Microtubule-Targeting Agents: Disruption of the Cellular Cytoskeleton as a Backbone of Ovarian Cancer Therapy.

Microtubules are dynamic polymers composed of α- and ß-tubulin heterodimers. Microtubules are universally conserved among eukaryotes and participate in nearly every cellular process, including intracellular trafficking, replication, polarity, cytoskeletal shape, and motility. Due to their fundamental role in mitosis, they represent a classic target of anti-cancer therapy. Microtubule-stabilizing agents currently constitute a component of the most effective regimens for ovarian cancer therapy in both primary and recurrent settings. Unfortunately, the development of resistance continues to present a therapeutic challenge. An understanding of the underlying mechanisms of resistance to microtubule-active agents may facilitate the development of novel and improved approaches to this disease.

Taxane and epothilone-induced peripheral neurotoxicity: From pathogenesis to treatment.

Taxane-induced peripheral neurotoxicity (TIPN) is the most common non-hematological side effect of taxane-based chemotherapy, and may result in dose reductions and discontinuations, having as such a detrimental effect on patients' overall survival. Epothilones share similar mechanism of action with taxanes. The typical TIPN clinical presentation is mainly comprised of numbness and paresthesia, in a stocking-and-glove distribution and may progress more proximally over time, with paclitaxel being more neurotoxic than docetaxel. Motor and autonomic involvement is less common, whereas an acute taxane-induced acute pain syndrome is frequent. Patient reported outcomes questionnaires, clinical evaluation, and instrumental tools offer complementary information in TIPN. Its electrodiagnostic features include reduced/abolished sensory action potentials, and less prominent motor involvement, in keeping with a length-dependent, axonal dying back predominately sensory neuropathy. TIPN is dose-dependent and may be reversible within months after the end of chemotherapy. The single and cumulative delivered dose of taxanes is considered the main risk factor of TIPN development. Apart from the cumulative dose, other risk factors for TIPN include demographic, clinical, and pharmacogenetic features with several single-nucleotide polymorphisms potentially linked with increased susceptibility of TIPN. There are currently no neuroprotective strategies to reduce the risk of TIPN, and symptomatic treatments are very limited. This review critically examines the pathogenesis, incidence, risk factors (both clinical and pharmacogenetic), clinical phenotype and management of TIPN.

Phase IB trial of ixabepilone and vorinostat in metastatic breast cancer.

PURPOSE: To translate promising preclinical data on the combination of vorinostat and ixabepilone for metastatic breast cancer (MBC) into clinical trials. METHODS: We conducted a randomized two-arm Phase IB clinical trial of ascending doses of vorinostat and ixabepilone in prior -treated MBC patients. To determine the maximum tolerated dose (MTD), 37 patients were randomized to schedule A: every-3-week ixabepilone + vorinostat (days 1-14), or schedule B: weekly ixabepilone + vorinostat (days 1-7; 15-21) Pharmacokinetics were assessed. Nineteen additional patients were randomized to schedule A or B and objective response rate (ORR), clinical benefit rate (CBR), toxicity, progression-free survival (PFS), and overall survival (OS) were assessed. RESULTS: The schedule A MTD was vorinostat 300 mg daily (days 1-14), ixabepilone 32 mg/m2 (day 2); 21-day cycle 27% dose-limiting toxicities (DLTs). The schedule B MTD was vorinostat 300 mg daily (days 1-7; 15-21), ixabepilone 16 mg/m2 (days 2, 9, 16); 28-day cycle; no DLTs. Vorinostat and ixabepilone clearances were 194 L/h and 21.3 L/h/m2, respectively. Grade 3 peripheral sensory neuropathy was reported in 8% (A) and 21% (B) of patients. The ORR and CBR were 22 and 22% (A); 30 and 35% (B). Median PFS was 3.9 (A) and 3.7 (B) months. OS was 14.8 (A) and 17.1 (B) months. CONCLUSIONS: We established the MTD of vorinostat and ixabepilone. This drug combination offers a novel therapy for previously treated MBC patients. The potential for lower toxicity and comparable efficacy compared to current therapies warrants further study.

