Taxol and taxotere in bladder cancer: in vitro activity and urine stability

Novel intravesical therapeutics in the treatment of non-muscle invasive bladder cancer: Horizon scanning

Introduction

Non-muscle-invasive bladder cancer (NMIBC) is a common and heterogeneous disease; many patients develop recurrent or progress to muscle-invasive disease. Intravesical drug therapy is a pillar in the current management of NMIBC; notwithstanding, Mitomycin C (MMC) and Bacillus Calmette-Guérin (BCG) have numerous limitations including international supply issues, and local and systemic toxicity. Here we review novel intravesical therapeutic options and drug delivery devices with potential for clinical use in the treatment of NMIBC.

Methods

PubMed, ClinicalTrials.gov and Cochrane Library searches were undertaken. Systematic reviews, meta-analyses, randomised controlled trials, single-arm clinical trials and national/international conference proceedings were included.

Results

Novel intravesical drugs, including chemotherapeutic agents, immune checkpoint inhibitors, monoclonal antibodies and gene therapies, have demonstrated varying efficacy in the treatment of NMIBC. Current evidence for the majority of treatments is mostly limited to single-arm trials in patients with recurrent NMIBC. Various novel methods of drug delivery have also been investigated, with encouraging preliminary results supporting the intravesical delivery of hyperthermic MMC and MMC hydrogel formulations.

Conclusions

Novel therapeutic agents and drug delivery systems will be important in the future intravesical management of NMIBC. As our understanding of the molecular diversity of NMIBC develops, molecular subtyping will become fundamental in the personalisation of intravesical treatments. Further randomised studies are urgently required to investigate the efficacy of novel intravesical treatments and novel regimens, in comparison to current standards-of-care, particularly in the context of international BCG shortages.

Characterization of lipid droplets from a Taxus media cell suspension and their potential involvement in trafficking and secretion of paclitaxel

Our paper describes the potential roles of lipid droplets of Taxus media cell suspension in the biosynthesis and secretion of paclitaxel and, therefore, highlights their involvement in improving its production. Paclitaxel (PTX) is a highly potent anticancer drug that is mainly produced using Taxus sp. cell suspension cultures. The main purpose of the current study is to characterize cellular LDs from T. media cell suspension with a particular focus on the biological connection of their associated proteins, the caleosins (CLOs), with the biosynthesis and secretion of PTX. A pure LD fraction obtained from T. media cells and characterized in terms of their proteome. Interestingly, the cellular LD in T. media sequester the PTX. This was confirmed in vitro, where about 96% of PTX (C⁰_PTX,_aq [mg L^-1]) in the aqueous solution was partitioned into the isolated LDs. Furthermore, silencing of CLO-encoding genes in the T. media cells led to a net decrease in the number and size of LDs. This coincided with a significant reduction in expression levels of TXS, DBAT and DBTNBT, key genes in the PTX biosynthesis pathway. Subsequently, the biosynthesis of PTX was declined in cell culture. In contrast, treatment of cells with 13-hydroperoxide C18:3, a substrate of the peroxygenase activity, induced the expression of CLOs, and, therefore, the accumulation of cellular LDs in the T. media cells cultures, thus increasing the PTX secretion. The accumulation of stable LDs is critically important for effective secretion of PTX. This is modulated by the expression of caleosins, a class of LD-associated proteins with a dual role conferring the structural stability of LDs as well as regulating lipidic bioactive metabolites via their enzymatic activity, thus enhancing the biosynthesis of PTX.

Analysis of resistance-associated gene expression in docetaxel-resistant prostate cancer cells

Docetaxel-based chemotherapy is the standard treatment for metastatic castration-resistant prostate cancer (CRPC). However, a number of patients with metastatic CRPC are refractory to docetaxel or develop docetaxel resistance. The underlying molecular mechanisms of docetaxel resistance remain unclear, which is a significant burden to the management of metastatic prostate cancer. In the present study, the differential gene expression between docetaxel-sensitive (PC3) and docetaxel-resistant (PC3DR2) prostate cancer cells was identified using DNA microarrays, western blot analysis and reverse transcription-quantitative polymerase chain reaction. Of the genes implicated in cancer-associated pathways, insulin-like growth factor 1 receptor, DBF4 homolog, sterile α motif and leucine zipper-containing kinase AZK, Patched 1, serpin peptidase inhibitor, clade E, member 1 and breast cancer 2 (BRCA2) were >3-fold upregulated in PC3DR2 cells compared with PC3 cells. BRCA2 knockdown with small interfering RNA decreased the docetaxel resistance of PC3DR2 cells. These results suggest that BRCA2 serves an important role in the docetaxel resistance of prostate cancer cells. In addition, BRCA2 modulation may be a strategy to partially reverse docetaxel resistance in prostate cancer.

