Paclitaxel (Taxol) and docetaxel (Taxotere): not simply two of a kind

In vitro search for synergy and antagonism: evaluation of docetaxel combinations in breast cancer cell lines

The use of combination chemotherapy is the accepted standard for most human malignancies but little attention has been paid to drug interactions. A combination of drugs may be synergistic, additive, or antagonistic in cytotoxic activity. This study evaluated combinations of agents with docetaxel, one of the most active agents in human breast cancer, using a median effects model to look at synergy or antagonism in vitro as a potential predictor of clinical outcome. Three human breast cancer cell lines, MCF7/wt, MCF7/adr (multiply drug resistant), and BT474 were grown to confluence, plated into 96 well dishes, and incubated with combinations of drugs for 72h. Cytotoxic effect was measured by the MTT assay. Median effect analysis was used to calculate the combination index (CI) with values less than 1 indicating synergism, 1 additive effects, and greater than 1 antagonism. Potentially useful combinations for clinical study which were identified included docetaxel with vinorelbine, docetaxel with dexrazoxane, docetaxel with cis-retinoic acid, docetaxel with disulfiram and either doxorubicin or epirubicin, and docetaxel with dexrazoxane and epirubicin.

Phase I study of eniluracil and oral 5-fluorouracil in combination with docetaxel in the treatment of patients with metastatic breast carcinoma

PURPOSE

The authors conducted a single-institution Phase I clinical trial to determine the maximum tolerated doses and to define the toxic effects of oral eniluracil and oral 5-fluorouracil (5-FU) combined with docetaxel in patients with metastatic breast carcinoma.

PATIENTS AND METHODS

Patients with metastatic breast carcinoma were eligible if they had disease progression after anthracycline-based therapy and had never been exposed to taxanes. The starting doses of oral eniluracil and oral 5-FU were 11.5 mg/m(2) and 1.15 mg/m(2), respectively, twice daily on Days 1-14. Docetaxel was given intravenously at a starting dose of 50 mg/m(2) on Day 1 only. The dose of docetaxel was escalated among cohorts until a maximum tolerated dose was reached. Courses were repeated every 21 days.

RESULTS

The authors treated 19 patients with Stage IV breast carcinoma, of whom 5 had received prior chemotherapy for their metastatic disease. Fifty-three percent had a performance status of 1, and 53% had bone or soft tissue involvement as the dominant site of disease. All patients had received prior therapy with doxorubicin. The dose-limiting toxicity was neutropenic fever. No episodes of sepsis were observed. Significant antitumor activity was observed with a total of two complete and nine partial responses. The recommended doses for Phase II studies are 72 mg/m(2) docetaxel on Day 1 and 10.0/1.0 mg/m(2) oral eniluracil/5-FU twice daily for a total of 14 days, with courses being repeated every 21 days.

CONCLUSIONS

The combination of oral eniluracil/5-FU and intravenous docetaxel is a safe and well tolerated regimen. Significant antitumor activity is associated with this combination.

Prevention and management of antineoplastic-induced hypersensitivity reactions

Acute hypersensitivity reactions (HSRs) are an unpredictable and potentially catastrophic complication of treatment with chemotherapeutic agents. Reactions may affect any organ system in the body and range widely in severity from mild pruritus to systemic anaphylaxis. Certain classes of chemotherapeutic agents, such as the taxanes, platinum compounds, asparaginases, and epipodophyllotoxins are commonly associated with HSRs. The clinical characteristics of these high risk agents with respect to HSRs are discussed in this review. Protocols to prevent or reduce the severity of these reactions have been developed, but despite these attempts, HSRs will still happen. Should a reaction occur, it is imperative that it be recognised quickly in order to minimise exposure to the inciting agent and implement appropriate therapeutic and supportive measures. When a patient becomes sensitised to a chemotherapeutic agent, avoidance of re-exposure is the mainstay of future prevention. For sensitised patients who have derived clinically meaningful benefit from a particular agent, however, continuation of treatment with the agent is desirable. Options may include attempting a trial of desensitisation or treatment with a related compound. Virtually all patients demonstrating HSRs to paclitaxel and docetaxel are able to successfully tolerate re-treatment following discontinuation and administration of diphenhydramine and hydrocortisone. Re-treatment has generally been less successful with platinum compounds. with recurrent HSRs occurring in up to 50% of patients following desensitisation protocols. Patients sensitised to asparaginase are often able to tolerate the alternative preparations, Erwinia carotovora asparaginase or polyethylene glycol-modified Escherichia coli asparaginase. There is very little experience with re-treatment following sensitisation to the epipodophyllotoxins. As re-treatment may have serious consequences, careful consideration of the risks and benefits of these strategies is imperative when deciding among these options.

A phase I-II study of docetaxel-ifosfamide-cisplatin (DIP) combination chemotherapy regimen in advanced nonsmall cell lung cancer

In an attempt to develop more effective chemotherapy regimens in advanced nonsmall cell lung cancer (NSCLC), we evaluated docetaxel-ifosfamide-cisplatin (DIP) based on our previous experience with paclitaxel-ifosfamide-cisplatin. Patients with advanced NSCLC (stages III-IV), WHO-PS< or =2, no prior chemotherapy and unimpaired hematopoietic and organ function were eligible. Chemotherapy was administered in successive dose levels (DLs) and included docetaxel (80-100 mg/m2 day 1), ifosfamide (4-5 g/m2) and cisplatin (80-100 mg/m2), both divided over days 1 and 2 every 21 days. G-CSF (lenograstin) was administered from days 4-13. Fifty-five patients were accrued (phase I: 15; phase II: 40) and all are evaluable for response and toxicity: median age = 58 (40-72); PS = 1 (0-2); gender = 48 males, 7 females; stages IIIA = 8, IIIB = 19, IV = 28; and histologies were adenocarcinoma (29), squamous (20), large cell (6). Metastatic sites at diagnosis included lymph nodes (33), bone (8), liver (6), brain (6), lung nodules (9), adrenals (7) and soft tissue (1). The dose-limiting toxicity (DLT) was reached at DL4 (Docetaxel: 100 mg/m2-Ifosfamide: 5 g/m2-Cisplatin: 100 mg/m2) consisting of 2 cases of febrile neutropenia (FN), and DL3 (Docetaxel: 100 mg/m2-Ifosfamide: 5 g/m2-Cisplatin: 80 mg/m2) was considered as the maximum tolerated dose (MTD) and recommended for further phase II testing. Among evaluable patients in phase II, 31/46 (67%; CI = 54-81%) responded; 4 were complete responses, 27 partial responses, 12 with stable disease and 3 with progressive disease. The median response duration was 7 months (2-21+), median time to progression (TTP) 8 months (1-23+) and median overall survival (OS) 13 months (2-23+). The 1-year survival was 57%. Grade (Gr) 3/4 toxicities included neutropenia 39/46 with 27 developing Gr4 (< or =7 days) and 20% FN managed successfully with broad-spectrum antibiotics, thrombocytopenia Gr3 3/46-Gr4 1/46, no Gr3 neuropathy, Gr1-2 CNS toxicity in 12, no renal toxicity, 15 Gr2 myalgias, 17 Gr2 diarrhea and 10 Gr3 vomiting. In the present phase I-II study, DIP appears highly active and tolerable in advanced NSCLC in the outpatient setting. Randomized comparisons to current standard 2-drug regimens will be warranted.

