Epothilones as Natural Compounds for Novel Anticancer Drugs Development.

Epothilone is a natural 16-membered macrolide cytotoxic compound produced by the metabolism of the cellulose-degrading myxobacterium Sorangium cellulosum. This review summarizes results in the study of epothilones against cancer with preclinical results and clinical studies from 2010-2022. Epothilone have mechanisms of action similar to paclitaxel by inducing tubulin polymerization and apoptosis with low susceptibility to tumor resistance mechanisms. It is active against refractory tumors, being superior to paclitaxel in many respects. Since the discovery of epothilones, several derivatives have been synthesized, and most of them have failed in Phases II and III in clinical trials; however, ixabepilone and utidelone are currently used in clinical practice. There is robust evidence that triple-negative breast cancer (TNBC) treatment improves using ixabepilone plus capecitabine or utidelone in combination with capecitabine. In recent years innovative synthetic strategies resulted in the synthesis of new epothilone derivatives with improved activity against refractory tumors with better activities when compared to ixabepilone or taxol. These compounds together with specific delivery mechanisms could be developed in anti-cancer drugs.

Improved i.p. drug delivery with bioadhesive nanoparticles.

The i.p. administration of chemotherapy in ovarian and uterine serous carcinoma patients by biodegradable nanoparticles may represent a highly effective way to suppress peritoneal carcinomatosis. However, the efficacy of nanoparticles loaded with chemotherapeutic agents is currently hampered by their fast clearance by lymphatic drainage. Here, we show that a unique formulation of bioadhesive nanoparticles (BNPs) can interact with mesothelial cells in the abdominal cavity and significantly extend the retention of the nanoparticles in the peritoneal space. BNPs loaded with a potent chemotherapeutic agent [epothilone B (EB)] showed significantly lower systemic toxicity and higher therapeutic efficacy against i.p. chemotherapy-resistant uterine serous carcinoma-derived xenografts compared with free EB and non-BNPs loaded with EB.

Continuous low-dose infusion of patupilone increases the therapeutic index in mouse and rat tumour models.

Patupilone is a microtubule-targeted cytotoxic agent with clinical efficacy, but causes diarrhoea in more than 80% of patients. The efficacy and tolerability of patupilone delivered continuously by subcutaneous (s.c.) mini-pumps [(mini-pump dose (MPD)] or by intravenous bolus administration [intravenous bolus dose (IVBD)] were compared preclinically to determine whether the therapeutic index could be improved. The antiproliferative potency in vitro of patupilone was determined by measuring total cell protein. Tumours were grown s.c. in rats (A15) or nude mice (KB31, KB8511) or intracranially in nude mice (NCI-H460-Luc). Efficacy was monitored by measuring tumour volumes, bioluminescence or survival. Toxicity was monitored by body weight and/or diarrhoea. Total drug levels in blood, plasma, tissues or dialysates were quantified ex-vivo by liquid chromatography-mass spectroscopy/mass spectroscopy. Patupilone was potent in vitro with GI50s of 0.24-0.28 nmol/l and GI90s of 0.46-1.64 nmol/l. In rats, a single IVBD of patupilone dose dependently inhibited the growth of A15 tumours, but also caused dose-dependent body weight loss and diarrhoea, whereas MPD achieved similar efficacy, but no toxicity. In mice, MPD showed efficacy similar to that of IVBD against KB31 and KB8511 tumours, but with reduced toxicity. In a mouse intracranial tumour model, IVBD was more efficacious than MPD, consistent with patupilone concentrations in the brain. MPD provided constant plasma levels, whereas IVBD had very high C0/Cmin ratios of 70-280 (rat) or 8000 (mouse) over the dosing cycle. Overall, the correlation of plasma and tumour levels with response indicated that a Cave of at least GI90 led to tumour stasis. Continuous low concentrations of patupilone by MPD increased the therapeutic index in s.c. rodent tumour models compared with IVBD by maintaining efficacy, but reducing toxicity.

Dynamic Microtubules in Alzheimer's Disease: Association with Dendritic Spine Pathology.

Alzheimer's disease (AD) is the most common incurable neurodegenerative disorder that affects the processes of memory formation and storage. The loss of dendritic spines and alteration in their morphology in AD correlate with the extent of patient's cognitive decline. Tubulin had been believed to be restricted to dendritic shafts, until recent studies demonstrated that dynamically growing tubulin microtubules enter dendritic spines and promote their maturation. Abnormalities of tubulin cytoskeleton may contribute to the process of dendritic spine shape alteration and their subsequent loss in AD. In this review, association between tubulin cytoskeleton dynamics and dendritic spine morphology is discussed in the context of dendritic spine alterations in AD. Potential implications of these findings for the development of AD therapy are proposed.

