Article Tools
Breast Cancer
Article Tools
Phase II Trial of Ixabepilone, an Epothilone B Analog, in Patients With Metastatic Breast Cancer Previously Untreated With Taxanes
Abstract
Ixabepilone is an epothilone B analog that binds to microtubules and results in microtubule stabilization and mitotic arrest. Ixabepilone was evaluated for efficacy and safety in a phase II clinical trial for women with metastatic breast cancer.
Patients were eligible if they had not previously received treatment with a taxane and had measurable metastatic breast cancer. Ixabepilone was administered at 6 mg/m2/d intravenously days 1 through 5 every 3 weeks until unacceptable toxicity or disease progression. Patients underwent pretreatment and post-treatment tumor biopsies, and tissues were analyzed for acetylated α-tubulin, tau-1, and p53 expression when possible.
Twenty-three patients received 210 cycles with a median of eight cycles (range, two to 22 cycles) per patient. Thirteen patients (57%; exact 95% CI, 34.5% to 76.8%) had partial responses, six patients (26%) had stable disease, and four patients (17%) had progressive disease. Median time to progression and duration of response were 5.5 and 5.6 months, respectively. Four patients required dose reductions for neutropenia, neuropathy, or fatigue. Grade 3 or 4 toxicities included neutropenia (22%), fatigue (13%), anorexia (9%), and motor neuropathy (4%). Thirty-nine percent of patients experienced grade 1, 13% experienced grade 2, and none experienced grade 3/4 sensory neuropathy. The six patients with paired biopsies all had increases in tumor α-tubulin acetylation after treatment. Baseline or cycle 2 acetylated α-tubulin, tau-1, or p53 expression did not correlate with clinical response.
Breast cancer is estimated to account for more than 40,910 deaths in 2007 in the United States.1 Taxanes, potent microtubule stabilizers, have remained the mainstay of cytotoxic therapy for patients with metastatic breast cancer during the last decade. Adjuvant therapy with taxanes is the standard of care for patients with node-positive breast cancer.2-4 Although taxanes are efficacious, routine steroid premedication use, neuropathy, and bone marrow suppression continue to be problematic. In addition, increasing use of taxanes in the adjuvant setting has led to development of resistance and decreased response rates with single-agent use in the metastatic setting.5 This highlights the need for development of novel agents with greater or equal efficacy and improved adverse effect profiles.
Microtubules are comprised of αβ-tubulin heterodimers. Dynamic equilibrium of αβ-tubulin polymerization and depolymerization is necessary for adequate microtubule function and normal cell division.6 Polymerized α-tubulin undergoes post-translational modifications such as acetylation, a marker for microtubule stabilization. Several microtubule-associated proteins, including tau-1, play a role in microtubule stabilization.7 Taxanes induce mitotic arrest by inhibiting depolymerization of the microtubules. The epothilones are a new class of microtubule-stabilizing chemotherapeutic agents derived from the myxobacterium Sorangium cellulosum. Epothilones are poor substrates for P-glycoprotein, and exhibit activity in paclitaxel-resistant cancer cell lines.8,9 Ixabepilone is a semisynthetic analog of epothilone B. Ixabepilone binds to β-tubulin, stabilizes tubulin, disrupts microtubule homeostasis, and induces G2/M cell cycle arrest and apoptosis.9,10
Promising preclinical data prompted evaluation of ixabepilone in multiple phase I studies. A phase I study completed at the National Cancer Institute established that ixabepilone administered at 6 mg/m2/d for 5 days every 3 weeks was the maximum tolerated dose.11 The dose-limiting toxicity was neutropenia in heavily pretreated patients. Objective responses were noted in patients with breast cancer. Neurotoxicity was noted, but seemed to be decreased on this administration schedule compared with schedules in other phase I trials. This trial also established that corticosteroid premedication is not required with ixabepilone, in contrast to treatment with paclitaxel or docetaxel.11
Because of encouraging results and tolerable toxicity profiles in phase I studies, a phase II trial with two cohorts was initiated at our institution to evaluate efficacy of ixabepilone in the metastatic breast cancer population. The cohort of patients previously treated with taxanes before ixabepilone treatment has been published.12 We present the clinical efficacy, safety, and correlative studies in the cohort of patients that did not receive taxanes in the adjuvant or metastatic setting. Although microtubule function and mechanisms of microtubule-stabilizing agents are well understood, biomarkers of tumor response or tumor resistance to microtubule-stabilizing agents are yet to be fully elucidated. In tumor biopsies obtained before and during treatment with ixabepilone, we evaluated p53, tau-1 expression, and α-tubulin acetylation to determine whether baseline or cycle 2 levels and changes between these time points were associated with clinical response to ixabepilone.
