-resistant cells to the cytotoxic effects of paclitaxel. The current study was undertaken in an effort to determine the mechanism by which Src resensitizes drug-resistant ovarian cancer cells. The paclitaxel-resistant human (CaOV3TaxR) and mouse (ID8TaxR) ovarian cancer cell lines express large amounts of the multidrug resistance-1 (MDR-1) protein compared with the paclitaxel-sensitive parent cell lines. Src inhibition had no effect on MDR-1 protein expression. Furthermore, Src inhibition did not affect MDR-1 function as determined by rhodamine 123 and paclitaxel uptake or retention. Coinhibition of both Src and MDR-1 synergistically enhanced paclitaxel-induced cytotoxicity in paclitaxel-resistant ovarian cancer cell lines. Inhibition of Src enhanced microtubule stabilization in paclitaxel-resistant ovarian cancer cells treated with paclitaxel without affecting expression of beta-tubulin isotypes and resulted in multipolar spindle formation and apoptosis. These results show that Src inhibition restores paclitaxel sensitivity to paclitaxel-resistant ovarian cancer cells by an MDR-independent mechanism, possibly by decreasing the critical intracellular concentration at which paclitaxel induces tubulin stabilization and bundling. Src tyrosine kinase may provide a viable target for therapeutic intervention in drug-resistant ovarian cancer.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1996

Sequence-dependent alteration of doxorubicin pharmacokinetics by paclitaxel in a phase I study of paclitaxel and doxorubicin in patients with metastatic breast cancer.

PURPOSE: To determine whether a schedule-dependent interaction occurs when paclitaxel and doxorubicin are administered sequentially. PATIENTS AND METHODS: Ten patients with metastatic breast cancer received paclitaxel 125 mg/m2 over 24 hours either immediately before or after doxorubicin 48 mg/m2 over 48 hours as the initial chemotherapy treatment. Two such courses were given, and the sequence of administration was reversed after course 1. In cohort 1, paclitaxel preceded doxorubicin for course 1. In cohort 2, doxorubicin preceded paclitaxel for course 1. Doxorubicin levels were measured serially during the infusion and for 24 hours following it. Patients were assessed clinically for the occurrence of stomatitis and infection and granulocyte counts were measured twice weekly. RESULTS: Eight patients had complete pharmacokinetic sampling for both courses. The mean end-of-infusion plasma doxorubicin concentrations (Cmax) were 70% higher in the paclitaxel-doxorubicin sequence compared with the reverse sequence (45 +/- 8 ng/mL v 26 +/- 5 ng/ mL). The mean doxorubicin clearance was 32% lower in the paclitaxel-doxorubicin sequence (34.3 +/- 10.3 L/h v 51.6 +/- 16.1 L/h, P < .01). Clinically, hematologic and mucosal toxic effects were worse in the paclitaxel-doxorubicin sequence. The median absolute granulocyte count was 0.2/microL in the paclitaxel-doxorubicin sequence and 1.3/microL in the doxorubicin-paclitaxel sequence. Seven of 10 patients who received the paclitaxel-doxorubicin sequence had grade 2 (n = 4) or 3 (n = 3) stomatitis, while only one of 10 patients who received the doxorubicin-paclitaxel sequence had grade 2 stomatitis and none had grade 3. CONCLUSION: When paclitaxel by 24-hour infusion precedes doxorubicin by 48-hour infusion, doxorubicin clearance is reduced by nearly one third, which results in grade 2 and 3 stomatitis. To prevent this effect when paclitaxel (by 24-hour infusion) and doxorubicin are administered sequentially, doxorubicin should be given first. The mechanisms for this effect are under investigation.

Adult↗

PubMed2003

Phase III trial of doxorubicin, paclitaxel, and the combination of doxorubicin and paclitaxel as front-line chemotherapy for metastatic breast cancer: an intergroup trial (E1193).