Microtubule stabilization promoted axonal regeneration and functional recovery after spinal root avulsion.

A spinal root avulsion injury disconnects spinal roots with the spinal cord. The rampant motoneuron death, inhibitory CNS/PNS transitional zone (TZ) for axonal regrowth and limited regeneration speed together lead to motor dysfunction. Microtubules rearrange to assemble a new growth cone and disorganized microtubules underline regeneration failure. It has been shown that microtubule-stabilizing drug, Epothilone B, enhanced axonal regeneration and attenuated fibrotic scaring after spinal cord injury. Here, we are reporting that after spinal root avulsion+ re-implantation in adult rats, EpoB treatment improved motor functional recovery and potentiated electrical responses of motor units. It facilitated axons to cross the TZ and promoted more and bigger axons in the peripheral nerve. Neuromuscular junctions were reformed with better preserved postsynaptic structure, and muscle atrophy was prevented by EpoB administration. Our study showed that EpoB was a promising therapy for promoting axonal regeneration after peripheral nerve injury.

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.

Phase II Clinical Trial of Ixabepilone in Metastatic Cervical Carcinoma.

LESSONS LEARNED: Accrual to cervical cancer studies remains a puzzling challenge given the lack of options and the dismal prognosis of this disease. The majority of patients referred for a trial such as this have very advanced disease that is difficult to manage.The observation of 4 partial responses among the 41 patients indicates that ixabepilone has some activity but not sufficient for further development without greater understanding of mechanisms of sensitivity and resistance. BACKGROUND: Ixabepilone is a microtubule-stabilizing agent approved for metastatic breast cancer. Preclinical data have shown that ixabepilone is active in taxane-sensitive and -resistant cells. Metastatic cervical carcinoma (mCC) has a poor prognosis and no established second-line therapies. This study assessed the efficacy and safety of ixabepilone in previously treated mCC. METHODS: Patients with histologically confirmed mCC and at least one prior cisplatin-containing regimen were treated with ixabepilone [6 mg/m(2) per day for 5 days] every 21 days. The primary endpoint was progression-free survival (PFS) according to the Response Evaluation Criteria in Solid Tumors (RECIST). Secondary endpoints were response rate, rate of tumor growth, overall survival (OS), and safety. Levels of glu-terminated and acetylated tubulin, markers of microtubule stabilization, and surrogates for target engagement were assessed by Western blot. RESULTS: In total, 41 patients were enrolled; 34 had tumors with primarily squamous histology. The median number of prior therapies was 2 (range 1-6). Four patients (9.7%) had a partial response. Median PFS in months was 2.3 for all, 3.84 for taxane-naïve, and 2.03 for taxane-pretreated patients (p = .13). Consistent with this, we found statistically similar (p = 1) rates of growth in taxane-naive patients (0.0035 per day) and taxane pretreated patients (0.0053 per day). Median OS was 5.84 months. G1/2 toxicities included vomiting (43%), sensory neuropathy (21%), and fatigue (60%). Bowel fistulas were observed in 7% of patients. Glu and acetylated tubulin were assessed in tumor samples from 11 patients during the first cycle of treatment. Although there was clear evidence of "target engagement" and microtubule stabilization in all tumors, a correlation between the extent of tubulin stabilization and response to therapy could not be demonstrated. CONCLUSION: Ixabepilone was well tolerated but showed very modest activity in second- or later-line mCC and cannot be recommended as a therapy. Target engagement was demonstrated but was not correlated with responses, suggesting that other factors mediate drug sensitivity. New strategies are needed for refractory mCC.

Neurotoxicity as a prognostic factor in patients with metastatic breast cancer treated with ixabepilone as a first-line therapy.

OBJECTIVE: This study is a longitudinal follow-up of metastatic breast cancer patients treated with ixabepilone as first-line chemotherapy, with the aim to evaluate the association between a mechanism-based neurotoxicity and the efficacy of ixabepilone. PATIENTS AND METHODS: At the 2 main investigational sites of a phase II clinical trial, 50 patients previously treated with anthracycline received ixabepilone. A chart review was performed to evaluate overall survival (OS) and time to progression (TTP) and to describe the subsequent treatments. RESULTS: The severe neurotoxicity induced by ixabepilone (38%) is correlated with a higher overall response rate to ixabepilone (79 vs. 48%; p = 0.042), a longer TTP (11.4 vs. 6.8 months; p = 0.023) and a longer OS (36.6 vs. 19.9 months; p = 0.05). After ixabepilone discontinuation, patients received a median of 4 subsequent chemotherapy lines (range 1-12). Among the 31 patients who received taxanes, neither the neurotoxicity incidence under treatment with taxanes nor the response was affected by a previous occurrence under ixabepilone treatment. CONCLUSION: These findings suggest that neurotoxicity development under ixabepilone treatment is a predictor of treatment outcomes as well as a favorable prognostic factor. It highlights the risk-to-benefit ratio issue of ixabepilone. We noticed the possibility to treat patients with taxanes after ixabepilone without systematic recurrent neurotoxicity.