Eligible patients had a diagnosis of metastatic breast adenocarcinoma that was confirmed pathologically; an Eastern Cooperative Oncology Group performance status of 0, 1, or 2; and measurable disease by Response Criteria in Solid Tumors criteria.13 Patients could not have received a taxane in either the adjuvant or metastatic setting, but there were no other limits for prior therapy. Laboratory values required a total bilirubin ≤ 1.5× institutional upper limit of normal, ALT and AST ≤ 2.5× institutional upper limit of normal, creatinine within normal institutional limits, an absolute neutrophil count of ≥ 1.5 × 109/L, and platelet count of ≥ 100 × 109/L. Because of possible interference of cytochrome P450 3A4 activity by ixabepilone, patients were excluded from receiving the following medications at enrollment and while enrolled onto the study: amiodarone, clarithromycin, erythromycin, fluconazole, itraconazole, ketoconazole, indinavir, nelfinavir, ritonavir, and saquinavir. Patients with grade 2 or greater neuropathy at baseline were excluded.
This phase II study was approved by the Institutional Review Board for the Center for Cancer Research, National Cancer Institute (NCI; Bethesda, MD). All patients signed the Institutional Review Board–approved informed consent before participating. Ixabepilone (provided by the Cancer Therapy Evaluation Program, NCI, through a cooperative agreement with Bristol-Myers Squibb, Wallingford, CT) was administered during 1 hour intravenously (IV) on 5 consecutive days every 3 weeks. All patients received a starting dose of 6 mg/m2/d for the first cycle. Patients received premedication with diphenhydramine at 25 to 50 mg IV or orally, or hydroxyzine at 25 mg orally, and ranitidine at 50 mg IV, 30 to 60 minutes before each dose of ixabepilone. Prophylactic antiemetics were not administered routinely. An absolute neutrophil count ≥ 1.0 × 109/L and a platelet count ≥ 75 × 109/L was required on the first day of each cycle.
Toxicities were assessed using NCI Common Toxicity Criteria version 2.0 at baseline and at the conclusion of each cycle of treatment.14 Dose reductions to 5 mg/m2/d and then to 4 mg/m2/d were implemented for patients experiencing grade 3 and 4 nonhematologic toxicities during the prior cycle, or for grade 1 or 2 toxicities requiring treatment delays. Toxicities required resolution to grade 1 or baseline before the next cycle of treatment. Granulocyte colony-stimulating factors were not administered at cycle 1, but could be added subsequently. Treatment intervals could be extended up to 5 weeks between cycles for patients with optimal responses who completed six cycles of treatment.
Measurable disease was assessed by computed tomography imaging using Response Criteria in Solid Tumors guidelines.13 Patients underwent baseline imaging within 4 weeks of enrollment, and were scanned before every other cycle.
This protocol was designed to evaluate efficacy of ixabepilone, and was conducted using a two-stage optimal design to rule out a low 5% response rate in favor of a 30% response rate.15 With 10% probabilities each of accepting a poor agent and rejecting a good agent, an early stopping rule would be implemented if no responses were seen in the first seven patients. Three or more responses in 21 patients were considered consistent with an active agent worthy of additional development. Under the null hypothesis (5% response probability), the study had a 70% probability of early termination.
Progression-free survival probabilities as a function of time were calculated using the Kaplan-Meier method with censoring at last follow-up (without progression), or removal from study for toxicity. Duration of response was calculated actuarially for 13 patients who had confirmed partial responses, and was calculated from the day of first radiologic partial response until the date of progression. An exact Wilcoxon rank sum test was performed to compare continuous parameters between responders (partial response) and nonresponders (stable and progressive disease). P values are two tailed, and are presented without adjustment for multiple comparisons.
Patients with tumors that could be biopsied under local anesthesia had core or punch biopsies obtained at baseline and on cycle 2 day 2, approximately 18 to 24 hours after the cycle 2 day 1 dose. If a tumor biopsy was not feasible at baseline, tissue blocks from prior tumor biopsy were obtained.
Immunohistochemistry on tissue sections of formalin-fixed paraffin-embedded samples was performed using a standard avidin-biotin-peroxidase complex indirect immunoperoxidase procedure. Mouse monoclonal antibodies to p53 (Vector Laboratories Inc, Burlingame, CA), acetylated α-tubulin (Sigma, St Louis, MO), and tau-1 (Chemicon International Inc, Temecula, CA) were applied. Immunohistochemistry staining signal was analyzed quantitatively with assistance of the Automated Cellular Imaging System ( Chroma Vision Medical Systems Inc, San Juan Capistrano, CA). Six areas of each tumor were scored using a free-scoring or 40× tool to generate an average percentage and intensity of stained tumor cells. Staining index was calculated by multiplying the percentage of positively stained cells by average staining intensity after subtracting machine readouts of the corresponding negative control for each marker. An average labeling percentage was reported for p53 and staining index was reported for acetylated α-tubulin and tau-1.
