cabazitaxel and Breast-Neoplasms

Docetaxel remains a cornerstone of therapy for the patient with metastatic castration-resistant prostate cancer (CRPC). However, the landscape of CRPC therapy is changing rapidly - recently, data from the phase III TROPIC study revealed a survival advantage with the novel taxane cabazitaxel/prednisone (compared with mitoxantrone/prednisone) in a cohort of 755 men with docetaxel-refractory metastatic CRPC. Interestingly, cabazitaxel bears substantial structural similiarity to docetaxel but appears to be mechanistically distinct. In preclinical studies, the agent has antitumor activity in a variety of docetaxel-refractory in vitro and in vivo models. Subsequent to phase I testing in advanced solid tumors (where neutropenia was identified as a dose-limiting toxicity), the agent was assessed in a phase II trial in advanced, taxane-refractory breast cancer and in the aforementioned phase III TROPIC study. This review describes in detail the preclinical and clinical development of cabazitaxel.

Topics: Animals; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Breast Neoplasms; Clinical Trials, Phase I as Topic; Clinical Trials, Phase II as Topic; Clinical Trials, Phase III as Topic; Docetaxel; Drug Resistance, Neoplasm; Female; Humans; Male; Mice; Neutropenia; Prednisone; Prostatic Neoplasms; Rats; Taxoids

Cabazitaxel is a novel taxane that might be active in breast cancer resistant to first-generation taxanes.. The purpose of the current multicentre phase II trial was to evaluate the activity and safety of cabazitaxel, as second-line treatment, in patients with human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer (MBC) previously treated with taxanes. The primary endpoint was objective response rate (ORR).. Eighty-four patients were enrolled between October 2012 and November 2016. Taxane resistance to previous treatment was detected in 43 cases. The ORR was 22.6% in the intent-to-treat population, 23.3% in taxane-resistant and 20.5% in taxane-non-resistant cases. At a median follow-up of 39.6 months, the median progression-free survival and overall survival were 3.7 months (95% CI 2.2-4.4) and 15.2 months (95% CI 11.3-19.4), respectively. Regarding toxicity, grade 3-4 neutropenia was reported in 22.6% and febrile neutropenia in 6% of the patients, respectively. Two fatal events (one febrile neutropenia and one sepsis) were reported as being related to study treatment.. This phase II trial suggests that cabazitaxel is active as second-line treatment in taxane-pretreated patients with HER2-negative MBC, with manageable toxicity.

Topics: Adult; Aged; Breast Neoplasms; Drug Resistance, Neoplasm; Female; Humans; Middle Aged; Neoplasm Metastasis; Receptor, ErbB-2; Survival Analysis; Taxoids; Treatment Outcome

The GENEVIEVE study compared the pathological complete response (pCR) rate (ypT0/is ypN0/+) in patients with operable human epidermal growth factor receptor 2 (HER2)-negative breast cancer (BC) treated with either cabazitaxel or paclitaxel.. GENEVIEVE was a prospective, multicentre, randomised, open-label, phase II study comparing the efficacy and the safety of four 3-weekly cycles cabazitaxel versus 12 weeks of paclitaxel given as neoadjuvant treatment. Primary end-point was the pCR rate defined as the complete absence of invasive carcinoma on histological examination of the breast irrespective of lymph node involvement (ypT0/is, ypN0/+) after the taxane treatment. Patients could receive an anthracycline-based therapy thereafter.. Overall, 333 patients were randomised and started treatment with 74.7% and 83.2% of patients completing treatment in the cabazitaxel and paclitaxel arms, respectively. Patients in cabazitaxel arm had a significantly lower pCR rate compared to the paclitaxel arm (1.2% versus 10.8%; p = 0.001). A total of 42 (25.3%) patients in the cabazitaxel arm and 17 (10.2%) in the paclitaxel arm had at least one serious adverse event (p < 0.001). Dose reductions were observed in 9.6% patients in the cabazitaxel arm compared to 11.4% in the paclitaxel arm (p = 0.721). Main reason for dose reductions was non-haematological toxicities in 3.0% versus 7.8% (p = 0.087), respectively.. The GENEVIEVE study showed no short-term effect of cabazitaxel in triple-negative or luminal B/HER2-negative primary BC, while there seemed to be no differences in drug exposure and patient compliance between the two arms.. ClinicalTrials.gov NCT01779479.