PURPOSE: Between February 1993 and September 1995, 739 patients with metastatic breast cancer were entered on an Intergroup trial (E1193) comparing doxorubicin (60 mg/m(2)), paclitaxel (175 mg/m(2)/24 h), and the combination of doxorubicin and paclitaxel (AT, 50 mg/m(2) and 150 mg/m(2)/24 h, plus granulocyte colony-stimulating factor 5 mg/kg) as first-line therapy. Patients receiving single-agent doxorubicin or paclitaxel were crossed over to the other agent at time of progression. PATIENTS AND METHODS: Patients were well balanced for on-study characteristics. RESULTS: Responses (complete response and partial response) were seen in 36% of doxorubicin, 34% of paclitaxel, and 47% of AT patients (P =.84 for doxorubicin v paclitaxel, P =.007 for v AT, P =.004 for paclitaxel v AT). Median time to treatment failure (TTF) is 5.8, 6.0, and 8.0 months for doxorubicin, paclitaxel, and AT, respectively (P =.68 for doxorubicin v paclitaxel, P =.003 for doxorubicin v AT, P =.009 for paclitaxel v AT). Median survivals are 18.9 months for patients taking doxorubicin, 22.2 months for patients taking paclitaxel, and 22.0 months for patients taking AT (P = not significant). Responses were seen in 20% of patients crossing from doxorubicin --> paclitaxel and 22% of patients crossing from paclitaxel --> doxorubicin (P = not significant). Changes in global quality-of-life measurements from on-study to week 16 were similar in all three groups. CONCLUSION: (1) doxorubicin and paclitaxel, in the doses used here, have equivalent activity; (2) the combination of AT results in superior overall response rates and time to TTF; and (3) despite these results, combination therapy with AT did not improve either survival or quality of life compared to sequential single-agent therapy.

Adult↗

PubMed1998

Comparative in vivo studies with paclitaxel and liposome-encapsulated paclitaxel.

Our study was designed to evaluate the pharmacokinetics, tissue distribution, toxicity and therapeutic efficacy of liposome-encapsulated paclitaxel (LET) in comparison to conventional paclitaxel. In normal mice, LET was much less toxic than the conventional drug. A dose of 32.5 mg/kg of conventional paclitaxel administered i.v. on three consecutive days produced 100% mortality by day three, while liposomal paclitaxel exhibited no mortality. The control group which received Diluent 12 (Chremophor EL and ethanol; 1:1 v/v), a vehicle used in conventional paclitaxel, 30% mortality was observed at this dosage level. In murine ascitic L1210 leukemia model, liposomal paclitaxel and conventional paclitaxel showed comparable antitumor activity. The pharmacokinetics of conventional paclitaxel and LET was studied in mice at dose levels of 5 mg/kg and 20 mg/kg. After intravenous administration of conventional paclitaxel at a dose of 5 mg/kg, the area under the plasma-concentration-time curve (AUC) was 2-fold lower and, the elimination half-life was 2-times shorter compared to LET. At a dose of 20 mg/kg, the terminal half-lives were comparable, however, conventional paclitaxel displayed non-linear pharmacokinetics with disproportionate increase in AUC. At the two dose levels studied, LET demonstrated linear kinetics. Tissue distribution of paclitaxel after administration of LET showed levels 10-fold higher in spleen and 3.5-fold higher in liver as compared to conventional paclitaxel. The significant decrease in toxicity shown by LET, coupled with an increase in plasma AUC and half-life indicates that LET may be a viable alternative to the therapeutic use of the conventional preparation of paclitaxel.

Animals↗

PubMed2002

Safety and efficacy of the multidrug resistance inhibitor Incel (biricodar; VX-710) in combination with paclitaxel for advanced breast cancer refractory to paclitaxel.

PURPOSE: VX-710 (biricodar, Incel) restores drug sensitivity to P-glycoprotein (MDR1) and multidrug resistance-associated protein (MRP1)-expressing cells. This Phase II study evaluated the safety/tolerability, pharmacokinetics, and efficacy of VX-710 plus paclitaxel in women with locally advanced or metastatic breast cancer who were refractory to prior paclitaxel therapy. EXPERIMENTAL DESIGN: Eligible patients had paclitaxel-refractory disease defined as progressive disease after a minimum of two cycles of paclitaxel (weekly or 3-week schedule) or relapsed/progressive disease within 6 months of prior paclitaxel therapy. Patients received 80 mg/m(2) paclitaxel over 3 h starting 4 h after initiation of a 24-h continuous i.v. infusion of 120 mg/m(2)/h VX-710. Cycles were repeated every 3 weeks. RESULTS: Thirty-seven patients received study treatment and 35 were evaluable for response. VX-710 + paclitaxel therapy was generally well tolerated. Myelosuppression was the principal toxicity, with a median nadir ANC cycle 1 of 0.76 x 10(9) cells/liter and a 40% overall incidence of Grade 4 neutropenia. Nonhematological side effects (asthenia, paresthesia, headache, myalgia, nausea, and diarrhea) were generally mild to moderate and reversible. Paclitaxel AUC (16.8 +/- 5.0 microg x h/ml) and clearance (5.1 +/- 1.3 liters/h/m(2)) during the first treatment cycle were comparable with standard 175 mg/m(2) paclitaxel administered in a 3-h schedule. Four patients achieved partial responses (three of the four had progressive disease on prior paclitaxel) with a mean response duration of 5.5 months. CONCLUSIONS: The 11.4% (4 of 35) objective response rate observed in this study suggests that VX-710 can resensitize a subgroup of paclitaxel-refractory patients to paclitaxel. The safety and pharmacokinetics of the VX-710/pacitaxel regimen support further evaluation in breast cancer patients with initial paclitaxel therapy to prevent emergence of the MDR phenotype in recurrent disease.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1996

