Taxanes in the Treatment of Breast Cancer: A Prodigy Comes of Age

Brachial plexopathy after breast cancer: A persistent late effect of radiotherapy

Radiation-induced brachial plexopathy (RIBP) is an iatrogenic, progressively disabling, and often very late effect of adjuvant radiotherapy most commonly seen in breast cancer survivors but also in those treated for lymphoma, lung, and head and neck cancers. In late-onset RIBP following breast cancer, the nerve injury is chronic and irreversible, occurring more commonly when axillary and/or supraclavicular nodes have been irradiated, as well as the breast/chest wall. RIBP is manifested initially by paresthesia, hypoesthesia, dysesthesia, and later by weakness in the ipsilateral hand with those symptoms progressing distally to proximally up through the shoulder. Depressed/absent deep tendon reflexes in the upper extremity and muscle fasciculations occur also. Neither patients nor their health care providers tend to associate these unusual neurological symptoms with cancer treatments received ≥20 years prior, often failing to link these sensory-motor symptoms with radiotherapy decades before. Because long-term follow-up of these patients now typically falls to general practitioners, many cases may be missed or misdiagnosed because of the rarity of this disorder. Physiatrists and allied rehabilitation professionals must be aware of this progressively disabling, incurable condition to provide appropriate diagnoses and compensatory rehabilitation therapies. Additionally, professional oncology organizations should include RIBP in their long-term, survivorship guidelines for breast cancer. Researchers examining the iatrogenic late effects of radiotherapy should extend their follow-up periods well beyond the current 5-6 years to ascertain the true incidence of RIBP today. Rehabilitation providers must continue to advocate for awareness, diagnosis, and management of iatrogenic outcomes experienced by long-term cancer survivors.

Docetaxel-encapsulating small-sized polymeric micelles with higher permeability and its efficacy on the orthotopic transplantation model of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) elicits a dense stromal response that blocks vascular access because of pericyte coverage of vascular fenestrations. In this way, the PDAC stroma contributes to chemotherapy resistance, and the small-sized nanocarrier loaded with platinum has been adopted to address this problem which is not suitable for loading docetaxel (DTX). In the present study, we used the poly(d,l-lactide)-b-polyethylene glycol-methoxy (mPEG-b-PDLLA) to encapsulate DTX and got a small-sized polymeric micelle (SPM); meanwhile we functionalized the SPM’s surface with TAT peptide (TAT-PM) for a higher permeability. The diameters of both SPM and TAT-PM were in the range of 15–26 nm. In vitro experiments demonstrated that TAT-PM inhibited Capan-2 Luc PDAC cells growth more efficiently and induced more apoptosis compared to SPM and Duopafei. The in vivo therapeutic efficiencies of SPM and TAT-PM compared to free DTX was investigated on the orthotopic transplantation model of Capan-2 Luc. SPM exerted better therapeutic efficiency than free DTX, however, TAT-PM didn’t outperformed SPM. Overall, these results disclosed that SPM could represent a new therapeutic approach against pancreatic cancer, but its permeability to PDAC was not the only decisive factor.

Small-sized polymeric micelles incorporating docetaxel suppress distant metastases in the clinically-relevant 4T1 mouse breast cancer model

BACKGROUND

The small size of ultra-small nanoparticles makes them suitable for lymphatic delivery, and many recent studies have examined their role in anti-metastasis therapy. However, the anti-metastatic efficacy of small-sized nanocarriers loaded with taxanes such as docetaxel has not yet been investigated in malignant breast cancer.

METHODS

We encapsulated docetaxel using poly(D,L-lactide)1300-b-(polyethylene glycol-methoxy)2000 (mPEG2000-b-PDLLA1300) to construct polymeric micelles with a mean diameter of 16.76 nm (SPM). Patient-like 4T1/4T1luc breast cancer models in Balb/c mice, with resected and unresected primary tumors, were used to compare the therapeutic efficacies of SPM and free docetaxel (Duopafei) against breast cancer metastasis using bioluminescent imaging, lung nodule examination, and histological examination.

RESULT

SPM showed similar efficacy to Duopafei in terms of growth suppression of primary tumors, but greater chemotherapeutic efficacy against breast cancer metastasis. In addition, lung tissue inflammation was decreased in the SPM-treated group, while many tumor cells and neutrophils were found in the Duopafei-treated group.

CONCLUSION

Small-sized mPEG2000-b-PDLLA1300 micelles could provide an enhanced method of docetaxel delivery in breast cancer metastasis, and may represent a valid chemotherapeutic strategy in breast cancer patients with resected primary tumors.