Urinary excretion of paclitaxel and metabolites in a large series study

Objective. Paclitaxel is an antineoplastic agent with significant activity against several tumour types. The major portion of the drug disposition (80-90%) in volves metabolism and biliary excretion. The purpose of this study was to investigate the relationships between the mean urinary paclitaxel excretion frac tion and the administered dose, creatinine clearance, or the measured paclitaxel area under the plasma concentration versus time curve.

Design. The design used was a retrospective convenience sample study.

Setting. The setting for this study was a hospi talised care center.

Patients. A total of 103 24-hour urine collections from 60 patients treated with paclitaxel were used to investigate these relationships.

Results. In this large series study, the paclitaxel urinary fraction was 5 ± 3% (mean ± SD) as a fraction of the administered paclitaxel dose. No correlations were found between the paclitaxel urinary excretion fraction and the administered dose, creatinine clear ance, and plasma concentration-time curve. In addi tion, the paclitaxel metabolites 6α-hydroxypaclitaxel, 3'- p-hydroxypaclitaxel and some unidentified com pounds were detected in the 24-hour urine samples of two patients, of whom one had a mild impaired renal function.

Conclusions. Considering the low urinary ex cretion of paclitaxel, it is anticipated that patients with renal dysfunction require no dose adjustments. Metabolites were found in the urine.

Intravesical and alternative bladder-preservation therapies in the management of non-muscle-invasive bladder cancer unresponsive to bacillus Calmette-Guérin

Intravesical Bacillus Calmette-Guérin (BCG) remains the standard of care in the treatment of bladder carcinoma in situ and as adjuvant therapy after thorough transurethral resection of high-grade non-muscle-invasive bladder cancer. Despite BCG therapy, in up to 40% of patients it would recur and 60% to 70% of those would fail repeat BCG induction be deemed BCG unresponsive. For such patients, cystectomy remains the preferred treatment option per the American Urological Association and European Association of Urology, though some patients would be medically unfit or refuse radical surgery. Further intravesical therapy for bladder-preservation therapies may preserve quality of life in these patients and in some cases can be curative. There are numerous non-BCG intravesical salvage options available, including immunotherapy, single-agent chemotherapy, combination chemotherapy, and device-assisted chemotherapy. In addition, investigation of radiation-based treatment and other novel therapies including checkpoint inhibitors (programmed death-1/programmed death ligand-1), are currently underway. In this review, we examine the current status of alternatives to BCG in salvage therapy for bladder preservation.

Docetaxel for the treatment of bladder cancer

INTRODUCTION

Docetaxel has had a significant impact on the management of urothelial carcinoma (UC). Multiple phase II trials have been conducted to evaluate the efficacy of docetaxel in the treatment of metastatic UC. Docetaxel is an accepted community standard for the therapy of platinum-treated patients with metastatic UC.

AREAS COVERED

This review focuses on the data supporting a role for docetaxel in the therapy of advanced UC. It also explores the future development of docetaxel and describes the ongoing clinical trials in the treatment of UC.

EXPERT OPINION

Docetaxel plays an important role as one of the standard agents used in the comparator arms of randomized trials evaluating new agents as salvage therapy for metastatic UC. Furthermore, biologic agents are being developed in chemo-biologic regimens using docetaxel as the platform. In the context of emerging novel agents such as T-cell checkpoint inhibitors, docetaxel may continue to play a role as a salvage therapy in select patients ineligible for immunotherapy or following checkpoint inhibitors.

Targeted agents in second-line bladder cancer therapy

The treatment of metastasized urothelial cancer has been evolving in recent years. In particular, in the second-line setting after the failure of platinum-containing therapy, options are few and besides vinflunine, the recently approved standard in Europe, well-designed highly selective clinical trials may be possible alternatives for patients in this palliative situation. However, targeted therapy approaches have not achieved the same results in urothelial cancer as for instance in renal cell carcinoma. Many of the new targeted drugs have been investigated as single agents in phase II clinical trials without convincing oncologic outcome. This review aims to highlight the most relevant clinical studies examining targeted agents in the second-line setting of metastasized transitional carcinoma of the urothelium.