Paclitaxel retreatment in patients with platinum and paclitaxel resistant ovarian cancer.

The optimal role of paclitaxel in the treatment of epithelial ovarian cancer has not been determined. Dose intense paclitaxel therapy is safe and often recommended as second-line treatment for platinum resistant ovarian cancer. Retreatment with a higher dose-intense schedule of paclitaxel is feasible and patients who had a prior dose of 135 mg/m2 or paclitaxel free interval of at least six months may respond. Sensitivity to initial doses and a prolonged paclitaxel-free interval are predictors of a successful reinduction. We report 10 patients who had paclitaxel as second-line treatment and were later retreated with paclitaxel. Three of these patients had a partial response (30%; 95% CI 6-66%). All but one patient had platinum resistant disease. Initial dose and the best response to initial paclitaxel were assessed in relation to reinduction response. Patients with at least a six-month paclitaxel-free interval and previously low dose paclitaxel (135 mg/m2), or a complete response with high dose paclitaxel (250 mg/m2) may respond to high dose paclitaxel retreatment. Prospective trials of paclitaxel retreatment are warranted.

Adult↗

PubMed2002

A phase II study of the MDR inhibitor biricodar (INCEL, VX-710) and paclitaxel in women with advanced ovarian cancer refractory to paclitaxel therapy.

PURPOSE: Incel (biricodar, VX-710) restores drug sensitivity to P-glycoprotein (MDR1) and multidrug-resistance-associated protein (MRP1) expressing cells. This phase II study evaluated the safety/tolerability, pharmacokinetics, and efficacy of VX-710 plus paclitaxel in women with advanced ovarian cancer refractory to prior paclitaxel therapy. EXPERIMENTAL DESIGN: Eligible patients had paclitaxel-refractory disease defined as progressive disease after a minimum of two cycles of paclitaxel (weekly or 3-week schedule) or relapsed disease within 4 months of prior paclitaxel therapy. Patients received 80 mg/m(2) paclitaxel over 3 h starting 4 h after initiation of a 24-h continuous intravenous infusion of 120 mg/m(2)/h VX-710. Cycles were repeated every 3 weeks. RESULTS: Fifty patients received treatment and 45 were evaluable for response. VX-710 + paclitaxel therapy was generally well tolerated. Myelosuppression was the principal toxicity, with a median Cycle 1 nadir absolute neutrophil count of 0.27 x 10(9) cells/L and a 47% overall incidence of Grade 4 neutropenia. Mild to moderate peripheral neuritis or neuropathy was the primary nonhematologic toxicity, affecting 62% of patients. Other nonhematologic toxicities were generally mild to moderate and reversible. Paclitaxel area under the concentration-versus-time curve (AUC) (16 +/- 5.3 microg x h/mL) during the first treatment cycle was comparable to standard 175 mg/m(2) paclitaxel administered over 3 h. Of the 3 patients who achieved partial responses, 2 had progressed during prior paclitaxel therapy. Twelve patients maintained stable disease and 14/45 (31%) of patients had CA-125 reductions of 50-90% for up to 24 weeks. The median time-to-disease progression was 10 weeks for the intent-to-treat population and 20.7 weeks for the CA-125 responders. CONCLUSIONS: The results suggest that VX-710 with paclitaxel has modest activity in paclitaxel-resistant ovarian cancer. Further research is warranted in less heavily treated patients.

ATP Binding Cassette Transporter, Subfamily B, Mem↗