Interleukin-6, multidrug resistance protein-1 expression and response to paclitaxel in women with metastatic breast cancer: results of cancer and leukemia group B trial 159806

Several reports have suggested that breast cancer patients with elevated serum levels of interleukin-6 (IL-6) have a worse prognosis than patients with lower levels. We have studied IL-6 in breast cancer cell lines and have shown that autocrine production of IL-6 can confer multi-drug resistance in vitro by inducing multidrug resistance gene-1 transcription with subsequent overexpression of P-glycoprotein (PGP). Both IL-6 and PGP expression can be measured in malignant cells using immunohistochemical (IHC) techniques. We hypothesized that patients whose tumors expressed higher amounts of IL-6 or PGP would be less likely to respond to paclitaxel, an agent affected by the PGP pathway. If so, then IL-6 could serve as a predictive factor for paclitaxel sensitivity. Both IL-6 and PGP expression were measured in patients treated in a randomized trial that compared three doses of single agent paclitaxel (175, 210, and 250 mg/m(2) over 3 h every 3 weeks) in 469 women with metastatic breast cancer (CALGB 9342). No difference in complete and partial response was found among the three treatment arms. Tissue blocks in this trial were analyzed for IL-6 (154 patients) and PGP (149 patients) in paraffin-embedded sections from tumor samples; clinical characteristics of these patients were similar to the total sample of 469 patients. There were no significant differences among IL-6 or PGP scores whether measured as continuous or dichotomous variables, or by other scoring, and response to paclitaxel. In multivariate analysis neither IL-6 nor PGP was a significant predictor of time to progression or overall survival. IHC expression of IL-6 and PGP levels in tumor cells is not a predictive marker for response to paclitaxel in women with metastatic breast cancer.

Sequential preoperative or postoperative docetaxel added to preoperative doxorubicin plus cyclophosphamide for operable breast cancer:National Surgical Adjuvant Breast and Bowel Project Protocol B-27

PURPOSE

This study was designed to determine the effect of adding docetaxel (T) to preoperative doxorubicin and cyclophosphamide (AC) on breast cancer response rates and disease-free survival (DFS) and overall survival (OS).

PATIENTS AND METHODS

Women with operable breast cancer (N = 2,411) were randomly assigned to receive preoperative AC followed by surgery, AC followed by T and surgery, or AC followed by surgery and then T. Tamoxifen was initiated concurrently with chemotherapy. Median time on study for 2,404 patients with follow-up was 77.9 months.

RESULTS

Addition of T to AC did not significantly impact DFS or OS. There were trends toward improved DFS with addition of T. The addition of T reduced the incidence of local recurrences as first events (P = .0034). Preoperative T, but not postoperative T, significantly improved DFS in patients who had a clinical partial response after AC (hazard ratio [HR] = 0.71; 95% CI, 0.55 to 0.91; P = .007). Pathologic complete response, which was doubled by addition of preoperative T, was a significant predictor of OS regardless of treatment (HR = 0.33; 95% CI, 0.23 to 0.47; P < .0001). Pathologic nodal status after chemotherapy was a significant predictor of OS (P < .0001).

CONCLUSION

The addition of preoperative or postoperative T after preoperative AC did not significantly affect OS, slightly improved DFS, and decreased the incidence of local recurrences. The sample size of this study was not sufficient to yield significance for the moderate DFS improvement. Concurrent use of tamoxifen may have limited the impact of adding T.

Cytotoxicity, apoptosis induction, and mitotic arrest by a novel podophyllotoxin glucoside, 4DPG, in tumor cells

AIM

To define the in vitro cytotoxic activities of 4-demethyl-picropodophyllotoxin 7'-O-beta-D-glucopyranoside (4DPG), a new podophyllotoxin glucoside.

METHODS

Antiproliferation activity was measured in several tumor cell lines by using the microculture tetrazolium MTT assays. Cell cycle distribution was analyzed using flow cytometry and mitosis index assays. Furthermore, transmission electron microscopy, TUNEL, DNA agarose electrophoresis, and activated caspase-3 were used to analyze the induction of apoptotic cell death. Moreover, intracellular changes in the cytoskeleton were detected using immunocytochemistry.