Docetaxel versus paclitaxel for antiangiogenesis

Cytoskeleton-toxic chemotherapeuticals, such as vinblastine and paclitaxel, display antiangiogenic activity. This study was designed to compare paclitaxel to its analog docetaxel and assess their doses still antiangiogenic in vitro and in vivo. Human endothelial cell functions involved in angiogenesis, namely proliferation, chemotaxis, morphogenesis, and secretion of matrix metalloproteinase-2 (MMP-2), MMP-9, and urokinase-type plasminogen activator (uPA) were studied in vitro upon exposure to docetaxel and paclitaxel, whereas their effect on angiogenesis was studied in vivo by using the chick embryo chorioallantoic membrane (CAM) model. Proliferation of mouse embryo fibroblasts and human Kaposi's sarcoma, breast and endometrial carcinoma, and lymphoid tumor cells was also studied. In vitro, 0.5, 0.75, and 1 nM docetaxel and 2, 3, and 4 nM paclitaxel, i.e., non-cytotoxic doses, impacted all endothelial cell functions, but not protease secretion, in a dose-dependent fashion, whereas they did not affect the proliferation of other cells, except those of Kaposi's sarcoma. No apoptosis was induced by 0.5 nM docetaxel and 2 nM paclitaxel, and moderate apoptosis was induced by 1 nM docetaxel and 4 nM paclitaxel. The antiangiogenic effect rapidly disappeared on drug suspension and was accompanied ultrastructurally by thin lesions of cytoskeleton in the form of slight and equally reversible depolymerization and accumulation of microfilaments. Massive endothelial cell apoptosis with evident cytotoxicity and irreversibility were associated with 2 nM docetaxel and 5 nM paclitaxel, although these higher doses were ineffective on other cells except Kaposi's sarcoma cells. In vivo, 1, 2, and 3 nM docetaxel and 4, 8, and 12 nM paclitaxel displayed a dose-dependent antiangiogenic activity. We suggest that very low docetaxel and paclitaxel doses selectively cause organic and functional damage of endothelial cells and that docetaxel is four times stronger. Their antiangiogenic activity could be applied to treat Kaposi's sarcoma and cancers.

Enhanced transgene expression in androgen independent prostate cancer gene therapy by taxane chemotherapeutic agents

PURPOSE

Chemotherapy is often used as a primary therapy for metastatic cancer because it kills cells en masse. However, high doses of chemotherapeutic drugs can cause toxicity in nontarget organs. Gene therapy may provide a better alternative to chemotherapy because its targeting of specific genes may reduce the undesirable toxicity associated with chemotherapy. We evaluated whether the chemotherapeutic agent docetaxel or paclitaxel may be combined with gene therapy to create a new therapeutic regimen for metastatic androgen independent prostate cancer.

MATERIALS AND METHODS

The 2 androgen independent prostate cancer cell lines PC-3 and DU 145 were treated with docetaxel or paclitaxel. Three recombinant adenoviruses containing p21WAF-1/CIP1, p53 protein or beta-galactosidase complementary DNA under the control of cytomegalovirus promoter were used to determine transgene expression. They were evaluated by Western blot analysis, beta-galactosidase activity or in vitro growth assays. The [(3)H] labeled E1 deleted adenovirus dl312 was used to determine adenovirus uptake into cells.

RESULTS

Docetaxel and paclitaxel enhanced adenovirus mediated transgene expression. Docetaxel appears to be a more potent growth inhibitor in vitro. Elevated transgene expression in virus infected cells induced by these 2 drugs was produced by increased cytomegalovirus promoter activity rather than increased virus uptake.

CONCLUSIONS

The potential synergy of gene therapy with docetaxel and paclitaxel may be an important direction for future therapy for metastatic androgen independent prostate cancer.

Premenopausal Breast Cancer

Modern treatment of premenopausal breast cancer is based on well-established prognostic and predictive factors for disease outcome such as nodal status, hormone receptor expression, tumour size, tumour grading and patient age. The development of strategies according to such individual risk profiles has resulted in significant improvements both in overall and disease-free survival. An abundant number of new prognostic and predictive factors in addition to those already mentioned may help to increase our understanding of the biology of breast cancer and to individualize therapy in premenopausal patients. Although less than 10% of patients directly benefit, it is estimated that approximately each year the life of more than 4000 women in Germany will be saved or prolonged by adjuvant treatment. Whether dose intensive modifications and new antineoplastic drugs can improve disease outcome will be clarified when ongoing studies have increased observation time. At present, hormone ablation via surgical, radiotherapeutical or drug-induced castration in addition to selective estrogen response modifiers (SERM), such as tamoxifen, with or without chemotherapy remains the cornerstone of adjuvant treatment in premenopausal patients with breast cancer. In advanced disease, new highly effective hormonal and other target-oriented antineoplastic agents with few adverse effects have been recently introduced. However, overall survival in metastatic disease remains poor, even when intensive or high-dose chemotherapy is used. Special attention must be given to longer follow up and potential toxic long-term adverse effects of therapy when new regimens are applied in clinical trials.

Combination chemotherapy of the taxanes and antimetabolites: its use and limitations

In an effort to improve response rates of chemotherapy, taxanes have been combined with other cytotoxic agents such as antimetabolites. However, the use of some of these combinations in patients has been restricted by severe toxicity. The significance of the sequence of drug administration in combining methotrexate (MTX) and taxanes was recognised in in vitro studies, showing synergistic effects for the sequence of MTX followed by paclitaxel, and antagonism for exposure in the reverse order. A possible explanation might be an MTX-induced synchronisation of cells in the S phase of the cell cycle, after which cells are more susceptible for the cytotoxic action of taxanes. Clinical studies using this sequence were hampered by severe neutropenia and mucositis at relatively low doses of both drugs. As no pharmacokinetic interactions were observed, the excess of toxicity may have been due to sequence-dependent synergistic actions on bone marrow and mucosa. In contrast, and confusingly, in vitro studies on 5-fluorouracil (5-FU) and taxanes indicate that 5-FU preceeding or simultaneously given to paclitaxel impairs cytotoxicity as compared with paclitaxel monotherapy, while the reverse sequence results in additive or synergistic cytotoxicity. While almost all clinical studies have used the sequence of a taxane followed by 5-FU, various schedules appeared feasible and effective. The combination of a 5-FU analogue, capecitabine and taxanes was supported by in vitro data. A large phase III trial confirmed the feasibility and superior efficacy of this combination in breast cancer patients relapsing after an anthracycline. Conflicting results exist on the benefit of combining gemcitabine and taxanes in tumour cell lines. Although the accumulation of gemcitabine triphosphate (dFdCTP) in mononuclear cells was significantly higher with an increasing dose of paclitaxel, no pharmacokinetic interactions for both agents were noticed. A pharmacokinetic analysis of the gemcitabine-docetaxel combination therapy has not been published in detail. Despite numerous trials, so far no optimum schedule has been established. Regarding data on actually delivered dose intensities, a 2- or 3-weekly cycle seems favourable and feasible. However, possible severe pulmonary toxicity warrants cautious monitoring of patients treated with this combination. Different outcomes of preclinical and clinical studies reveal that combining two chemotherapeutic agents is not simply a matter of putting antitumour activities together. Drug interaction may result in synergism, not only of efficacy but also of toxic side-effects. Adding two drugs may also implicate antagonism in drug efficacy due to unwanted interference in cytotoxicity or pharmacokinetics. For agents acting at a specific phase of the cell cycle, the sequence of administration may determine the efficacy and toxicity of a combination therapy. Because of an observed discrepancy between in vitro data and clinical studies, we would like to emphasise the need for adequate dose-finding clinical trials together with pharmacokinetic data analysis before examining any new combination chemotherapy in more detail in phase II studies.

