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Supplementary Tables 1, 2, and 3 and Supplementary Figures 1 and 2

Kinesin spindle protein (KSP) is a mitotic kinesin required for the formation of the bipolar mitotic spindle, and inhibition of this motor protein results in mitotic arrest and cell death. KSP inhibitors show preclinical antitumor activity and are currently undergoing testing in clinical trials. These agents have been dosed intravenously using various dosing schedules. We sought to identify a KSP inhibitor that could be delivered orally and thus provide convenience of dosing as well as the ability to achieve more continuous exposure via the use of dose-dense administration. We discovered SCH 2047069, a potent KSP inhibitor with oral bioavailability across species and the ability to cross the blood-brain barrier. The compound induces mitotic arrest characterized by a monaster spindle and is associated with an increase in histone H3 and mitotic protein monoclonal 2 phosphorylation both in vitro and in vivo. SCH 2047069 showed antitumor activity in a variety of preclinical models as a single agent and in combination with paclitaxel, gemcitabine, or vincristine. Mol Cancer Ther; 9(11); 2993–3002. ©2010 AACR.

Pompe disease is a rare inherited disorder of lysosomal glycogen metabolism due to acid α-glucosidase (GAA) deficiency. Enzyme replacement therapy (ERT) using alglucosidase alfa, a recombinant human GAA (rhGAA), is the only approved treatment for Pompe disease. Although alglucosidase alfa has provided clinical benefits, its poor targeting to key disease-relevant skeletal muscles results in suboptimal efficacy. We are developing an rhGAA, ATB200 (Amicus proprietary rhGAA), with high levels of mannose-6-phosphate that are required for efficient cellular uptake and lysosomal trafficking. When administered in combination with the pharmacological chaperone AT2221 (miglustat), which stabilizes the enzyme and improves its pharmacokinetic properties, ATB200/AT2221 was substantially more potent than alglucosidase alfa in a mouse model of Pompe disease. The new investigational therapy is more effective at reversing the primary abnormality — intralysosomal glycogen accumulation — in multiple muscles. Furthermore, unlike the current standard of care, ATB200/AT2221 dramatically reduces autophagic buildup, a major secondary defect in the diseased muscles. The reversal of lysosomal and autophagic pathologies leads to improved muscle function. These data demonstrate the superiority of ATB200/AT2221 over the currently approved ERT in the murine model.

Intercellular adhesion molecule-1 (ICAM-1) promotes adhesion and transmigration of circulating leukocytes across the blood-brain barrier. Traumatic brain injury (TBI) causes transmigrated immunocompetent cells to release mediators (LFA-1 and Mac-1) that stimulate glial and endothelial cells to express ICAM-1 and release cytokines, sustaining neuroinflammation and neurodegeneration. Although a strong correlation exists between TBI-mediated inflammation and impairment in functional outcome following brain trauma, the role of ICAM-1 in impairing functional outcome by inducing neuroinflammation and neurodegeneration after TBI remains inconclusive. The experimental TBI was induced in vivo by fluid percussion injury (10 and 20 psi) in wild-type and ICAM-1-/- mice and in vitro by stretch-injury (3 psi) in brain endothelial cells. We manipulate ICAM-1 pharmacologically and genetically and conducted several biochemical analyses to gain insight into the mechanisms underlying ICAM-1-mediated neuroinflammation and performed rotarod, grid-walk, sucrose preference, and light-dark tests to assess functional outcome. TBI-induced ICAM-1-mediated neuroinflammation and cell death occur via LFA-1 or Mac-1 signaling pathways that rely on oxidative stress, matrix metalloproteinase (MMPs), and VEGF pathways. The deletion or blocking of ICAM-1 resulted in a better outcome in attenuating neuroinflammation and cell death as marked by the markers such as NF-kB, IL-1β, TNF-α, cleaved-caspase-3, annexin V, and by TUNEL, and Trypan blue staining. ICAM-1 deletion in TBI improves sensorimotor, depression, and anxiety-like behavior with significant upregulation of norepinephrine, dopamine D1R, 5-HT1AR, and neuropeptide-Y. This study could establish the significance of ICAM-1 as a novel therapeutic target against the pathophysiology to establish functional recovery after TBI. SIGNIFICANCE STATEMENT Intercellular adhesion molecule-1 (ICAM-1) is known to initiate neuroinflammatory responses and causes neurodegeneration and cognitive and sensory-motor deficits in several pathophysiological conditions. However, the mechanisms of ICAM-1-mediated neuroinflammation and cell death, and its link with functional deficits following TBI are not clear. In this study, using an in vitro stretch-injury in human brain microvascular endothelial cells and an animal model of fluid percussion injury, we elucidated the mechanisms of activation of ICAM-1 signaling and subsequent neuroinflammation and neurodegeneration leading to sensorimotor deficits and psychological stress. We propose ICAM-1 signaling cascade as a target for developing new therapeutic strategies against TBI related neurological diseases.