A phase II study of frontline paclitaxel/carboplatin/bevacizumab, paclitaxel/carboplatin/temsirolimus, or ixabepilone/carboplatin/bevacizumab in advanced/recurrent endometrial cancer.

OBJECTIVE: Paclitaxel and carboplatin (PC) is a standard initial therapy for advanced endometrial cancer. We evaluated the efficacy and tolerability of incorporating three novel agents into initial therapy. METHODS: In this randomized phase II trial, patients with chemotherapy-naïve stage III/IVA (with measurable disease) and stage IVB or recurrent (with or without measurable disease) endometrial cancer were randomly assigned to treatment with PC plus bevacizumab (Arm 1), PC plus temsirolimus (Arm 2) or ixabepilone and carboplatin (IC) plus bevacizumab (Arm 3). The primary endpoint was progression-free survival (PFS). Comparable patients on the PC Arm of trial GOG209 were used as historical controls. Secondary endpoints were response rate, overall survival (OS), and safety. RESULTS: Overall, 349 patients were randomized. PFS duration was not significantly increased in any experimental arm compared with historical controls (p > 0.039). Treatment HRs (92% CI) for Arms 1, 2, and 3 relative to controls were 0.81 (0.63-1.02), 1.22 (0.96-1.55) and 0.87 (0.68-1.11), respectively. Response rates were similar across arms (60%, 55% and 53%, respectively). Relative to controls, OS duration (with censoring at 36 months), was significantly increased in Arm 1 (p < 0.039) but not in Arms 2 and 3; the HRs (92% CIs) were 0.71 (0.55-0.91), 0.99 (0.78-1.26), and 0.97 (0.77-1.23), respectively. No new safety signals were identified. Common mutations and rates of mismatch repair protein loss are described by histotype. Potential predictive biomarkers for temsirolimus and bevacizumab were identified. CONCLUSION: PFS was not significantly increased in any experimental arm compared to historical controls. NRG Oncology/Gynecologic Oncology Group Study GOG-86P.

TITAN: phase III study of doxorubicin/cyclophosphamide followed by ixabepilone or paclitaxel in early-stage triple-negative breast cancer.

PURPOSE: Ixabepilone is a microtubule stabilizer with activity in taxane-refractory metastatic breast cancer and low susceptibility to taxane-resistance mechanisms including multidrug-resistant phenotypes and high ß-III tubulin expression. Since these resistance mechanisms are common in triple-negative breast cancer (TNBC), ixabepilone may have particular advantages in this patient population. This study evaluated the substitution of ixabepilone for paclitaxel following doxorubicin/cyclophosphamide (AC) in the adjuvant treatment of early-stage TNBC. METHODS: Patients with operable TNBC were eligible following definitive breast surgery. Patients were randomized (1:1) to receive four cycles of AC followed by either four cycles (12 weeks) of ixabepilone or 12 weekly doses of paclitaxel. RESULTS: 614 patients were randomized: 306 to AC/ixabepilone and 308 to AC/paclitaxel. At a median follow-up of 48 months, 59 patients had relapsed (AC/ixabepilone, 29; AC/paclitaxel, 30). The median time from diagnosis to relapse was 20.8 months. The 5-year disease-free survival (DFS) rates of the two groups were similar [HR 0.92; ixabepilone 87.1% (95% CI 82.6-90.5) vs. paclitaxel 84.7% (95% CI 79.7-88.6)]. The estimated 5-year overall survival (OS) rates were also similar [HR 1.1; ixabepilone 89.7% (95% CI 85.5-92.7) vs. paclitaxel 89.6% (95% CI 85.0-92.9)]. Peripheral neuropathy was the most common grade 3/4 event. Dose reductions and treatment discontinuations occurred more frequently during paclitaxel treatment. CONCLUSIONS: Treatment with AC/ixabepilone provided similar DFS and OS in patients with operable TNBC when compared to treatment with AC/paclitaxel. The two regimens had similar toxicity, although treatment discontinuation, dose modifications, and overall peripheral neuropathy were more frequent with AC/paclitaxel. TRIAL REGISTRATION: Clinical Trials.gov Identifier, NCT00789581.

