epothilone-a and Ovarian-Neoplasms

Ovarian cancer is the most lethal gynecologic malignancy worldwide with extremely poor patient prognosis. Elucidation of the detailed mechanisms of action of drugs targeting this cancer type is necessary to optimize treatment efficacy. Epothilones, a new class of microtubule-stabilizing anticancer drugs, show strong cytotoxic properties in vitro and in vivo and are additionally effective in taxane-resistant cells. In this report, we focus on inhibitors of microtubule depolymerization, taxanes, and the novel antimicrotubule agents, epothilones. Current knowledge regarding the effects of epothilone B on ovarian tumor cell metabolism is reviewed, along with recent advances in therapeutic strategies, such as novel agents and biologic drug combinations containing epothilone that target aberrant pathways in ovarian cancer.

Topics: Animals; Antineoplastic Agents; Carcinoma; Epothilones; Female; Humans; Ovarian Neoplasms; Tubulin Modulators

Despite more modern therapeutics approaches and the use of new drugs for chemotherapy, patients with ovarian cancer still have poor prognosis and therefore, new strategies for its cure are highly needed. One of the promising ways is combined therapy, which has many advantages as minimizing drug resistance, enhancing efficacy of treatment, and reducing toxicity. Combined therapy has rich and successful history in the field of ovarian cancer treatment. Currently use therapy is usually based on platinum-containing agent (carboplatin or cisplatin) and a member of taxanes (paclitaxel or docetaxel). In the mid-2000s this standard regimen has been expanded with bevacizumab, monoclonal antibody directed to Vascular Endothelial Growth Factor (VEGF). Another drug combination with promising perspectives is WP 631 given together with epothilone B (Epo B). WP 631 is a bisanthracycline composed of two molecules of daunorubicin linked with a p-xylenyl linker. Epo B is a 16-membered macrolide manifesting similar mechanism of action to taxanes. Their effectiveness against ovarian cancer as single agents is well established. However, the combination of WP 631 and Epo B appeared to act synergistically, meaning that it is much more potent than the single drugs. The mechanism lying under its efficacy includes disturbing essential cell cycle-regulating proteins leading to mitotic slippage and following apoptosis, as well as affecting EpCAM and HMGB1 expression. In this article, we summarized the current state of knowledge regarding combined therapy based on WP 631 and Epo B as a potential way of ovarian cancer treatment.

Topics: Antibiotics, Antineoplastic; Antineoplastic Combined Chemotherapy Protocols; Daunorubicin; Epothilones; Female; Humans; Ovarian Neoplasms

To describe the clinical outcome and tolerability of weekly ixabepilone (16-20mg/m(2) days 1, 8, 15 of a 28-day cycle)±biweekly bevacizumab (10mg/kg days 1 and 15) in patients with recurrent/persistent uterine or ovarian/primary peritoneal/fallopian tube cancers.. A single-institution retrospective review was performed inclusive of all patients who received ≥2cycles from 01/2010 to 06/2014. Progression-free (PFS) and overall (OS) survival were determined using the Kaplan-Meier method. Toxicities were graded according to CTCAEv4.0. Best response was categorized using RECIST or by CA-125 criteria.. A total of 60 patients (24 uterine and 36 ovarian cancers) were identified. Patients had received a median of 3.5 (range:1-10) prior lines of chemotherapy. Patients completed a mean of 4.7±2.9cycles of ixabepilone; 66.7% (16/24) and 91.7% (33/36) of patients with uterine and ovarian cancers received concurrent bevacizumab. For uterine cancers, objective response rate (ORR) was 41.7% (12.5% complete, 29.2% partial); median duration of response or stabilization was 7months (range:2-30). Median PFS and OS were 5.2 and 9.6months, respectively. PFS and OS were improved in the setting of concurrent bevacizumab (6.5 versus 3.0months, p=0.01, HR 0.2, 95% CI 0.05-0.77; 9.6 versus 4.2months, p=0.02, HR 0.58, 95% CI 0.04-0.74). Similar ORR was observed among ovarian cancers; median PFS/OS were not yet reached. Most toxicities were grade 1/2.. Weekly ixabepilone with or without biweekly bevacizumab has promising activity and acceptable toxicity in patients with platinum-/taxane-resistant endometrial and ovarian cancers. This combination warrants further prospective study in these populations.

Topics: Angiogenesis Inhibitors; Antibodies, Monoclonal, Humanized; Antineoplastic Combined Chemotherapy Protocols; Bevacizumab; Disease-Free Survival; Drug Administration Schedule; Epothilones; Fallopian Tube Neoplasms; Female; Humans; Middle Aged; Neoplasm Recurrence, Local; Ovarian Neoplasms; Peritoneal Neoplasms; Prospective Studies; Retrospective Studies

Epothilones are a new group of microtubule-stabilizing agents that have demonstrated antitumor activity in taxane-resistant models. Taxanes remain some of the most active cytotoxic agents in current cancer therapy. Primary or acquired resistance to taxanes in tumor cells partly prevents their long-term efficacy. Certain side effects, such as myelosupression or irreversible neuropathy, can also limit prolonged taxane administration. Epothilone B (EPO906; patupilone), a natural compound, and its semisynthetic derivative, ixabepilone (BMS-247550), differ in their pharmacokinetic and toxicity profiles. Ovarian cancer patients frequently relapse after first-line treatment based on platinum-taxane doublets. Therefore, epothilones might represent a therapeutic alternative in this setting. Patupilone and ixabepilone have undergone parallel clinical development, but their future role in ovarian cancer therapeutics remains ill defined.

Topics: Clinical Trials as Topic; Drug Evaluation, Preclinical; Epothilones; Female; Humans; Ovarian Neoplasms; Tubulin Modulators

Epothilones are cytotoxic macrolides that share a similar mechanism of action with the taxanes but demonstrate antitumor activity in taxane-resistant settings. Six epothilones are in early clinical trials for cancer treatment.. This review summarizes data from phase II clinical studies of the epothilones ixabepilone (BMS-247550), patupilone (EPO906), and KOS-862. Data were identified by searches of PubMed and of the proceedings of the American Society of Clinical Oncology annual meetings and the Federation of European Cancer Societies biennial conference for the period 2000-2006. Studies were included if safety and efficacy data were available for at least 10 patients with a given tumor type in a standard phase II design.. Epothilones have demonstrated activity in lung, ovarian, breast, prostate, and renal carcinomas and in non-Hodgkin's lymphoma in phase II studies. Little or no evidence of clinical activity has been reported in studies of epothilones in other tumor types. Preliminary data indicate that epothilones can be combined safely with other cytotoxic agents such as carboplatin.. The epothilones may play a role as an alternative to taxanes if activity in resistant settings can be confirmed together with an acceptable toxicity profile. Randomized studies are awaited to investigate the utility of epothilones in single-agent and combination regimens.

Topics: Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Breast Neoplasms; Clinical Trials, Phase II as Topic; Epothilones; Female; Humans; Kidney Neoplasms; Lung Neoplasms; Lymphoma, Non-Hodgkin; Male; Neoplasms; Ovarian Neoplasms; Tubulin Modulators

This multi-center RP2 study assessed activity/safety of ixabepilone + bevacizumab compared to ixabepilone in platinum-resistant/refractory ovarian/fallopian tube/primary peritoneal cancer. Additional objectives were to examine the role of prior bevacizumab and taxanes, and explore class III-ß-tubulin (TUBB3) as a predictive biomarker.. Among 76 evaluable patients who received IXA + BEV (n = 39) compared to IXA (n = 37), the ORR was 33% (n = 13) versus 8% (n = 3)(P = 0.004), durable at 6 months in 37% (n = 14) and 3% (n = 1) (P < 0.001). BEV significantly improved PFS (median:5.5 vs 2.2 months, HR = 0.33, 95%CI 0.19-0.55, P < 0.001) and OS (median:10.0 vs 6.0 months, HR = 0.52, 95%CI 0.31-0.87, P = 0.006). Both regimens were well-tolerated. TUBB3 expression did not predict response. Subgroup analyses revealed minimal effect of prior BEV or taxane resistant/refractory status on response to IXA + BEV.. IXA + BEV is a well-tolerated, effective combination for platinum/taxane-resistant ovarian cancer that extends PFS and likely OS relative to IXA monotherapy. Prior receipt of BEV should not preclude the use of IXA + BEV. TUBB3 is not a predictive biomarker.. NCT3093155.

Topics: Antineoplastic Combined Chemotherapy Protocols; Bevacizumab; Carcinoma, Ovarian Epithelial; Epothilones; Fallopian Tube Neoplasms; Fallopian Tubes; Female; Humans; Ovarian Neoplasms; Peritoneal Neoplasms; Platinum

Peripheral neuropathy (PN) is a recognized side effect of microtubule-targeting agents and the most clinically relevant toxicity observed with the epothilone sagopilone (SAG). Studies suggest that acetyl-L-carnitine (ALC) may prevent chemotherapy-induced PN. We conducted a prospective, placebo (PBO)-controlled, double-blind, randomized trial to investigate the safety and efficacy of ALC for the prevention of SAG-induced PN. Methods. Patients with ovarian cancer (OC) or castration-resistant prostate cancer (CRPC) and no evidence of neuropathy received SAG (16 mg/m(2) intravenously over 3 hours every 3 weeks) with ALC (1,000 mg every 3 days) or placebo (PBO). The primary endpoint was incidence of PN within six or fewer cycles in both treatment groups. Results. Overall, 150 patients enrolled (98 OC patients, 52 CRPC patients), with 75 per treatment arm. No significant difference in overall PN incidence was observed between treatment arms. The incidence of grade ≥3 PN was significantly lower in the ALC arm in OC patients. Median duration of neuropathy was similar between treatment arms. The best overall response (according to the modified Response Evaluation Criteria in Solid Tumors), response according to tumor markers, time-to-event variables, and discontinuations because of adverse events (AEs) were comparable between treatment arms. Conclusion. Administration of ALC with SAG did not result in a significant difference in overall PN incidence compared with a PBO. OC patients in the SAG/ALC arm had a significantly lower incidence of grade 3 or 4 PN compared with OC patients in the SAG/PBO arm.