Twenty-three patients were enrolled between June 2002 and September 2005, two of whom were enrolled due to a registration error. The baseline characteristics and patients' prior therapy for breast cancer are summarized in Table 1. Sixteen of 23 patients received prior chemotherapy, and 11 of 18 patients with hormone receptor–positive breast cancer were treated with prior hormonal therapy. Twelve patients received prior anthracycline therapy. Patients received a median of eight cycles (range, two to 22 cycles). Of 23 patients enrolled, 17 patients were removed from study because of disease progression, four patients were removed because of toxicity, and two patients remain on study (with treatment times of 9 and 10 months each).
The objective response rate was 57% (95% CI, 34.5% to 76.8%), with 13 partial responses. Stable disease for at least 6 weeks was the best response for 26% (six patients) of patients. The median time to progression for all patients was 5.5 months (Fig 1). For 13 patients who achieved a partial response, median duration of response from date of first documentation of response was 5.6 months. The best response in each patient's target tumor measurements from baseline are presented in Figure 2. Measurable responses were observed in visceral sites such as lung and liver, soft tissue masses, and lymph nodes. Improvements were also seen in nontarget lesions, including breast, skin, and bone. Of five patients who received ixabepilone as initial therapy for their metastatic breast cancer, three had partial responses and one patient each had stable disease and progressive disease. Of 12 patients who had prior anthracycline therapy, seven patients (58%) had partial responses, four patients (33%) had stable disease, and one patient (8%) had progressive disease. Of the 18 patients with hormone receptor–positive disease, 12 (67%) had partial responses, four patients (22%) had stable disease, and two patients (11%) had progressive disease. One of five patients with hormone receptor–negative disease achieved a partial response.
A total of 210 cycles of therapy were administered. Toxicity information was collected for all patients. The worst toxicity grades are summarized in Table 2. No patients experienced febrile neutropenia. Only one patient required filgrastim. The most notable and frequent nonhematologic toxicities were fatigue, neuropathy, and nail changes. Four patients were removed from the study because of toxicity. Reasons for removal from the study included the following: one patient because of grade 3 weight loss, one patient with grade 3 motor neuropathy, one patient because of prolonged autonomic neuropathy, and one patient because of grade 2 fatigue. Four patients required dose reductions while on study, and two of these four patients required two dose reductions. The dose was reduced due to prolonged neutropenia in one patient, neuropathy in three patients, and fatigue in two patients. The patient with prolonged neutropenia received filgrastim for subsequent cycles. Eight patients required antinausea medication for one cycle, and two patients required antinausea medication for two cycles.
Five of 23 patients had grade 1 baseline neuropathy before treatment with ixabepilone. Three of five patients with baseline grade 1 sensory neuropathy developed worsening neuropathy: two patients had grade 2 sensory neuropathy, and one patient had grade 2 motor neuropathy. Of 18 patients with no baseline neuropathy, nine patients developed grade 1, and two patients developed grade 2 sensory neuropathy. One of 18 patients developed grade 3 motor neuropathy. In total, three patients developed at least grade 2 sensory neuropathy, one patient developed grade 2 motor neuropathy, and one patient developed grade 3 motor neuropathy. The patient who developed grade 3 motor neuropathy had severe rheumatoid arthritis and did not regain function of her fingers due to both ixabepilone and worsening rheumatoid arthritis.
Three markers (p53, tau-1, acetylated α-tubulin) were examined in available biopsies for at least one time point in 13 patients. Biopsies at both baseline and during cycle 2 were available from six patients for acetylated α-tubulin and five patients for both acetylated α-tubulin and p53 (four patients had partial response, and one patient had progressive disease). Increased acetylation of α-tubulin was seen (Fig 3) in all six paired biopsies regardless of clinical response. Notably, two tumor samples showed increased abnormal expression of p53 at baseline. Baseline, cycle 2, or changes from baseline to post-treatment biopsies in tau-1 and p53 expression and acetylation of α-tubulin were not associated with response to ixabepilone (Table 3).