Topics: Adult; Aged; Antineoplastic Agents, Phytogenic; Biomarkers, Tumor; Breast Neoplasms; Chemotherapy, Adjuvant; Drug Administration Schedule; Female; Germany; Humans; Mastectomy; Medication Adherence; Middle Aged; Neoadjuvant Therapy; Neoplasm Grading; Neoplasm Staging; Paclitaxel; Prospective Studies; Receptor, ErbB-2; Taxoids; Time Factors; Treatment Outcome; Triple Negative Breast Neoplasms; Young Adult

Most patients with metastatic breast cancer (MBC) progress after chemotherapy. Cabazitaxel (XRP6258) is a new taxoid that is active in chemotherapy-resistant tumour cell lines. The objectives of this phase I/II study were to assess the maximum tolerated dose (MTD), safety profile, pharmacokinetics, and activity of cabazitaxel plus capecitabine in patients with MBC who had been previously treated with taxanes and anthracyclines.. In part I, we used a 3+3 dose-escalation scheme to assess the MTD of intravenous cabazitaxel (day 1) with oral capecitabine twice daily (days 1-14) every 3 weeks. In part II, we evaluated the objective response rate (ORR) at the MTD.. Thirty-three patients were enrolled and treated (15 in part I; 18 in part II). Cabazitaxel 20mg/m(2) plus capecitabine 1000 mg/m(2) was the MTD. Pharmacokinetic analysis showed no apparent drug-drug interaction. In all patients, the main grade 3-4 toxicities were asthenia (n=5), hand-foot syndrome (n=5), neutropenia (n=21), neutropenic infection (n=1), and neutropenic colitis (n=1). One patient had febrile neutropenia. Antitumour activity was observed at all dose-levels with two complete responses, five partial responses (PRs), and 20 disease stabilisations (seven unconfirmed PR). At the MTD, 21 patients were evaluable for efficacy. The ORR was 23.8% (95% CI: 8.2-47.2%). The median response duration was 3.1 months (95% CI: 2.1-8.4 months), with four of five lasting for more than 3 months. Median time to progression was 4.9 months.. Cabazitaxel combined with capecitabine is active, has a safety profile consistent with a taxane plus capecitabine combination and warrants further investigation in patients with MBC.

Topics: Adult; Aged; Antineoplastic Combined Chemotherapy Protocols; Area Under Curve; Breast Neoplasms; Capecitabine; Deoxycytidine; Drug Resistance, Neoplasm; Female; Fluorouracil; Humans; Maximum Tolerated Dose; Middle Aged; Neoplasm Metastasis; Taxoids; Treatment Outcome

XRP6258 is a novel taxoid with a low affinity for P-glycoprotein. This multicenter phase II study assessed the activity of XRP6258 in the treatment of taxane-resistant metastatic breast cancer (MBC).. XRP6258 was administered as a 1-h i.v. infusion every 3 weeks at 20 mg/m(2) (then, in the absence of severe toxicity, at 25 mg/m(2) from cycle 2). The primary end point was the objective response rate (ORR) assessed according to response evaluation criteria in solid tumours (RECIST) guidelines.. Seventy-one patients were enrolled. The median relative dose intensity was 0.98. The ORR was 14% (two complete, eight partial responses). Eighteen patients (25%) had stable disease of >3 months duration. At a median follow-up of 20.0 months, the median time to progression was 2.7 months, and the median overall survival 12.3 months. The most common grade 3/4 adverse events (AEs) were neutropenia (73%) and leucopenia (55%), with a low febrile neutropenia rate (3%) and infrequent grade 3/4, treatment-related, non-hematological AEs (<5% patients for any AE). Two deaths were reported, one related to study drug and one to unknown cause.. XRP6258 was active and well tolerated in this group of MBC patients with taxane-resistant disease. These results support the further clinical development of this agent.