Development and in vitro characterization of paclitaxel and docetaxel loaded into hydrophobically derivatized hyperbranched polyglycerols

In this study we report the development and in vitro characterization of paclitaxel (PTX) and docetaxel (DTX) loaded into hydrophobically derivatized hyperbranched polyglycerols (HPGs). Several HPGs derivatized with hydrophobic groups (C(8/10) alkyl chains) (HPG-C(8/10)-OH) and/or methoxy polyethylene glycol (MePEG) chains (HPG-C(8/10)-MePEG) were synthesized. PTX or DTX were loaded into these polymers by a solvent evaporation method and the resulting nanoparticle formulations were characterized in terms of size, drug loading, stability, release profiles, cytotoxicity, and cellular uptake. PTX and DTX were found to be chemically unstable in unpurified HPGs and large fractions (∼80%) of the drugs were degraded during the preparation of the formulations. However, both PTX and DTX were found to be chemically stable in purified HPGs. HPGs possessed hydrodynamic radii of less than 10nm and incorporation of PTX or DTX did not affect their size. The release profiles for both PTX and DTX from HPG-C(8/10)-MePEG nanoparticles were characterized by a continuous controlled release with little or no burst phase of release. In vitro cytotoxicity evaluations of PTX and DTX formulations demonstrated a concentration-dependent inhibition of proliferation in KU7 cell line. Cellular uptake studies of rhodamine-labeled HPG (HPG-C(8/10)-MePEG(13)-TMRCA) showed that these nanoparticles were rapidly taken up into cells, and reside in the cytoplasm without entering the nuclear compartment and were highly biocompatible with the KU7 cells.

Investigational therapies for non-muscle invasive bladder cancer

IMPORTANCE OF THE FIELD

Bacillus Calmette-Guérin (BCG) is currently the most effective adjuvant intravesical agent at preventing disease recurrence and the only therapy shown to inhibit disease progression in non-muscle invasive bladder cancer (NMIBC). However, recurrence rates as high as 30% and significant local/systemic toxicity have resulted in an increased interest in the use of alternative intravesical agents.

AREAS COVERED IN THE REVIEW

Our aim is to discuss recent clinical trial evidence utilizing novel intravesical agents for treatment of NMIBC. A systematic literature review was performed via the National Center for Biotechnology Information databases to identify pertinent studies from 2000-2009.

WHAT THE READER WILL GAIN

A durable response has been demonstrated with alternative agents in patients refractory to or intolerant of BCG. This review compares the merits and shortcomings of these emerging agents, focusing on clinical trial safety and efficacy results.

TAKE HOME MESSAGE

Despite recent enthusiasm for novel agents, radical cystectomy remains the treatment of choice for patients with NMIBC who have failed intravesical therapy. However, evidence is accumulating that novel agents provide an efficacious alternative in patients refractory or intolerable to BCG or unfit for cystectomy. Further randomized prospective data are required to demonstrate a recurrence- and progression-free benefit compared with BCG.

Long-term clinical outcomes of a phase I trial of intravesical docetaxel in the management of non-muscle-invasive bladder cancer refractory to standard intravesical therapy

OBJECTIVES

To report the long-term clinical outcomes and durability of response after treatment with induction intravesical docetaxel. Most novel agents used to treat bacillus Calmette-Guerin refractory high-grade non-muscle-invasive (NMI) bladder cancer are evaluated only after short follow-up periods. Our previously published phase I trial demonstrated that docetaxel is a safe agent for intravesical therapy with minimal toxicity and no detectable systemic absorption. We sought to determine long-term clinical outcomes after treatment with intravesical docetaxel.

METHODS

Eighteen patients with recurrent Ta (n = 7), T1 (n = 5), and Tis (n = 6) transitional cell carcinoma who experienced treatment failure with at least 1 prior intravesical therapy completed the phase I trial. Docetaxel was administered as 6 weekly intravesical instillations using a dose-escalation model terminated at 0.75 mg/mL. Efficacy was evaluated by interval cystoscopy with biopsies when indicated, cytology, and computed tomography imaging. Follow-up consisted of quarterly cystoscopy, cytology, computed tomography, and biopsy when indicated.

RESULTS

With a median follow-up of 48.3 months, 4 patients (22%) have demonstrated a complete durable response and currently remain disease-free without further treatment. Three patients (17%) had a partial response, defined as a single NMI recurrence with no further therapy for bladder cancer. Eleven patients (61%) failed treatment, and required another intervention. One patient developed stage progression. No delayed toxicities were noted. The median disease-free survival time was 13.3 months.

CONCLUSIONS

After 4 years of follow-up without maintenance therapy, intravesical docetaxel has demonstrated the ability to prevent recurrence in a select number of patients with refractory NMI bladder cancer and warrants further investigation.