Our data demonstrate that ixabepilone administered daily for 5 days every 3 weeks is an efficacious agent in metastatic breast cancer. The high partial response rate of 57% and 5.6-month duration of response in a taxane-naïve patient population are encouraging. Of 12 patients who received prior anthracyclines on our study, seven (58%) achieved a partial response. A trial evaluating ixabepilone 40 mg/m2 as a single dose every 3 weeks in a taxane-naïve metastatic breast cancer population that was treated with anthracyclines reported a response rate of 34%.16 Patient populations treated with ixabepilone exposed to prior taxanes achieved response rates between 11.5% and 31%.12,17-19
Our response rate compares favorably to response rates (25% to 68%) in studies that evaluated docetaxel or paclitaxel in patient populations that did not previously receive taxanes.20-26 In a trial in which 21% of patients received adjuvant chemotherapy, the response rate was 29% and the median time to progression was 5.3 months after paclitaxel therapy.27 Patients treated with docetaxel after anthracycline therapy achieved a 30% response rate and a 4.25-month time to progression.24 Patients treated with ABI-007 (American BioScience, Santa Monica, CA), a taxane that does not require corticosteroid premedication, experienced a 33% response rate and a 5.75-month time to progression.28 The median time to progression of 5.5 months on our trial is similar to that of these agents.
Bone marrow suppression, an issue with taxanes and other schedules of ixabepilone, was not predominant in our patients.20,26,27,29 Only one patient had neutropenia requiring growth factor support and delay in ixabepilone therapy. Our rates of neuropathy with this schedule were less frequent than in other trials using ixabepilone during shorter administration schedules or taxanes including ABI-007.16,21,22,25,30 Relatively low rates of grade 2 and 3 neuropathy (13% grade 2 sensory neuropathy, 0% grade 3 sensory neuropathy, 4% grade 2 motor neuropathy, 4% grade 3 motor neuropathy) on our trial as well as other trials evaluating this dosing schedule of ixabepilone may be due to daily administration with lower peak doses.11,12,31 Increased duration of peak concentrations of microtubule-stabilizing agents may contribute to increased neurotoxicity.32 There is also a report that genetic polymorphisms in P-glycoprotein may increase the risk of developing neuropathy after treatment with paclitaxel, and similar studies should be performed with ixabepilone.33 Neurologic function tests such as the Jebsen Test of Hand Function may predict grade 2 or higher peripheral neuropathy with ixabepilone.34
Biomarkers of tumor response to microtubule-stabilizing agents are not yet established. A recently completed pharmacogenomic study using ixabepilone in the neoadjuvant setting showed that low concentration or lack of estrogen receptor was the best single-gene predictor of tumor response to ixabepilone.35 From six paired tumor biopsies available on our study, we observed increased levels of acetylated α-tubulin after treatment in all patients, regardless of clinical response. Acetylation of α-tubulin is a post-translational modification that only occurs in stable microtubules.6 The increase in acetylation confirms that ixabepilone stabilized microtubules in target tissue, and similar findings were observed in patients with breast and renal cell cancer treated with ixabepilone.12,31 Acetylation of α-tubulin should be evaluated in large randomized studies to assess if changes correlate with clinical response.
Our data did not show any association with p53 expression and response to ixabepilone treatment. Nine patients with tissue available had p53 levels in tumor consistent with wild-type p53. Six of these patients achieved partial responses, and three patients achieved stable disease. Two patients on our study with inflammatory breast cancer had increased expression of p53 in the tumor samples, suggesting a mutated p53 phenotype.36 One of these patients achieved a partial response; the other patient had progressive disease. These results are consistent with prior evidence that tumor response to microtubule-stabilizing agents is indifferent to intact p53 status.37
tau-1 is a microtubule-associated protein that promotes tubulin stabilization.7 There is no consensus whether tau-1 expression inhibits or enhances cytotoxicity to microtubule-stabilizing agents. Our data did not show association between tau-1 expression and clinical response to ixabepilone. Similarly, tau-1 expression did not correlate with pathologic complete response to ixabepilone in a pharmacogenomic study.35 However, low tumor tau-1 expression did correlate with response to paclitaxel.38-40
An absence of significant trends in the biomarkers in our study may be due to small numbers of patients with available biopsies and few patients with progressive disease. Another possible reason we were unable to detect significant trends is that we assessed each biomarker using immunohistochemistry. Immunohistochemistry shows an effect in target tissue, but the degree of expression is not necessarily quantitative and may not be an ideal method to predict response to cytotoxic therapy. Future studies to validate predictive markers of response to ixabepilone may be more fruitful with microarray analyses.35,39
In conclusion, our study establishes that ixabepilone has efficacy in patients previously untreated with taxanes similar to response rates seen with docetaxel or paclitaxel in the first- or second-line metastatic setting.21,23-26,29 Most patients tolerated ixabepilone well, with low hematologic toxicity and minimal nausea, vomiting, and diarrhea. Unlike paclitaxel and docetaxel, ixabepilone does not require corticosteroid premedication. Neurotoxicity, a major concern for microtubule-stabilizing drugs, was relatively mild on this schedule. Continued evaluation of potential predictors of response to ixabepilone should be pursued. The favorable efficacy and tolerability seen in our trial and other trials discussed must be confirmed. We await data from two phase III trials examining capecitabine and ixabepilone compared with capecitabine alone in approximately 2,000 patients who have been treated previously with anthracyclines and taxanes. If these trials are positive, additional evaluation of ixabepilone in randomized phase III studies in the first-line metastatic and adjuvant settings would be warranted.