RESULTS

4DPG effectively inhibited the proliferation of cancer cells (HeLa, CNE, SH-SY5Y, and K562 cell lines). For the K562 cell line, the antiproliferation effect of 4DPG was much more potent than that of etoposide (IC50 value: 7.79 x 10(-9) mol/L for 4DPG vs 2.23 x 10(-5) mol/L for etoposide). Further, 4DPG blocked the cell cycle in the mitotic phase. The induction of apoptosis and elevated levels of activated caspase-3 were confirmed in cells treated with 4DPG. The microtubule skeleton of HeLa cells was disrupted immediately after treatment with 4DPG.

CONCLUSION

The cytotoxicity of 4DPG is due to its inhibition of the microtubule assembly of cancer cells at a low concentration, thus inducing apoptosis. These properties qualify 4DPG to be a potential antitumor drug.

The bioactive Taxol conformation on beta-tubulin: experimental evidence from highly active constrained analogs

The important anticancer drug Taxol (paclitaxel) binds to tubulin in a stoichiometric ratio and promotes its assembly into microtubules. The conformation of microtubule-bound drug has been the subject of intense study, and various suggestions have been made. In this work we present experimental and theoretical evidence that Taxol adopts a T-shaped conformation when it is bound to tubulin.

Microtubule-targeted anticancer agents and apoptosis

Over the past decade, significant progress has been made in our understanding of the biology of microtubule (MT) assembly into the mitotic spindle during mitosis and the molecular signaling and execution of the various pathways to apoptosis. In the same period, the microtubule-targeted tubulin-polymerizing agents (MTPAs), notably paclitaxel and taxotere, have come to occupy a central role in the treatment of a variety of human epithelial cancers. Following their binding to B-tubulin, MTPAs inhibit MT dynamic instability, cell cycle G2/M phase transition and mitotic arrest of cancer cells. MTPA-induced anti-MT and cell cycle effects trigger the molecular signaling for the mitochondrial pathway of apoptosis. This triggering is orchestrated through different molecular links and determined by the threshold for apoptosis that is set and controlled diversely in various cancer types. The complexity and regulatory potential of the links and the apoptosis threshold are integral to the transformed biology of the cancer cell. The emerging understanding of this biology and how it is influenced by treatment with MTPAs has highlighted novel strategies to further enhance the antitumor activity and overcome resistance to MTPA-induced apoptosis in cancer cells.

The effect on tumor response of adding sequential preoperative docetaxel to preoperative doxorubicin and cyclophosphamide: preliminary results from National Surgical Adjuvant Breast and Bowel Project Protocol B-27

PURPOSE

The National Surgical Adjuvant Breast and Bowel Project Protocol B-27 was designed to determine the effect of adding docetaxel after four cycles of preoperative doxorubicin and cyclophosphamide (AC) on clinical and pathological response rates and on disease-free and overall survival of women with operable breast cancer.

PATIENTS AND METHODS

Women (N = 2,411) with operable primary breast cancer were randomly assigned to receive either four cycles of preoperative AC followed by surgery (group I), or four cycles of AC followed by four cycles of docetaxel, followed by surgery (group II), or four cycles of AC followed by surgery and then four cycles of docetaxel (group III). Clinical and pathologic tumor responses to preoperative therapy were assessed.

RESULTS

Mean tumor size (4.5 cm) and other key characteristics were evenly balanced among the three treatment arms. Grade 4 toxicity was observed in 10.3% of 2,400 patients during AC treatment, and in 23.4% of 1584 patients during docetaxel treatment. Compared to preoperative AC alone, preoperative AC followed by docetaxel increased the clinical complete response rate (40.1% v 63.6%; P <.001), the overall clinical response rate (85.5% v 90.7%; P <.001), the pathologic complete response rate (13.7% v 26.1%; P <.001), and the proportion of patients with negative nodes (50.8% v 58.2%; P <.001). Pathologic primary breast tumor response was a significant predictor of pathologic nodal status (P <.001).

CONCLUSION

The addition of four cycles of preoperative docetaxel after four cycles of preoperative AC significantly increased clinical and pathologic response rates for operable breast cancer.