A phase II evaluation of ixabepilone in the treatment of recurrent/persistent carcinosarcoma of the uterus, an NRG Oncology/Gynecologic Oncology Group study.

BACKGROUND: The primary objectives were to determine the objective response rate (ORR) and safety profile of ixabepilone in women with recurrent or persistent uterine carcinosarcoma (UCS). Secondary objectives included progression-free survival (PFS) and overall survival (OS). Exploratory translational objectives included characterization of class III beta tubulin expression and its association with response, PFS, and OS. METHODS: Patients had measurable disease; up to two prior chemotherapeutic regimens were allowed, but must have included a taxane. Women received ixabepilone 40mg/m2 as a 3hour IV infusion on day 1 of a 21daycycle. Treatment was continued until disease progression or unacceptable toxicity occurred. RESULTS: Forty-two women were enrolled, with 34 eligible and evaluable. Median age was 68years. ECOG performance status was 0 in 56% of women, 38% had received radiation, and 15% had received 2 lines of chemotherapy. Overall ORR was 11.8% (4/34, 90% CI 4.2-25.1%); all were partial responses. Stable disease for at least 8weeks was achieved in 8 patients (23.5%). Median PFS and OS were 1.7mo and 7.7mo, respectively, with a median follow-up of 37mo. Six month PFS was 20.6%. Major grade≥3 toxicities were neutropenia (47%), fatigue (15%), dehydration (15%), hypertension (15%), and hyponatremia (15%); grade 2 peripheral neuropathy was reported in 18%. In this small sample size, class III beta tubulin expression in the primary tumor was not associated with the response to ixabepilone, PFS, or OS. CONCLUSION: In this cohort of women, single agent ixabepilone showed modest but insufficient clinical activity.

Update on Chemotherapy-Induced Peripheral Neuropathy.

PURPOSE OF REVIEW: The purpose of this study was to briefly discuss chemotherapy-induced peripheral neuropathy (CIPN) and detail the most important and most recent chemotherapeutic agents implicated. This review will examine neuropathy mechanisms, risk factors, and clinical patterns; novel and prospective drugs with similar effects that are less well known to neurologists are discussed. RECENT FINDINGS: CIPN is increasingly recognized for its clinical importance and effect on patient quality of life. Identification of risk factors is ongoing and may enable future risk stratification. Newer classes of agents and new members of existing classes are continually recognized, notably immune check point inhibitors, other monoclonal antibody treatments, novel immunomodulatory agents, and proteasome inhibitors. Advances regarding established classes including taxanes, platins, and vinca alkaloids are also reviewed. CIPN is an important often dose-limiting toxicity. Multiple agents cause neuropathy; various clinical patterns are described. Future studies should aim at improved understanding of toxicity mechanisms and development of preventive and therapeutic strategies.

Zampanolide, a Microtubule-Stabilizing Agent, Is Active in Resistant Cancer Cells and Inhibits Cell Migration.

Zampanolide, first discovered in a sponge extract in 1996 and later identified as a microtubule-stabilizing agent in 2009, is a covalent binding secondary metabolite with potent, low nanomolar activity in mammalian cells. Zampanolide was not susceptible to single amino acid mutations at the taxoid site of ß-tubulin in human ovarian cancer 1A9 cells, despite evidence that it selectively binds to the taxoid site. As expected, it did not synergize with other taxoid site microtubule-stabilizing agents (paclitaxel, ixabepilone, discodermolide), but surprisingly also did not synergize in 1A9 cells with laulimalide/peloruside binding site agents either. Efforts to generate a zampanolide-resistant cell line were unsuccessful. Using a standard wound scratch assay in cell culture, it was an effective inhibitor of migration of human umbilical vein endothelial cells (HUVEC) and fibroblast cells (D551). These properties of covalent binding, the ability to inhibit cell growth in paclitaxel and epothilone resistant cells, and the ability to inhibit cell migration suggest that it would be of interest to investigate zampanolide in preclinical animal models to determine if it is effective in vivo at preventing tumor growth and metastasis.