New therapies for non-muscle-invasive bladder cancer

The treatment of non-muscle-invasive bladder cancer (NMIBC) remains a challenge owing to its increased tendency to recur and the possibility of progression to potentially dangerous muscle-invasive disease. Treatment outcomes by current therapeutic modalities are still not optimal. In recent years, there have been a number of substantive advances in the therapeutic options for the management of NMIBC. New chemotherapeutic drugs have been introduced, along with efforts made to improve the efficacy of existing agents and enhance delivery of agents to the bladder. There is also a growing trend toward combination of agents and multimodal therapy. Also of considerable interest are the investigation of newer approaches such as gene therapy, chemoenhancement and newer forms of immunotherapy. Here, we review the recent pre-clinical and clinical developments in the treatment of NMIBC, described in the broad categories of immunotherapy, chemotherapeutic agents, improved or device-assisted agent delivery and gene therapy.

Phase I trial of intravesical docetaxel in the management of superficial bladder cancer refractory to standard intravesical therapy

PURPOSE

Up to 50% of patients treated with intravesical agents for superficial bladder cancer will experience recurrence. Response rates to second-line intravesical therapies range from 20% to 40%. For these high-risk patients, novel agents are necessary to prevent recurrence. Docetaxel is a microtubule depolymerization inhibitor with unique physiochemical properties, making it an excellent candidate for investigation as an intravesical agent.

PATIENTS AND METHODS

This phase I trial included patients with recurrent Ta, T1, and Tis transitional cell carcinoma who experienced treatment failure with at least one prior intravesical treatment. Docetaxel was administered as six weekly instillations at a starting dose of 5 mg, with a dose-escalation model used until a maximum tolerated dose (MTD) was achieved. Primary end points were dose-limiting toxicity (DLT) and MTD. Efficacy was evaluated by cystoscopy with biopsy, cytology, and computed tomography imaging.

RESULTS

Eighteen patients (100%) completed the trial, and the distribution of stages included six patients with Tis, seven with Ta, and five with T1 disease. No grade 3 or 4 DLTs occurred in 108 infusions, and no patient had systemic absorption of docetaxel. Eight (44%) of 18 patients experienced grade 1 or 2 toxicities, with dysuria being the most common. Ten (56%) of 18 patients had no evidence of disease at their post-treatment cystoscopy and biopsy. None of the patients who experienced relapse had disease progression.

CONCLUSION

Intravesical docetaxel exhibited minimal toxicity and no systemic absorption in the first human intravesical clinical trial. This suggests that docetaxel is a safe agent for further evaluation of efficacy in a phase II trial.

Effect of combination therapy with a novel bisphosphonate, minodronate (YM529), and docetaxel on a model of bone metastasis by human transitional cell carcinoma

PURPOSE

Transitional cell carcinoma (TCC) of the urinary tract is a chemosensitive tumor. Most deaths from TCC of the urinary tract are caused by metastasis, which is resistant to conventional chemotherapy. Frequent sites of metastases from TCC of the urinary tract are regional lymph nodes, liver, lung, and bone. Of these distant metastases, bone metastasis is consistently resistant to cisplatin-based conventional chemotherapy. Therefore, in this study, we investigated whether or not a newly developed minodronate, YM529, could prevent osteolytic bone metastasis of human TCC and also enhance the effect of docetaxel in a bone tumor model of athymic nude mice.

EXPERIMENTAL DESIGN

In the present study, we evaluated the effect of in vitro treatment with minodronate and/or docetaxel on the proliferation by cell count, the induction of apoptosis by terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) assay, and the biological activity of osteoclast by pit formation assay in human bladder cancer cell line, UMUC-14, and mouse osteoclast cells. In vivo, we examined the effect of minodronate in a bone tumor model of athymic nude mice, in which the percutaneous intraosseal injection in the tibia of UMUC-14, leads to osteolytic bone tumor, as a bone metastasis model. To examine whether or not minodronate could inhibit tumorigenicity and enhance the effect of the chemotherapeutic agent, docetaxel, we gave minodronate i.p. and/or docetaxel i.p. to nude mice 3 days after an intraosseal tumor implantation. Moreover, proliferation and the induction of apoptosis of cancer cells and osteoclasts in bone tumors were determined by immunohistochemistry and the TUNEL assay.

RESULTS

In vitro: In vitro treatment with docetaxel inhibited proliferation and resorption pit-forming activity and induced apoptosis of mouse osteoclast cells and UMUC-14 cells. In vitro treatment with minodronate inhibited proliferation and activity and induced apoptosis of mouse osteoclast cells but not UMUC-14 cells. The treatment with minodronate enhanced the inhibition of proliferation and activity by docetaxel in osteoclasts. In vivo: In vivo combination therapy with docetaxel and minodronate significantly reduced the tumor incidence compared with the control (P < 0.05) and also growth of intraossal TCC in athymic nude mice compared with the control (P < 0.001), single therapy with docetaxel (P < 0.01), and minodronate (P < 0.05). Drug-induced body weight loss was not significantly different in any treatment group. Therapy with minodronate significantly enhanced inhibition of proliferation by docetaxel in osteoclasts of bone tumors compared with the control (P < 0.01), single therapy with docetaxel (P < 0.01), and minodronate (P < 0.05).