Inhibition of microtubule polymerization by 3-bromopropionylamino benzoylurea (JIMB01), a new cancericidal tubulin ligand

3-Bromopropionylamino benzoylurea (JIMB01) is a small molecular weight compound (MW 313) that has been synthesized in our laboratory. This compound showed antiproliferative activities in a panel of thirteen human tumor cell lines with IC(50) values in the range of 0.25 to 0.51 micro M for leukemia and lymphoma cell lines and 0.33 to 9.26 micro M for solid tumor cell lines. The primary action of JIMB01 is to inhibit microtubule polymerization but not depolymerization. A 4 micro M concentration of the compound caused a complete inhibition of microtubule assembly in a cell-free reaction. An increase in the number of human hepatocarcinoma cells blocked in the M-phase was detected 12hr after exposure to JIMB01. The kinase activity of cyclin B1, which is responsible for the G(2)/M transition, was increased accordingly. Bcl-2 phosphorylation became visible, in a western blot, within 6hr in hepatocarcinoma cells treated with JIMB01 at 0.8 micro M or higher. JIMB01-induced apoptosis in liver cancer cells was confirmed by morphological methods, flow cytometry, as well as DNA gel electrophoresis, which clearly demonstrated DNA degradation in the form of a multiple-unit DNA ladder. Furthermore, in vivo experiments using nude mice showed that intraperitoneal injection of JIMB01 at 15mg/kg (with seven injections at 4-day intervals) significantly inhibited the growth of a human hepatocarcinoma (BEL-7402) by 66% in tumor volume (P=0.01), at least compatible to the inhibition by vincristine (43% inhibition), indicating good bioavailability of the compound in the circulation. Side-effects of the compound were not observed, and the body weight of the treated mice remained stable during the 4-week treatment. Since JIMB01 is a small compound, targets a specific molecule in tumor cells, and has promising activity against human hepatocarcinoma in vivo, we believe JIMB01 merits consideration for further investigation.

Neoadjuvant chemotherapy with a combination of pegylated liposomal doxorubicin (Caelyx) and paclitaxel in locally advanced breast cancer: a phase II study by the Hellenic Cooperative Oncology Group

BACKGROUND

To determine the activity and safety of the combination of paclitaxel and pegylated liposomal doxorubicin (Caelyx) in patients with locally advanced breast cancer.

PATIENTS AND METHODS

This was a multicenter phase II study. Thirty-five newly diagnosed patients with locally advanced breast cancer were included in the study. Histological or cytological diagnosis was necessary for inclusion. Median age was 54 years (range 26-73 years). Fifteen patients were premenopausal and 20 postmenopausal. Paclitaxel was administered at a dose of 175 mg/m(2) and pegylated liposomal doxorubicin 35 mg/m(2) every 3 weeks for six cycles.

RESULTS

Twenty-five patients (71%) responded. Six (17%) had a complete response, 19 (54%) had a partial response, four remained stable, two progressed and four were not evaluated for response due to discontinuation of chemotherapy. Three patients had a pathologically complete response. A total of 173 cycles were administered. The primary toxicity observed was skin toxicity. Grade 3 skin toxicity was noted in four patients (11%). Palmar-plantar erythrodysesthesia (PPE) grade 3 was experienced by three (9%). Two patients presented with PPE and skin toxicity. Hematological toxicities included grade 3 leukopenia in four patients (3%). Other grade 3 toxicities were uncommon and included only alopecia in 29 patients (83%). Grade 3 or 4 neurotoxicity was not observed in any patient. Dose reduction was necessary in seven patients; in six due to skin toxicity and in one due to neutropenia. Four patients discontinued treatment due to skin toxicity. There were no treatment-related deaths.

CONCLUSIONS

The combination of pegylated liposomal doxorubicin and paclitaxel was active in locally advanced breast cancer. The primary toxicity was cutaneous toxicity and it was manageable.

Combined effects on tumor growth and metastasis by anti-estrogenic and antiangiogenic therapies in MMTV-neu mice

Breast tumor growth and metastasization are both hormone-sensitive and angiogenesis-dependent. Recent work carried out in our laboratory on a transgenic model of breast cancer displaying many similarities to its human counterpart, has shown that liposome-mediated angiostatin cDNA delivery partially inhibits both local and metastatic growth. However, it is now recognized that anti-angiogenesis strategy alone cannot completely arrest tumor growth and spread, and this led to the suggestion that approaches based on different molecular mechanisms could usefully be combined. In the present work, we investigated whether tamoxifen, a classical antiestrogen agent widely used in human therapy, could improve the results obtained with angiostatin alone. Further reduction of local growth was achieved with the combined regimen with respect to angiostatin or tamoxifen alone, while, as expected, no metastatic growth was detected in either group. We therefore conclude that a combination of angiogenesis inhibitors with antiestrogen drugs might be useful in humans and that other associations between conventional and gene transfer-mediated therapy are worth investigating and will soon become important components of anticancer therapy.

Evaluation of in vitro chemosensitivity of vaccine-associated feline sarcoma cell lines to vincristine and paclitaxel

OBJECTIVE

To determine the in vitro sensitivity of 4 vaccine-associated feline sarcoma (VAFS) cell lines to the chemotherapeutic agents vincristine and paclitaxel.