Topics: Acetylcarnitine; Adult; Aged; Aged, 80 and over; Antineoplastic Agents; Benzothiazoles; Double-Blind Method; Epothilones; Female; Humans; Male; Middle Aged; Ovarian Neoplasms; Peripheral Nervous System Diseases; Prospective Studies; Prostatic Neoplasms, Castration-Resistant

Sagopilone is the first fully synthetic epothilone in clinical development and has demonstrated promising preclinical activity. This phase I/II, prospective, open-label trial investigated the efficacy and safety of sagopilone plus carboplatin in patients with recurrent platinum-sensitive ovarian cancer (OC).. In phase I (dose-escalation stage), patients with OC recurring at least 6 months after platinum-containing chemotherapy received 3-h infusions of sagopilone (initial dose of 12 mg m(-2)) followed by carboplatin every 3 weeks, for 2-6 treatment courses. Patients enrolled in phase II received 3-h infusions of 16 mg m(-2) sagopilone. Efficacy was assessed using modified Response Evaluation Criteria in Solid Tumors (modRECIST) and Gynecologic Cancer InterGroup CA125 criteria. The safety and tolerability of sagopilone were also evaluated.. In all, 45 patients received sagopilone at 12 mg m(-2) or 16 mg m(-2). There were 29 confirmed tumour responses (21 modRECIST and 8 CA125) across both treatment groups, indicating that the primary objective of the study was reached. The main adverse events (AEs) reported were peripheral neuropathy (75.6%), fatigue (71.1%) and nausea (64.4%). Grade ≥3 AEs occurred in 35 patients (77.8%). No deaths related to the study drug were reported.. Sagopilone in combination with carboplatin was effective and toxicities were manageable in patients with recurrent platinum-sensitive OC.

Topics: Adult; Aged; Antineoplastic Combined Chemotherapy Protocols; Benzothiazoles; Carboplatin; Epothilones; Female; Humans; Middle Aged; Ovarian Neoplasms; Recurrence

This study compared the efficacy and safety of patupilone with those of pegylated liposomal doxorubicin (PLD) in patients with platinum-refractory or -resistant epithelial ovarian, primary fallopian tube, or primary peritoneal cancer.. Patients with three or fewer prior regimens were eligible if they had received first-line taxane/platinum-based combination chemotherapy and were platinum refractory or resistant. Patients were randomly assigned to receive patupilone (10 mg/m(2) intravenously every 3 weeks) or PLD (50 mg/m(2) intravenously every 4 weeks).. A total of 829 patients were randomly assigned (patupilone, n = 412; PLD, n = 417). There was no statistically significant difference in overall survival (OS), the primary end point, between the patupilone and PLD arms (P = .195; hazard ratio, 0.93; 95% CI, 0.79 to 1.09), with median OS rates of 13.2 and 12.7 months, respectively. Median progression-free survival was 3.7 months for both arms. The overall response rate (all partial responses) was higher in the patupilone arm than in the PLD arm (15.5% v 7.9%; odds ratio, 2.11; 95% CI, 1.36 to 3.29), although disease control rates were similar (59.5% v 56.3%, respectively). Frequently observed adverse events (AEs) of any grade included diarrhea (85.3%) and peripheral neuropathy (39.3%) in the patupilone arm and mucositis/stomatitis (43%) and hand-foot syndrome (41.8%) in the PLD arm.. Patupilone did not demonstrate significant improvement in OS compared with the active control, PLD. No new or unexpected serious AEs were identified.

Topics: Adult; Aged; Aged, 80 and over; Antibiotics, Antineoplastic; Antineoplastic Agents; Carcinoma, Ovarian Epithelial; Doxorubicin; Drug Resistance, Neoplasm; Epothilones; Fallopian Tube Neoplasms; Female; Humans; Middle Aged; Neoplasm Recurrence, Local; Neoplasms, Glandular and Epithelial; Organoplatinum Compounds; Ovarian Neoplasms; Peritoneal Neoplasms; Polyethylene Glycols; Treatment Outcome

Sagopilone, the first fully synthetic epothilone, has shown promising preclinical activity in tumour models. This open-label randomised phase II study investigated two infusion schedules of sagopilone in women with ovarian cancer.. Women with ovarian cancer recurring within 6 months of end of last platinum-containing treatment received sagopilone 16 mg/m(2) as a 3- or 0.5-h i.v. infusion every 21 days for up to 6 weeks.. Sixty-three patients received sagopilone as a 3-h (n=38) or 0.5-h (n=25) infusion. There were nine confirmed tumour responses [by modified RECIST (n=8) and by Gynecologic Cancer Intergroup CA-125 criteria (n=1)] in 57 patients assessable for efficacy overall [three (13%) with 0.5-h and six (18%) with 3-h infusions]. The 0.5-h arm was closed when it failed to meet its target efficacy. Main drug-related adverse events were peripheral sensory neuropathy (73%; 16% grade 3), nausea (37%; 2% grade 3), fatigue (35%; 3% grade 3) and arthralgia (30%; 5% grade 3). Overall incidence of peripheral sensory neuropathy was similar in both treatment arms, with no grade 4 neuropathy events. No acute allergic infusion reactions were observed.. Sagopilone is effective, with balanced tolerability, in patients with recurrent platinum-resistant ovarian cancer.

Topics: Adult; Aged; Aged, 80 and over; Antineoplastic Agents; Benzothiazoles; Disease-Free Survival; Drug Administration Schedule; Drug Resistance, Neoplasm; Epothilones; Female; Humans; Infusions, Intravenous; Middle Aged; Ovarian Neoplasms

PURPOSE Ixabepilone (BMS-247550) is a microtubule-stabilizing epothilone B analog with activity in taxane-resistant metastatic breast cancer. The Gynecologic Oncology Group conducted a phase II evaluation of the efficacy and safety of ixabepilone in patients with recurrent or persistent platinum- and taxane-resistant primary ovarian or peritoneal carcinoma. PATIENTS AND METHODS Patients with measurable platinum- and taxane-resistant ovarian or peritoneal carcinoma, defined as progression during or within 6 months of one prior course of treatment with each agent, received intravenous ixabepilone 20 mg/m(2) administered over 1 hour on days 1, 8, and 15 of a 28-day cycle. Results Of 51 patients entered, 49 were eligible. The objective response rate was 14.3% (95% CI, 5.9% to 27.2%), with three complete and four partial responses. Twenty patients (40.8%) had stable disease, whereas sixteen (32.7%) had increasing disease. The median time to progression was 4.4 months (95% CI, 0.8 to 32.6+ months); median survival was 14.8 months (95% CI, 0.8 to 50.0) months. Patients received a median of two treatment cycles (range, 1 to 29 cycles), and 18.4% of patients received > or = six cycles. Adverse effects included peripheral grade 2 (28.5%) and grade 3 (6.1%) neuropathy, grades 3 to 4 neutropenia (20.4%), grade 3 fatigue (14.3%), grade 3 nausea/emesis (22%), grade 3 diarrhea (10%), and grade 3 mucositis (4%). CONCLUSION Ixabepilone 20 mg/m(2) over 1 hour on days 1, 8, and 15 of a 28-day cycle demonstrates antitumor activity and acceptable safety in patients with platinum- and taxane-resistant recurrent or persistent ovarian or primary peritoneal carcinoma.

Topics: Adult; Aged; Aged, 80 and over; Bridged-Ring Compounds; Drug Resistance, Neoplasm; Epothilones; Female; Humans; Middle Aged; Neoplasm Recurrence, Local; Organoplatinum Compounds; Ovarian Neoplasms; Peritoneal Neoplasms; Taxoids; Tubulin Modulators

Ixabepilone is a semisynthetic epothilone B analogue that is active in taxane-resistant cell lines and has shown activity in patients with refractory breast and ovarian cancer. We carried out a phase I trial of ixabepilone plus pegylated liposomal doxorubicin (PLD) in patients with advanced taxane-pretreated ovarian and breast cancer.. Patients with recurrent ovarian or breast carcinoma received PLD every 3 or 4 weeks plus five different dose schemas of ixabepilone in cohorts of three to six patients.. Thirty patients received a total of 142 treatment cycles of the PLD-ixabepilone combination. The recommended phase II dose and schedule of ixabepilone was 16 mg/m(2) on days 1, 8, and 15 plus PLD 30 mg/m(2) given on day 1, repeated every 4 weeks. Hand-foot syndrome and mucositis were dose limiting when both ixabepilone and PLD were given every 3 or 4 weeks. Objective responses were observed in 3 of 13 patients (23%) with breast cancer and 5 of 17 patients (29%) with ovarian cancer.. Ixabepilone may be safely combined with PLD, but tolerability is highly dependent upon the scheduling of both agents. This combination demonstrated efficacy in patients with breast and ovarian cancer and merits further evaluation in these settings.

Topics: Adenocarcinoma; Adult; Aged; Antineoplastic Combined Chemotherapy Protocols; Breast Neoplasms; Bridged-Ring Compounds; Doxorubicin; Epothilones; Female; Humans; Male; Maximum Tolerated Dose; Middle Aged; Neoplasm Staging; Ovarian Neoplasms; Polyethylene Glycols; Survival Rate; Taxoids; Treatment Outcome

PURPOSE To evaluate the safety, maximum tolerated dose (MTD), and pharmacokinetics of patupilone administered once every 3 weeks with proactive standardized diarrhea management in patients with resistant or refractory ovarian, fallopian, or peritoneal cancer. PATIENTS AND METHODS Patients received patupilone (6.5 to 11.0 mg/m(2)) every 3 weeks via 20-minute infusion. Adverse events, dose-limiting toxicities (DLT), MTD, and tumor response were determined. The tumor response was measured by Response Evaluation Criteria in Solid Tumors (RECIST) and cancer antigen 125 levels. Results Forty-five patients were enrolled. Adverse events were mild to moderate in intensity, and grade 3 diarrhea (13%) was the most commonly reported serious adverse event. Grade 3 peripheral neuropathy was noted in two patients (4%). Diarrhea, peripheral neuropathy, and fatigue were the most common DLTs; however, these were uncommon in the first cycle and the MTD was therefore not reached in this study. Overall response (OR; complete and partial responses; median cycles, 8) per RECIST in patients with measurable disease (n = 36) was 19.5%. Median duration of disease stabilization (complete and partial responses and stable disease) was 15.8 months. These results appear improved from a previous study in a similar patient population using a weekly schedule (2.5 mg/m(2)/week; N = 53; OR, 5.7%). CONCLUSION Patupilone once every 3 weeks was well-tolerated at doses up to 11.0 mg/m(2). Patupilone demonstrated promising antitumor activity in patients with drug-resistant/refractory disease. An ongoing phase III study in this patient population is testing the 10.0 mg/m(2) dose.