Silencing A7-nAChR levels increases the sensitivity of gastric cancer cells to ixabepilone treatment.

Gastric cancer is an important health issue worldwide. Currently, improving the therapeutic efficacy of chemotherapy drugs is an important goal of cancer research. Alpha-7 nicotine acetylcholine receptor (A7-nAChR) is the key molecule that mediates gastric cancer progression, metastasis, and therapy responses; however, the role of A7-nAChR in the therapeutic efficacy of ixabepilone remains unclear. A7-nAChR expression was silenced by small interfering RNA (siRNA) technology. The cytotoxicity of ixabepilone was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and ixabepilone-induced apoptosis was analyzed by flow cytometry and annexin V/propidium iodide (PI) apoptotic assay. The expression patterns of anti-apoptotic proteins (AKT, phospho-AKT, Mcl-1, and Bcl-2) and pro-apoptotic proteins (Bad and Bax) were determined by western blot. Our study found that A7-nAChR knockdown (A7-nAChR-KD) AGS cells were more sensitive to ixabepilone administration than scrambled control AGS cells. We found that A7-nAChR knockdown enhanced ixabepilone-induced cell death as evidenced by the increased number of annexin V-positive (apoptotic) cells. After scrambled control and A7-nAChR-KD cells were treated with ixabepilone, we found that pAKT and AKT levels were significantly reduced in both groups of cells. The levels of Bcl-2 and the anti-apoptotic Mcl-1 isoform increased dramatically after ixabepilone treatment in scrambled control cells but not in A7-nAChR-KD cells. Bad and Bax levels did not change between the treatment group and vehicle group in both A7-nAChR-KD and scrambled control cells, whereas cleaved PARP levels dramatically increased in ixabepilone-treated A7-nAChR-KD cells. Our results demonstrated that knockdown of A7-nAChR enhanced the sensitivity of gastric cancer cells to ixabepilone administration. Thus, the A7-nAChR expression level in patients with gastric cancer may be a good indicator of ixabepilone sensitivity.

Chemotherapy reaction induced by ixabepilone, a microtubule stabilizing agent, mimicking extramammary Paget's disease in a patient with breast carcinoma.

The histopathologic characteristics of reactions caused by the many novel anticancer agents are under-recognized. We report a case of a 67-year-old female with locally advanced metastatic breast cancer, who initially presented with an extensive reticulated erythematous patch on the trunk caused by intravascular metastases confirmed by a skin biopsy. Owing to disease progression, she was started on ixabepilone, a mitotic inhibitor. While receiving ixabepilone, another skin biopsy was obtained and initially interpreted as extramammary Paget's disease. However, the biopsy showed metaphase arrest of numerous keratinocytes in the basilar and suprabasilar epidermis. Atypical epithelial cells were only present in the intravascular spaces similar to the initial biopsy. Given the temporal association between the initiation of ixabepilone therapy and the epidermal mitotic arrest, a diagnosis of chemotherapy reaction to ixabepilone was rendered. Ixabepilone is an analog of epothilone, a microtubule stabilizer causing mitotic arrest of the cell cycle approved for the treatment of metastatic and locally advanced treatment-resistant breast cancer. The demonstration of epidermal mitotic arrest caused by ixabepilone is without precedent. The case emphasizes the importance of considering a chemotherapy reaction in the histologic differential diagnosis of epidermal mitotic arrest in a cancer patient receiving chemotherapy.