Cremophor EL: the drawbacks and advantages of vehicle selection for drug formulation

Cremophor EL (CrEL) is a formulation vehicle used for various poorly-water soluble drugs, including the anticancer agent paclitaxel (Taxol). In contrast to earlier reports, CrEL is not an inert vehicle, but exerts a range of biological effects, some of which have important clinical implications. Its use has been associated with severe anaphylactoid hypersensitivity reactions, hyperlipidaemia, abnormal lipoprotein patterns, aggregation of erythrocytes and peripheral neuropathy. The pharmacokinetic behaviour of CrEL is dose-independent, although its clearance is highly influenced by duration of the infusion. This is particularly important since CrEL can affect the disposition of various drugs by changing the unbound drug concentration through micellar encapsulation. In addition, it has been shown that CrEL, as an integral component of paclitaxel chemotherapy, modifies the toxicity profile of certain anticancer agents given concomitantly, by mechanisms other than kinetic interference. A clear understanding of the biological and pharmacological role of CrEL is essential to help oncologists avoid side-effects associated with the use of paclitaxel or other agents using this vehicle. With the present development of various new anticancer agents, it is recommended that alternative formulation approaches should be pursued to allow a better control of the toxicity of the treatment and the pharmacological interactions related to the use of CrEL.

Chemotherapy of metastatic breast cancer: what to expect in 2001 and beyond

Chemotherapy plays an important role in the management of metastatic breast cancer. The anthracyclines (doxorubicin, epirubicin) and the taxanes (paclitaxel, docetaxel) are considered the most active agents for patients with advanced breast cancer. Traditionally, the anthracyclines have been used in combination with cyclophosphamide and 5-fluorouracil (FAC, FEC). The taxanes have single-agent activity similar to older combination chemotherapy treatments. There is great interest in developing anthracycline/taxane combinations. Capecitabine is indicated for patients who progress after anthracycline and taxane therapy. Vinorelbine and gemcitabine have activity in patients with metastatic breast cancer and are commonly used as third- and fourth-line palliative therapy. The role of high-dose chemotherapy is not well-defined and remains experimental. Novel cytotoxic therapy strategies include the development of anthracycline, taxane, and oral fluoropyrimidine analogues; antifolates; topoisomerase I inhibitors, and multidrug resistance inhibitors. A better understanding of the biology of breast cancer is providing novel treatment approaches. Oncogenes and tumor-supressor genes are emerging as important targets for therapy. Trastuzumab, a monoclonal antibody directed against the Her-2/neu protein, has been shown to prolong survival in patients with metastatic breast cancer. Other novel biologic therapies interfere with signal transduction pathways and angiogenesis. The challenge for the next decade will be to integrate these promising agents in the management of metastatic and primary breast cancer.

Role of formulation vehicles in taxane pharmacology

The non-ionic surfactants Cremophor EL (CrEL) and Tween 80, both used as formulation vehicles of many (anticancer) agents including paclitaxel and docetaxel, are not physiological inert compounds. We describe their biological properties, especially the toxic side effects, and their pharmacological properties, such as modulation of P-glycoprotein activity. In detail, we discuss their influence on the disposition of the solubilized drugs, with focus on CrEL and paclitaxel, and of concomitantly administered drugs. The ability of the surfactants to form micelles in aqueous solution as well as biological fluids (e.g. plasma) appears to be of great importance with respect to the pharmacokinetic behavior of the formulated drugs. Due to drug entrapment in the micelles, plasma concentrations and clearance of free drug change significant leading to alteration in pharmacodynamic characteristics. We conclude with some perspectives related to further investigation and development of alternative methods of administration.

Antitumour activity of novel taxanes that act at the same time as cytotoxic agents and P-glycoprotein inhibitors

Taxanes antitumour agents such as paclitaxel and docetaxel represent a successful family of chemotherapeutic drugs. Unfortunately, acquired and innate resistance represents a clinical problem for these drugs. We investigated, on a panel of 7 human cancer cell lines, the growth inhibition effect of 3 newly developed taxanes (SB-T-1213, SB-T-1250 and SB-T-101187) with modification at the C10 and C3' positions of the taxane framework. These positions have been previously characterized as critical to make taxanes highly active against cells overexpressing the efflux pump P-glycoprotein (P-gp). Paclitaxel and docetaxel were used as reference compounds. Results unambiguously indicate the exceptional activity of the novel taxanes toward P-gp positive cells (up to >400 fold higher potency than that of paclitaxel). SB-T-1213 and SB-T-1250 are also substantially more active than the reference compounds against P-gp negative cells. To better understand the mechanisms underlying the enhanced activity of the newly developed taxanes, we performed cell cycle and apoptosis analysis. This study demonstrates that the striking growth inhibition effect exhibited by the novel taxanes is ascribed to their increased ability in inducing apoptosis and G(2)/M cell cycle block. SB-T-1213 and SB-T-1250 are also more active than reference compounds in inducing intracellular accumulation of the beta-tubulin subunits. Finally, it is revealed that these novel taxanes have ability to inhibit the function of the P-gp efflux pump on the basis of the Rhodamine 123 assay. These findings strongly suggest that SB-T-1213, SB-T-1250 and SB-T-101187 represent a new tool to overcome innate or acquired P-gp mediated taxane-resistance.