Topics: Antineoplastic Agents; Area Under Curve; Dose-Response Relationship, Drug; Epothilones; Fallopian Tube Neoplasms; Female; Humans; Maximum Tolerated Dose; Middle Aged; Ovarian Neoplasms; Peritoneal Neoplasms

Ixabepilone (BMS-247550) is a semi-synthetic, microtubule stabilizing epothilone B analogue which is more potent than taxanes and has displayed activity in taxane-resistant patients. The human plasma pharmacokinetics of ixabepilone have been described. However, the excretory pathways and contribution of metabolism to ixabepilone elimination have not been determined. To investigate the elimination pathways of ixabepilone we initiated a mass balance study in cancer patients. Due to autoradiolysis, ixabepilone proved to be very unstable when labeled with conventional [14C]-levels (100 microCi in a typical human radio-tracer study). This necessitated the use of much lower levels of [14C]-labeling and an ultra-sensitive detection method, Accelerator Mass Spectrometry (AMS). Eight patients with advanced cancer (3 males, 5 females; median age 54.5 y; performance status 0-2) received an intravenous dose of 70 mg, 80 nCi of [14C]ixabepilone over 3 h. Plasma, urine and faeces were collected up to 7 days after administration and total radioactivity (TRA) was determined using AMS. Ixabepilone in plasma and urine was quantitated using a validated LC-MS/MS method. Mean recovery of ixabepilone-derived radioactivity was 77.3% of dose. Fecal excretion was 52.2% and urinary excretion was 25.1%. Only a minor part of TRA is accounted for by unchanged ixabepilone in both plasma and urine, which indicates that metabolism is a major elimination mechanism for this drug. Future studies should focus on structural elucidation of ixabepilone metabolites and characterization of their activities.

Topics: Adenocarcinoma; Antineoplastic Agents; Carcinoma, Non-Small-Cell Lung; Carcinoma, Squamous Cell; Chromatography, Liquid; Colonic Neoplasms; Epothilones; Feces; Female; Humans; Lung Neoplasms; Male; Middle Aged; Neoplasms; Ovarian Neoplasms; Pancreatic Neoplasms; Sigmoid Neoplasms; Tandem Mass Spectrometry

The purpose of this study is to establish the maximum tolerated dose and define the dose-limiting toxicity of the investigational epothilone BMS-247550 in combination with fixed dose-rate gemcitabine. Patients with advanced, recurrent solid tumors who had received or=7 days occurred in one of six patients. Two of three patients in cohort 2 (gemcitabine 900 mg/m2 plus BMS-247550 30 mg/m2) had dose-limiting toxicities of grade 4 neutropenia. An additional three patients were treated at dose level 1 with no additional dose-limiting toxicities observed. At an intermediate dose level (gemcitabine 750 mg/m2 plus BMS-247550 30 mg/m2), two of six patients experienced a dose-limiting toxicity (febrile neutropenia and grade 3 hypophosphatemia in 1, grade 3 hypophosphatemia and grade 3 hyponatremia in (1), and five of six patients experienced dose delays. In the final cohort (gemcitabine 750 mg/m2 plus BMS-247550 25 mg/m2), two of two patients experienced a dose-limiting toxicity. Treatment-related toxicities included neutropenia, thrombocytopenia, neutropenic fever, hypophosphatemia, and hyponatremia. Nine of 14 patients evaluable for response had stable disease. The maximum tolerated dose for this schedule is gemcitabine 900 mg/m2 over 90 min days 1 and 8 plus BMS-247550 20 mg/m2 on day 8. Attempts to increase the dose of BMS-247550 by decreasing the gemcitabine dose did not sufficiently ameliorate myelosuppression. Stable disease was observed in some patients with prior taxane exposure.

Topics: Aged; Antineoplastic Combined Chemotherapy Protocols; Carcinoma, Small Cell; Cohort Studies; Deoxycytidine; Dose-Response Relationship, Drug; Epothilones; Female; Gemcitabine; Humans; Kidney Neoplasms; Leukopenia; Lung Neoplasms; Male; Melanoma; Middle Aged; Neoplasms; Ovarian Neoplasms; Sarcoma; Urinary Bladder Neoplasms; Uterine Neoplasms; Water-Electrolyte Imbalance

Patupilone is a microtubule-targeting chemotherapeutic agent with clinical activity in a broad range of taxane-sensitive/resistant tumor types. The present phase Ib study examined the safety/tolerability and pharmacokinetics of patupilone in combination with carboplatin in patients with advanced solid tumors.. Patients with advanced cancer received patupilone via a 5- to 10-min i.v. infusion at doses of 3.6 to 6.0 mg/m(2) q3w, immediately followed by carboplatin area under the curve (AUC) 5 or 6 mg/mL/min.. Of the 37 patients enrolled, the majority previously received taxanes (81%) and/or platinum-containing drugs (97.3%). The maximum tolerated dose (MTD) of patupilone with carboplatin AUC 6 was 4.8 mg/m(2); additional patients were enrolled to consolidate experience at this dose. Of the 22 patients who received the MTD, the most common nonhematologic adverse events were fatigue in six (27.3%) and diarrhea, nausea, vomiting, abdominal pain, and neuropathy in one each (4.5%; all grade 3); hematologic toxicities included two patients (9.1%) with grade 3 neutropenia. The pharmacokinetics of patupilone were similar to those in a previous study of patupilone monotherapy. Of the 26 patients with recurrent platinum-sensitive ovarian cancer, tumor response was assessable by response evaluation criteria in solid tumors in 17; 1 patient (6%) achieved a complete response, and 10 (59%) achieved a partial response.. The combination of patupilone 4.8 mg/m(2)/carboplatin AUC 6 was well tolerated and showed antitumor activity similar to established regimens in patients with recurrent platinum-sensitive ovarian cancer. The optimal dose for this regimen is currently being further refined in phase II trials.

Topics: Adult; Aged; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Carboplatin; Epothilones; Female; Gastrointestinal Neoplasms; Humans; Male; Middle Aged; Neoplasm Staging; Neoplasms; Ovarian Neoplasms; Uterine Cervical Neoplasms; Uterine Neoplasms

Epothilones are microtubule-targeting agents that induce death in a variety of cancer cell types. Here, we focus on the cellular and molecular mechanisms underlying epothilone A (Epo A) and epothilone B (Epo B)-induced autophagy and apoptosis in ovarian cancer cells, compared to the actions of the widely used clinical chemotherapy drug paclitaxel (PTX).. Autophagy was examined in two cell lines, SKOV-3 (human ovarian adenocarcinoma) and OV-90 (human ovarian papillary serous adenocarcinoma), which differ in the levels of p-glycoprotein and drug resistance, based on the LC3 ELISA assay, fluorescence detection of autophagosome formation, morphological changes evaluated via acridine orange staining, and visualization of LC3 protein using confocal microscopy. Cell viability was detected using the 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) assay. Apoptosis was measured via the caspase-3/7 assay and immunofluorescence labeling of caspase-3. Differences in microtubule organization in epothilone-treated cells were investigated using specific antibodies against β-tubulin. All probes were analyzed both in the presence and absence of the autophagy inhibitor, bafilomycin A1 (Baf), and apoptosis inhibitor, Z-FA-FMK.. Epothilone and PTX treatment induced a dose-dependent decrease in cell viability, along with increased apoptosis and disruption of microtubule dynamics. Furthermore, under conditions of inhibition of autophagy with Baf, apoptosis triggered by these compounds was significantly increased.. Our collective results suggest that treatment with epothilones in combination with autophagy inhibitors present a potentially more effective chemotherapeutic approach for ovarian cancer.

Topics: Antineoplastic Agents; Apoptosis; Autophagy; Caspase 3; Cell Line, Tumor; Dose-Response Relationship, Drug; Epothilones; Female; Humans; Macrolides; Microtubules; Ovarian Neoplasms; Paclitaxel

High mortality rates in ovarian and liver cancer are largely a result of resistance to currently used chemotherapy. Here, we investigated genotoxic and pro-oxidant effects of metformin (MET) and epothilone A (A) in combination with respect to apoptosis in HepG2 and SKOV-3 cancer cells. Reactive oxygen species (ROS) was studied using 2',7'-dichlorodihydrofluoresein diacetate, and samples were analyzed for the presence and absence of the N-acetylcysteine (NAC). Expression of genes involved in programmed cell death, oxidative and alkylating DNA damage was measured. Probes were analyzed in the presence of Akt or nuclear factor-κB inhibitor. Compared to either drug alone, combination of epothilone A and metformin was more potent; decreased Akt level; and elevated percentage of apoptotic cells, induced cell cycle arrest at G1 phase and elevated the sub-G1 cell population by increasing the mRNA level of caspase-3, poly (ADP-ribose) polymerase-1 and H2AX. The anticancer effect of the drug combination was partially reversed by NAC supplementation, suggesting that ROS generation is required to induce apoptosis. The present study demonstrates that novel combination such as epothilone A and MET show promise in expanding ovarian and liver cancer therapy.