A phase II trial of ixabepilone and cyclophosphamide as neoadjuvant therapy for patients with HER2-negative breast cancer: correlation of pathologic complete response with the 21-gene recurrence score.

Ixabepilone and the taxanes have similar activity in the first-line treatment of metastatic breast cancer, and ixabepilone is sometimes effective in taxane-refractory patients. We conducted a phase 2 trial to evaluate ixabepilone in combination with cyclophosphamide as neoadjuvant treatment for patients with locally advanced HER2-negative breast cancer. Response to neoadjuvant treatment was correlated with the baseline 21-gene Recurrence Score® (Oncotype DX; Genomic Health Inc, Redwood City, CA). Eligible women with HER2-negative locally advanced breast cancer received ixabepilone 40 mg/m(2) plus cyclophosphamide 600 mg/m(2) on day 1 of each 21-day cycle. Following 6 cycles, patients underwent definitive surgery. Primary endpoint was rate of pathologic complete response (pCR). Breast biopsy tumor samples were obtained at pretreatment and at surgery in patients with residual disease. Tumor specimens were analyzed using the 21-gene assay. One hundred sixty-eight patients (median age 52 years; 45 % triple-negative) were enrolled; 161 (96 %) underwent definitive surgery following neoadjuvant ixabepilone/cyclophosphamide. Overall, 27 patients (17 %) achieved pCR, including 19 of 73 (26 %) triple-negative patients. The most frequently occurring grade 3/4 toxicity was neutropenia (98 patients; 58 %). Recurrence Scores were highly correlated with achievement of pCR (0/36 with low or intermediate Recurrence Scores vs. 19/72 with high Recurrence Scores; p = 0.002). There was high concordance between baseline and post-treatment Recurrence Scores in the 72 patients with paired samples. The combination of ixabepilone and cyclophosphamide yielded a pCR rate of 17 %, similar to other neoadjuvant chemotherapy regimens. Pathologic complete responses occurred only in patients with high-risk baseline Recurrence Scores.

Weekly ixabepilone with or without biweekly bevacizumab in the treatment of recurrent or persistent uterine and ovarian/primary peritoneal/fallopian tube cancers: A retrospective review.

OBJECTIVE: To describe the clinical outcome and tolerability of weekly ixabepilone (16-20mg/m(2) days 1, 8, 15 of a 28-day cycle)±biweekly bevacizumab (10mg/kg days 1 and 15) in patients with recurrent/persistent uterine or ovarian/primary peritoneal/fallopian tube cancers. METHODS: A single-institution retrospective review was performed inclusive of all patients who received ≥2cycles from 01/2010 to 06/2014. Progression-free (PFS) and overall (OS) survival were determined using the Kaplan-Meier method. Toxicities were graded according to CTCAEv4.0. Best response was categorized using RECIST or by CA-125 criteria. RESULTS: A total of 60 patients (24 uterine and 36 ovarian cancers) were identified. Patients had received a median of 3.5 (range:1-10) prior lines of chemotherapy. Patients completed a mean of 4.7±2.9cycles of ixabepilone; 66.7% (16/24) and 91.7% (33/36) of patients with uterine and ovarian cancers received concurrent bevacizumab. For uterine cancers, objective response rate (ORR) was 41.7% (12.5% complete, 29.2% partial); median duration of response or stabilization was 7months (range:2-30). Median PFS and OS were 5.2 and 9.6months, respectively. PFS and OS were improved in the setting of concurrent bevacizumab (6.5 versus 3.0months, p=0.01, HR 0.2, 95% CI 0.05-0.77; 9.6 versus 4.2months, p=0.02, HR 0.58, 95% CI 0.04-0.74). Similar ORR was observed among ovarian cancers; median PFS/OS were not yet reached. Most toxicities were grade 1/2. CONCLUSIONS: Weekly ixabepilone with or without biweekly bevacizumab has promising activity and acceptable toxicity in patients with platinum-/taxane-resistant endometrial and ovarian cancers. This combination warrants further prospective study in these populations.