Risks and benefits of taxanes in breast and ovarian cancer

The taxanes are a unique class of agents with a broad spectrum of clinical activity. They act by binding to tubulin, producing unnaturally stable microtubules and subsequent cell death. The distribution and elimination of paclitaxel depend on dose and administration rate. This nonlinearity is much less evident at lower infusion rates (24-hour infusions) and more evident at high plasma concentrations (3-hour infusions). The pharmacokinetics of docetaxel also suggest the presence of nonlinear pathways, but these appear to be clinically insignificant at the current doses utilised (60 to 100 mg/m2). Both agents undergo hepatic metabolism and biliary excretion and require dose adjustment in the setting of liver dysfunction. Drug interactions are quite common with these agents, some of which are sequence-dependent and clinically significant. The optimal dose of paclitaxel is not known at this time, and controversy over possible dose- or schedule-related differences in efficacy still remain. Docetaxel is somewhat more consistent in its dose and scheduling information, but controversy remains regarding a dose-benefit relationship as well as scheduling differences (weekly vs every 3 weeks). Toxicity profiles for these agents are somewhat different. Paclitaxel is more likely to be associated with peripheral neuropathy and myalgias/arthralgias than docetaxel. Docetaxel is more likely to be associated with a cumulative fluid retention syndrome that can be dose limiting. Paclitaxel and docetaxel are both highly active agents against breast cancer, including tumours that are resistant to anthracyclines. Docetaxel tends to have higher response rates overall, but direct comparisons at maximally tolerated doses have not been completed. Combination regimens with many different agents are attempting to improve on the responses seen with single-agent taxanes. The combination of paclitaxel and a platinum compound should be utilised as first-line therapy of advanced ovarian cancer. Controversy lies in the choice of the platinum compound and the dose and administration schedule of paclitaxel. Substitution of docetaxel for paclitaxel in these platinum-containing regimens is also being investigated. The taxanes also exhibit activity against ovarian cancer in patients previously exposed to platinum agents. These agents may also be administered intraperitoneally for local therapy of metastatic ovarian cancer. Although docetaxel and paclitaxel are often considered similar in activity and tolerability, this review emphasises the fact that these agents are indeed different. Clinicians need to be familiar with the benefits and adverse events related to each agent in order to make informed, appropriate clinical decisions.

Treatment of advanced, refractory breast cancer with alternating docetaxel and epirubicin/cyclophosphamide plus human granulocyte colony-stimulating factor

PURPOSE

A phase II study was performed to investigate the efficacy and tolerance of alternating docetaxel and epirubicin/cyclophosphamide plus recombinant human granulocyte colony-stimulating factor (G-CSF) in patients with advanced breast cancer who failed previous non-anthracycline/taxane-containing palliative chemotherapy.

PATIENTS AND METHODS

Between November 96 and June 98, a total of 45 patients participated in this trial. Chemotherapy consisted of docetaxel 100 mg/m2 given as a 1-h infusion on day 1, and epirubicin 100 mg/m2 plus cyclophosphamide 800 mg/m2 both administered on day 21. G-CSF 5 microg/kg/day was given subcutaneously from days 22-28 during each cycle. Treatment courses were repeated every 42 days for a total of three courses unless prior evidence of progressive disease.

RESULTS

The overall response rate was 57.8% (95% confidence interval, 42.1-72.3%), including seven complete (15.5%) and 19 partial remissions (42.3%); nine patients (20%) had stabilization of disease and 10 (22.3%) progressed. The median time to treatment failure was 7.0 months (range 1.5-26.0), and the median overall survival time 15.0 months (range 2.0-37.0+) with 12 patients (27%) currently still alive with metastatic disease. Myelosuppression was commonly observed with WHO grade 3/4 neutropenia in 20 patients (44%) complicated by septicemia in five (11%). Severe nonhematologic toxicity included stomatitis in five patients (11%), skin and peripheral neurotoxicity each in one patient; alopecia was seen in all 45 patients with complete hair loss in 26 (58%).

CONCLUSIONS

Our data suggest that alternating docetaxel and epirubicin/cyclo-phosphamide plus G-CSF is an effective and tolerable second-line combination regimen for the treatment of advanced breast cancer.

Front-line treatment of advanced breast cancer with docetaxel and epirubicin: a multicenter phase II study

PURPOSE

In a previous phase I trial we evaluated the toxicity and determined the maximum tolerated doses of the docetaxel (D)-epirubicin (Epi) combination. We conducted a multicenter phase II study to evaluate the efficacy and tolerability of this regimen as front-line treatment in women with advanced breast cancer (ABC).

PATIENTS AND METHODS

Fifty-four women with ABC stage IIIB (4 patients) or IV (50 patients) received front-line treatment with Epi 70 mg/m2 on day 1 and D 90 mg/m2 on day 2. The median age was 55 years, performance status (WHO) was 0-1 in 49 patients and visceral disease was present in 45 (83%).

RESULTS

All patients were evaluable for toxicity and 50 for response. In an intent-to-treat analysis complete remission was observed in 5(9%) patients, partial remission in 31 (57%) (overall response rate 66%, 95% confidence interval: 54% 79%), stable disease in 9 (17%) and disease progression in 9 (17%). After a median follow-up of 11.5 months, the median duration of responses was 8 months, the median time to disease progression 11.5 months and the median survival has not yet been reached. The probability of one-year survival was 65%. Three hundred six cycles of treatment were administered (median 6 cycles per patient). Grade 3 and 4 neutropenia was observed in 8 (15%) and 31 (57%) patients, respectively, and febrile neutropenia in 19 (35%). Prophylactic rh-G-CSF was used in 45 (83%) patients or 226 (74%) cycles. Other hematologic or non-hematologic toxicities were usually mild. In five (9%) patients the left ventricular ejection fraction (LVEF) was decreased by more than 10% with the treatment. Two patients died during the treatment of respiratory failure without associated neutropenia.

CONCLUSIONS

The combination of docetaxel epirubicin is an effective and well tolerated front-line treatment in patients with ABC.

Single-agent docetaxel in metastatic breast cancer patients pre-treated with anthracyclines and paclitaxel: partial cross-resistance between paclitaxel and docetaxel

The purpose of this study was a retrospective analysis of docetaxel in a cohort of anthracyclines and paclitaxel pretreated patients with metastatic breast cancer. From July 1998 to June 1999, 24 consecutive patients were included for this study. The regimen consisted of docetaxel 75 mg/m2 in combination with a 3-day schedule of dexamethasone every 3 weeks until disease progression or unacceptable toxicity. The median age of patients was 53 (ranged 32-67) years with a median performance status of 2. Twenty of the 24 patients (84%) had measurable disease. The median number of organs involved was 2 (range 1-4). A total of 146 cycles chemotherapy were given with a mean of 6. There was a 25% (six of 24) overall response rate including one complete response, 37.5% stable disease and 37.5% progressive disease. The major toxicity included grade 3-4 leukopenia (41.7%) and eight episodes of infection. No treatment-related death was observed. The responders included patients refractory to or resistant to prior paclitaxel treatment. The median survival and median time to disease progression was 12 and 9 months, respectively. We conclude that docetaxel has a modest activity in breast cancer patients pre-treated with anthracyclines and paclitaxel, indicating a partial cross-resistance between paclitaxel and docetaxel.