Traumatic brain injury (TBI) can result in persistent sensorimotor and cognitive deficits, which occur through a cascade of deleterious pathophysiological events over time. In this study, we investigated the hypothesis that neurodegeneration caused by TBI leads to impairments in sensorimotor function. TBI induces the activation of the caspase-3 enzyme, which triggers cell apoptosis in an in vivo model of fluid percussion injury (FPI). We analyzed caspase-3 mediated apoptosis by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining and poly (ADP-ribose) polymerase (PARP) and annexin V western blotting. We correlated the neurodegeneration with sensorimotor deficits by conducting the animal behavioral tests including grid walk, balance beam, the inverted screen test, and the climb test. Our study demonstrated that the excess cell death or neurodegeneration correlated with the neuronal dysfunction and sensorimotor impairments associated with TBI.

The imidazo-[1,2-a]-pyrazine (1) is a dual inhibitor of Aurora kinases A and B with modest cell potency (IC50 = 250 nM) and low solubility (5 μM). Lead optimization guided by the binding mode led to the acyclic amino alcohol 12k (SCH 1473759), which is a picomolar inhibitor of Aurora kinases (TdF K d Aur A = 0.02 nM and Aur B = 0.03 nM) with improved cell potency (phos-HH3 inhibition IC50 = 25 nM) and intrinsic aqueous solubility (11.4 mM). It also demonstrated efficacy and target engagement in human tumor xenograft mouse models.

BACKGROUND: The design of implants comprised of biodegradable electrospun nanofibers for the purpose of bridging injuries in damaged spinal cord is discussed. Electrospun nanofibers structurally mimic the extracellular matrix on which neurons and other cell types grow in vivo. This property has created great interest for their use in tissue engineering applications. However, their employment as biomimetic surfaces for such in vivo applications is still in its infancy. RESULTS: A nonwoven fabric comprised of electrospun polyamide nanofibers supported modest axonal regeneration in injured adult rat spinal cord. Covalent modification of the nanofibers with a bioactive peptide derived from the neuroregulatory extracellular matrix molecule tenascin-C enhanced the ability of the nanofibers to facilitate axonal regrowth. However, the random orientation of the nanofibrillar fabric folds was an impediment to the forward movement of axons. CONCLUSIONS: Polyamide nanofibers covalently modified with neuroactive molecules provide a promising material for grafts to promote spinal cord regeneration. However, for the proper guidance of regrowing axons, attention must be paid to the engineering of ordered nanofibrillar structures.  2007 Society of Chemical Industry

Current methods to promote growth of cultured neurons use two-dimensional (2D) glass or polystyrene surfaces coated with a charged molecule (e.g. poly-L-lysine (PLL)) or an isolated extracellular matrix (ECM) protein (e.g. laminin-1). However, these 2D surfaces represent a poor topological approximation of the three-dimensional (3D) architecture of the assembled ECM that regulates neuronal growth in vivo. Here we report on the development of a new 3D synthetic nanofibrillar surface for the culture of neurons. This nanofibrillar surface is composed of polyamide nanofibers whose organization mimics the porosity and geometry of the ECM. Neuronal adhesion and neurite outgrowth from cerebellar granule, cerebral cortical, hippocampal, motor, and dorsal root ganglion neurons were similar on nanofibers and PLL-coated glass coverslips; however, neurite generation was increased. Moreover, covalent modification of the nanofibers with neuroactive peptides derived from human tenascin-C significantly enhanced the ability of the nanofibers to facilitate neuronal attachment, neurite generation, and neurite extension in vitro. Hence the 3D nanofibrillar surface provides a physically and chemically stabile cell culture surface for neurons and, potentially, an exciting new opportunity for the development of peptide-modified matrices for use in strategies designed to encourage axonal regrowth following central nervous system injury.