The author(s) indicated no potential conflicts of interest.
Conception and design: Neelima Denduluri, Jennifer A. Low, James J. Lee, Seth M. Steinberg, Sandra M. Swain
Administrative support: Neelima Denduluri, Jennifer A. Low, Arlene W. Berman
Provision of study materials or patients: Neelima Denduluri, Jennifer A. Low, James J. Lee, Arlene W. Berman, Janice M. Walshe, Catherine K. Chow, Sherry X. Yang, Sandra M. Swain
Collection and assembly of data: Neelima Denduluri, Jennifer A. Low, James J. Lee, Arlene W. Berman, Janice M. Walshe, Ujala Vatas, Sherry X. Yang, Sandra M. Swain
Data analysis and interpretation: Neelima Denduluri, Jennifer A. Low, James J. Lee, Ujala Vatas, Seth M. Steinberg, Sherry X. Yang, Sandra M. Swain
Manuscript writing: Neelima Denduluri, Jennifer A. Low, James J. Lee, Seth M. Steinberg, Sherry X. Yang, Sandra M. Swain
Final approval of manuscript: Neelima Denduluri, Jennifer A. Low, James J. Lee, Sandra M. Swain
Other: Catherine K. Chow [radiologist who evaluates responses by Response Evaluation Criteria in Solid Tumors Group]
Fig 1. Kaplan and Meier progression-free survival for patients with metastatic breast cancer receiving ixabepilone treatment during study. Patients were censored (tick marks) due to toxicity (four patients), or because they were progression-free (two patients). *All patients. Seventeen of 23 patients experienced treatment failure.
Fig 2. Best response from baseline in radiographic measurements of target lesions. Each patient's response is represented by a bar.
Fig 3. Expression of acetylated α-tubulin by immunohistochemistry. Acetylated α-tubulin (A) at baseline and (B) on cycle 2 day 2 in a patient with partial response (PR). (C) Expression of acetylated α-tubulin in six patients with paired biopsies. Shown are acetylated α-tubulin at baseline and during ixabepilone treatment. SD, stable disease; PD, progressive disease.
|
| Characteristic | No. of Patients | % | |
|---|---|---|---|
| Age, years | |||
| Median | 55 | ||
| Range | 22-79 | ||
| Race/ethnicity | |||
| African American | 3 | 13 | |
| Asian | 3 | 13 | |
| White | 16 | 70 | |
| Hispanic | 1 | 4 | |
| ECOG performance status | |||
| 0 | 5 | 22 | |
| 1 | 17 | 74 | |
| 2 | 1 | 4 | |
| ER or PR positive | 18 | 78 | |
| HER-2/neu 3+/FISH positive | 0 | ||
| Sites of metastatic disease | |||
| Visceral | 14 | 61 | |
| Visceral/bone | 12 | 52 | |
| Soft tissue | 9 | 39 | |
| Soft tissue/bone | 5 | 22 | |
| Prior therapy | |||
| Chemotherapy (any) | 16 | 70 | |
| Anthracycline | 12 | 52 | |
| Metastatic | 3 | ||
| Adjuvant | 9 | ||
| Capecitabine | 4 | 17 | |
| Doxorubicin and capecitabine | 3 | 13 | |
| Hormonal therapy | 13 | 57 | |
| Metastatic | 8 | ||
| Adjuvant | 8 | ||
| No prior hormonal therapy or chemotherapy | 5 | 22 | |
Abbreviations: ECOG, Eastern Cooperative Oncology Group; ER, estrogen receptor; PR, progesterone receptor; HER-2, human epidermal growth factor receptor 2; FISH, fluorescent in situ hybridization.