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.

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.

Current use of drugs affecting the central nervous system for chemotherapy-induced peripheral neuropathy in cancer patients: a systematic review.

PURPOSE: Chemotherapy-induced peripheral neuropathy (CIPN) is common among cancer patients who undergo chemotherapy with platinum analogues, taxanes, vinca alkaloids, epothilone, bortezomib, and thalidomide. The purpose of this study was to investigate the evidence of using drugs affecting the central nervous system (CNS) to alleviate CIPN in cancer patients. METHODS: A systematic literature search was conducted using the CINAHL, EMBASE, and Medline databases to identify randomized controlled clinical trials (RCTs) reported in English up to 2013. We identified ten trials of CNS-acting drugs used to treat CIPN in cancer patients and reviewed efficacy and safety of CNS-acting drugs for CIPN using a standard data collection form. The risk of bias in each RCT was also assessed. RESULTS: Antidepressants were used in six studies and anticonvulsants in four studies. We found positive results for amitriptyline (topical), venlafaxine, and oxcarbazepine in one study each, but the results were not sufficient to draw definite conclusions. One trial with duloxetine showed a moderate effect (effect size, 0.513, P = .003) on CIPN pain relief. However, none of the results has yet been duplicated in an RCT with a large sample size. CONCLUSIONS: Insufficient RCTs exist to confirm the efficacy of CNS agents to reduce CIPN. This study highlighted the need for and the importance of conducting well-designed RCTs to generate evidence on CIPN symptom management. Additional RCTs are warranted to accelerate the potential use of CNS drugs for CIPN in cancer patients.

[TUBB3 role in the response of tumor cells to epothilones and taxanes]. / Rola TUBB3 w odpowiedzi komórek nowotworowych na epotilony i taksany

Because of increased incidence of cancer and the development of resistance after treatment with typical drugs, new insights into the mechanisms of action of individual compounds are extremely valuable. In this article, we focus on taxanes, drugs belonging to the group of microtubule stabilizers, and their new generation - epothilones. Facing the fact that the molecular target for these compounds are microtubules, our attention was focused primarily on the role of overexpression of one of tubulin isotypes in response of tumor cells, particularly ovarian cancer to treatment with these compounds. On the basis of the literature data it can be concluded that one reason for the ineffectiveness of taxane is the resistance growing in the case of overexpression of b-tubulin class III- (TUBB3). Epothilones, however, due to their ability to bind equally to b-tubulin class I and III are effective in these cells, giving them an advantage over taxanes. It is necessary to emphasize the role of mikroRNA, transcription factors and other proteins associated with the activation of microtubules in development of resistance to taxanes and overcoming the resistance of the epothilones. Particularly interesting tubuseems to be the link between expression of TUBB3 and Glis proteins, which are end-effectors of Hedgehog pathway. Thanks to the confirmation that Gli1 overexpression is associated with decreased response to chemotherapy, it was possible to sensitize cells to epothilones after addition a suitable inhibitor.

Neuronal transport defects of the MAP6 KO mouse - a model of schizophrenia - and alleviation by Epothilone D treatment, as observed using MEMRI.

The MAP6 (microtubule-associated protein 6) KO mouse is a microtubule-deficient model of schizophrenia that exhibits severe behavioral disorders that are associated with synaptic plasticity anomalies. These defects are alleviated not only by neuroleptics, which are the gold standard molecules for the treatment of schizophrenia, but also by Epothilone D (Epo D), which is a microtubule-stabilizing molecule. To compare the neuronal transport between MAP6 KO and wild-type mice and to measure the effect of Epo D treatment on neuronal transport in KO mice, MnCl2 was injected in the primary somatosensory cortex. Then, using manganese-enhanced magnetic resonance imaging (MEMRI), we followed the propagation of Mn(2+) through axonal tracts and brain regions that are connected to the somatosensory cortex. In MAP6 KO mice, the measure of the MRI relative signal intensity over 24h revealed that the Mn(2+) transport rate was affected with a stronger effect on long-range and polysynaptic connections than in short-range and monosynaptic tracts. The chronic treatment of MAP6 KO mice with Epo D strongly increased Mn(2+) propagation within both mono- and polysynaptic connections. Our results clearly indicate an in vivo deficit in neuronal Mn(2+) transport in KO MAP6 mice, which might be due to both axonal transport defects and synaptic transmission impairments. Epo D treatment alleviated the axonal transport defects, and this improvement most likely contributes to the positive effect of Epo D on behavioral defects in KO MAP6 mice.