Pharmacokinetics of ifosfamide are changed by combination with docetaxel: results of a phase I pharmacologic study

The pharmacokinetics of the combination of docetaxel and ifosfamide were studied in a phase I study. Docetaxel was given to cancer patients as a 1-hour infusion followed by a 24-hour infusion of ifosfamide (schedule A). After the dose-limiting toxicity of the combination was reached, ifosfamide was administered as a 24-hour infusion followed after 24 hours by a 1-hour infusion of docetaxel (schedule B). Cycle duration was 21 days. Docetaxel was determined by high-performance liquid chromatography, and ifosfamide and its metabolites, by gas chromatography-mass spectrometry. Twenty-seven patients were treated according to schedule A, and 6 according to schedule B. Combining the two drugs did not change their respective plasma half-lives. The sequence of drug administration did not affect the clearance and the area under the curve (AUC) of docetaxel. There was a decrease in the AUC of ifosfamide in schedule A compared with schedule B, resulting from an increase in the clearance of ifosfamide. The pharmacokinetics of docetaxel are not influenced by combination with ifosfamide, regardless of the drug sequence, but ifosfamide pharmacokinetics are changed by docetaxel, depending on the sequence of administration. The increase of clearance in schedule A may be due to the pretreatment with corticosteroids.

Use of docetaxel (Taxotere) in patients with paclitaxel (Taxol) hypersensitivity

Anaphylaxis or significant hypersensitivity reaction is one of the most catastrophic potential complications of chemotherapy. There is a 2-5% risk of hypersensitivity with paclitaxel, a commonly used chemotherapeutic agent for various cancers. Three patients, who developed hypersensitivity to paclitaxel infusion, received docetaxel without allergic reactions. Docetaxel may therefore be an alternative treatment for patients with paclitaxel hypersensitivity.

Syntheses and biological activity of C-3'-difluoromethyl-taxoids

A series of new taxoids bearing difluoromethyl group at the C-3' position and modifications at the C-10 and C-14 positions has been synthesized and their biological activities studied. The in vitro cytotoxicity assay results indicate that these newly developed taxoids exhibit comparable to several times better activity against drug-sensitive cell line LCC6-WT, and 40-70 times better activity against the corresponding drug-resistant cancer cell line LCC6-MDR as compared to that of paclitaxel. Apoptosis analysis has revealed the exceptional activity of SB-T-12843 (1e) in inducing apoptosis in both MDR-bearing and MDR-negative cancer cells.

Synthesis of highly potent second-generation taxoids through effective kinetic resolution coupling of racemic beta-lactams with baccatins

A series of highly potent second-generation taxoids bearing a 2-methylprop-1-enyl or a 2-methylpropyl group at C-3' with modifications at the C-2, C-10, and C-14 positions was synthesized through the coupling of racemic cis-beta-lactams with properly protected/modified baccatin and 14-OH-baccatin. A high level of kinetic resolution was observed for all cases examined. The observed highly efficient enantiomer differentiation is ascribed to the markedly different chiral environment between the (+)- and (-)-beta-lactams in their approach to the chiral framework of the enantiopure lithium alkoxide of a baccatin in the ring-opening coupling process. It was also observed that substantially higher selectivity was achieved when 14-OH-baccatin-1,14-carbonate was used. Analysis of the transition state models revealed that the repulsive interactions between the 3-TIPS group of a (-)-beta-lactam with 1, 14-carbonate group of the baccatin substantially increases the asymmetric bias in the kinetic resolution process, favoring the reaction of a (+)-beta-lactam, which leads to the observed excellent selectivity.

Inter-relationships of paclitaxel disposition, infusion duration and cremophor EL kinetics in cancer patients

Cremophor EL (CrEL) is a castor oil surfactant used as a vehicle for formulation of a variety of poorly water-soluble agents, including paclitaxel. Recently, we found that CrEL can influence the in vitro blood distribution of paclitaxel by reducing the free drug fraction, thereby altering drug accumulation in erythrocytes. The purpose of this study was to investigate the clinical pharmacokinetics of CrEL, and to examine inter-relationships of paclitaxel disposition, infusion duration and CrEL kinetics. The CrEL plasma clearance, studied in 17 patients for a total of 28 courses, was time dependent and increased significantly with prolongation of the infusion duration from 1 to 3 to 24 h (p<0.03). An indirect response model, applied based on use of a Hill function for CrEL concentration-dependent alteration of in vivo blood distribution of paclitaxel, was used to fit experimental data of the 3 h infusion (r2=0.733; p=0.00001). Simulations for 1 and 24 h infusions using predicted parameters and CrEL kinetic data revealed that both short and prolonged administration schedules induce a low relative net change in paclitaxel blood distribution. Our pharmacokinetic/pharmacodynamic model demonstrates that CrEL causes disproportional accumulation of paclitaxel in plasma in a 3 h schedule, but is unlikely to affect drug pharmacokinetics in this manner with alternative infusion durations.

Cytotoxic effects of topotecan combined with various active G2/M-phase anticancer drugs in human tumor-derived cell lines

Topotecan (TPT) is a DNA-Topoisomerase I poison that exhibits antitumor activity. TPT, like other DNA-damaging agents, arrests or delays cell cycle progression during S- and G2-phase in a wide variety of tumor-derived cell lines. Particularly, the G2-arrest gives time for the cell to repair its DNA lesions prior to starting a new cell cycle. Based on these observations, we assessed the interaction between TPT and G2/M-active agents in p53-mutated cell lines of diverse origin in order to achieve cell toxicity. Two short-term sequential schedules were administered (TPT --> G2/M-active drug at the interval of greatest TPT-induced G2/M-phase cell arrest, and G2/M-active drug --> TPT), in three human tumor-derived cell lines with proven sensitivity to the following drugs: Bleomycin in HEp-2 (squamous larynx carcinoma); Docetaxel in SKBr-3 (breast adenocarcinoma); Etoposide in NCI-H23 (non-small-cell lung cancer). Our results show that: 1) Sequential TPT --> G2/M-active drugs are synergistic when administration overlapped the maximum percentage of TPT-induced G2/M-phase cell arrest interval in all three mutated p53 cell lines; 2) the reverse sequential schedule (G2/M-active drug --> TPT) was antagonistic, and being only additive for Etoposide --> TPT association. In conclusion, our findings further support the potential cytotoxic role of TPT in combination with other active drugs when the correct schedule of administration is applied. In addition, they provide a rationale for new applications in clinical trials using short-term sequential TPT --> G2/M-active drugs.

Docetaxel (Taxotere)-cisplatin (TC): an effective drug combination in gastric carcinoma. Swiss Group for Clinical Cancer Research (SAKK), and the European Institute of Oncology (EIO)

PURPOSE

A multi-centric trial was performed to explore the clinical activity, in terms of response and toxicity (primary objectives), duration of response and survival (secondary objectives), of docetaxel with cisplatin in advanced gastric cancer (AGC).

PATIENTS AND METHODS

Patients with measurable unresectable and/or metastatic gastric carcinoma, performance status < or = 1, normal hematological, hepatic and renal functions and not pretreated for advanced disease by chemotherapy received up to eight cycles of TC (docetaxel 85 mg/m2 dl, cisplatin 75 mg/m2 dl) q3w. Dose escalation to 100 mg/m2 was performed in five patients and was discontinued for excessive toxicity.