Topics: Adenocarcinoma; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Carcinoma, Hepatocellular; Caspase 3; Cell Line, Tumor; DNA Damage; Drug Resistance, Neoplasm; Epothilones; Female; Gene Expression Regulation, Neoplastic; Histones; Humans; Hypoglycemic Agents; Liver Neoplasms; Metformin; Neoplasm Proteins; Ovarian Neoplasms; Oxidative Stress; Poly (ADP-Ribose) Polymerase-1; Proto-Oncogene Proteins c-akt

Despite clinical remission of epithelial ovarian cancer (EOC) after surgical resection and first-line chemotherapy, about 60% of patients will re-develop peritoneal metastasis and about 50% will relapse with chemoresistant disease. Clinical studies suggest that intra-peritoneal (i.p.) chemotherapy effectively treats residual EOC after cyto-reduction by gaining direct access into the peritoneal cavity, enabling elevated drug levels versus intravenous (i.v.) injection. However, chemoresistant disease is still problematic. To overcome resistance against microtubule stabilizing agents such as taxanes, epothilone B (EpoB) has merit, especially in combination with molecular targeted agents that inhibit heat shock protein 90 (Hsp90) and/or mammalian target of rapamycin (mTOR). In this paper, we report on the successful loading and solubilization of EpoB in a poly(d,l-lactic-co-glycolic acid)-block-poly(ethylene glycol)-block-poly(d,l-lactic-co-glycolic acid) (PLGA-b-PEG-b-PLGA) thermosensitive gel (g-E). Further, we report on successful co-loading of 17-AAG (Hsp90) and rapamycin (mTOR) (g-EAR). After i.p. injection in mice, g-EAR showed gelation in the peritoneum and sustained, local-regional release of EpoB, 17-AAG, and rapamycin. In a luciferase-expressing ES-2 (ES-2-luc) ovarian cancer xenograft model, single i.p. injections of g-E and g-EAR delayed bioluminescence from metastasizing ES-2-luc cells for 2 and 3weeks, respectively, despite fast drug release for g-EAR in vivo versus in vitro. In summary, a PLGA-b-PEG-b-PLGA sol-gel has loading and release capacities for EpoB and its combinations with 17-AAG and rapamycin, enabling a platform for i.p. delivery, sustained multi-drug exposure, and potent antitumor efficacy in an ES-2-luc, ovarian cancer i.p. xenograft model.

Topics: Animals; Antineoplastic Agents; Benzoquinones; Cell Line, Tumor; Drug Liberation; Epothilones; Female; Gels; HSP90 Heat-Shock Proteins; Humans; Lactams, Macrocyclic; Mice, Nude; Ovarian Neoplasms; Polyesters; Polyethylene Glycols; Sirolimus; TOR Serine-Threonine Kinases

Photoaffinity labeling with an epothilone A photoprobe led to the identification of the β-tubulin peptides TARGSQQY and TSRGSQQY as targets of the photoprobe for polymerized tubulin. These peptides represent residues 274-281 in different β-tubulin isotypes. Placing the carbene producing 21-diazo/triazolo moiety of the photoprobe in the vicinity of the TARGSQQY peptide in a homology model of TBB3 predicted a binding pose and conformation of the photoprobe that are very similar to the ones reported for 1) the high resolution cocrystal structure of epothilone A with an α,β-tubulin complex and for 2) a saturation transfer difference NMR and transferred NOESY NMR study of dimeric and polymerized tubulin. Our findings thus provide additional support for these models as physiologically the most relevant among several modes of binding that have been proposed for epothilone A in the taxane pocket of β-tubulin.

Topics: Animals; Binding Sites; Brain; Cattle; Crystallography, X-Ray; Drug Resistance, Neoplasm; Epothilones; Female; Humans; Mass Spectrometry; Models, Molecular; Molecular Conformation; Molecular Probes; Ovarian Neoplasms; Peptide Fragments; Photoaffinity Labels; Polymerization; Tubulin; Tubulin Modulators; Tumor Cells, Cultured

Our previous studies clearly demonstrated that a combination of WP 631 and Epo B has higher activity against ovarian cancer cells than either of these compounds used separately. In order to fully understand the exact mechanism of action in combination, we assessed effects on the cell cycle of SKOV-3 cells. We evaluated three control points essential for WP 631 and Epo B action to determine which cell cycle-regulating proteins (CDK1/cyclin B complex, EpCAM or HMGB1) mediate activity. The effects of the drug on the cell cycle were measured based on the nuclear DNA content using flow cytometry. Expression of cell cycle-regulating genes was analyzed using real-time PCR. It was discovered that WP 631, at the tested concentration, did not affect the SKOV-3 cell cycle. Epo B caused significant G2/M arrest, whereas the drug combination induced stronger apoptosis and lower mitotic arrest than Epo B alone. This is very important information from the point of view of the fight against cancer, as, while mitotic arrest in Epo B-treated cells could be overcame after DNA damage repair, apoptosis which occurs after mitotic slippage in combination-treated cells is irreversible. It clearly explains the higher activity of the drug combination in comparison to Epo B alone. Epo B acts via the CDK1/cyclin B complex and has the ability to inhibit CDK1, which may be a promising strategy for ovarian cancer treatment in the future. The drug combination diminishes EpCAM and HMGB1 expression to a greater degree than either WP 631 and Epo B alone. Owing to the fact that the high expression of these two proteins is a poor prognostic factor for ovarian cancer, a decrease in their expression, observed in our studies, may result in improved efficacy of cancer therapy. The presented findings show that the combination of WP 631 and Epo B is a better therapeutic option than either of these drugs alone.

Topics: Antineoplastic Agents; Apoptosis; Cell Cycle; Cell Cycle Proteins; Daunorubicin; Drug Synergism; Drug Therapy, Combination; Epothilones; Female; Humans; Mitosis; Ovarian Neoplasms; Real-Time Polymerase Chain Reaction; Tumor Cells, Cultured

We evaluated molecular events associated with apoptosis induced by Epothilone B (EpoB, Patupilone) and paclitaxel (PTX) in human ovarian papillary serous adenocarcinoma cell line (OV-90). Epothilones are compounds of natural origin with mechanisms of action similar to taxanes, but with more potent antiproliferative activity. Apoptosis was one of the major forms of cell death induced by EpoB. The mode of cell death was assessed colorimetrically, fluorimetrically, cytometry, and by immunoblot analyses through measuring DNA fragmentation, the level of TRAIL, the cleavage of poly(ADP-ribose) polymerase (PARP) and the activation of caspase-9, -8 and -3. We measured also additional markers of apoptosis, like phosphatidylserine externalization and morphological changes. Moreover, we estimated glycoprotein P (P-gp) activity in OV-90 ovarian cancer cell line. The studies indicated that the extrinsic pathway of apoptosis, which is triggered by certain TNF family members and engages their respective receptors on the surface of the target cell, was predominant. We were the first to have demonstrated (using immunoassay) the release of TNF-related apoptosis-inducing ligand (TRAIL) after treatment with EpoB. EpoB and PTX mediate activation of both initiator caspases-8 and -9, leading to the appearance of caspase-3. In EpoB treated cells, DNA fragmentation was also detected. EpoB leads to the reduction in DNA repair capacity. In summary, we report that Epothilone B induces apoptosis in OV-90 cells via a TRAIL and caspase 8-dependent pathway. PTX leads to smaller apoptotic events in comparison to EpoB.

Topics: Antineoplastic Agents; Apoptosis; ATP Binding Cassette Transporter, Subfamily B; Caspases; Cell Line, Tumor; Comet Assay; DNA Damage; Epothilones; Female; Humans; Ovarian Neoplasms; Paclitaxel; Poly(ADP-ribose) Polymerases; TNF-Related Apoptosis-Inducing Ligand

To test if TP53 hot spot mutations (HSMs) confer differential chemotherapy resistance or survival outcomes, the effects of microtubule stabilizers on human ovarian carcinoma cells (OCCs) expressing TP53 HSMs were studied in vitro. Survival outcomes of patients with high grade serous epithelial ovarian carcinoma (HGS EOC) expressing matched HSMs were compared using The Cancer Genome Atlas (TCGA) data.. Growth inhibition of OCCs transfected with a HSM (m175, m248 or m273) was measured during treatment with paclitaxel, epothilone B (epoB), or ixabepilone. Effects of epoB on p53 expression, phosphorylation, and acetylation, as well as p53-regulated expression of p21 and mdm2 proteins, were determined by Western blot analysis. Expression of p53 target genes P21, GADD45, BAX, PIDD, NF-kB2, PAI-1, and MDR1 was measured by RT-PCR. cBioPortal.org identified patients with codon R175, R248 or R273 HSMs from TCGA data. Survival outcomes were characterized.. p53-m248 confers chemoresistance and is not acetylated during epoB treatment. m273 demonstrated high MDR1 expression and resistance to paclitaxel. P21, GADD45 and PAI-1 expression were down-regulated in mutant OCCs. Optimally cytoreduced patients with codon R273 (n=17), R248 (n=13), R175 (n=7) HSMs, or any other TP53 mutation demonstrated median 14.9, 17.6, 17.8 and 16.9months (p=0.806) progression free survival and 84.1, 33.6, 62.1 and 44.5months (p=0.040) overall survival, respectively.. Human OCCs harboring different TP53 HSMs were selectively resistant to microtubule stabilizers. Patients with different HSMs had significantly different overall survival. Both in vitro data and clinical experience support further studying the outcomes of particular TP53 HSMs.

Topics: Carcinoma, Ovarian Epithelial; Cell Death; Cell Line, Tumor; Drug Resistance, Neoplasm; Epothilones; Female; Genes, p53; Humans; Middle Aged; Mutation; Neoplasms, Glandular and Epithelial; Ovarian Neoplasms; Paclitaxel; Tubulin Modulators; Tumor Suppressor Protein p53

Combined therapy is one of the basic methods of treatment different types of cancer. It allows to reduce the side effects of each component while maximizing the therapeutic action. The aim of this study was to evaluate the impact of two new drugs: WP 631 (bisanthracycline) and epothilone B (Epo B), added in combination on the SKOV-3 human ovarian cancer cells. To assess the type of interaction between WP 631 and Epo B isobolografic analysis was applied based on the cytotoxicity of drugs determined by the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolinum bromide) assay. Apoptotic and necrotic cell levels were measured by double staining with Hoechst 33258 and propidium iodide, Annexin V-FITC staining and by using TUNEL assay. The combination of WP 631 and Epo B is more potent than drugs added alone. The quantitative analysis indicated that the major mode of cell death induced by the combination after 72 h treatment was early apoptosis, whereas drugs administered alone generated less intensive apoptosis. The present report demonstrates for the first time that WP 631 and Epo B co-administered synergize in SKOV-3 cell line (Z(ex)/Z(th)<1).