Topics: Adenocarcinoma; Adult; Aged; Antineoplastic Agents; Breast Neoplasms; Bridged-Ring Compounds; Confidence Intervals; Dose-Response Relationship, Drug; Drug Administration Schedule; Drug Resistance, Neoplasm; Female; Humans; Infusions, Intravenous; Kaplan-Meier Estimate; Maximum Tolerated Dose; Middle Aged; Neoplasm Staging; Prognosis; Risk Assessment; Survival Analysis; Taxoids; Treatment Outcome

Cabazitaxel (CBZ) is a taxane derivative and an anti-microtubule agent effective against numerous cancers including drug-resistant cancers. In this study, CBZ loaded nanostructured lipid carriers (NLCs) were prepared by using Design-Expert (DoE) and optimized for various formulation parameters (ratio of lipids and surfactant concentration, homogenization speed and time). The optimized CBZ loaded NLCs formulation was characterized and evaluated through multiple physicochemical characterization techniques like FTIR, DSC, PXRD, SEM and in-vitro drug release. FTIR and DSC results suggested that NLCs entrapped drug inside and had no chemical bonding between drug and NLCs. SEM analysis confirmed homogeneous, spherical, and uniformly distributed NLCs. In-vitro cell culture studies suggested that CBZ loaded NLCs produced ∼ 6- and 2.5-times higher cytotoxicity against MDA-MB-468 and MCF-7 cell lines, respectively compared to pure drug. Cellular uptake of NLC was ∼2.5 and 2.1-fold higher than CBZ alone in MDA-MB-468 and MCF-7 cell lines, respectively. Furthermore, CBZ loaded NLCs produced significantly higher apoptosis and inhibited the mobility of MDA-MB-468 and MCF-7 cells. The results from this study demonstrate the utility of CBZ loaded NLCs as an effective treatment against breast cancer and NLCs as effective drug carriers to deliver the highly lipophilic drug such as CBZ.

Topics: Breast Neoplasms; Drug Carriers; Drug Liberation; Female; Humans; Lipids; MCF-7 Cells; Nanostructures; Particle Size; Taxoids

Targeted drug delivery for cancer therapy is an emerging area of research. Cancer cells overexpress certain biomarkers that can be exploited for their targeted therapy. Cyclic cell-penetrating peptides (cCPP) are increasingly assessed for intracellular cargo delivery in cancer cells. In this study, we have conjugated cabazitaxel (CBT) to the cCPP via an ester bond to assist CBT release in the tumor's acidic environment. Integrin targeting (RGDC, TP1) and extra domain B of fibronectin (EDB-Fn) targeting (CTVRTSAD, TP2) peptides were linked to the peptide-drug conjugate (cCPP-CBT) via a disulfide bond to provide targeting ability to the conjugates until they reach the tumor site. Conjugate

Topics: Amino Acid Sequence; Antineoplastic Agents; Biomarkers, Tumor; Breast Neoplasms; Cell Line, Tumor; Cell Proliferation; Cell-Penetrating Peptides; Drug Delivery Systems; Female; HEK293 Cells; Humans; Male; Molecular Structure; Prostatic Neoplasms; Taxoids