|
| Toxicity | CTC Toxicity Grade | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | ||||||||||||
| No. of Patients | % | No. of Patients | % | No. of Patients | % | No. of Patients | % | ||||||||
| Hematologic | |||||||||||||||
| Neutropenia | 2 | 9 | 13 | 57 | 2 | 9 | 3 | 13 | |||||||
| Hemoglobin | 11 | 48 | 8 | 35 | 0 | 0 | 0 | 0 | |||||||
| Thrombocytopenia | 10 | 43 | 1 | 4 | 1 | 4 | 0 | 0 | |||||||
| Febrile neutropenia | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |||||||
| Nonhematologic | |||||||||||||||
| Alopecia | 6 | 26 | 14 | 61 | 0 | 0 | 0 | 0 | |||||||
| Arthralgia/myalgia | 4 | 17 | 2 | 9 | 0 | 0 | 1 | 4 | |||||||
| Constipation | 3 | 13 | 10 | 43 | 0 | 0 | 0 | 0 | |||||||
| Diarrhea | 9 | 39 | 1 | 4 | 1 | 4 | 0 | 0 | |||||||
| Dysgeusia | 10 | 43 | 5 | 22 | 0 | 0 | 0 | 0 | |||||||
| Fatigue | 9 | 39 | 6 | 26 | 3 | 13 | 0 | 0 | |||||||
| Nail changes | 7 | 30 | 6 | 26 | 0 | 0 | 0 | 0 | |||||||
| Neuropathy, autonomic | 0 | 0 | 1 | 4 | 0 | 0 | 0 | 0 | |||||||
| Neuropathy, motor | 0 | 0 | 1 | 4 | 1 | 4 | 0 | 0 | |||||||
| Neuropathy, sensory | 9 | 39 | 3 | 13 | 0 | 0 | 0 | 0 | |||||||
| Nausea | 8 | 35 | 4 | 17 | 2 | 9 | 0 | 0 | |||||||
| Vomiting | 6 | 26 | 3 | 13 | 0 | 0 | 0 | 0 | |||||||
Abbreviation: CTC, National Cancer Institute Common Toxicity Criteria.
|
| Marker | Time Point | Response | No. of Patients | Median | Range | P |
|---|---|---|---|---|---|---|
| p53 (labeling percentage) | Baseline | PR | 7 | 1.20 | 0.0-39.7 | .68 |
| SD/PD | 4 | 7.80 | 0.0-94.8 | |||
| C2 | PR | 5 | 16.8 | 1.4-69.9 | .33 | |
| SD/PD | 1 | |||||
| Change from baseline to C2 | PR | 5 | 4.8 | 1.4-59.4 | .33 | |
| SD/PD | 1 | |||||
| tau-1 (staining index) | Baseline | PR | 7 | 0.50 | −2.9-73.5 | .68 |
| SD/PD | 4 | 0.10 | 0.0-18.3 | |||
| C2 | PR | 5 | 1.20 | 0.1-60.9 | .62 | |
| SD/PD | 2 | 0.90 | 0.1-1.7 | |||
| Change from baseline to C2 | PR | 4 | 17.80 | −0.4-50.7 | .80 | |
| SD/PD | 2 | 0.80 | 0.0-1.6 | |||
| Acetylated α-tubulin (staining index) | Baseline | PR | 8 | 0.35 | 0.10-46.8 | .71 |
| SD/PD | 4 | 4.81 | 0.1-21.4 | |||
| C2 | PR | 5 | 12.20 | 1.8-63.8 | .86 | |
| SD/PD | 2 | 12.85 | 1.9-23.8 | |||
| Change from baseline to C2 | PR | 4 | 13.00 | 1.7-50.1 | .99 | |
| SD/PD | 2 | 12.45 | 1.8-23.1 |
Abbreviations: C2, cycle 2; PR, partial response; SD, stable disease; PD, progressive disease.
published online ahead of print at www.jco.org on July 2, 2007.
Supported by the Intramural Research Program of the Center for Cancer Research, National Cancer Institute, National Institutes of Health.
Presented in part at the 41st and 42nd Annual Meetings of the America Society of Clinical Oncology, May 13-17, 2005, Orlando, FL, and June 2-6, 2006, Atlanta, GA, respectively.
Authors' disclosures of potential conflicts of interest and author contributions are found at the end of this article.
We thank Diana Nguyen, MD, for technical support and A. Tito Fojo, MD, PhD, for helpful discussion.