CONCLUSIONS

These studies indicate that combination therapy with minodronate and docetaxel may be beneficial in patients with bone metastasis of human TCC in the urinary tract.

Bioadhesive drug delivery system using glyceryl monooleate for the intravesical administration of paclitaxel

BACKGROUND

Many reports have shown that the efficacy of intravesical therapy for bladder cancer is in part limited by the poor penetration of drugs into the urothelium. The present study evaluated the effect of glyceryl monooleate (GMO) on the absorption of intravesically administered paclitaxel in a rabbit model of bladder cancer.

METHODS

Urine, plasma, and tissue pharmacokinetics were determined in rabbits treated for 120 min with paclitaxel (500 microg/20 ml) by intravesical instillation. Two formulations of GMO/paclitaxel were evaluated using different proportions of water, 15 and 30%, and Taxol was used as a control. Animals were observed for clinical signs of toxicity and necropsy was performed.

RESULTS

120 min after instillation, the bladder was emptied and excised. In the urine, paclitaxel concentration was decreased by 39.6 and 41.2% in the two experimental groups and by 25.2% in the control group. The paclitaxel concentrations in the urothelium were 53 and 56% of the urine concentration in both experimental groups, but 11% in the control group. The concentration then declined exponentially in the underlying capillary-perfused tissues, reaching equilibrium at a depth of 1,400-1,700 microm. The plasma concentrations were extremely low compared with concentrations in urine and bladder tissues and were not associated with clinical toxicity.

CONCLUSIONS

We conclude that GMO has a significantly increased bioadhesiveness to bladder mucosa. Therefore, intravesical administration of GMO/paclitaxel/water provides a significant advantage for drugs targeting the bladder tissue, and paclitaxel represents a viable option for intravesical bladder cancer therapy.

New drugs and new approaches in metastatic bladder cancer

The median survival of patients with metastatic cancer of the urothelium who receive best supportive care only in 4-6 months. With the introduction of combination chemotherapy regimens including cisplatin and methotrexate for the management of metastatic urothelial cancer, median overall survival has doubled. Nevertheless, death due to cancer ultimately occurs in more than 80% of these patients, thus more effective therapy is required. The new available treatment modalities range from new combinations of conventional chemotherapeutic agents to combinations incorporating novel drugs like gemcitabine and the taxanes. These new combinations incorporate the new active agents in two, three or multiple drug combinations, administered either in one regimen or sequentially in various combinations and schedules intended to improve the outcome of bladder cancer patients. Ongoing phase III studies will help to define the role of these new combinations in the treatment of advanced bladder cancer. The improved understanding of the molecular biology of urothelial malignancies is helping to define the role of new prognostic indices that can direct the most appropriate choice of treatment for advanced disease. In addition, advances in the molecular biology of urothelial malignancies may allow identification of specific genetic lesions and biochemical pathways upon which future therapeutic approaches can be focused. The integration of newer biologic agents, probably to supplement rather than to supplant chemotherapeutic drugs, should be a primary direction of research with the objective to interfere with multiple aspects of bladder cancer progression.

Feasibility trial of methotrexate-paclitaxel as a second line therapy in advanced urothelial cancer

To evaluate the clinical value of the concurrent use of methotrexate administered immediately before paclitaxel, we investigated the efficacy and toxicity of this two-drug combination administered as palliative second line therapy in patients with advanced urothelial cancer. The design of the schedule and sequence used was based on our previous preclinical data from a comparative study on sequential combinations of paclitaxel and methotrexate in a human bladder cancer cell line. As a confirmation study, we further extended our analysis of in vitro synergism. Twenty patients with advanced transitional cell carcinoma of the urinary tract previously treated with platinum-based therapy, with adequate renal function and a performance status > or = 60 were considered eligible. They received therapy with methotrexate 30 mg/m2 administered as an intravenous bolus, followed immediately by paclitaxel 175 mg/m2 given as a 3-hr infusion, both on day 1 every 21 days. Therapy was given on a compassionate-use basis until either disease progression was documented or the patient became intolerant to therapy. In vitro data were further analyzed using the median-effect principle and the combination index method. Twenty patients with metastatic (16 patients) or locally advanced disease (four patients) received a median of three cycles of therapy. Of the 19 patients assessable for response, there were six partial responses and seven disease stabilizations with no complete responses. Median duration of response was 3 months (range, 2-7) and median survival was 5 months. Three patients developed grade 3-4 neutropenia, one patient had grade 3 anemia, four patients had grade 2-3 sensory neuropathy, and three patients had myalgias. Eighteen patients developed alopecia. Gastrointestinal toxicity was mild. One patient died after the first cycle due to pulmonary thrombo-embolism and could not be evaluated for response. The synergistic in vitro effect of the concurrent combination was confirmed in analyses performed under mutually exclusive and mutually nonexclusive criteria. In conclusion, the combination of methotrexate and paclitaxel at this dose and sequence is feasible and active as a palliative therapy in patients with advanced urothelial cancer previously treated with platinum-based therapies. This schedule merits further investigation in a phase-II trial.