Cabazitaxel as microtubule inhibitor and thymoquinone as HDAC inhibitor affects the important genes like p53, STAT3, Bax, BCL-2, p21 and down regulation of NF-κB are reported for potential activity against breast tumors. However, poor aqueous solubility and permeability hinders the delivery of these drugs to target site. To address the delivery challenges cabazitaxel and thymoquinone co-loaded lipospheres were developed. Lipospheres are the lipid based self-assemblies of particle size below 150 nm were prepared with more than 90% entrapment efficiency for both the drugs. In vitro drug release studies revealed there was a sustained diffusion controlled drug release from liposphere matrix leading to decrease in particle size with increase in zeta potential. Cytotoxicity studies on MCF-7 and MDA-MB-231 cells demonstrated cabazitaxel and thymoquinone as synergistic combination for the treatment of breast cancer which was proved by CompuSyn software. Enhanced efficacy of developed lipospheres can be due to rapid cellular internalization which was observed in confocal laser scanning microscopy. Drastic changes in cancer cell morphology such as nuclear fragmentation were observed upon treatment with these lipospheres in comparison to combination solution as observed in fluorescent imaging which are the hall marks of apoptosis. Cell cycle analysis and apoptosis studies confirmed the increased Sub G1 phase arrest as well as cell death due to apoptosis. Thus, as per observed results, it can be concluded that cabazitaxel and thymoquinone co-loaded lipospheres are the efficient delivery vehicles in management of breast cancer.

Topics: Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Benzoquinones; Breast Neoplasms; Cell Line, Tumor; Cell Membrane Permeability; Drug Compounding; Drug Liberation; Female; Humans; Lipids; Liposomes; Optical Imaging; Solubility; Taxoids

The effect of poly(2-ethyl-butyl cyanoacrylate) nanoparticles containing the cytotoxic drug cabazitaxel was studied in three breast cancer cell lines and one basal-like patient-derived xenograft model grown in the mammary fat pad of immunodeficient mice. Nanoparticle-encapsulated cabazitaxel had a much better efficacy than similar concentrations of free drug in the basal-like patient-derived xenograft and resulted in complete remission of 6 out of 8 tumors, whereas free drug gave complete remission only with 2 out of 9 tumors. To investigate the different efficacies obtained with nanoparticle-encapsulated versus free cabazitaxel, mass spectrometry quantification of cabazitaxel was performed in mice plasma and selected tissue samples. Nanoparticle-encapsulated drug had a longer circulation time in blood. There was approximately a three times higher drug concentration in tumor tissue 24 h after injection, and two times higher 96 h after injection of nanoparticles with drug compared to the free drug. The tissue biodistribution obtained after 24 h using mass spectrometry analyses correlates well with biodistribution data obtained using IVIS® Spectrum in vivo imaging of nanoparticles labeled with the fluorescent substance NR668, indicating that these data also are representative for the nanoparticle distribution. Furthermore, immunohistochemistry was used to estimate infiltration of macrophages into the tumor tissue following injection of nanoparticle-encapsulated and free cabazitaxel. The higher infiltration of anti-tumorigenic versus pro-tumorigenic macrophages in tumors treated with the nanoparticles might also contribute to the improved effect obtained with the nanoparticle-encapsulated drug. Tumor infiltration of pro-tumorigenic macrophages was four times lower when using nanoparticles containing cabazitaxel than when using particles without drug, and we speculate that the very good therapeutic efficacy obtained with our cabazitaxel-containing particles may be due to their ability to reduce the level of pro-tumorigenic macrophages in the tumor. In summary, encapsulation of cabazitaxel in poly(2-ethyl-butyl cyanoacrylate) nanoparticles seems promising for treatment of breast cancer.

Topics: Animals; Antineoplastic Agents; Breast Neoplasms; Cell Line, Tumor; Cell Survival; Cyanoacrylates; Female; Humans; Mice, Nude; Nanoparticles; Taxoids; Tissue Distribution; Treatment Outcome

Cancer metastasis is the primary cause of high mortality in breast cancer patients. In this study, we loaded an anti-cancer drug, cabazitaxel (CTX), into polymeric micelles (CTX-loaded polymeric micelles, PCMs), and explored their therapeutic efficacy in breast cancer metastasis. The characteristics of PCMs were investigated, and their anti-metastatic efficacy was assessed using in vitro and in vivo evaluations. PCMs had an average diameter of 50.13±11.96 nm with a CTX encapsulation efficiency of 97.02%±0.97%. PCMs could be effectively internalized into metastatic 4T1 breast cancer cells in vitro. CTX (10 ng/mL) or an equivalent concentration in PCMs did not significantly affected the viability of 4T1 cells, but dramatically decreased the cell migration activities. In an orthotopic metastatic breast cancer model, intravenously administered PCMs could be efficiently delivered to the tumor sites, resulting in a 71.6% inhibition of tumor growth and a 93.5% reduction of lung metastases. Taken together, our results verify the anti-metastatic efficacy of PCMs, thus providing an encouraging strategy for treating breast cancer metastasis.