RESULTS

Forty-eight patients were accrued. A median of 5 cycles/patient was given. We observed 2 complete and 25 partial responses for an overall intent to treat response rate of 56% (95% CI: 41%-71%). Twelve patients had stable disease for > or = 9 weeks (3 cycles). The median time to progression and overall survival were 6.6 and 9 months, respectively. Grade > or = 3 toxicities were neutropenia 81%, anemia 32%, thrombocytopenia 4%, alopecia 36%, fatigue 9%, mucositis 9%, diarrhea 6%, nausea/vomiting 4%, neurologic 2%, and one anaphylaxis precluding treatment administration. We recorded nine episodes of non-fatal febrile neutropenia in eight patients, two of them with docetaxel at 100 mg/m2. There were no direct treatment-related deaths.

CONCLUSIONS

TC is active in AGC with a high response rate in a multicentric trial. Despite its hematotoxicity, this regimen is well tolerated and can be recycled as originally planned in 78% of the cases. These results may serve as basis for further developments of docetaxel containing regimens in this disease.

Current options in treatment of anthracycline-resistant breast cancer

Breast cancer is a chemosensitive tumour and anthracyclines are one of the most active cytotoxic agents in chemotherapy treatment. Failure after anthracycline-containing chemotherapy is a poor prognostic factor because of low response rate to salvage chemotherapy. Several factors like P-glycoprotein mediated drug resistance (MDR-1 or MRP), glutathione or amplification of topoisomerase II have been found to be involved in anthracycline resistance. No clear benefit for patients treated with 'resistance-modifier' agents like verapamil, dexverapamil or quinidine has yet been demonstrated. Most clinical studies with non-cross resistant cytotoxic agents are lacking a strict definition of anthracycline resistance. A strict definition of anthracycline resistance implies progressive disease during anthracycline chemotherapy. Among the cytotoxic drugs only 5-Fluorouracil (given as 24 h continuous infusion with folinic acid) and the taxanes produce more than 20% objective remission (RR) in case of anthracycline resistance, whereas the highest response rate was reported for docetaxel (32-57%). Only few randomized studies were performed: docetaxel showed higher anti-tumor activity than methotrexat/5-FU (RR: 42% vs 19%, P<0.001) or mitomycin/vinblastine (RR: 30% vs 12%;P<0.001) and treatment with paclitaxel (175 mg/m(2)) was in favour to mitomycin (RR 17% vs 6%). In combination chemotherapy most activity have been reported for paclitaxel plus high-dose 5-fluorouracil (given as 24 h continuous infusion with folinic acid) (RR: 58%) or for docetaxel plus cisplatinum (RR: 46%). High-dose regimens with growth factor or stem cell support seems to be active in anthracycline-resistant disease but the toxicity is considerable. In conclusion, the taxanes, especially docetaxel as single agent or paclitaxel plus high-dose 5-FU, are the most promising therapeutic options in treatment of anthracycline resistant disease. Further clinical phase II/III studies in breast cancer should include exact definition of anthracycline pretreatment and resistance.

Paclitaxel efficacy and tolerability in second-line treatment of refractory and relapsed ovarian cancer patients

Nineteen patients with recurrent or refractory ovarian carcinoma after a first-line platinum-based chemotherapy were treated with a 3-hour i.v. infusion of paclitaxel 175 mg/m2 every 3 weeks from November 1992 to October 1996. The major hematologic toxicity was neutropenia (63.2%). No febrile neutropenia was observed. Other hematologic effects were leukopenia (47.4%) and anemia (47.4%). The main non-hematologic toxicities were as follows: neuropathy (52.6%), nausea and vomiting (36.8%), myalgia (36.8%), cardiac toxicity (15.8%) and mucositis (10.5%). Alopecia was observed in the majority of cases. The overall response rate was 47.4%, with 5 (26.3%) complete responses (CRs) and 4 (21.1%) partial responses (PRs). The median duration of response was 7 months (range: 3-19), with a median follow-up of 17 months (range: 3-61). Quality of life of responding patients was good. Our results confirm that paclitaxel as second-line therapy in relapsed and refractory ovarian cancer patients is an acceptable treatment with a good safety profile, and can be safely administered at the dose of 175 mg/m2. In our study paclitaxel was more active in relapsed than in refractory patients. Consequently, further studies are needed to identify more effective drugs for the refractory subset.

Front-line treatment of metastatic breast cancer with docetaxel and epirubicin: a multicenter dose-escalation study. The Greek Breast Cancer Cooperative Group (GBCCG)

PURPOSE

To determine the maximum tolerable dose (MTD) and the dose-limiting toxicity (DLT) of docetaxel (D) in combination with epirubicin (Epi) in patients with advanced breast cancer.

PATIENTS AND METHODS

Forty-seven chemotherapy-naïve metastatic breast cancer patients aged < 75 years with PS (WHO) 0-2 and adequate bone marrow, renal, liver and cardiac function, were enrolled in the study. Epi was given as a five-min bolus i.v. infusion on day 1 (d1) in escalated doses with increments of 10 mg/m2; D was given in a one-hour infusion after appropriate premedication on either day 1 or on day 2 in escalated doses with increments of 10 mg/m2. The patients' median age was 60 years, 42 (89%) had a PS (WHO) 0-1, 16 (34%) were premenopausal and 25 (53%) had visceral disease.

RESULTS

When the two drugs were given on the same day, the MTD1 was reached at the doses of Epi 60 mg/m2 and D 80 mg/m2; administration of G-CSF could not result in a dose intensification. When the drugs were given on two consecutive days, the MTD2 was reached at the doses of Epi 80 mg/m2 (d1) and D 90 mg/m2 (d2). The dose-limiting events were febrile neutropenia and grade 4 neutropenia, which developed in 30 (64%) patients during the study; among 227 delivered cycles grade 3-4 neutropenia occurred in 64 (28%) cycles but only 22 (10%) of them were complicated by fever. There were no septic deaths. Grade 1-2 neurosensory toxicity occurred in nine (19%) patients, mild edema in eight (17%) and allergic reactions in five (11%). Four (9%) patients presented a greater than 10% decrease of LVEF and treatment discontinuation was required in two of them; none of the patients developed congestive heart failure. Nevertheless, one patient suddenly died 10 days after treatment initiation of myocardial ischemia, and this death is considered treatment-related. Five (14.7%) complete and thirteen (38.2%) partial responses (ORR: 53.9%; 95% confidence interval: 36.1%-69.7%) were observed in 34 evaluable patients. Ten (29.4%) and six (17.6%) patients had stable and progressive disease, respectively. The median duration of response and time to tumor progression were five and seven months, respectively. The median survival has not yet been reached.

CONCLUSIONS

The combination of epirubicin and docetaxel is a feasible and well tolerated regimen, but the MTD depends on the administration schedule of the drugs.

Monotherapy of Metastatic Breast Cancer: A Review of Newer Agents

Purpose. New agents for the palliative treatment of metastatic breast cancer have emerged in the 1990s. This review summarizes the response rates of these agents with an emphasis on recent findings, such as presentations from the 1998 Meeting of the American Society of Clinical Oncology.