Phase III randomized trial of second-line ixabepilone versus paclitaxel or doxorubicin in women with advanced endometrial cancer.

OBJECTIVE: The purpose of this multicenter, open label, randomized phase III study was to determine whether ixabepilone resulted in improved overall survival (OS) compared with commonly used single-agent chemotherapy (doxorubicin or paclitaxel) in women with locally advanced, recurrent, or metastatic endometrial cancer with at least one failed prior platinum-based chemotherapeutic regimen. METHODS: Patients were randomized 1:1 to ixabepilone (40mg/m(2)), or either paclitaxel (175mg/m(2)) or doxorubicin (60mg/m(2)), every 21days. Patients that had previously received an anthracycline were randomized to ixabepilone or paclitaxel; all other patients were randomized to ixabepilone or doxorubicin. An interim analysis of futility for OS was planned. RESULTS: At the time of database lock, 496 patients were randomized to receive ixabepilone (n=248) or control (n=248); nine patients in the control arm were not treated. The interim analysis of futility for OS (219 events) favored the control chemotherapy arm (hazard ratio=1.3 [95% confidence interval: 1.0-1.7], stratified log rank test P=0.0397), indicating that the study would not meet its primary objective. The study was discontinued based on the interim OS results. The frequency of adverse events was comparable between the treatment arms. CONCLUSIONS: The study did not meet its primary objective of improving OS in the ixabepilone arm compared to the control chemotherapy arm. A favorable risk/benefit ratio was not observed for ixabepilone versus control at the time of the interim analysis. The safety results were consistent with the known safety profiles of ixabepilone and control.

Chemotherapy options for patients suffering from heavily pretreated metastatic breast cancer.

The identification of additional chemotherapy agents for anthracycline- and taxane-pretreated advanced breast cancer (ABC) is an urgent medical need. Single agent chemotherapy is most times administered because combined therapy is only associated with modest, if any, improvement in median progression-free survival. Randomized trials failed to show overall survival benefit compared with single agent chemotherapy. We hope to modify the natural history of ABC by the consecutive use of treatments with documented activity in heavily pretreated patients. Quality of life remains an important end point as cure is in general not possible. We first review the activity of the approved and the most frequently used agents in heavily pretreated ABC. Thereafter, the potential role and safety profile of etirinotecan pegol is discussed given the results recently released of a Phase III trial comparing this agent to Treatment of Physician's Choice.

A Phase II evaluation of ixabepilone (IND #59699, NSC #710428) in the treatment of recurrent or persistent leiomyosarcoma of the uterus: an NRG Oncology/Gynecologic Oncology Group Study.

OBJECTIVE: The combination of gemcitabine and docetaxel is the standard first-line therapy for recurrent or metastatic uterine leiomyosarcoma. There is no standard second-line therapy. Ixabepilone is a semi-synthetic analog of epothilone B that binds to the same site on beta tubulin as paclitaxel and may be a more potent polymerizer of tubulin. We sought to determine the activity of ixabepilone as a single agent as second-line treatment for patients with metastatic uterine leiomyosarcoma who had received taxane based therapy. METHODS: Eligible women with unresectable uterine leiomyosarcoma progressing after prior cytotoxic therapy containing a taxane were treated with ixabepilone 40 mg/m(2) on day one of a 21 day cycle. Patients with prior pelvic radiation were treated without dose reduction. Response Evaluation Criteria in Solid Tumors (RECIST) response was assessed by computed tomography (CT). RESULTS: Twenty-three of 26 women were evaluable (two wrong histology, one never treated) with two of 23 receiving 1 cycle of therapy. There were no complete or partial responses. Stable disease (SD) was seen in four patients (17.4%, median 3.4 months). Seventeen patients (73.9%) had increasing disease (PD) and two patients were inevaluable per RECIST. One patient had SD over 6 cycles of treatment. Median PFS for all 23 patients was 1.4 months and overall survival was 7.0 months. The predominant grade 3 or 4 toxicity was uncomplicated myelosuppression: neutropenia grade 3 (13%), grade 4 (17%), and anemia grade 3 (22%). CONCLUSION: Ixabepilone as a single agent is not an active second-line therapy for uterine leiomyosarcoma previously treated with a taxane.