Research focused on deciphering the biochemical mechanisms that regulate cell proliferation and function has largely depended on the use of tissue culture methods in which cells are grown on two-dimensional (2D) plastic or glass surfaces. However, the flat surface of the tissue culture plate represents a poor topological approximation of the more complex three-dimensional (3D) architecture of the extracellular matrix (ECM) and the basement membrane (BM), a structurally compact form of the ECM. Recent work has provided strong evidence that the highly porous nanotopography that results from the 3D associations of ECM and BM nanofibrils is essential for the reproduction of physiological patterns of cell adherence, cytoskeletal organization, migration, signal transduction, morphogenesis, and differentiation in cell culture. In vitro approximations of these nanostructured surfaces are therefore desirable for more physiologically mimetic model systems to study both normal and abnormal functions of cells, tissues, and organs. In addition, the development of 3D culture environments is imperative to achieve more accurate cell-based assays of drug sensitivity, high-throughput drug discovery assays, and in vivo and ex vivo growth of tissues for applications in regenerative medicine.

The long-term clinical effects of ACE-inhibitors have similarities with those of both fibrates and glitazones, activators of peroxisome proliferator activator receptor (PPAR) alpha and gamma, respectively. The antioxidant enzyme catalase, a heme protein that degrades hydrogen peroxide, is found at high concentrations in peroxisomes. Catalase activity is one of the recognized surrogate markers indicative of PPAR activation in the rat liver. The purpose of the study was to establish the effect of moexipril on catalase activity and to compare it with the effect of both saline controls and that of the known PPAR agonist clofibrate (positive control). Three groups of seven rats were used. All substances were applied i.p. daily for 5 days, followed by a 2-day break. The cycle was repeated eight times. After the final cycle (day 56) the animals were sacrificed and liver tissue collected. The number of catalase positive cells in both moexipril group (95% CI 57–61) and clofibrate group (95% CI 72–80) is higher than in controls (95% CI 3–16) (p ≤ 0.01). The number of catalase positive cells in the clofibrate group is higher than in the moexipril group (p ≤ 0.01). High-dose subchronic exposure to the ACE-inhibitor moexipril induces catalase activity in the rat liver to an extent comparable to fibrates. We suggest that some of the long-term advantages of ACE inhibitor use – beyond mere BP lowering – might be due to a PPAR mediated effect. (Mol Cell Biochem xxx: 159–163, 2005)

Background and aims: Vasoactive intestinal polypeptide (VIP) is present in pancreatic islet cells and stimulates insulin and glucagon release from normal and diabetic rats. The aim of this study was to examine the effect of noradrenaline (NA) and acetylcholine (ACh) on VIP release from pancreatic islets of normal and diabetic rats. Methods: NA- and ACh-induced VIP release from isolated pancreatic tissue fragments was measured using radioimmunoassay technique. Results: The basal VIP release from the islets of diabetic rats was significantly (p = 0.02) higher compared to normal. NA at and 10-6 M also evoked large and significant (p = 0.04) increases in VIP release from the islets of normal rat. Moreover, NA at 10-8 M, significantly (p < 0.05) stimulated VIP release from the islets of diabetic rats. ACh (10-4 M), induced up to 46.6% increase in VIP secretion from the islet cells of normal (n = 6) rats. However, a more dilute concentration of ACh (10-8 M) was sufficient for the induction of maximal VIP secretion from the isolated islets of diabetic (n = 6) rat. ACh (10-6 M) evoked 32.3% increase in VIP secretion in diabetic rat islets. Conclusion: NA and ACh stimulated VIP secretion from pancreatic islets of normal rat. NA and ACh can also induce increases in VIP secretion from the islets of diabetic rat. The increase in VIP in the islets of diabetic rats may also play a role in the pathogenesis of diabetic complications.

Ghrelin is a novel 28-amino acid gut-brain peptide, which was first isolated in the rat stomach. This study examined the effect of ghrelin on insulin secretion from the isolated pancreas of normal and diabetic rats. Diabetes was induced by a single dose of streptozotocin. Four weeks after the induction of diabetes, pancreatic tissue fragments of normal and diabetic rats were treated with different concentrations (10(-12), 10(-9) and 10(-6) M) of ghrelin. Ghrelin evoked large and significant increases in insulin secretion from the pancreas of both normal and diabetic rats. In the pancreas of normal rats, diltiazem (calcium channel antagonist) or a combination of atropine (muscarinic cholinergic receptor antagonist), propranolol (beta-adrenergic receptor antagonist) and yohimbine (alpha2-adrenergic receptor antagonist) significantly reduced the stimulatory effect of ghrelin on insulin secretion. Diltiazem and yohimbine failed to inhibit ghrelin-evoked insulin release in diabetic rat pancreas. Ghrelin-immunoreactivity cells was observed in 2.6% and 3.8% of the total cell population in the islet of Langerhans of normal and diabetic rats, respectively.