Topics: Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Cell Survival; Daunorubicin; Drug Synergism; Epothilones; Female; Humans; Ovarian Neoplasms

The molecular mechanisms underlying epothilone B (EpoB) induced apoptosis were investigated in SKOV-3 human ovarian cancer cells. The aim of this research was to compare EpoB's, which belongs to the new class of anticancer drugs, with paclitaxel's (PTX) ability to induce apoptosis. The mode of cell death was assessed colorimetrically, fluorimetrically and by immunoblot analyses through measuring DNA fragmentation, the level of intracellular calcium, the level of cytochrome c, TRAIL, the cleavage of poly(ADP-ribose) polymerase (PARP) and the activation of caspase-9, -8 and -3. EpoB leads to an increase of the cytosolic level of cytochrome c after 4 h of cell treatment. After 24 and 48 h of cell treatment the level of intracellular calcium also increased by about 21% and 24% respectively. Moreover, EpoB, similarly to PTX, promoted the expression of TRAIL in lymphocytes, although high TRAIL expression on tumor cells was detected only after adding EpoB to SKOV-3 cells. EpoB mediates caspases-8 and -3 activation, which is independent of the reduction in the amount of caspase-9. Epitope-specific monoclonal and polyclonal antibodies revealed characteristic apoptotic changes that included cleavage of the 116 kDa PARP polypeptide to 25 kDa fragments. The results of our study show that EpoB induces mainly the extrinsic pathway.

Topics: Antineoplastic Agents; Apoptosis; Calcium; Caspases; Cell Line, Tumor; Cytochromes c; DNA Damage; Edetic Acid; Epothilones; Female; Gene Expression Regulation; Humans; Ovarian Neoplasms; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerases; Trypsin

In this article, the synergistic effects of WP 631 and epothilone B (Epo B) combination in human ovarian cancer cells (SKOV-3) cells are investigated and the reasons for the exact mechanisms of action of both drugs co-administered are explained. Compared with single drugs, the combination treatment significantly enhances apoptosis as confirmed by increases in caspases (-8, -9, -3) activity, ROS level and DNA damage and decreases in mitochondrial membrane potential. The combination of the compounds activated both caspase - 8 and -9, indicates that both pathways of apoptosis, extrinsic (induced by the effect of Epo B) and intrinsic (triggered mainly by WP 631) participate in the proposed treatment. Thus, the results of this study strongly suggest a synergistic action of the combined treatment with WP 631 and Epo B in SKOV-3 cells death induction.

Topics: Antineoplastic Agents; Apoptosis; Caspases; Cell Line, Tumor; Daunorubicin; DNA Damage; DNA Repair; Drug Synergism; Epothilones; Female; Humans; Membrane Potential, Mitochondrial; Ovarian Neoplasms; Reactive Oxygen Species

Clear cell carcinoma of the ovary is a distinct subtype of epithelial cancer associated with chemoresistance and poor outcome compared with serous papillary carcinomas. Resistance to paclitaxel has been linked to serous papillary overexpression of class III β-tubulin in several human cancers but inadequately characterized among clear cell carcinoma of the ovary. Chemoresistance has also been variably linked to the drug efflux pump p-glycoprotein. Epothilones are microtubule-stabilizing agents with putative activity in paclitaxel-resistant malignancies. In this study, we clarify the relationship between class III β-tubulin and p-glycoprotein expression in clear cell carcinoma of the ovary, clinical outcome, and in vitro responsiveness to patupilone and paclitaxel.. Class III β-tubulin and p-glycoprotein were quantified by real time polymerase chain reaction in 61 fresh-frozen tissue samples and 11 cell lines. Expression by polymerase chain reaction was correlated with immunohistochemistry and overall survival. IC50 was determined using viability/metabolic assays. Impact of class III β-tubulin down-regulation on IC50 was assessed with small interfering RNAs.. Clear cell carcinoma of the ovary overexpressed class III β-tubulin and p-glycoprotein relative to serous papillary carcinomas carcinomas in fresh-frozen tissues and cell lines. Class III β-tubulin immunohistochemistry reflected real time polymerase chain reaction results and overexpression stratified patients by overall survival. P-glycoprotein correlated with in vitro paclitaxel resistance, but not clinical outcome. Clear cell carcinoma of the ovary were exquisitely sensitive to patupilone in a manner that correlated with class III β-tubulin expression.. Class III β-tubulin overexpression in clear cell carcinoma of the ovary discriminates poor prognosis, serves as a marker for sensitivity to patupilone, and may contribute to paclitaxel resistance. Immunohistochemistry reliably identifies tumors with overexpression of class III β-tubulin, and accordingly a subset of individuals likely to respond to patupilone.

Topics: Antineoplastic Agents; ATP Binding Cassette Transporter, Subfamily B, Member 1; Cell Line; Cystadenocarcinoma, Serous; Dose-Response Relationship, Drug; Down-Regulation; Drug Resistance, Neoplasm; Epothilones; Female; Humans; Immunohistochemistry; Kaplan-Meier Estimate; Microtubules; Neoplasms, Glandular and Epithelial; Ovarian Neoplasms; Paclitaxel; Prognosis; Real-Time Polymerase Chain Reaction; Taxoids; Tubulin; Tubulin Modulators

Topics: Doxorubicin; Epothilones; Fallopian Tube Neoplasms; Female; Humans; Neoplasm Recurrence, Local; Neoplasms, Glandular and Epithelial; Ovarian Neoplasms; Peritoneal Neoplasms; Polyethylene Glycols

The epothilones, a new class of microtubule-targeting agents, seem to be a very promising alternative to the current strategy of cancer treatment. We have analyzed the aspects of epothilone B (Epo B) on cellular metabolism of tumor (OV-90) and normal (MM 14) ovarian cells. The observed effects were compared with those of paclitaxel (PTX), which is now a standard for the treatment of ovarian cancer. The results provide direct evidence that Epo B is considerably more cytotoxic to human OV-90 ovarian cancer cells than PTX. We have found, that antitumor efficacy of this new drug is related to its apoptosis-inducing ability, which was confirmed during measurements typical markers of the process. Epo B induced changes in morphology of cells, mitochondrial membrane potential and cytochrome c release. Also a slight increase of the intracellular calcium level was observed. Moreover, we have found that ROS production, stimulated by Epo B, is directly involved in the induction of apoptosis via mitochondrial pathway.

Topics: Animals; Antineoplastic Agents; Apoptosis; Calcium; Cell Line, Tumor; Cell Shape; Cytochromes c; Dose-Response Relationship, Drug; Epothilones; Female; Humans; Membrane Potential, Mitochondrial; Mice; Mitochondria; Ovarian Neoplasms; Ovary; Paclitaxel; Reactive Oxygen Species; Signal Transduction; Time Factors; Tubulin Modulators

Topics: Doxorubicin; Epothilones; Fallopian Tube Neoplasms; Female; Humans; Neoplasm Recurrence, Local; Neoplasms, Glandular and Epithelial; Ovarian Neoplasms; Peritoneal Neoplasms; Polyethylene Glycols

Topics: Doxorubicin; Epothilones; Fallopian Tube Neoplasms; Female; Humans; Neoplasm Recurrence, Local; Neoplasms, Glandular and Epithelial; Ovarian Neoplasms; Peritoneal Neoplasms; Polyethylene Glycols

Epothilones are a new group of compounds with action mechanisms similar to taxanes. The aim of this study was to compare the effects of epothilone A (Epo A) and epothilone B (Epo B) on ovarian cancer cell line SKOV-3 with those of paclitaxel (PTX), a classic taxane. We evaluate glycoprotein P (P-gp) activity in the ovarian cancer cell line. Apoptotic and necrotic cell levels were measured by double staining with Hoechst 33258 and propidium iodide (PI) as well as Annexin V staining. The production of reactive oxygen species (ROS) and changes in mitochondrial membrane potential (ΔΨm) in cells exposed to Epo A, Epo B and PTX were studied using specific fluorescence probes, DCFH(2)-DA (2',7'-dichlorodihydrofluorescein diacetate) and JC-1 (5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolcarbocyanine). The cytotoxic activity of the drugs was determined by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide) test. All probes were analyzed in both the presence and absence of the antioxidant N-acetylcysteine (NAC). The results obtained demonstrated that the antiproliferative capacity of Epo A and Epo B in SKOV-3 cell line (measured as IC(50) after 72 h continuous treatment) was six and five times greater than that of PTX's respectively. Epothilones induced timecourse-dependent apoptosis and necrosis. Apoptotic and necrotic events were partially blocked by NAC, indicating ROS played a substantial role in epothilone-induced apoptosis. Cell death was also associated with a decrease in mitochondrial membrane potential, which was more pronounced after treatment with epothilones as compared to paclitaxel.

Topics: Antineoplastic Agents; Apoptosis; ATP Binding Cassette Transporter, Subfamily B, Member 1; Cell Line, Tumor; Cell Proliferation; Cell Survival; Epothilones; Female; Humans; Membrane Potential, Mitochondrial; Ovarian Neoplasms; Paclitaxel; Reactive Oxygen Species

Microtubule-targeting agents, including taxanes (Tax) and ixabepilone (Ixa), are important components of modern breast cancer chemotherapy regimens, but no molecular parameter is currently available that can predict for their efficiency. We sought to develop pharmacogenomic predictors of Tax- and Ixa-response from a large panel of human breast tumor cell lines (BTCL), then to evaluate their performance in clinical samples. Thirty-two BTCL, representative of the molecular diversity of breast cancers (BC), were treated in vitro with Tax (paclitaxel (Pac), docetaxel (Doc)), and ixabepilone (Ixa), then classified as drug-sensitive or resistant according to their 50% inhibitory concentrations (IC50s). Baseline gene expression data were obtained using Affymetrix U133 Plus 2.0 human oligonucleotide microarrays. Gene expression set (GES) predictors of response to taxanes were derived, then tested for validation internally and in publicly available gene expression datasets. In vitro IC50s of Pac and Doc were almost identical, whereas some Tax-resistant BTCL retained sensitivity to Ixa. GES predictors for Tax-sensitivity (333 genes) and Ixa-sensitivity (79 genes) were defined. They displayed a limited number of overlapping genes. Both were validated by leave-n-out cross-validation (n = 4; for overall accuracy (OA), P = 0.028 for Tax, and P = 0.0005 for Ixa). The GES predictor of Tax-sensitivity was tested on publicly available external datasets and significantly predicted Pac-sensitivity in 16 BTCL (P = 0.04 for OA), and pathological complete response to Pac-based neoadjuvant chemotherapy in BC patients (P = 0.0045 for OA). Applying Tax and Ixa-GES to a dataset of clinically annotated early BC patients identified subsets of tumors with potentially distinct phenotypes of drug sensitivity: predicted Ixa-sensitive/Tax-resistant BC were significantly (P < 0.05, Fischer's exact test) more frequently ER/PR-positive, Ki67-negative, and luminal subtype than predicted Ixa-resistant/Tax-sensitive BC. Genomic predictors for Tax- and Ixa-sensitivity can be derived from BTCL and may be helpful for better selecting cytotoxic treatment in BC patients.