| 1. | Jemal A, Siegel R, Ward E, et al: Cancer statistics, 2007. CA Cancer J Clin 57::43,2007-66, Crossref, Medline, Google Scholar |
| 2. | Citron ML, Berry DA, Cirrincione C, et al: Randomized trial of dose-dense versus conventionally scheduled and sequential versus concurrent combination chemotherapy as postoperative adjuvant treatment of node-positive primary breast cancer: First report of Intergroup Trial C9741/Cancer and Leukemia Group B Trial 9741. J Clin Oncol 21::1431,2003-1439, Link, Google Scholar |
| 3. | Martin M, Pienkowski T, Mackey J, et al: Adjuvant docetaxel for node-positive breast cancer. N Engl J Med 352::2302,2005-2313, Crossref, Medline, Google Scholar |
| 4. | Henderson IC, Berry DA, Demetri GD, et al: Improved outcomes from adding sequential paclitaxel but not from escalating doxorubicin dose in an adjuvant chemotherapy regimen for patients with node-positive primary breast cancer. J Clin Oncol 21::976,2003-983, Link, Google Scholar |
| 5. | Miller K, Wang M, Gralow J, et al: A randomized phase III trial of paclitaxel versus paclitaxel plus bevacizumab as first-line therapy for locally recurrent or metastatic breast cancer : A trial coordinated by the Eastern Cooperative Oncology Group (E2100). San Antonio Breast Cancer Symposium, San Antonio, TX, December 8-11, 2005 Google Scholar |
| 6. | Westermann S, Weber K: Post-translational modifications regulate microtubule function. Nat Rev Mol Cell Biol 4::938,2003-947, Medline, Google Scholar |
| 7. | Lee G, Rook SL: Expression of tau protein in non-neuronal cells: Microtubule binding and stabilization. J Cell Sci 102::227,1992-237, (part 2) Medline, Google Scholar |
| 8. | Kowalski RJ, Giannakakou P, Hamel E: Activities of the microtubule-stabilizing agents epothilones A and B with purified tubulin and in cells resistant to paclitaxel (Taxol). J Biol Chem 272::2534,1997-2541, Crossref, Medline, Google Scholar |
| 9. | Lee FY, Borzilleri R, Fairchild CR, et al: BMS-247550: a novel epothilone analog with a mode of action similar to paclitaxel but possessing superior antitumor efficacy. Clin Cancer Res 7::1429,2001-1437, Medline, Google Scholar |
| 10. | Goodin S, Kane MP, Rubin EH: Epothilones: Mechanism of action and biologic activity. J Clin Oncol 22::2015,2004-2025, Crossref, Medline, Google Scholar |
| 11. | Abraham J, Agrawal M, Bakke S, et al: Phase I trial and pharmacokinetic study of BMS-247550, an epothilone B analog, administered intravenously on a daily schedule for five days. J Clin Oncol 21::1866,2003-1873, Link, Google Scholar |
| 12. | Low JA, Wedam SB, Lee JJ, et al: Phase II clinical trial of ixabepilone (BMS-247550), an epothilone B analog, in metastatic and locally advanced breast cancer. J Clin Oncol 23::2726,2005-2734, Link, Google Scholar |
| 13. | Therasse P, Arbuck SG, Eisenhauer EA, et al: New guidelines to evaluate the response to treatment in solid tumors: European Organization for Research and Treatment of Cancer, National Cancer Institute of the United States, National Cancer Institute of Canada. J Natl Cancer Inst 92::205,2000-216, Crossref, Medline, Google Scholar |
| 14. | National Cancer Institute: Common Toxicity Criteria version 2.0 (April 30, 1999), Cancer Therapy Evaluation Program. Bethesda, MD, National Cancer Institute, 1999 Google Scholar |
| 15. | Simon R: Optimal two-stage designs for phase II clinical trials. Control Clin Trials 10::1,1989-10, Crossref, Medline, Google Scholar |
| 16. | Roche H, Cure H, Bunnell C, et al: A phase II study of epothilone analog BMS-247550 in patients (pts) with metastatic breast cancer (MBC) previously treated with an anthracycline. Proc Am Soc Clin Oncol 22::18,2003, (abstr 69) Google Scholar |
| 17. | Thomas E, Tabernero J, Fornier M, et al: A phase II study of the epothilone B analog BMS-247550 in patients (pts) with taxane-resistant metastatic breast cancer (MBC). Proc Am Soc Clin Oncol 22::8,2003, (abstr 30) Google Scholar |
| 18. | Chen T, Molina A, Moore S, et al: Epothilone B analog (BMS-247550) at the recommended phase II dose (RPTD) in patients (pts) with gynecologic (gyn) and breast cancers. J Clin Oncol 22::155s,2004, (suppl; abstr 2115) Crossref, Google Scholar |
| 19. | Thomas E, Perez EA, Mukhopadhyay P, et al: Phase II trial of ixabepilone in patients with metastatic breast cancer (MBC) that is resistant to an anthracycline, a taxane and capecitabine. J Clin Oncol 24::42s,2006, (suppl; abstr 660) Link, Google Scholar |