The effect of noradrenaline (NA), adrenaline (ADR), and acetylcholine (ACh) on insulin secretion from the isolated pancreas of normal and diabetic rats was examined using radioimmunoassay technique. Diabetes mellitus was induced by streptozotocin. Pancreatic tissue fragments of normal and diabetic rats were removed and incubated with different concentrations (10 -8 , 10 -6 , 10 -4 M) of NA, ADR and ACh. Insulin secretion into the supernatant was later determined by radioimmunoassay. NA at a concentration of 10 -8 M evoked a six-fold increase in insulin secretion from normal pancreatic tissue fragments compared to basal. NA induced a three-fold increase in insulin output from the pancreas of diabetic rats when compared to basal. ADR (10 -8 M) induced a three-fold increase in insulin secretion from isolated normal rat pancreas. In contrast, inhibition of insulin secretion was observed when ADR (10 -8 , 10 -6 , 10 -4 M) was incubated with pancreatic tissue fragments of diabetic rats. ACh evoked a six-fold increase in insulin secretion when incubated with normal rat pancreas tissue fragments at a concentration of 10 -8 M. Similarly, ACh (10 -4 M) evoked a two-fold increase in insulin secretion from the in vitro diabetic rat pancreas. In conclusion NA, ADR and ACh have potent secretagogue effect on insulin secretion from the pancreas of normal rat.

Gamma amino butyric acid (GABA) and its related enzymes have been demonstrated in pancreatic beta cells of normal rat. Antibodies against GABA-synthesizing enzymes have been implicated in the pathogenesis of Type I diabetes. In spite of the importance of GABA in the aetiology of diabetes mellitus, detailed morphological data on the pattern of distribution of GABA in the pancreas of normal and diabetic rats are lacking. Diabetes mellitus (DM) was induced by a single dose of streptozotocin (STZ) given intraperitoneally (60 mg kg body weight(-1)). Four weeks after the induction of DM, normal (n = 6) and diabetic (n = 6) rats were anesthetized with chloral hydrate and their pancreata were removed and processed for the localization and effect of GABA on insulin secretion using immunohistochemistry and radioimmunoassay techniques. The number of GABA-like immunoreactive (GABA-LIR) cells in the pancreatic islets of STZ-diabetic rats decreased significantly (P

Although galanin has been shown to be present in pancreatic islet cells, there is no literature available on the pattern of distribution and the effect of galanin in the pancreas of diabetic animals or human models. The aim of this study was to examine whether galanin immunoreactivity changes after the onset of diabetes mellitus in the rat model. The present study used immunohistochemical techniques to examine the pattern of distribution of galanin-like immunoreactive cells in the pancreas of rats with streptozotocin-induced diabetes. The effect of galanin on insulin secretion from intact rat pancreatic tissue fragments was also investigated using a radioimmunoassay technique. Numerous galanin-like immunoreactive cells were observed in both the peripheral and central regions of the islet of Langerhans of normal rat pancreas. By contrast, the islets of diabetic rat pancreas contained significantly (P < 0.0001) fewer galanin-like immunoreactive cells than nondiabetic rats. Galanin was colocalized with insulin in the islets of normal and diabetic rats. Galanin had an inhibitory effect on insulin secretion from the isolated pancreatic tissue fragments of normal and diabetic rats at all concentrations (10(-12) to 10(-6) M) employed. Galanin at 10(-9) M caused a significant (P < 0.02) decrease in insulin secretion from normal rat pancreatic tissue fragments compared to basal. These observations indicate that galanin may play a significant role in the regulation of insulin secretion.