Overexpression of Bcl-2 regulates sodium butyrate- and/or docetaxel-induced apoptosis in human bladder cancer cells both in vitro and in vivo

Sodium butyrate (NaBt), a physiologically occurring short-chain fatty acid, induces differentiation as well as apoptosis in numerous cell types, and this induction is partially regulated by Bcl-2 expression. The objectives of our study were to characterize the in vitro effects of NaBt and/or docetaxel on the growth, cell cycle and apoptosis of human bladder cancer cells, and to determine whether tumor growth in vivo is inhibited by isobutyramide, an orally bioavailable Bt analogue, and/or docetaxel by using Bcl-2-transfected human bladder cancer cell line KoTCC-1/BH and control vector only-transfected cell line KoTCC-1/C. NaBt caused a decrease in growth of both KoTCC-1/C and KoTCC-1/BH cells, however, its growth inhibitory effect was significantly greater in KoTCC-1/C cells. One mM NaBt resulted in G1 cell cycle arrest, accompanied by up-regulation of p21 (waf1/cip1) and down-regulation of cyclin D1 in KoTCC-1/C cells, whereas KoTCC-1/BH showed resistance to G1 cell cycle arrest. An amount of 5 mM NaBt induced apoptosis, accompanied by up-regulation of Bak in KoTCC-1/C cells but failed to induce apoptosis in KoTCC-1/BH cells despite substantial down-regulation of Bcl-2. Oral administration of isobutyramide significantly reduced the KoTCC-1/C tumor volume compared with the KoTCC-1/BH tumor volume in nude mice. Furthermore, docetaxel induced Bcl-2 phosphorylation in KoTCC-1/BH cells and combined treatment with isobutyramide and docetaxel synergistically inhibited the growth of KoTCC-1/BH cells both in vitro and in vivo. These findings suggest that isobutyramide therapy could be a novel therapeutic strategy for patients with bladder cancer if docetaxel is combined according to the Bcl-2 expression status.

Phase I-II study of paclitaxel, cisplatin, and gemcitabine in advanced transitional-cell carcinoma of the urothelium. Spanish Oncology Genitourinary Group

PURPOSE

To determine the maximum-tolerated dose and the antitumor activity of a combination of paclitaxel, cisplatin, and gemcitabine in advanced transitional-cell carcinoma (TCC) of the urothelium.

PATIENTS AND METHODS

Patients with measurable, previously untreated, locally advanced or metastatic TCC and with Eastern Cooperative Oncology Group performance status < or = 2 and creatinine clearance > or = 55 mL/min were eligible. Cisplatin was given on day 1 at a fixed dose of 70 mg/m(2). Paclitaxel and gemcitabine were given on days 1 and 8 at increasing dose levels. Cycles were repeated every 21 days to a maximum of six cycles.

RESULTS

Sixty-one patients were registered. In phase I, 15 patients were entered at four different dose levels. Dose-limiting toxicity consisted of early onset (after the first cycle) grade 2 asthenia (two of six patients) and grade 3 asthenia (one of six patients) at dose level 4. A paclitaxel dose of 80 mg/m(2) and gemcitabine 1,000 mg/m(2) was recommended for phase II, and 46 additional patients were entered at this level for a total of 49 patients. Main nonhematologic toxicity was grade 2 asthenia in 18 patients, with early onset in five patients, and grade 3 in four patients. Grade 3/4 neutropenia and thrombocytopenia occurred in 27 (55%) and 11 (22%) patients, respectively. Overall, febrile neutropenia was seen in 11 patients, and one toxic death occurred because of neutropenic sepsis. The combination was active at all dose levels. In total, 58 of 61 eligible patients were assessable for response; 16 complete responses (27.6%) and 29 partial responses (50%) were observed for an overall response rate of 77.6% (95% confidence interval, 60% to 98%). The median survival time (MST) available for the phase I part of the study is 24.0 months. MST has not been reached for the whole group with the current follow-up.