| 20. | Jones SE, Erban J, Overmoyer B, et al: Randomized phase III study of docetaxel compared with paclitaxel in metastatic breast cancer. J Clin Oncol 23::5542,2005-5551, Link, Google Scholar |
| 21. | Seidman AD, Tiersten A, Hudis C, et al: Phase II trial of paclitaxel by 3-hour infusion as initial and salvage chemotherapy for metastatic breast cancer. J Clin Oncol 13::2575,1995-2581, Link, Google Scholar |
| 22. | Chevallier B, Fumoleau P, Kerbrat P, et al: Docetaxel is a major cytotoxic drug for the treatment of advanced breast cancer: A phase II trial of the Clinical Screening Cooperative Group of the European Organization for Research and Treatment of Cancer. J Clin Oncol 13::314,1995-322, Link, Google Scholar |
| 23. | Holmes FA, Walters RS, Theriault RL, et al: Phase II trial of Taxol, an active drug in the treatment of metastatic breast cancer. J Natl Cancer Inst 83::1797,1991-1805, Crossref, Medline, Google Scholar |
| 24. | Nabholtz JM, Senn HJ, Bezwoda WR, et al: Prospective randomized trial of docetaxel versus mitomycin plus vinblastine in patients with metastatic breast cancer progressing despite previous anthracycline-containing chemotherapy: 304 Study Group. J Clin Oncol 17::1413,1999-1424, Link, Google Scholar |
| 25. | Nabholtz JM, Gelmon K, Bontenbal M, et al: Multicenter, randomized comparative study of two doses of paclitaxel in patients with metastatic breast cancer. J Clin Oncol 14::1858,1996-1867, Link, Google Scholar |
| 26. | Trudeau ME, Eisenhauer EA, Higgins BP, et al: Docetaxel in patients with metastatic breast cancer: A phase II study of the National Cancer Institute of Canada-Clinical Trials Group. J Clin Oncol 14::422,1996-428, Link, Google Scholar |
| 27. | Bishop JF, Dewar J, Toner GC, et al: Initial paclitaxel improves outcome compared with CMFP combination chemotherapy as front-line therapy in untreated metastatic breast cancer. J Clin Oncol 17::2355,1999-2364, Link, Google Scholar |
| 28. | Gradishar WJ, Tjulandin S, Davidson N, et al: Phase III trial of nanoparticle albumin-bound paclitaxel compared with polyethylated castor oil-based paclitaxel in women with breast cancer. J Clin Oncol 23::7794,2005-7803, Link, Google Scholar |
| 29. | Reichman BS, Seidman AD, Crown JP, et al: Paclitaxel and recombinant human granulocyte colony-stimulating factor as initial chemotherapy for metastatic breast cancer. J Clin Oncol 11::1943,1993-1951, Link, Google Scholar |
| 30. | Lee JJ, Swain SM: Peripheral neuropathy induced by microtubule-stabilizing agents. J Clin Oncol 24::1633,2006-1642, Link, Google Scholar |
| 31. | Zhuang SH, Menefee M, Kotz H, et al: A phase II clinical trial of BMS-247550 (ixabepilone), a microtubule-stabilizing agent in renal cell cancer. J Clin Oncol 22::394s,2004, (suppl; abstr 4550) Google Scholar |
| 32. | Mielke S, Sparreboom A, Steinberg SM, et al: Association of Paclitaxel pharmacokinetics with the development of peripheral neuropathy in patients with advanced cancer. Clin Cancer Res 11::4843,2005-4850, Crossref, Medline, Google Scholar |
| 33. | Sissung TM, Mross K, Steinberg SM, et al: Association of ABCB1 genotypes with paclitaxel-mediated peripheral neuropathy and neutropenia. Eur J Cancer 42::2893,2006-2896, Crossref, Medline, Google Scholar |
| 34. | Lee JJ, Low JA, Croarkin E, et al: Changes in neurologic function tests may predict neurotoxicity caused by ixabepilone. J Clin Oncol 24::2084,2006-2091, Link, Google Scholar |
| 35. | Lee H, Xu L, Wu S: Predictive biomarker discovery and validation for the targeted chemotherapeutic ixabepilone. J Clin Oncol 24::123s,2006, (suppl; abstr 3011) Link, Google Scholar |
| 36. | Nenutil R, Smardova J, Pavlova S, et al: Discriminating functional and non-functional p53 in human tumours by p53 and MDM2 immunohistochemistry. J Pathol 207::251,2005-259, Crossref, Medline, Google Scholar |
| 37. | Weinstein JN, Myers TG, O'Connor PM, et al: An information-intensive approach to the molecular pharmacology of cancer. Science 275::343,1997-349, Crossref, Medline, Google Scholar |
| 38. | Wagner P, Wang B, Clark E, et al: Microtubule associated protein (MAP)-Tau: A novel mediator of paclitaxel sensitivity in vitro and in vivo. Cell Cycle 4::1149,2005-1152, Crossref, Medline, Google Scholar |
| 39. | Potti A, Dressman HK, Bild A, et al: Genomic signatures to guide the use of chemotherapeutics. Nat Med 12::1294,2006-1300, Crossref, Medline, Google Scholar |
| 40. | Rouzier R, Rajan R, Wagner P, et al: Microtubule-associated protein tau: A marker of paclitaxel sensitivity in breast cancer. Proc Natl Acad Sci U S A 102::8315,2005-8320, Crossref, Medline, Google Scholar |