Ultrastructural observations were made on myelinated fibers in the tibial nerves in order to investigate the beneficial effects of alpha-tocopherol administration in streptozotocin-diabetic rats. Male Wistar rats, aged 12 weeks and weighing between 250 g to 300 g were studied. Six onset control rats were used to obtain the baseline parameters for this strain and age. Further 3 groups--untreated diabetic animals, diabetic animals treated with alpha-tocopherol, and age-matched controls--were studied over a 3-month period. In the diabetic animal, administration of alpha-tocopherol resulted in a significant increase (p < 0.05) in total plasma vitamin E levels when compared with other groups. Myelinated fiber cross-sectional area (p < 0.05), axonal area (p < 0.01) and myelin sheath area (p < 0.05) were significantly less in the tibial nerve of diabetic animals than in age-matched controls, but not different from those of onset controls. In the alpha-tocopherol treated diabetic animals, the values for these parameters were intermediate without showing significant difference when compared with age-matched controls and untreated diabetics. The "g" ratio (axon to fiber area) did not differ between any experimental groups. The number of large myelinated fibers were less in the untreated diabetic animals, but in the alpha-tocopherol-treated diabetics, the values were significantly higher (p < 0.05) than with untreated diabetics and were similar to those of age-matched controls. In conclusion, this ultrastructural study reiterated the fact that structural abnormalities of myelinated fibers occur in experimental diabetes and that alpha-tocopherol administration may be useful in preventing the development of these abnormalities.

Vasoactive intestinal polypeptide (VIP) is an inhibitory non-adrenergic, non-cholinergic transmitter, which mediate in the relaxation of sphincters of the gastrointestinal tract. The aim of this study was to determine whether there is a change in the pattern of innervation and tissue content of VIP in the rat gastroduodenum after the onset of streptozotocin (STZ)-induced diabetes mellitus. Diabetes was induced by a single intraperitoneal injection of STZ (60 mg Kg(-1)). Four weeks after the induction of diabetes mellitus, the rats were anaethetised and the pancreata were removed for further processing. VIP was localized and measured in normal and diabetic rat gastroduodenal tissues by immunohistochemistry and radioimmunoassay, respectively. VIP immunoreactivity was stronger in the ganglion cells of the submucosal and myenteric plexuses of the gastric antrum and duodenum of normal rats (n = 6) when compared to that of diabetic rats (n = 6). Moreover, the number of VIP-positive neurons was significantly lower in the gastrointestinal tract of diabetic rats compared to normal. The VIP content of the gastric antrum and duodenum of diabetic rat was significantly lower (p0.05) than that of normal rat. In contrast to the lower tissue levels of VIP in the gastroduodenal segment of diabetic rats, the plasma level of VIP was significantly higher (p0.04) in diabetic rat compared to normal. The plasma level of VIP in normal rats was comparable to that measured in normal human beings. A low tissue level of VIP in the gastroduodenal tract of diabetic rat may contribute in part to the abnormal gut motility observed in diabetic patients.

Steroid hormones are used to treat a variety of diseases in both diabetic and non-diabetic people. Since steroid hormones affect glucose metabolism, the aim of this study was to examine whether 3.3 mg/kg body weight of orally administered 17 beta-estradiol (E2) would adversely affect the body weight, blood glucose and plasma insulin levels of streptozotocin (STZ)-induced diabetic rats. Diabetes was induced by a single dose of STZ given intraperitoneally (60 mg/kg body weight). Administration of E2 caused a decrease in the weight of diabetic rats compared to untreated diabetic rats two weeks after the experiment. Although the blood glucose level in the E2-treated rats was numerically lower than that of untreated diabetics, the difference was not statistically significant. The plasma insulin level in E2-treated diabetic rats (0.44 +/- 0.1 ng/ml) was not significantly different from that of untreated diabetic rats (0.52 +/- 0.1 ng/ml). The plasma insulin levels of E2-treated and untreated diabetic rats were, however, significantly (p0.05) lower than that of normal rats (1.18 +/- 0.5 ng/ml). In conclusion, E2 caused progressive loss of body weight, but did not significantly alter the blood glucose and plasma insulin levels of diabetic rats when compared to normal controls. This shows that E2 may be given to diabetic patients without significantly disrupting glucose homeostasis.