Topics: Antineoplastic Agents; Breast Neoplasms; Cell Line, Tumor; Cell Proliferation; Cell Survival; Computer Simulation; Docetaxel; Drug Resistance, Neoplasm; Epothilones; Female; Gene Expression Profiling; Genetic Association Studies; Humans; Inhibitory Concentration 50; Middle Aged; Models, Biological; Oligonucleotide Array Sequence Analysis; Ovarian Neoplasms; Paclitaxel; Phenotype; Receptor, ErbB-2; Receptors, Estrogen; Taxoids; Tubulin Modulators

The aim was to evaluate antitumor activity of the combination of ixabepilone and sunitinib in pre-clinical models of chemotherapy naïve and refractory epithelial ovarian tumors, and to investigate the mechanism of synergy of such drug combination.. HOVTAX2 cell line was derived from a metastatic serous papillary epithelial ovarian tumor (EOC) and a paclitaxel-resistant derivative was established. Dose response curves for ixabepilone and sunitinib were generated and synergy was determined using combination indexes. The molecular mechanism of antitumor synergy was examined using shRNA silencing.. The combination of ixabepilone and sunitinib demonstrated robust antitumor synergy in naïve and paclitaxel-resistant HOVTAX2 cell lines due to increased apoptosis. The GTPase, RhoB, was synergistically upregulated in cells treated with ixabepilone and sunitinib. Using shRNA, RhoB was demonstrated to mediate antitumor synergy. These results were validated in two other EOC cell lines.. Ixabepilone plus sunitinib demonstrated antitumor synergy via RhoB in naïve and paclitaxel-resistant cells resulting in apoptosis. This study demonstrates a novel mechanism of action leading to antitumor synergy and provides 'proof-of-principle' for combining molecular targeted agents with cytotoxic chemotherapy to improve antitumor efficacy. RhoB could be envisioned as an early biomarker of response to therapy in a planned Phase II clinical trial to assess the efficacy of ixabepilone combined with a receptor tyrosine kinase inhibitor such as sunitinib. To the best of our knowledge, this is the first demonstration of antitumor synergy between these two classes of drugs in EOC and the pivotal role of RhoB in this synergy.

Topics: Antineoplastic Combined Chemotherapy Protocols; Carcinoma, Ovarian Epithelial; Cell Growth Processes; Cell Line, Tumor; Cystadenocarcinoma, Serous; Dose-Response Relationship, Drug; Drug Synergism; Epothilones; Female; Humans; Indoles; Neoplasms, Glandular and Epithelial; Ovarian Neoplasms; Pyrroles; rhoB GTP-Binding Protein; Sunitinib; Up-Regulation

To compare the in vitro sensitivity/resistance to patupilone versus paclitaxel in uterine and ovarian carcinosarcomas (CS).. Five primary carcinosarcoma cell lines, two from uterine and three of ovarian origin, were evaluated for growth rate and tested for their in vitro sensitivity/resistance to patupilone versus paclitaxel by MTS assays. To identify potential mechanisms underlying the differential sensitivity/resistance to patupilone, expression levels of β-tubulin III (TUBB3) were determined with quantitative-real-time-polymerase-chain-reaction (q-RT-PCR) in primary uterine and ovarian CS cell lines and in 26 uterine and 9 ovarian CS fresh-frozen-tissues.. No appreciable difference in sensitivity to patupilone versus paclitaxel was noted in ovarian CS cell lines, or when uterine and ovarian CS cell lines were compared in their response to paclitaxel. In contrast, uterine CS cell lines were found to be significantly more sensitive to patupilone than to paclitaxel (P<0.002) and demostrated lower IC(50s) to patupilone (range 0.76-0.93nM) when compared to ovarian CS (range 1.9-3.4 nM, p<0.05). Higher levels of TUBB3 were detected in uterine CS cell lines and fresh frozen tissues when compared to ovarian CS (P<0.05).. Uterine CS cell lines are significantly more sensitive than ovarian CS cell lines to patupilone versus paclitaxel. High expression of TUBB3 is associated with sensitivity to patupilone in primary CS cell lines and may act as a genetic marker to predict chemotherapy efficacy. Patupilone may represent a promising drug in the treatment of this subset of rare but highly aggressive gynecological tumors.

Topics: Aged; Antineoplastic Agents; Biomarkers, Tumor; Carcinosarcoma; Cell Line, Tumor; Cell Proliferation; Cell Survival; Drug Resistance, Neoplasm; Epothilones; Female; Humans; Inhibitory Concentration 50; Middle Aged; Ovarian Neoplasms; Paclitaxel; Real-Time Polymerase Chain Reaction; Tubulin; Uterine Neoplasms

Epothilones constitute a novel class of antitubulin agents that are active in patients who relapse after treatment with other chemotherapeutics. This study investigated the molecular mechanisms leading to the onset of epothilone-B (patupilone) resistance in ovarian cancer. Results demonstrated that the Gli family of transcription factors was overexpressed in resistant cells and that treatment with a specific Gli1 inhibitor (GANT58) made cells more susceptible to treatment, partially reversing drug resistance. We also demonstrated that Gli1 knockdown halted growth in resistant cells that were exposed to patupilone, confirming that Gli1 is capable of directly mediating epothilone-B resistance. Another observation from our research was that patupilone-resistant cells produced HGF and acquired characteristics of a mesenchymal phenotype. However, HGF silencing alone was not capable of converting the drug-resistant phenotype to a susceptible one, and in this case we demonstrated that Gli1 overexpression led to an increase in HGF, establishing a functional link between Gli1 and HGF. These results demonstrated that Gli1 played a key role in driving resistance to patupilone, suggesting that the combination of epothilones and Gli1-targeted agents could be exploited to improve outcomes in ovarian cancer patients resistant to standard treatments.

Topics: Antineoplastic Agents; Base Sequence; Cell Line, Tumor; Chromatin Immunoprecipitation; DNA Primers; Drug Resistance, Neoplasm; Enzyme-Linked Immunosorbent Assay; Epithelial-Mesenchymal Transition; Epothilones; Female; Humans; Ovarian Neoplasms; Real-Time Polymerase Chain Reaction; Transcription Factors

Topics: Carcinoma, Ovarian Epithelial; Doxorubicin; Epothilones; Fallopian Tube Neoplasms; Female; Humans; Neoplasm Recurrence, Local; Neoplasms, Glandular and Epithelial; Ovarian Neoplasms; Peritoneal Neoplasms; Polyethylene Glycols

Ovarian cancer is the leading cause of death from gynecologic cancers in the United States. Epothilone B (EpoB), Taxol and vinblastine are anti-neoplastic agents that interfere with microtubules and arrest the cell cycle in the G2/M phase. EpoB is being evaluated in phase III clinical trials, and its analogs are currently being used in the treatment of taxane-resistant metastatic breast cancer. Little is known about the effect of these drugs on the immune response to tumors. Cancer cells evade immune recognition by down-regulating HLA Class I expression, allowing escape from immune surveillance and destruction. Our data illustrates the effect of microtubule-interacting agents on HLA Class I and HLA-A2 expression as well as the modulation of cytokine expression in ovarian cancer cells.. Ovarian cancer cells were treated with different concentrations of drugs. Cell surface expression and mRNA transcription of HLA Class I molecules and HLA-A2 was examined. IFNα, IL1β, IL12 and IL6 mRNA expression was also evaluated upon EpoB treatment.. Low-dose EpoB, Taxol and vinblastine greatly increased expression of HLA Class I and HLA-A2 molecules in Hey ovarian cancer cells. EpoB does not modulate HLA expression in drug-resistant ovarian cancer cells. The expression of IFNα, IL1β, IL12 and IL6 is also markedly increased upon EpoB treatment.. Nanomolar concentrations of microtubule-interacting agents enhance immune-visibility of ovarian cancer cells by increasing HLA Class I and pro-inflammatory cytokine expression. Immune recognition of tumor cells may be improved.

Topics: Cell Line, Tumor; Cytokines; Dose-Response Relationship, Drug; Epothilones; Female; HLA Antigens; HLA-A2 Antigen; Humans; Ovarian Neoplasms; Paclitaxel; RNA, Messenger; Tubulin Modulators; Vinblastine

A series of conformationally restrained epothilone analogues with a short bridge between the methyl groups at C6 and C8 was designed to mimic the binding pose assigned to our recently reported EpoA-microtubule binding model. A versatile synthetic route to these bridged epothilone analogues has been successfully devised and implemented. Biological evaluation of the compounds against A2780 human ovarian cancer and PC3 prostate cancer cell lines suggested that the introduction of a bridge between C6-C8 reduced potency by 25-1000 fold in comparison with natural epothilone D. Tubulin assembly measurements indicate these bridged epothilone analogues to be mildly active, but without significant microtubule stabilization capacity. Molecular mechanics and DFT energy evaluations suggest the mild activity of the bridged epo-analogues may be due to internal conformational strain.