Topics: Animals; Antineoplastic Agents; Breast Neoplasms; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cell Survival; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Female; Humans; Lactates; Mammary Neoplasms, Experimental; Mice; Mice, Inbred BALB C; Mice, Nude; Micelles; Particle Size; Polyethylene Glycols; Structure-Activity Relationship; Surface Properties; Taxoids

Cabazitaxel is a novel taxane approved for treatment of metastatic hormone-refractory prostate cancer in patients pretreated with docetaxel. Cabazitaxel, docetaxel, and paclitaxel bind specifically to tubulin in microtubules, disrupting functions essential to tumor growth. High levels of βIII-tubulin isotype expression are associated with tumor aggressivity and drug resistance. To understand cabazitaxel's increased efficacy, we examined binding of radio-labeled cabazitaxel and docetaxel to microtubules and the drugs' suppression of microtubule dynamic instability in vitro in microtubules assembled from purified bovine brain tubulin containing or devoid of βIII-tubulin. We found that cabazitaxel suppresses microtubule dynamic instability significantly more potently in the presence of βIII-tubulin than in its absence. In contrast, docetaxel showed no βIII-tubulin-enhanced microtubule stabilization. We also asked if the selective potency of cabazitaxel on βIII-tubulin-containing purified microtubules in vitro extends to cabazitaxel's effects in human tumor cells. Using MCF7 human breast adenocarcinoma cells, we found that cabazitaxel also suppressed microtubule shortening rates, shortening lengths, and dynamicity significantly more strongly in cells with normal levels of βIII-tubulin than after 50% reduction of βIII-tubulin expression by siRNA knockdown. Cabazitaxel also more strongly induced mitotic arrest in MCF7 cells with normal βIII-tubulin levels than after βIII-tubulin reduction. In contrast, docetaxel had little or no βIII-tubulin-dependent selective effect on microtubule dynamics or mitotic arrest. The selective potency of cabazitaxel on purified βIII-tubulin-containing microtubules and in cells expressing βIII-tubulin suggests that cabazitaxel may be unusual among microtubule-targeted drugs in its superior anti-tumor efficacy in tumors overexpressing βIII-tubulin.

Topics: Adenocarcinoma; Animals; Antineoplastic Agents; Brain; Breast Neoplasms; Cattle; Docetaxel; Drug Resistance, Neoplasm; Female; Gene Expression Regulation, Neoplastic; Gene Knockdown Techniques; Humans; MCF-7 Cells; Microtubules; RNA, Small Interfering; Taxoids; Tubulin; Tubulin Modulators

Compared with conventional chemotherapy, encapsulation of drugs in nanoparticles can improve efficacy and reduce toxicity. However, delivery of nanoparticles is often insufficient and heterogeneous because of various biological barriers and uneven tumor perfusion. We investigated a unique multifunctional drug delivery system consisting of microbubbles stabilized by polymeric nanoparticles (NPMBs), enabling ultrasound-mediated drug delivery. The aim was to examine mechanisms of ultrasound-mediated delivery and to determine if increased tumor uptake had a therapeutic benefit. Cellular uptake and toxicity, circulation and biodistribution were characterized. After intravenous injection of NPMBs into mice, tumors were treated with ultrasound of various pressures and pulse lengths, and distribution of nanoparticles was imaged on tumor sections. No effects of low pressures were observed, whereas complete bubble destruction at higher pressures improved tumor uptake 2.3 times, without tissue damage. An enhanced therapeutic effect was illustrated in a promising proof-of-concept study, in which all tumors exhibited regression into complete remission.