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.

Development of other microtubule-stabilizer families: the epothilones and their derivatives.

Chemotherapy is the mainstay of treatment for numerous cancer types, but resistance to chemotherapy remains a major clinical issue and is one of the driving influences underlying the development of new anticancer medications. One of the most important classes of chemotherapy agents is the taxanes, which target the cytoskeleton and spindle apparatus of tumor cells by binding to the microtubules, thereby disrupting key cellular mechanisms, including mitosis. Taxane resistance, however, limits treatment options and creates a major challenge for clinicians. Ongoing research has identified several newer classes of microtubule-targeting chemotherapies that may retain activity despite clinical resistance to taxanes. Among these classes, the epothilones have been studied most extensively in the clinical setting. Like taxanes, epothilones stabilize microtubulin turnover, and they have properties favoring their development as anticancer agents. The most clinically advanced epothilone analog is ixabepilone, which is currently the only approved epothilone derivative. Ixabepilone is indicated for the treatment of metastatic or locally advanced breast cancer in combination with capecitabine after failure of an anthracycline and a taxane, or as monotherapy after failure of an anthracycline, a taxane, and capecitabine. In phase II and III trials, ixabepilone showed efficacy in several patient subgroups and in various stages of breast cancer. Common adverse reactions include peripheral sensory neuropathy and asthenia. This paper will discuss the preclinical and clinical development of epothilones and their derivatives across a variety of cancer types.

Intestinal permeability in patients with metastatic colon cancer treated with patupilone.

BACKGROUND: Only a limited number of cytotoxic drugs have shown activity in metastatic colorectal carcinoma. Patupilone is a novel agent with promising activity in this common cancer. Diarrhea represents the dose-limiting toxicity of patupilone. Measurement of intestinal permeability is one of the potential methods of non-invasive laboratory assessment of gastrointestinal toxicity. METHODS: We have assessed intestinal permeability by measuring absorption of lactulose, mannitol and xylose in 27 previously treated patients with metastatic colorectal cancer enrolled in a phase I trial of patupilone. RESULTS: Lactulose/mannitol and lactulose/xylose ratios increased after the treatment. Significantly higher lactulose/mannitol ratio was observed in patients who had severe diarrhea. Moreover, patients who subsequently had an adverse event of grade 3 or higher had significantly higher baseline lactulose/mannitol or lactulose/xylose ratios. CONCLUSIONS: Measurement of intestinal permeability using the lactulose/mannitol test may represent a biomarker for the monitoring, or even prediction of toxicity of cytotoxic drugs, including patupilone.

Hyperdynamic microtubules, cognitive deficits, and pathology are improved in tau transgenic mice with low doses of the microtubule-stabilizing agent BMS-241027.

Tau is a microtubule (MT)-stabilizing protein that is altered in Alzheimer's disease (AD) and other tauopathies. It is hypothesized that the hyperphosphorylated, conformationally altered, and multimeric forms of tau lead to a disruption of MT stability; however, direct evidence is lacking in vivo. In this study, an in vivo stable isotope-mass spectrometric technique was used to measure the turnover, or dynamicity, of MTs in brains of living animals. We demonstrated an age-dependent increase in MT dynamics in two different tau transgenic mouse models, 3xTg and rTg4510. MT hyperdynamicity was dependent on tau expression, since a reduction of transgene expression with doxycycline reversed the MT changes. Treatment of rTg4510 mice with the epothilone, BMS-241027, also restored MT dynamics to baseline levels. In addition, MT stabilization with BMS-241027 had beneficial effects on Morris water maze deficits, tau pathology, and neurodegeneration. Interestingly, pathological and functional benefits of BMS-241027 were observed at doses that only partially reversed MT hyperdynamicity. Together, these data suggest that tau-mediated loss of MT stability may contribute to disease progression and that very low doses of BMS-241027 may be useful in the treatment of AD and other tauopathies.

The microtubule-stabilizing agent, epothilone D, reduces axonal dysfunction, neurotoxicity, cognitive deficits, and Alzheimer-like pathology in an interventional study with aged tau transgenic mice.