Topics: Antineoplastic Agents; Cell Line, Tumor; Drug Design; Drug Screening Assays, Antitumor; Epothilones; Female; Humans; Models, Molecular; Ovarian Neoplasms; Protein Binding; Structure-Activity Relationship

Epothilone B (EpoB), like Taxol, stabilizes microtubules resulting in an inhibition of microtubule dynamic instability. The drug is being evaluated in phase III clinical trials. An EpoB analog, Ixabepilone, was approved by the FDA for the treatment of taxane-resistant metastatic breast cancer. Epithelial cell adhesion antigen (EpCAM) expression is significantly higher in epithelial ovarian cancer cells compared to normal cells. The effects of EpoB and other microtubule-interacting agents on surface EpCAM expression were studied.. Biochemical methods, immunofluorescence and flow cytometry were used to identify EpCAM expression on the surface of the ovarian cancer cell line, Hey, after exposure to EpoB. The relationship between EpoB-mediated surface EpCAM expression and EpoB-induced α-tubulin acetylation, a surrogate marker for stable microtubules, in Hey cells also was investigated.. Nanomolar concentrations of EpoB, Taxol, discodermolide or vinblastine caused a marked increase in surface EpCAM expression in Hey cells. Alpha-tubulin acetylation was increased following treatment with Taxol, EpoB and discodermolide, but not with vinblastine, indicating that drug-enhanced surface EpCAM expression does not correlate with tubulin acetylation or stabilization. Unexpectedly, EpoB did not have a significant effect on EpCAM mRNA expression, nor did it alter the level of total cellular EpCAM in Hey cells.. The results indicate that disruption of the microtubule cytoskeleton is associated with the redistribution of cell surface antigens in ovarian cancer cells. The increase in cell surface EpCAM antigen density may facilitate the antibody targeting of EpCAM-positive ovarian cancer cells.

Topics: Acetylation; Alkanes; Antigens, Neoplasm; Carbamates; Cell Adhesion Molecules; Cell Line, Tumor; Epithelial Cell Adhesion Molecule; Epothilones; Female; Humans; Hydroxamic Acids; Lactones; Ovarian Neoplasms; Paclitaxel; Pyrones; Tubulin; Tubulin Modulators; Vinblastine

Patupilone is an epothilone in advanced clinical development that has shown promising efficacy in heavily pretreated patients. This study aimed at characterizing the mechanisms of patupilone activity in resistant patients. To this end, we generated patupilone-resistant cells using two cellular models, the first characterized by high chemosensitivity and low class III beta-tubulin (TUBB3) expression (A2780), and the second by low chemosensitivity and high TUBB3 expression (OVCAR-3). The obtained cell lines were named EPO3 and OVCAR-EPO, respectively. The same selection procedure was done in A2780 cells to generate a paclitaxel-resistant cell line (TAX50). Factors of resistance are expected to increase in the drug-resistant cell lines, whereas factors of drug sensitivity will be down-regulated. Using this approach, we found up-regulation of TUBB3 in TAX50, but not EPO3, cells, showing that TUBB3 mediates the resistance to paclitaxel but not to patupilone. Moreover, TUBB3 was a factor of patupilone sensitivity because OVCAR-EPO cells exhibited a dramatic reduction of TUBB3 and a concomitant sensitization to hypoxia and cisplatin-based chemotherapy. To identify the mechanisms underlying patupilone resistance, tubulin genes were sequenced, thereby revealing that a prominent mechanism of drug resistance is represented by point mutations in class I beta-tubulin. Overall, these results suggest that paclitaxel and patupilone have nonoverlapping mechanisms of resistance, thus allowing the use of patupilone for those patients relapsing after paclitaxel-based chemotherapy. Furthermore, patupilone represents a promising first-line option for the treatment of high-risk ovarian cancer patients, who exhibit high TUBB3 levels and poor response to standard paclitaxel-platin chemotherapy.

Topics: Antineoplastic Agents; ATP Binding Cassette Transporter, Subfamily B; ATP Binding Cassette Transporter, Subfamily B, Member 1; ATP Binding Cassette Transporter, Subfamily G, Member 2; ATP-Binding Cassette Transporters; Cell Hypoxia; Cell Line, Tumor; Drug Resistance, Neoplasm; Epothilones; Female; Humans; Multidrug Resistance-Associated Proteins; Neoplasm Proteins; Ovarian Neoplasms; Paclitaxel; Point Mutation; Protein Isoforms; RNA, Messenger; Tubulin; Up-Regulation

Compounds that bind to microtubules (MTs) and alter their dynamics are highly sought as a result of the clinical success of paclitaxel and docetaxel. The naturally occurring compound (-)-dictyostatin binds to MTs, causes cell cycle arrest in G(2)/M at nanomolar concentrations, and retains antiproliferative activity in paclitaxel-resistant cell lines, making dictyostatin an attractive candidate for development as an antineoplastic agent. In this study, we examined a series of dictyostatin analogs to probe biological and biochemical structure-activity relationships. We used a high-content multiparameter fluorescence-based cellular assay for MT morphology, chromatin condensation, mitotic arrest, and cellular toxicity to identify regions of dictyostatin that were essential for biological activity. Four analogs (6-epi-dictyostatin, 7-epi-dictyostatin, 16-normethyldictyostatin, and 15Z,16-normethyldictyostatin) retained low nanomolar activity in the cell-based assay and were chosen for analyses with isolated tubulin. All four compounds were potent inducers of MT assembly. Equilibrium binding constant (K(i)) determinations using [(14)C]epothilone B, which has a 3-fold higher affinity for the taxoid binding site than paclitaxel, indicated that 6-epi-dictyostatin and 7-epi-dictyostatin displaced [(14)C]epothilone B with K(i) values of 480 and 930 nM, respectively. 16-Normethyldictyostatin and 15Z,16-normethyldictyostatin had reduced affinity (K(i) values of 4.55 and 4.47 muM, respectively), consistent with previous reports showing that C16-normethyldictyostatin loses potency in paclitaxel-resistant cell lines that have a Phe270-to-Val mutation in the taxoid binding site of beta-tubulin. Finally, we developed a set of quantitative structure-activity relationship equations correlating structures with antiproliferative activity. The equations accurately predicted biological activity and will help in the design of future analogs.

Topics: Alkanes; Animals; Benzimidazoles; Binding Sites; Brain Chemistry; Carbamates; Carcinoma; Cattle; Cell Line, Tumor; Cell Nucleus; Cell Proliferation; Epothilones; Female; Fluorescein-5-isothiocyanate; Fluorescent Antibody Technique, Indirect; Fluorescent Dyes; G2 Phase; HeLa Cells; Histones; Humans; Kinetics; Lactones; Macrolides; Microtubules; Molecular Structure; Ovarian Neoplasms; Paclitaxel; Phosphorylation; Protein Binding; Pyrones; Quantitative Structure-Activity Relationship; Radioligand Assay; Tubulin; Tubulin Modulators

Resistance to Taxol (paclitaxel) or the epothilones (Epo) occurs via the acquisition of point mutations in beta-tubulin residues important for drug-tubulin binding. We have isolated four drug-resistant clones selected with Taxol or Epo A, which harbor distinct beta-tubulin mutations. During the development of a stable drug-resistant phenotype, early clones expressing both wild-type (wt) and mutant beta-tubulin sequences exhibited a 10-fold drug resistance, while more advanced clones expressing only the mutant beta-tubulin sequence exhibited 30 to 50-fold drug resistance. The drug-sensitive parental 1A9 ovarian carcinoma cell line and the drug resistant clones (1A9-A8, 1A9-PTX10 and 1A9-PTX22) were evaluated for loss of heterozygosity (LOH) for beta-tubulin (6p25) by single nucleotide polymorphism (SNP) and fluorescent in situ hybridization (FISH) analyses. Functional assays such as drug-induced tubulin polymerization, cell cycle analysis by FACS, DNA sequencing for beta-tubulin and mitotic index by immunofluorescence were performed to correlate the beta-tubulin LOH status with drug response in the early- and late-step drug-resistant clones. Late-step drug resistant clones revealed LOH in one allele for wt beta-tubulin in addition to a beta-tubulin mutation in the other allele leading to increased levels of drug resistance, while the early-step clones that contained both a wt and a mutant beta-tubulin allele were considerably less drug resistant. The LOH and functional assays revealed cell response that was proportional to the tubulin gene and heterozygosity status. Acquired tubulin mutations in conjunction with LOH for the wt tubulin resulted in a highly resistant phenotype, revealing a new mechanism for taxane resistance.

Topics: Alleles; Antineoplastic Agents; Cell Division; Cell Line, Tumor; Chromosomes, Human, Pair 6; DNA Mutational Analysis; Drug Resistance, Neoplasm; Epothilones; Female; G2 Phase; Genome, Human; Humans; In Situ Hybridization, Fluorescence; Loss of Heterozygosity; Microtubules; Mitotic Index; Models, Biological; Mutation; Ovarian Neoplasms; Paclitaxel; Polymers; Protein Isoforms; Tubulin

Epothilone B (EpoB) is a non-taxane microtubule-stabilizing agent with a mode of action similar to that of paclitaxel, but with the advantage of being active in paclitaxel-resistant cells. Knowledge regarding other mechanisms of EpoB action is limited. The purpose of this study was to identify gene expression profiles associated with the biological response to EpoB in an ovarian cancer cell line (SKOV3).. SKOV3 cells were maintained in McCoy's 5A media. Equal densities cells were treated with or without EpoB, and were evaluated for cell growth arrest and apoptosis. mRNA expression was evaluated by cDNA microarrays and quantitative, real time reverse transcription polymerase chain reaction (QRTPCR).. EpoB (10 nM) led to cell cycle arrest and apoptosis in SKOV3 cells. Microarray analysis, comparing EpoB-treated to untreated cells, revealed altered expression of 41 genes. There was a predominance of sequences related to the TNFalpha stress response pathway. Differential expression of selected genes was confirmed by QRTPCR.. We demonstrated that cDNA microarrays are a useful tool to rapidly screen for patterns of gene expression that characterize drug response. The microarray data suggest that the microtubule-stabilizing agent, EpoB, triggers stress-related signal transduction pathways related to TNFalpha. These pathways may contribute to mechanisms of EpoB action and potential mechanisms of resistance in ovarian cancer.