CONCLUSION

This combination of paclitaxel, cisplatin, and gemcitabine is feasible and highly active in patients with advanced TCC of the urothelium. Further evaluation of this regimen in patients with TCC is warranted.

Gemcitabine/paclitaxel-based three-drug regimens in advanced urothelial cancer

Transitional cell carcinoma (TCC) of the urothelium is a highly chemosensitive tumour. Combination chemotherapy can provide both palliation and a modest survival advantage in patients with advanced disease. At present, the combination of cisplatin, methotrexate, doxorubicin and vinblastine (M-VAC) is the most widely used for advanced TCC with an overall response rate of 40-72% in phase II, and 35-45% in phase III studies, and a median survival of approximately 12 months. These modest results and the unsuccessful attempts to increase efficacy with dose intensive M-VAC schedules have prompted the identification of new active agents in TCC, such as the taxanes and gemcitabine. The overall response rates for two-drug regimens of cisplatin-paclitaxel, carboplatin-paclitaxel and cisplatin-gemcitabine range from 63 to 72%, 14 to 65% and 42 to 66%, respectively. The overall response rates for platinum-paclitaxel-gemcitabine three-drug regimens range from 58 to 80%. The potential clinical benefit of these new three-drug combinations in the treatment of TCC needs to be tested in future phase III studies.

Paclitaxel and carboplatin in bladder cancer: recent developments

Paclitaxel demonstrates significant single-agent activity in advanced urothelial carcinoma. Paclitaxel/carboplatin is an active and tolerable outpatient chemotherapy treatment regimen for these patients. This regimen has been studied in several phase II trials with response rates ranging from 14 to 65%. Paclitaxel/carboplatin may be considered in patients with advanced urothelial cancer and renal insufficiency, and a recent Eastern Cooperative Oncology Group (ECOG) phase II trial investigates this regimen specifically in this patient population. Ongoing ECOG trials are comparing paclitaxel/carboplatin with M-VAC (methotrexate, vinblastine, doxorubicin, cisplatin) in both the advanced disease and adjuvant settings.

Clinical pharmacokinetics of docetaxel

Docetaxel (Taxotere), a semi-synthetic analog of paclitaxel (Taxol), is a promoter of microtubule polymerization leading to cell cycle arrest at G2/M, apoptosis and cytotoxicity. Docetaxel has significant activity in breast, non-small-cell lung, ovarian and head and neck cancers. Docetaxel has undergone phase I study in a number of schedules, including different infusion durations and various treatment cycles. Doses studied in adults have ranged from 5 to 145 mg/m2 and those in children from 55 to 235 mg/m2. The most frequently used regimen in adults is 100 mg/m2 every 3 weeks. A 1-hour infusion every 3 weeks has been favoured in phase II and III studies, and the disposition of docetaxel after such treatment is best described by a 3 compartment model with alpha, beta and gamma half-lives of 4.5 minutes, 38.3 minutes and 12.2 hours, respectively. The disposition of docetaxel appears to be linear, the area under the plasma concentration-time curve (AUC) increasing proportionately with dose. Docetaxel is widely distributed in tissues with a mean volume of distribution of 74 L/m2 after 100 mg/m2, every 3 weeks. The mean total body clearance after this schedule is approximately 22 L/h/m2, principally because of hepatic metabolism by the cytochrome P450 (CYP)3A4 system and biliary excretion into the faeces. Renal excretion is minimal (< 5%). Docetaxel is > 90% bound in plasma. Population pharmacokinetic studies of docetaxel have demonstrated that clearance is significantly decreased with age, decreased body surface area, increased concentrations of alpha 1-acid glycoproteinand albumin. Importantly, patients with elevated plasma levels of bilirubin and/or transaminases have a 12 to 27% decrease in docetaxel clearance and should receive reduced doses. Although docetaxel is metabolised by CYP3A4, phase I combination studies have not shown major evidence of significant interaction between docetaxel and other drugs metabolised by the same pathway. Nevertheless, care should be taken with the use of known CYP3A4 inhibitors such as erythromycin, ketoconazole and cyclosporin. Conversely, increased doses may be required for patients receiving therapy known to induce this cytochrome (e.g. anticonvulsants). Perliminary data suggest the erythromycin breath test, an indicator of CYP3A4 function, is a predictor of toxicity after treatment with docetaxel. Such methodologies may eventually enable clinicians to individualise doses of docetaxel for patients with cancer.