SAMPLE POPULATION

Cell lines derived from 4 VAFS specimens.

PROCEDURES

Cell lines were cultured in vitro and individually exposed to various concentrations of vincristine and paclitaxel. Survival was estimated after 24 and 72 hours of exposure to each drug, and the drug concentrations that resulted in 50 and 90% reduction in number of viable cells (IC50 and IC90, respectively) were calculated.

RESULTS

Both vincristine and paclitaxel had significant dose-dependent effects on the viability of the VAFS cell lines. After 72 hours of drug exposure, the IC50 and IC90 of vincristine for the 4 cell lines were between 0.005 to 0.039 microg/ml and 0.045 to 1.027 microg/ml, respectively. The IC50 and IC90 values for paclitaxel were between 0.037 to 0.092 microg/ml and 2.450 to 15.413 microg/ml, respectively.

CONCLUSIONS

Results of pharmacokinetic studies on vincristine and paclitaxel in other species suggest that concentrations greater than the IC50 values may be possible for both drugs in feline patients as well. The drug concentrations at which viable cell numbers were reduced by 90% may also be attained in vivo for some cases, but detailed information is needed regarding the distribution, concentration, duration of availability, and toxicity of various drugs in cats. Carefully chosen combinations of antineoplastic agents need to be screened to identify treatment protocols that may be further evaluated clinically for the treatment of VAFS.

Pharmacokinetics and pharmacodynamics of combination chemotherapy with paclitaxel and epirubicin in breast cancer patients

AIMS

To investigate the pharmacokinetics and pharmacodynamics of epirubicin and paclitaxel in combination, as well as the effects of paclitaxel and its vehicle Cremophor EL on epirubicin metabolism.

METHODS

Twenty-seven female patients with metastatic breast cancer received epirubicin 90 mg m-2 i.v. followed 15 min or 30 h later by a 3 h i.v. infusion of paclitaxel 175, 200 and 225 mg m-2. Plasma concentrations of paclitaxel, epirubicin and epirubicinol were measured and the relationship between neutropenia and drug pharmacokinetics was evaluated using a sigmoid maximum effect (Emax) model. Finally, the influence of paclitaxel and Cremophor EL on epirubicin metabolism by whole blood was examined.

RESULTS

An increase in epirubicinol plasma concentrations occurred after the start of the paclitaxel infusion, resulting in a significant increase in the area under the plasma concentration-time curve (AUC) of epirubicinol (+0.5 micromol l-1 h [95% CI for the difference: 0.29, 0.71],+0.66 micromol l-1 h [95% CI for the difference: 0.47, 0.85] and +0.82 micromol l-1 h [95% CI for the difference: 0.53, 1.11] at paclitaxel doses of 175, 200 and 225 mg m-2, respectively), compared with epirubicin followed by paclitaxel 30 h later (0.61+/-0.1 micromol l-1 h). A significant increase in epirubicin AUC (+0.74 micromol l-1 h [95% CI for the difference: 0.14, 1.34] and +1.09 micromol l-1 h [95% CI for the difference: 0.44, 1.74]) and decrease in drug clearance (CLTB) (-25.35 l h-1 m-2[95% CI for the difference: -50.18, -0.52] and -35.9 l h-1 m-2[95% CI for the difference -63,4,-8,36]) occurred in combination with paclitaxel 200 and 225 mg m-2 with respect to the AUC (3.16+/-0.6 micromol l-1 h) and CLTB (74.4+/-28.4 l h-1 m-2) of epirubicin followed by paclitaxel 30 h later. An Emax relationship was observed between neutropaenia and the time over which paclitaxel plasma concentrations were equal to or greater than 0.1 micromol l-1 (tC0.1). The tC0.1 value predicted to yield a 50% decrease in neutrophil count was 7.7 h. Finally, Cremophor EL markedly inhibited the metabolism of epirubicin to epirubicinol in whole blood.

CONCLUSIONS

Paclitaxel/Cremophor EL affects the disposition of epirubicinol and epirubicin. Furthermore, the slope factor of the Emax relationship between neutropenia and tC0.1 of paclitaxel suggests that the drugs might also interact at the pharmacodynamic level.