Topics: Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Epothilones; Female; Flow Cytometry; Fluorescent Antibody Technique; G2 Phase; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Humans; Metallothionein; Mitosis; Oligonucleotide Array Sequence Analysis; Ovarian Neoplasms; Tetrazolium Salts; Thiazoles; Tumor Necrosis Factor-alpha; Up-Regulation

We determined the cytotoxic effects BMS 247550 (Epo B), a derivative of epothilone B, on cisplatinum- or paclitaxel-sensitive or -resistant human ovarian cancer cells. Additionally, we determined the effect of Epo B on Apo-2L/TRAIL-induced apoptosis of ovarian cancer cells.. Epo B-induced cytotoxic and cell cycle effects were evaluated by the MTT assay and flow cytometry, respectively. Epo B-induced apoptosis was assessed by immunoblot analyses of the processing and proteolytic activity of caspases, flow cytometric measurement of annexin V staining, and the TUNEL assay. The effects of Epo B and/or Apo-2L/TRAIL on the protein expressions of the death receptors DR4 and DR5 as well as of XIAP and survivin were determined by immunoblot analyses.. In the cell cycle-synchronized ovarian cancer cells, Epo B induced tubulin polymerization and mitotic arrest, followed by apoptosis. This was associated with the cytosolic accumulation of cytochrome (cyt) c and Smac/DIABLO as well as PARP cleavage activity of caspase-3. Epo B was able to exert cytotoxic effects against cisplatinum- and paclitaxel-resistant ovarian cancer cells. Epo B increased the expressions of DR4 and DR5, as well as augmented Apo-2L/TRAIL-induced processing of caspase-8 and Bid. This was associated with more caspase-3 activity, a decline in the intracellular levels of XIAP, cIAP, and survivin, and apoptosis of ovarian cancer cells.. These data support the in vivo testing of Epo B against cisplatinum- and paclitaxel-resistant ovarian cancers, and suggest that a pretreatment with Epo B may sensitize human ovarian cancers to the cytotoxic effects of Apo-2L/TRAIL.

Topics: Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Apoptosis Regulatory Proteins; Caspase 3; Caspases; Cisplatin; Cytochrome c Group; Down-Regulation; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Drug Synergism; Epothilones; Female; Humans; Inhibitor of Apoptosis Proteins; Membrane Glycoproteins; Microtubule-Associated Proteins; Mitosis; Neoplasm Proteins; Ovarian Neoplasms; Paclitaxel; Protein Biosynthesis; Proteins; Proto-Oncogene Proteins c-bcl-2; Recombinant Proteins; Survivin; TNF-Related Apoptosis-Inducing Ligand; Tumor Cells, Cultured; Tumor Necrosis Factor-alpha; X-Linked Inhibitor of Apoptosis Protein

BMS 310705 is a novel water-soluble analog of epothilone B currently in phase I clinical evaluation in the treatment of malignancies such as ovarian, renal, bladder, and lung carcinoma. Using an early passage cell culture model derived from the ascites of a patient clinically refractory to platinum/paclitaxel therapy, we evaluated the pathway of caspase-mediated apoptosis.. Cells were treated for 1 h and subsequently evaluated for apoptosis, survival, and caspase activity. Apoptosis was determined by fluorescent microscopy. Caspase-3, -8, and -9 activities were determined by fluorometry using target tetrapeptide substrates. Mitochondrial release of cytochrome c was determined by immunoblot analysis.. After treatment with BMS 310705, apoptosis was confirmed in >25% of cells at 24 h. Survival was significantly lower (P < 0.02) in cells treated with 0.05 micro M BMS 310705 vs paclitaxel. Analysis revealed an increase of caspase-9 and -3 activity; no caspase -8 activity was observed. Release of cytochrome c was detected at 12 h following treatment. SN-38 and topotecan failed to induce apoptosis.. BMS 310705 induces significant apoptosis, decreases survival, and utilizes the mitochondrial-mediated pathway for apoptosis in this model.

Topics: Antineoplastic Agents; Apoptosis; Camptothecin; Caspases; Cytochrome c Group; Drug Resistance, Neoplasm; Enzyme Activation; Epothilones; Female; Humans; Irinotecan; Isoenzymes; Organoplatinum Compounds; Ovarian Neoplasms; Paclitaxel; Topotecan; Tumor Cells, Cultured

BMS-247550, a novel epothilone derivative, is being developed by Bristol-Myers Squibb Company (BMS) as an anticancer agent for the treatment of patients with malignant tumors. BMS-247550 is a semisynthetic analogue of the natural product epothilone B and has a mode of action analogous to that of paclitaxel (i.e., microtubule stabilization). In vitro, it is twice as potent as paclitaxel in inducing tubulin polymerization. Like paclitaxel, BMS-247550 is a highly potent cytotoxic agent capable of killing cancer cells at low nanomolar concentrations. Importantly, BMS-247550 retains its antineoplastic activity against human cancers that are naturally insensitive to paclitaxel or that have developed resistance to paclitaxel, both in vitro and in vivo. Tumors for which BMS-247550 demonstrated significant antitumor activity encompass both paclitaxel-sensitive and -refractory categories, i.e., (a) paclitaxel-resistant: HCT116/VM46 colorectal (multidrug resistant), Pat-21 breast and Pat-7 ovarian carcinoma (clinical isolates; mechanisms of resistance not fully known), and A2780Tax ovarian carcinoma (tubulin mutation); (b) paclitaxel-insensitive: Pat-26 human pancreatic carcinoma (clinical isolate) and M5076 murine fibrosarcoma; and (c) paclitaxel sensitive: A2780 ovarian, LS174T, and HCT116 human colon carcinoma. In addition, BMS-247550 is p.o. efficacious against preclinical human tumor xenografts grown in immunocompromised mice or rats. Schedule optimization studies indicate that BMS-247550 is efficacious when administered frequently (every 2 days x 5) or intermittently (every 4 days x 3 or every 8 days x 2). These efficacy data demonstrate that BMS-247550 has the potential to surpass Taxol in both clinical efficacy and ease of use (i.e., less frequent treatment schedule and/or oral administration).

Topics: Administration, Oral; Animals; Antineoplastic Agents; Breast Neoplasms; Cell Cycle; Cell Survival; Colonic Neoplasms; Disease Models, Animal; Drug Resistance, Neoplasm; Epothilones; Epoxy Compounds; Female; Humans; Infusions, Parenteral; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Mice, Inbred DBA; Neoplasm Transplantation; Ovarian Neoplasms; Paclitaxel; Pancreatic Neoplasms; Sarcoma; Thiazoles; Tubulin; Tumor Cells, Cultured; Tumor Stem Cell Assay; Xenograft Model Antitumor Assays

The epothilones are naturally occurring, cytotoxic macrolides that function through a paclitaxel (Taxol)-like mechanism. Although structurally dissimilar, both classes of molecules lead to the arrest of cell division and eventual cell death by stabilizing cellular microtubule assemblies. The epothilones differ in their ability to retain activity against multidrug-resistant (MDR) cell lines and tumors where paclitaxel fails. In the current account, we focus on the relationship between epothilone and paclitaxel in the context of tumors with multiple drug resistance. The epothilone analogue Z-12,13-desoxyepothilone B (dEpoB) is >35,000-fold more potent than paclitaxel in inhibiting cell growth in the MDR DC-3F/ADX cell line. Various formulations, routes, and schedules of i.v. administration of dEpoB have been tested in nude mice. Slow infusion with a Cremophor-ethanol vehicle proved to be the most beneficial in increasing efficacy and decreasing toxicity. Although dEpoB performed similarly to paclitaxel in sensitive tumors xenografts (MX-1 human mammary and HT-29 colon tumor), its effects were clearly superior against MDR tumors. When dEpoB was administered to nude mice bearing our MDR human lymphoblastic T cell leukemia (CCRF-CEM/paclitaxel), dEpoB demonstrated a full curative effect. For human mammary adenocarcinoma MCF-7/Adr cells refractory to paclitaxel, dEpoB reduced the established tumors, markedly suppressed tumor growth, and surpassed other commonly used chemotherapy drugs such as adriamycin, vinblastine, and etoposide in beneficial effects.

Topics: Animals; Antineoplastic Agents; Breast Neoplasms; Cell Survival; Drug Resistance, Neoplasm; Epothilones; Female; Humans; Lactones; Leukemia P388; Leukemia-Lymphoma, Adult T-Cell; Mice; Mice, Nude; Ovarian Neoplasms; Paclitaxel; Structure-Activity Relationship; Thiazoles; Transplantation, Heterologous; Tumor Cells, Cultured

Acquired resistance to paclitaxel can be mediated by P-glycoprotein or by alterations involving tubulin. We report two paclitaxel-resistant sublines derived from 1A9 human ovarian carcinoma cells. Single-step paclitaxel selection with verapamil yielded two clones that are resistant to paclitaxel and collaterally sensitive to vinblastine. The resistant sublines are not paclitaxel-dependent, and resistance remained stable after 3 years of drug-free culture. All cell lines accumulate [3H]paclitaxel equally, and no MDR-1 mRNA was detected by polymerase chain reaction following reverse transcription. Total tubulin content is similar, but the polymerized fraction increased in parental but not in resistant cells following the paclitaxel addition. Purified tubulin from parental cells demonstrated paclitaxel-driven increased polymerization, in contrast to resistant cell tubulin, which did not polymerize under identical conditions. In contrast, epothilone B, an agent to which the resistant cells retained sensitivity, increased assembly. Comparable expression of beta-tubulin isotypes was found in parental and resistant cells, with predominant expression of the M40 and beta2 isotypes. Sequence analysis demonstrated acquired mutations in the M40 isotype at nucleotide 810 (T --> G; Phe270 --> Val) in 1A9PTX10 cells and nucleotide 1092 (G --> A; Ala364 --> Thr) in 1A9PTX22 cells. These results identify residues beta270 and beta364 as important modulators of paclitaxel's interaction with tubulin.

Topics: Antineoplastic Agents, Phytogenic; Binding Sites; Drug Resistance, Neoplasm; Epothilones; Epoxy Compounds; Female; Humans; Models, Molecular; Nucleic Acid Hybridization; Ovarian Neoplasms; Paclitaxel; Phenotype; Polymerase Chain Reaction; Polymers; Thiazoles; Tubulin; Tumor Cells, Cultured