Topics: Animals; Antineoplastic Agents; Breast Neoplasms; Cell Line, Tumor; Disease Models, Animal; Female; Heterografts; Humans; Mice; Microbubbles; Nanoparticles; Taxoids; Ultrasonic Therapy

Metastatic cancer is responsible for 90% of deaths in world. Usage of nano-carriers improve the delivery and efficacy of chemotherapeutic agents. Recent studies suggest that decoration of the surface of nano-carriers with various targeting agents may further improve their overall therapeutic efficacy. Using specified peptides in targeted drug delivery is a key point in recent researches. In this study, tumor metastasis targeting (TMT) homing peptide was applied as a targeting group to improve specific drug delivery to tumor cells. TMT peptide is conjugated to poly ethylene glycol-poly caprolactone (PEG-PCL) micellar nanoparticles as carriers for targeted delivery of cabazitaxel to metastatic breast cancer cells. Synthesis of PEG-PCL copolymer was performed by amidation reaction between carboxylic acid group of PEG and amine group of PCL. Nanomicelles were prepared via solvent evaporation method. TMT peptide was covalently conjugated onto nanomicelles through the amine group of PEG. TMT-PEG-PCL nanoparticles were analyzed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), dynamic light scattering (DLS), gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR). Toxicity and cellular uptake of nanomicelles were investigated by in vitro cytotoxicity assays and confocal scanning microscopy in MCF-7 (non-metastatic breast cancer cells) and MDA-MB-231 (metastatic breast cancer cells). The final nanomicelles had about 110nm mean size and encapsulation efficiency of 82.5%. Treatment of metastatic breast cancer cells with targeted nanomicelles significantly increased the necrosis rate to 65%, compared to 33% in non-targeted nanomicelles and 8% in control group. The MDA-MB-231 cells treated with targeted nanomicelles exhibited a strong increase in the fluorescence intensity of coumarin in comparison to the cells treated with non-targeted nanomicelles (p<0.001). It could be concluded that the present carrier has the potential to be considered in treatment of metastatic breast cancer cells.

Topics: Breast Neoplasms; Caproates; Drug Carriers; Drug Delivery Systems; Humans; Lactones; Micelles; Nanostructures; Peptides; Polyethylene Glycols; Taxoids

We studied mechanisms of resistance to the novel taxane cabazitaxel in established cellular models of taxane resistance. We also developed cabazitaxel-resistant variants from MCF-7 breast cancer cells by stepwise selection in drug alone (MCF-7/CTAX) or drug plus the transport inhibitor PSC-833 (MCF-7/CTAX-P). Among multidrug-resistant (MDR) variants, cabazitaxel was relatively less cross-resistant than paclitaxel and docetaxel (15- vs. 200-fold in MES-SA/Dx5 and 9- vs. 60-fold in MCF-7/TxT50, respectively). MCF-7/TxTP50 cells that were negative for MDR but had 9-fold resistance to paclitaxel were also 9-fold resistant to cabazitaxel. Selection with cabazitaxel alone (MCF-7/CTAX) yielded 33-fold resistance to cabazitaxel, 52-fold resistance to paclitaxel, activation of ABCB1, and 3-fold residual resistance to cabazitaxel with MDR inhibition. The MCF-7/CTAX-P variant did not express ABCB1, nor did it efflux rhodamine-123, BODIPY-labeled paclitaxel, and [(3)H]-docetaxel. These cells are hypersensitive to depolymerizing agents (vinca alkaloids and colchicine), have reduced baseline levels of stabilized microtubules, and impaired tubulin polymerization in response to taxanes (cabazitaxel or docetaxel) relative to MCF-7 parental cells. Class III β-tubulin (TUBB3) RNA and protein were elevated in both MCF-7/CTAX and MCF-7/CTAX-P. Decreased BRCA1 and altered epithelial-mesenchymal transition (EMT) markers are also associated with cabazitaxel resistance in these MCF-7 variants, and may serve as predictive biomarkers for its activity in the clinical setting. In summary, cabazitaxel resistance mechanisms include MDR (although at a lower level than paclitaxel and docetaxel), and alterations in microtubule dynamicity, as manifested by higher expression of TUBB3, decreased BRCA1, and by the induction of EMT.