Pharmacologic insights into the future of trastuzumab

A combination of factors has been responsible for improvements in cancer survival and cure rates. In addition to new therapies with novel/genetic targets, these include improvements in drug delivery, new schedules/sequencing of drug administration and the identification of combination therapies with greater activity/dose density than existing regimens. The recognition that such criteria can affect treatment outcome has led to their incorporation into clinical trials of new drugs. Furthermore, pharmacokinetic and pharmacodynamic parameters have become increasingly important for the rational selection of dose, administration route and schedule. The humanized monoclonal antibody trastuzumab (Herceptin) has been rationally developed to target the human epidermal growth factor receptor-2 (HER2), which is overexpressed in 20%-30% of breast cancers and is associated with poor prognosis. Trastuzumab when administered i.v. on a weekly schedule either alone or in combination with taxanes, improves survival of women with HER2-positive metastatic breast cancer. Based upon pharmacokinetic considerations, current studies are examining whether trastuzumab can be administered i.v. every three weeks or by the s.c. route. These regimens would have advantages for patients and medical staff in terms of acceptability, ease of administration and, potentially, cost effectiveness. Furthermore, various combinations of trastuzumab and chemotherapeutic agents are being explored with the aim of identifying the optimal combination regimen for clinical use. The rationale for these various studies and the studies themselves are described.

Mitoxantrone and paclitaxel combination chemotherapy in metastatic breast cancer

This study evaluated mitoxantrone and paclitaxel combination chemotherapy in the treatment of patients with metastatic breast cancer. Thirty-seven patients who had developed progressive disease after prior chemotherapy were treated with mitoxantrone (14 mg/m2) and paclitaxel (150 mg/m2) every 21 days for a maximum of six cycles. The most frequent grade 3 or 4 nonhematological toxicities were fever and nausea. Grade 4 neutropenia occurred in 71% of patients. Cardiotoxicity occurred in 2 patients, both of whom had previously received doxorubicin. Objective response was achieved in 35% of patients (5% complete response and 30% partial response) and 41% had stable disease. Median time to disease progression and median survival were 6 and 12 months, respectively. The percent of patients with an objective response was not different for those who had received prior doxorubicin or had chemotherapy in the preceding 6 months. This regimen appears to be effective and well tolerated as salvage therapy and merits further evaluation.

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.

Novel suicide ligands of tubulin arrest cancer cells in S-phase

It is presently accepted that the mechanism of action for all anti-tumor tubulin ligands involves the perturbation of microtubule dynamics during the G2/M phase of cell division and subsequent entry into apoptosis [1]. In this report, we challenge the established dogma by describing a unique mechanism of action caused by a novel series of tubulin ligands, halogenated derivatives of acetamido benzoyl ethyl ester. We have developed a suicide ligand for tubulin, which covalently attaches to the target and shows potent cancericidal activity in tissue culture assays and in animal tumor models. These compounds target early S-phase at the G1/S transition rather than the G2/M phase and mitotic arrest. Bcl-2 phosphorylation, a marker of mitotic microtubule inhibition by other tubulin ligands was dramatically altered, phosphorylation was rapid and biphasic rather than a slow linear event. The halogenated ethyl ester series of derivatives thus constitute a unique set of tubulin ligands which induce a novel mechanism of apoptosis.

Paclitaxel derivatives for targeted therapy of cancer: toward the development of smart taxanes

The pharmacologic efficacy of the promising antitumor agent paclitaxel (Taxol) may be potentially enhanced through derivatization of the drug to a water-soluble tumor-recognizing conjugate. This work reports the design and synthesis of the first tumor-directed derivative of paclitaxel. A 7-amino acid synthetic peptide, BBN[7-13], which binds to the cell surface bombesin/gastrin-releasing peptide (BBN/GRP) receptor, was conjugated to the paclitaxel-2'-hydroxy function by a heterobifunctional poly(ethylene glycol) linker. The resulting conjugate, designated PTXPEGBBN[7-13], was soluble to the upper limit of tested concentrations (250 mg/mL). The conjugate completely retained the receptor binding properties of the attached peptide as compared with those of the unconjugated BBN[7-13]. In experiments with NCI-H1299 human nonsmall cell lung cancer cells, the cytotoxicity of the PTXPEGBBN[7-13] conjugate at a 15 nM dose was enhanced by a factor of 17.3 for 24 h and 10 for 96 h exposure times, relative to paclitaxel. The IC(50) of the conjugate, tested against the same cell line, was lower than the free drug by a factor of 2.5 for both 24 h and 96 h exposures. These results describe, for the first time, the design and synthesis of a soluble tumor-directed paclitaxel prodrug which may establish a new mode for the utilization of this drug in cancer therapy.