Paclitaxel and carboplatin in patients with metastatic urothelial cancer: results of a phase II trial

The present phase II trial was undertaken to assess the efficacy and toxicity of a combination of paclitaxel and carboplatin as first-line chemotherapy in patients with metastatic transitional cell carcinoma of the urothelium. Twenty patients (age range 50-79 years; inclusion criteria: WHO performance status 0-2, no previous cytotoxic treatment) with metastatic transitional cell carcinoma of the urothelium were recruited and received cytotoxic treatment with paclitaxel at a dosage of 175 mg m(-2) administered over a 3-h infusion and carboplatin given at an AUC of 5 mg ml(-1) min (according to creatinine clearance) administered every 21 days. A total of 65% of patients achieved remissions (CR+PR), with CR occurring in 40% of patients. A further 15% of patients experienced stable disease. Remissions occurred after 2.4 +/- 0.8 (mean +/- standard deviation; range two to four) treatment cycles. The mean duration of responses (CR+PR) was 8.5 +/- 5.5 months. After a mean observation period of 11.4 +/- 4.8 months, 16 patients (80%) are alive. Toxicity included alopecia of WHO grade 3 in all patients, leucopenia of WHO grades 1 and 2 in ten patients, grade 3 in eight and grade 4 in two patients and, finally, severe thrombocytopenia grade 3 in only three patients. Non-haematological toxicity consisted of polyneuropathy of WHO grade 1 in 13 patients and grade 2 in five patients. We thus conclude that a combination of paclitaxel and carboplatin at the given dosage and schedule constitutes an active, well-tolerated first-line cytotoxic treatment for patients with metastatic urothelial cancer.

Phase II study of paclitaxel in pretreated patients with locally advanced/metastatic cancer of the bladder and ureter

Fourteen patients with previously treated, locally advanced/metastatic transitional cell carcinoma (TCC) of the bladder or ureter received paclitaxel at a dose of 200 mg m-2 administered as a 3-h infusion every 21 days. The activity of paclitaxel in this group of patients was modest. The response rates were one partial response (PR) (7%) and three stable disease (SD). There were two early deaths.

In vitro investigations of new therapeutic agents on bladder tumor cell lines

In this study sensitivity of human transitional cancer cells to the anticancer agent paclitaxel, an antimicrotubular drug, and to gallium nitrate, a group IIIa metal, was compared to that of the standard MVAC (methotrexate, vinblastine, doxorubicin and cisplatin) drugs. The reduction of cell proliferation was evaluated after 48 h of incubation of six different cell lines with each agent using the mean transit time (MTT) assay. We investigated both monolayers and spheroids. Paclitaxel showed significantly higher growth inhibitory effects on monolayers than vinblastine, both agents targeting the antimicrotubular apparatus. This could not be reproduced on spheroids, where a survival fraction of 50% was observed even at high concentrations (10 microM). High concentrations of gallium nitrate were needed to achieve sufficient toxicity. These concentrations are beyond the concentration achievable by systemic application. Our findings suggest that paclitaxel may be a clinically useful agent for systemic and intravesical use in bladder cancer.

Cytotoxicity of paclitaxel and docetaxel in human neuroblastoma cell lines

Taxanes are an important new class of anticancer agents that inhibit cell division by the unique mechanism of increasing the rate of microtubule assembly and preventing microtubule depolymerisation. Using the colony inhibition assay, we compared the cytotoxicity of paclitaxel and docetaxel in three human neuroblastoma (NB) cell lines, SH-SY5Y, BE(2)M17 and CHP100. Different exposure times (3, 6, 12, 24, 48 and 72 h) and different concentrations ranging from 0.1 nM to 10 microM were tested. Both paclitaxel and docetaxel show antineoplastic activity in human NB cell lines. Taxanes' antitumour activity varied among the different cell lines, CHP100 being the most sensitive and SH-SY5Y the least sensitive. Paclitaxel cytotoxicity appears schedule-dependent, with marked cell kill observed only for exposures of 24 h or longer. Docetaxel cytotoxicity was dependent upon prolonged exposure only in the SH-SY5Y cell line, while an exposure time of 3-6 h resulted in exponential cell kill in the other two cell lines. Docetaxel was more cytotoxic than paclitaxel with a mean ratio of (paclitaxel/docetaxel) IC50 values ranging from 2 to 11. For both taxanes, we observed good correlation between cytotoxic effect and percentage of cells blocked in G2/M phase. A cytotoxic effect occurred at concentrations comparable with those achieved in the plasma of patients treated with these agents in initial clinical trials. The full potential of prolonged infusion or repeated daily administrations of taxanes should be explored in clinical studies, and responses to taxanes in neuroblastoma should be assessed in paediatric phase II studies.