Total Synthesis of an Epothilone Analogue Based on the Amide-Triazole Bioisosterism.

Epothilones are 16-membered macrolides that act as microtubule-targeting agents to tackle cancer. Many synthetic analogues have been investigated for their activity, yet often based on macrolide structures. A notable exception is Ixabepilone, an azalide whose metabolic stability and pharmacokinetics are significantly improved. Exploiting the amide-triazole bioisosterism, in this work we report the synthesis of the first generation of epothilones lacking the macrolide or azalide structure, with the ester or amide linkage replaced by a triazole unit. Together with the synthesis of this new analogue, computational and biological evaluations have been performed too.

Ixabepilone related angiographically silent macular edema.

INTRODUCTION: We present a single-eyed case with a previous diagnosis of breast cancer who had intraretinal cystoid changes associated with the systemic administration of ixabepilone in her only seeing eye. To our best knowledge, this is the first reported case describing this phenomenon related to the ixabepilone administration. CASE DESCRIPTION: A 54-year-old woman with a history of breast cancer was examined due to visual deterioration in her only good left eye. The patient had undergone cataract surgery and lens implantation in her right eye following a childhood accident, but subsequently had developed a refractory glaucoma and lost her right vision. Six cycles of 40 mg/m2 systemic ixabepilone (3-hly intravenous infusion once every 3 weeks) had been administered within the past six months. Her visual decline started two weeks following the last treatment session. She was offered intravitreal anti-vascular endothelial growth factor injection elsewhere. Fluorescein angiogram showed no dye leakage whereas spectral-domain optical coherence tomography demonstrated parafoveal intraretinal cystoid changes. En-face optical coherence tomography revealed petaloid type roundish hyporeflective areas at the level of superficial and deep vascular plexus. Ixabepilone-associated cystoid maculopathy was suspected as she received only ixabepilone for the chemotherapy in the last six months. We thus recommended her not to continue ixabepilone therapy. Ten weeks after the ixabepilone cessation, intraretinal cystoid changes had resolved completely. CONCLUSION: Angiographically silent intraretinal cystoid changes may develop in association with the use of ixabepilone. Referral to an ophthalmologist should be considered for the patients experiencing visual complaints as ixabepilone cessation may lead to visual improvement and avoid unnecessary treatment.

Neoadjuvant doxorubicin/cyclophosphamide followed by ixabepilone or paclitaxel in early stage breast cancer and evaluation of ßIII-tubulin expression as a predictive marker.

BACKGROUND: This randomized phase II trial was designed to compare the rate of pathologic complete response (pCR) induced by neoadjuvant cyclophosphamide plus doxorubicin (AC) followed by ixabepilone or paclitaxel in women with early stage breast cancer (BC). Expression of ßIII-tubulin as a predictive marker was also evaluated. PATIENTS AND METHODS: Women with untreated, histologically confirmed primary invasive breast adenocarcinoma received four cycles of AC followed by 1:1 randomization to either ixabepilone 40 mg/m2 (3-hour infusion) every 3 weeks for four cycles (n = 148) or weekly paclitaxel 80 mg/m2 (1-hour infusion) for 12 weeks (n = 147). All patients underwent a core needle biopsy of the primary cancer for molecular marker analysis prior to chemotherapy. ßIII-Tubulin expression was assessed using immunohistochemistry. RESULTS: There was no significant difference in the rate of pCR in the ixabepilone treatment arm (24.3%; 90% confidence interval [CI], 18.6-30.8) and the paclitaxel treatment arm (25.2%; 90% CI, 19.4-31.7). ßIII-Tubulin-positive patients obtained higher pCR rates compared with ßIII-tubulin-negative patients in both treatment arms; however, ßIII-tubulin expression was not significantly associated with a differential response to ixabepilone or paclitaxel. The safety profiles of both regimens were generally similar, although neutropenia occurred more frequently in the ixabepilone arm (grade 3/4: 41.3% vs. 8.4%). The most common nonhematologic toxicity was peripheral neuropathy. CONCLUSIONS: Neoadjuvant treatment of early stage BC with AC followed by ixabepilone every 3 weeks or weekly paclitaxel was well tolerated with no significant difference in efficacy. Higher response rates were observed among ßIII-tubulin-positive patients.