Topics: Antineoplastic Agents; ATP Binding Cassette Transporter, Subfamily B; BRCA1 Protein; Breast Neoplasms; Cell Proliferation; Cyclosporins; Drug Resistance, Neoplasm; Epithelial-Mesenchymal Transition; Female; Gene Expression Regulation, Neoplastic; Humans; MCF-7 Cells; Taxoids; Tubulin

Cabazitaxel, a novel chemotherapeutic taxane, is effective against docetaxel-resistant cells and tumors. It is approved for treatment of metastatic hormone-refractory prostate cancer in patients pretreated with docetaxel. Objective responses have been observed in many other cancers, including pretreated metastatic breast cancer. Cabazitaxel and docetaxel share a high degree of structural similarity. The basis for cabazitaxel's efficacy is unclear, and its mechanism has not been described. We compared the effects of cabazitaxel and docetaxel on MCF7 human breast cancer cells expressing fluorescent tubulin. Both drugs inhibited cell proliferation (IC50s, cabazitaxel, 0.4 ± 0.1 nmol/L, docetaxel, 2.5 ± 0.5 nmol/L) and arrested cells in metaphase by inducing mitotic spindle abnormalities. Drug concentrations required for half-maximal mitotic arrest at 24 hours were similar (1.9 nmol/L cabazitaxel and 2.2 nmol/L docetaxel). Cabazitaxel suppressed microtubule dynamic instability significantly more potently than docetaxel. In particular, cabazitaxel (2 nmol/L) suppressed the microtubule shortening rate by 59% (compared with 49% for 2 nmol/L docetaxel), the growing rate by 33% (vs. 19%), and overall dynamicity by 83% (vs. 64%). Cabazitaxel was taken up into cells significantly faster than docetaxel, attaining an intracellular concentration of 25 μmol/L within 1 hour, compared with 10 hours for docetaxel. Importantly, after washing, the intracellular cabazitaxel concentration remained high, whereas the docetaxel concentration was significantly reduced. The data indicate that the potency of cabazitaxel in docetaxel-resistant tumors is due to stronger suppression of microtubule dynamics, faster drug uptake, and better intracellular retention than occurs with docetaxel.

Topics: Antineoplastic Agents; Breast Neoplasms; Cell Cycle Checkpoints; Cell Proliferation; Docetaxel; Drug Screening Assays, Antitumor; Female; Humans; MCF-7 Cells; Microtubules; Mitosis; Protein Stability; Taxoids; Tubulin Modulators

The taxanes are recognized as a major class of chemotherapeutic agents; however, mechanisms of innate and acquired resistance can limit their usefulness. Cabazitaxel, a novel taxane with microtubule-stabilizing potency similar to docetaxel, exhibits activity against tumor cell lines resistant to paclitaxel and docetaxel. Cabazitaxel showed linear pharmacokinetics and a terminal elimination half-life comparable with that of docetaxel, findings which support dosing as a single infusion in three-week treatment cycles. Dose-ranging studies recommended doses of 20 or 25 mg/m(2) every three weeks. Antitumor activity was shown in patients with advanced cancer and chemotherapy failure (including taxane failure). Other early studies investigated the efficacy of cabazitaxel in pretreated metastatic breast cancer, either as a single agent or in combination with capecitabine. Objective antitumor response rates of up to 24% and sustained tumor stabilizations were also observed. The TROPIC phase III study, conducted in patients with metastatic castrate-resistant prostate cancer previously treated with docetaxel, established cabazitaxel as the first chemotherapeutic agent to offer a survival advantage in this patient population. Across these studies, the dose-limiting hematologic toxicity was neutropenia (including febrile neutropenia), usually controllable with colony-stimulating factor/granulocyte-colony stimulating factor support.

Topics: Antineoplastic Agents; Breast Neoplasms; Clinical Trials as Topic; Drug Resistance, Neoplasm; Female; Humans; Male; Neoplasm Metastasis; Prostatic Neoplasms; Taxoids