Leucine-enkephalin (Leu-Enk) has been shown to be present in endocrine cells of the rat pancreas and may play a role in the modulation of hormone secretion from the islets of Langerhans. Since little is known about the effect of Leu-Enk on insulin and glucagon secretion, it was the aim of this study to determine the role of Leu-Enk on insulin and glucagon secretion from the isolated pancreatic tissue fragments of normal and diabetic rats. Pancreatic tissue fragments of normal and streptozotocin-induced diabetic rats were incubated for 1 h with different concentrations of Leu-Enk (10(-12)-10(-6)M) alone or in combination with either atropine or yohimbine or naloxone. After the incubation period the supernatant was assayed for insulin and glucagon using radioimmunoassay techniques. Leu-Enk (10(-12 )-10(-6)M) evoked large and significant increases in insulin secretion from the pancreas of normal rats. This Leu-Enk-evoked insulin release was significantly (p < 0.05) blocked by atropine, naloxone and yohimbine (all at 10(-6)M). In the same way, Leu-Enk at concentrations of 10(-12)M and 10(-9)M induced significant (p < 0.05) increases in glucagon release from the pancreas of normal rats. Atropine, yohimbine but not naloxone significantly (p < 0.05) inhibited Leu-Enk-evoked glucagon release from normal rat pancreas. In contrast, Leu-Enk failed to significantly stimulate insulin and glucagon secretion from the pancreas of diabetic rats. In conclusion, Leu-Enk stimulates insulin and glucagon secretion from the pancreas of normal rat through the cholinergic, alpha-2 adrenergic and opioid receptor pathways.

Detailed spatial analysis of the propagation of individual slow waves was performed in the isolated gastroduodenal preparation of the cat. Use was made of a system that allowed the simultaneous recordings from 240 extracellular electrodes, which were positioned across the gastroduodenal region. Reconstructions of the spread of propagation (n = 31) revealed that (a) the antral slow wave never propagated into the duodenum but was blocked at the pyloric ring, (b) the duodenal slow wave did not activate the antral tissue, and (c) a quiescent zone in which no slow waves could be recorded was always present at the most proximal part of the duodenum immediately distal to the pyloric ring. Furthermore, phase density distributions of duodenal cycles revealed that antral activity had no influence on the rate of discharge of duodenal pacemakers. Light microscopic study of sections of the duodenum close to the pyloric ring and further away did not show any structural differences between the quiescent zone and the active areas. In conclusion, slow waves do not propagate across the gastroduodenal junction in the isolated feline preparation and therefore do not seem to play a role in the electro-mechanical integration between the stomach and the duodenum.

Kinesin spindle protein (KSP) is a mitotic kinesin required for the formation of the bipolar mitotic spindle, and inhibition of this motor protein results in mitotic arrest and cell death. KSP inhibitors show preclinical antitumor activity and are currently undergoing testing in clinical trials. These agents have been dosed intravenously using various dosing schedules. We sought to identify a KSP inhibitor that could be delivered orally and thus provide convenience of dosing as well as the ability to achieve more continuous exposure via the use of dose-dense administration. We discovered SCH 2047069, a potent KSP inhibitor with oral bioavailability across species and the ability to cross the blood-brain barrier. The compound induces mitotic arrest characterized by a monaster spindle and is associated with an increase in histone H3 and mitotic protein monoclonal 2 phosphorylation both in vitro and in vivo. SCH 2047069 showed antitumor activity in a variety of preclinical models as a single agent and in combination with paclitaxel, gemcitabine, or vincristine. Mol Cancer Ther; 9(11); 2993–3002. ©2010 AACR.

Aurora kinases are required for orderly progression of cells through mitosis, and inhibition of these kinases by siRNA or small molecule inhibitors results in cell death. We previously reported the synthesis of SCH 1473759, a novel sub-nanomolar Aurora A/B inhibitor. We utilized SCH 1473759 and a panel of tumor cell lines and xenograft models to gain knowledge about optimal dosing schedule and chemotherapeutic combinations for Aurora A/B inhibitors. SCH 1473759 was active against a large panel of tumor cell lines from different tissue origin and genetic backgrounds. Asynchronous cells required 24-h exposure to SCH 1473759 for maximal induction of >4 N DNA content and inhibition of cell growth. However, following taxane- or KSP inhibitor-induced mitotic arrest, less than 4-h exposure induced >4 N DNA content. This finding correlated with the ability of SCH 1473759 to accelerate exit from mitosis in response to taxane- and KSP inhibitor-induced arrest. We tested various dosing schedules in vivo and demonstrated SCH 1473759 dose- and schedule-dependent anti-tumor activity in four human tumor xenograft models. Further, the efficacy was enhanced in combination with taxanes and found to be most efficacious when SCH 1473759 was dosed 12-h post-taxane treatment. SCH 1473759 demonstrated potent mechanism-based activity, and activity was shown to be enhanced in combination with taxanes and KSP inhibitors. This information may be useful for optimizing the clinical efficacy of Aurora inhibitors.