A phase II study of ixabepilone and trastuzumab for metastatic HER2-positive breast cancer.

BACKGROUND: A multicenter NCI-sponsored phase II study was conducted to analyze the safety and efficacy of the combination of ixabepilone with trastuzumab in patients with metastatic HER2-positive breast cancer. PATIENTS AND METHODS: Two cohorts were enrolled: cohort 1 had received no prior chemotherapy or trastuzumab for metastatic disease and cohort 2 had received 1-2 prior trastuzumab-containing regimens for metastatic disease. Patients in both cohorts received ixabepilone 40 mg/m(2) as a 3-h infusion and trastuzumab on day 1 of a 21-day cycle. Tumor biomarkers that may predict response to trastuzumab were explored. RESULTS: Thirty-nine women entered the study with 15 patients in cohort 1 and 24 patients in cohort 2. Across both cohorts, the overall RR was 44%, with a clinical benefit rate (CR + PR + SD for at least 24 weeks) of 56%. Treatment-related toxic effects included neuropathy (grade ≥2, 56%), leukopenia (grade ≥2, 26%), myalgias (grade ≥2, 21%), neutropenia (grade ≥2, 23%), and anemia (grade ≥2, 18%). CONCLUSIONS: This represents the first study of the combination of ixabepilone with trastuzumab for the treatment of metastatic HER2-positive breast cancer. These results suggest that the combination has encouraging activity as first and subsequent line therapy for metastatic breast cancer.

The ixabepilone and vandetanib combination shows synergistic activity in docetaxel-resistant MDA-MB-231 breast cancer cells.

BACKGROUND: The lack of drug targets is an obstacle to the treatment of patients with triple-negative breast cancer (TNBC). At present, non-specific cytotoxic drugs are first-line agents, but the development of resistance is a major problem with these agents. The epidermal growth factor receptor (EGFR) is a potential target in some TNBCs, because its tyrosine kinase activity drives tumorigenesis. Thus, small molecule inhibitors of the EGFR in combination with cytotoxic agents could be important for the treatment of TNBCs. METHODS: The present study evaluated the efficacies of clinically approved EGFR inhibitors in combination with the cytotoxic agent ixabepilone in parental and docetaxel-resistant MDA-MB-231 cells (231C and TXT cells, respectively). Cell viability was assessed using MTT reduction assays, cell death pathways were evaluated using annexin V/7-aminoactinomycin D staining and flow cytometry and Western immunoblotting was used to assess the expression of pro- and anti-apoptotic proteins in cells. RESULTS: Ixabepilone and the EGFR inhibitors gefitinib and vandetanib inhibited 231C and TXT cell proliferation, but the alternate EGFR inhibitors erlotinib and lapatinib were poorly active. Using combination analysis, ixabepilone/vandetanib was synergistic in both cell types, whereas the ixabepilone/gefitinib combination exhibited antagonism. By flow cytometry, ixabepilone/vandetanib enhanced 231C and TXT cell death over that produced by the single agents and also enhanced caspase-3 cleavage and the pro/anti-apoptotic Bcl-2 protein ratios over ixabepilone alone. CONCLUSIONS: These findings suggest that the ixabepilone/vandetanib combination may have promise for the treatment of patients with drug-resistant TNBC.