Methods. The English medical literature was reviewed to identify clinical trials involving monotherapy for the treatment of metastatic breast cancer. Three agents—paclitaxel, vinorelbine, and docetaxel—are emphasized because their databases are extensive enough to allow interesting comparisons. Liposomal-encapsulated anthracyclines, losoxantrone, gemcitabine, oral surrogates of continuous-infusion fluorouracil, raltitrexed, LY 231514, edatrexate, topoisomerase I inhibitors, and trastuzumab are reviewed briefly.

Results. Many of the new agents produce response rates approaching or even surpassing those achievable with doxorubicin monotherapy. Compared with older agents, some new agents have improved or at least different safety profiles, and some are easier to administer.

Discussion and conclusions. The new agents offer useful therapeutic options that make them suitable for combining with each other and with older agents, which could result in more effective regimens for metastatic disease, and, ultimately, primary disease in the adjuvant setting. The chemotherapeutic paradigms governing the management of breast cancer for the past three decades are likely to change as we move into the 21st century.

Linearized colorimetric assay for cremophor EL: application to pharmacokinetics after 1-hour paclitaxel infusions

Cremophor EL (CrEL) is a polyoxyethylated castor oil surfactant used in the intravenous formulation of the anticancer drug paclitaxel (Taxol). Quantitative determination of CrEL in patient samples can be achieved by complexation of the compound with the Coomassie brilliant blue G-250 dye in protein-free extracts [Sparreboom, A., Loos, W. J., Verweij, J., De Vos, A. I., Van der Burg, M. E. L., Stoter, G., and Nooter, K., Anal. Biochem. 255, 171-175 (1998)]. A disadvantage of this method of CrEL determination is that the assay plot of absorbance at 595 nm, the peak wavelength of the CrEL-dye complex, versus the concentration of the surfactant is not linear. The present study shows that the nonlinearity is associated with a decrease in the free dye concentration and a reduction in complex formation by increasing the CrEL concentration. By measurement of the ratio of absorbances at the maxima of the red (450 nm) and blue charge forms (595 nm) of Coomassie brilliant blue G-250, a full-scale linear relationship can be obtained over the entire range studied (0.500 to 10.0 microliter/mL). Validation data revealed that transformation of the detection procedure exhibits significantly improved specificity, accuracy(</= 6.33% relative error), and precision (< 10.0%) compared to our previous assay. The modified method was successfully applied to the measurement of CrEL in plasma of 11 cancer patients treated with a 1-h infusion of paclitaxel.

Determination of paclitaxel in human plasma using single solvent extraction prior to isocratic reversed-phase high-performance liquid chromatography with ultraviolet detection

An isocratic reversed-phase high-performance liquid chromatographic method with ultraviolet detection at 230 nm has been developed for the determination of paclitaxel in human plasma. Plasma samples were prepared by a selective one-step liquid-liquid extraction involving a mixture of acetonitrile-n-butyl chloride (1:4, v/v). Paclitaxel and the internal standard docetaxel were separated using a column packed with ODS-80A material, and a mobile phase consisting of water-methanol-tetrahydrofuran-ammonium hydroxide (37.5:60:2.5:0.1, v/v). The calibration graph for paclitaxel was linear in the range 10-500 ng/ml, with a lower limit of quantitation of 10 ng/ml, using 1 ml plasma samples. The extraction recoveries of spiked paclitaxel and docetaxel to drug-free human plasma were 89.6+/-8.52 and 93.7+/-5.0%, respectively. Validation data showed that the assay for paclitaxel is sensitive, selective, accurate and reproducible. The assay has been used in a single pharmacokinetic experiment in a patient to investigate the applicability of the method in vivo.

Anthracycline-Resistant Breast Cancer

The management of breast cancer requires the judicious use of cytotoxic therapy, hormone therapy, radiotherapy, analgesics, and other forms of physical and psychological support for optimal palliation of symptoms and prolongation of survival. Patients with low-risk metastatic breast cancer often benefit from hormone therapy as initial management; other patients are best treated with early introduction of cytotoxic therapy. Combination chemotherapy is superior to single-agent treatment, and anthracycline-containing regimens are more effective than the rest. The development of primary or secondary resistance to anthracycline therapy represents an adverse prognostic indicator, associated, until recently, with poor response to subsequent cytotoxic therapy and short survival. Prior to the development of taxanes, response to second- and third-line chemotherapy for patients with primary anthracycline resistance was observed in 5% of patients. Paclitaxel and docetaxel retain substantial antitumor activity in anthracycline-resistant breast cancer, and vinorelbine is also moderately effective in this subset of patients. Attempts to reverse P-glycoprotein-related drug resistance, while encouraging in the laboratory, have not been successful in the clinic. A number of novel therapeutic interventions, many that bypass traditional mechanisms of drug resistance, are currently in clinical developments, with encouraging preliminary results.

Synthesis of novel 3'-trifluoromethyl taxoids through effective kinetic resolution of racemic 4-CF3-beta-lactams with baccatins

The coupling of racemic 1-tBoc-4-CF3-beta-lactams with various C-10 modified baccatins has resulted in CF3-taxoids with diastereoselectivities ranging from 9:1 to one single isomer. The observed high diastereoselectivity is ascribed to the highly efficient enantiomer-differentiation by the enantiopure lithium alkoxide of a baccatin III in the coupling reaction with a racemic 1-tBoc-beta-lactam. These novel CF3-taxoids have also been shown to exhibit significant increases in activity against various cancer cell lines compared to either paclitaxel or docetaxel. In addition, the first asymmetric synthesis of a CF3-beta-lactam via chiral ester enolate-imine cyclocondensation was performed with 50% enantioselectivity.

Differential modulation of cisplatin accumulation in leukocytes and tumor cell lines by the paclitaxel vehicle Cremophor EL

BACKGROUND

Several clinical studies have shown that polychemotherapy with the taxanes paclitaxel or docetaxel preceded or followed by cisplatin is associated with important schedule-dependent differences in toxicities, such as leukocytopenia. In general, the pharmacokinetics of both drugs during the combined treatment are unaltered, suggesting that a pharmacodynamic interaction might have occurred.

MATERIALS AND METHODS

In order to gain insight into this pharmacologic interaction, we performed in vitro drug accumulation studies using peripheral blood leukocytes and a panel of tumor and non-malignant cell lines with paclitaxel and docetaxel, as well as with their respective formulation vehicles Cremophor EL and Tween 80.

RESULTS

Our results show a significant reduction in the intracellular cisplatin concentration in leukocytes of up to 42% in the presence of Cremophor EL and Tween 80 as compared to the control. This pharmacodynamic interaction of these surfactants with cisplatin seems to be specific for haematopoietic cells, and does not occur in solid tumor cells.

CONCLUSION

The present data suggest that the pharmaceutical vehicles Cremophor EL and Tween 80 might contribute to the reduced cisplatin-associated myelotoxicity observed in the clinical combination chemotherapy studies with paclitaxel and docetaxel.