Neurodegenerative tauopathies, such as Alzheimer's disease (AD), are characterized by insoluble deposits of hyperphosphorylated tau protein within brain neurons. Increased phosphorylation and decreased solubility has been proposed to diminish normal tau stabilization of microtubules (MTs), thereby leading to neuronal dysfunction. Earlier studies have provided evidence that small molecule MT-stabilizing drugs that are used in the treatment of cancer may have utility in the treatment of tauopathies. However, it has not been established whether treatment with a small molecule MT-stabilizing compound will provide benefit in a transgenic model with pre-existing tau pathology, as would be seen in human patients with clinical symptoms. Accordingly, we describe here an interventional study of the brain-penetrant MT-stabilizing agent, epothilone D (EpoD), in aged PS19 mice with existing tau pathology and related behavioral deficits. EpoD treatment reduced axonal dystrophy and increased axonal MT density in the aged PS19 mice, which led to improved fast axonal transport and cognitive performance. Moreover, the EpoD-treated PS19 mice had less forebrain tau pathology and increased hippocampal neuronal integrity, with no dose-limiting side effects. These data reveal that brain-penetrant MT-stabilizing drugs hold promise for the treatment of AD and related tauopathies, and that EpoD could be a candidate for clinical testing.

A phase 2 study of epothilone B analog BMS-247550 (NSC 710428) in patients with relapsed aggressive non-Hodgkin lymphomas.

BACKGROUND: The management of relapsed aggressive lymphomas remains problematic. Ixabepilone (BMS-247550, epothilone B analog), a potent inhibitor of tubulin disassembly, has promising preclinical and early-phase clinical activity in drug-resistant malignancies. METHODS: This multicenter phase 2 clinical trial tested the activity and safety of ixabepilone in relapsed/refractory aggressive lymphoma patients with either chemosensitive (at least a partial response [PR] to most recent chemotherapy) or chemoresistant (less than PR to most recent chemotherapy) disease at 20 mg/m(2) given intravenously weekly on days 1, 8, and 15 of a 28-day cycle. RESULTS: Fifty-one enrolled patients with a median age of 66 years received at least 1 dose of ixabepilone. Diffuse large B-cell lymphoma (n = 25; 49%), mantle cell lymphoma (n = 16; 31%), and transformed follicular lymphoma (n = 5; 10%) were the most frequent histologies. Patients were heavily pretreated, with more than one-quarter having received 4 or more prior therapies. The overall response rate was 27% (14 of 51 patients) with 12% (6 patients) experiencing complete responses and 16% (8 patients) with PRs. All responses were in patients with chemosensitive disease. The median time to response was 2 cycles with a median duration of response of 9.7 months. CONCLUSIONS: Ixabepilone was well-tolerated, with neutropenia, peripheral sensory neuropathy, fatigue, and nausea as the major toxicities. Ixabepilone has modest single-agent activity in patients with recurrent chemosensitive aggressive lymphomas.

Locoregional interaction of ixabepilone (ixempra) after breast cancer radiation.

BACKGROUND: Radiation recall is an acute inflammatory reaction within a previously irradiated field triggered by chemotherapy administration. We observed a series of patients with unexpectedly severe reactions that included radiation recall and delayed healing when patients received the microtubule stabilizer ixabepilone (Ixempra; Bristol-Myers Squibb, Princeton, NJ) after radiation. We therefore decided to evaluate our experience in patients receiving ixabepilone following radiotherapy. METHODS: We performed a retrospective chart review of all patients treated with curative intent in the Department of Radiation Oncology at the MD Anderson Cancer Center from 2008-2011 who received any ixabepilone after completion of external-beam radiation therapy. These patients received adjuvant ixabepilone on one of two protocols, either for locally advanced breast cancer or for metastatic breast cancer. In total, 19 patients were identified and their charts were subsequently reviewed for evidence of ixabepilone-related toxicity. RESULTS: Of the 19 patients identified who received ixabepilone following radiation therapy, three (15.8%) had unexpectedly serious reactions in the months following radiation therapy. Complications included delayed wound closure and drain placement into the seroma, intense erythema, and delayed wound closure and grade 4 chest wall necrosis requiring latissimus flap and skin grafting. The average number of days between the end of radiation therapy and documentation of reaction was 99. CONCLUSIONS: Ixabepilone chemotherapy may induce radiation recall and delayed wound healing when used shortly after the completion of external-beam radiotherapy. Significant clinical interactions have not been previously reported and merit further evaluation.