[Docetaxel (taxotere) in non-small-cell bronchial carcinoma]

BACKGROUND

Various new drugs with different mechanisms of action are presently under investigation for the field of solid tumors. The taxanes, Taxotere and Taxol, are among those drugs possessing a unique mechanism of action but showing pharmacological differences.

CONCLUSION

The results of several phase I and II studies of Taxotere in monotherapy as well as in combination schedules with chemotherapy and Radiotherapy show Taxotere to be active in non small cell lung cancer and build the basis for further evaluation in clinical trials.

Activity and toxicity of docetaxel (Taxotere) in women with previously treated metastatic breast cancer

BACKGROUND

Metastatic breast cancer is a major cause of cancer death in Australian women. Docetaxel is a new cytotoxic drug that has shown promise in the treatment of metastatic breast cancer in patients who have previously received other chemotherapy, particularly an anthracycline, and has recently been approved for marketing in Australia.

AIM

To report the first Australian experience with docetaxel in a group of women with metastatic breast cancer.

METHODS

Patients with progressive metastatic breast cancer who had previously received other chemotherapy were treated with docetaxel 75 mg/m2 or 100 mg/m2 given as a one hour infusion every three weeks. All patients received oral dexamethasone for five days starting 24 hours prior to docetaxel as prophylaxis against fluid retention. The patients' response to docetaxel and toxicity were assessed by standard criteria.

RESULTS

Twenty-six patients were treated. The major toxicity was neutropenia with 92% of patients experiencing at least one episode of grade 4 (absolute neutrophil count < 0.5 x 10(9)/L) neutropenia. Hospital admission for febrile neutropenia occurred in 44% of patients with one death from sepsis. Cumulative fluid retention was observed but in only one patient was it dose-limiting. Apart from alopecia, other toxicities were infrequent and rarely serious. In 23 patients assessable for response, there were 11 partial responses (48%). Three other patients whose disease could not be assessed for response had clinical improvement. The median survival of all patients treated was eight months.

CONCLUSIONS

The response rate observed with docetaxel is comparable to that seen in trials in the United States and Europe and confirms the high activity of this new cytotoxic agent. Neutropenia is the major toxicity, and consideration should be given to the use of prophylactic oral antibiotics or colony stimulating factors to try and prevent febrile episodes. Clinicians will need to balance the benefits, toxicities, and cost of docetaxel in determining the appropriateness of its use in their patients.

Doubling epirubicin dose intensity (100 mg/m2 versus 50 mg/m2) in the FEC regimen significantly increases response rates. An international randomised phase III study in metastatic breast cancer. The Epirubicin High Dose (HEPI 010) Study Group

PURPOSE

A phase III study was performed in patients with metastatic breast cancer (MBC) to evaluate the effect on response rate and survival of a doubling of the epirubicin dose intensity.

PATIENTS AND METHODS

Four hundred fifty-six patients were randomised to receive either epirubicin 100 mg/m2 or 50 mg/m2 in combination with 5-FU (500 mg/m2) and cyclophosphamide (500 mg/m2) (FEC 100 vs. FEC 50) i.v., every 21 days for a maximum of six cycles (eight in case of CR).

RESULTS

Of 456 patients, 390 were evaluable for efficacy. Objective response (CR + PR) was seen in 57% (FEC 100) vs. 41% (FEC 50) of the evaluable patients (P = 0.003). The CR rate was higher in the FEC 100 arm (12% vs. 7%, P = 0.07). FEC 100 produced significantly higher response rates in patients with visceral localisation (50% vs. 34%, P = 0.011) and in patients with more than two metastatic organ sites (64% vs. 37%, P = 0.001). Median time to progression (7.6 vs. 7 months) and overall survival (18 months vs. 17 months) were similar. Myelosuppression was the principal toxic effect, with grade IV neutropenia observed in 57% of the patients treated with FEC 100 vs. 9% of those on FEC 50. Grade IV infection or febrile neutropenia were observed in 8% (FEC 100) vs. 0.4% (FEC 50), but the incidence of septic death was the same in the two arms (two patients each). Cardiac toxicity was similar in the two treatment groups, with 5% vs. 3% of the patients taken off study due to cardiac events, primarily due to a decline in LVEF. Only three patients (two in FEC 100) experienced congestive heart failure.

CONCLUSION

This trial shows that FEC with epirubicin at 100 mg/m2 can be administered for repeated cycles without bone marrow support with increased, though acceptable, toxicity and with a significant increase of antitumor effect (especially in visceral and/or high-burden disease), but no increased survival.

Influence of microtubule-associated proteins on the differential effects of paclitaxel and docetaxel

Microtubules are complex structures arising in part from the polymerization of tubulin dimers. Tubulin binds to a wide range of drugs which have been used as probes for tubulin conformation and assembly properties. There is some evidence that taxol and taxotere have differing effects on tubulin conformation. Previous work has shown that MAP2 and Tau, although they both induce microtubule assembly, have qualitatively different effects on tubulin's behavior. Since most microtubules in vivo are likely to be associated with MAPs, we decided to characterize the differential effects of MAP2, Tau, taxol, and taxotere on tubulin polymerization with the aim of understanding the mechanisms through which these agents stimulate microtubule assembly. Furthermore, the inhibitive effect of calcium has been used to elucidate the ability of the two drugs to force tubulin assembly. These observations suggest that docetaxel, in addition to its greater efficiency in tubulin assembly, may have the capacity to differently alter certain classes of microtubules. Tau and MAP2 accessory proteins may represent important cofactors modulating the effects of taxoids.

Pediatric drug development: a perspective from the Cancer Therapy Evaluation Program (CTEP) of the National Cancer Institute (NCI)

Well-designed and carefully conducted pediatric phase 1 trials are critical to the process of evaluating new agents for potential benefit in children with cancer, and the National Cancer Institute (NCI) has for a number of years sponsored pediatric phase I trials. The development of new agents for children with cancer differs in important ways from drug development for adults with cancer, primarily necessitated by the smaller number of children eligible for phase I trials in comparison to adults. Pediatric drug development is characterized by a greater need to prioritize new agents for evaluation, since many more agents can be evaluated in adults than can be evaluated in children. Pediatric phase I trials are also commonly conducted as multi-institutional collaborations, since most single institutions do not have enough eligible patients to complete phase I trials within a reasonable time. In addition, pediatric phase I trials begin at doses close to the adult maximum tolerated dose, thereby minimizing the number of patients required to complete pediatric phase I trials. While pediatric phase I trials have traditionally evaluated conventional cytotoxic agents, new classes of agents with distinctive mechanisms of action are entering clinical evaluation. These agents target specific cellular proteins (e.g., protein tyrosine kinases, protein kinase C isoforms, enzymes involved in controlling progression through the cell cycle). Determining whether these agents with specificity for critical cellular proteins will be effective anti-cancer agents will be an important objective of pediatric clinical investigations in the coming years.