Elosulfase alfa.

Mucopolysaccharidosis type IVA (MPS IVA), also known as Morquio A syndrome, is an inherited, lysosomal storage disorder caused by genetic mutations in N-acetylgalactosamine-6-sulfatase (GALNS) enzyme gene. GALNS is essential for breakdown of glycosaminoglycans. The disease is characterized by the early onset of severe skeletal dysplasia resulting in significant disability by the second decade of life. Until recently there have been no available treatments other than surgery and palliative care. BioMarin Pharmaceutical developed elosulfase alfa, a recombinant human GALNS coproduced with sulfatase-modifying factor 1, as an enzyme replacement therapy for patients with MPS IVA. In clinical studies, enzyme replacement therapy with elosulfase alfa significantly improved physical endurance, respiratory function, growth and quality of life in patients with MPS IVA. Treatment increased clearance of glycosaminoglycans and induced gene expression consistent with improved chondrocyte function. Elosulfase alfa is approved for the treatment of MPS IVA in the U.S. and Europe.

Vedolizumab for the treatment of inflammatory bowel disease.

The causes of inflammatory bowel diseases, such as ulcerative colitis (UC) and Crohn's disease (CD), remain to be elucidated. However, characteristic inflammation of the gastrointestinal mucosa is caused by infiltration of T lymphocytes into the submucosal layer. Inhibiting this immune response is a promising therapeutic target. Integrins expressed on the cell surface mediate gut homing of T lymphocytes. Blockade of integrin-cell adhesion molecule interaction using antibodies against α4-containing integrins, namely natalizumab, has shown clinical efficacy; however, this drug's lack of α4-containing integrin specificity leads to systemic immunosuppression that caused progressive multifocal leukoencephalopathy and death in some patients resulting in its withdrawal from the market. Vedolizumab specifically targets the α4ß7 integrin that is selectively expressed on gut-homing T lymphocytes. Vedolizumab successfully extended clinical remission in patients with UC or CD and reduced patient reliance on corticosteroid use. The drug is well tolerated and there have been no deaths or reports of progressive multifocal leukoencephalopathy infection in patients receiving vedolizumab. A phase III long-term 7-year safety study in patients with UC and CD is under way. Regulatory applications are under review in the U.S. and E.U. for its use in the treatment of patients with UC and CD, with decisions expected in mid-2014.

Turoctocog alfa for the treatment of hemophilia A.

Patients with hemophilia A lack functional coagulation factor VIII (FVIII), causing excessive spontaneous bleeding episodes and bleeding during trauma or surgery. Plasma-derived or synthetic recombinant FVIII is used to control bleeding, but currently available treatments are limited because of patient development of FVIII inhibitors and cross-contamination of human and animal-derived infectious agents. Turoctocog alfa is a recombinant FVIII produced in Chinese hamster ovary cells that has demonstrated good efficacy in thrombin generation and clot formation in preclinical evaluations in murine and canine models of hemophilia A and in patient-derived whole blood. Evaluation in clinical trials in pediatric and adult patients with hemophilia A have demonstrated that the drug has good pharmacokinetic parameters, excellent efficacy in improving annualized bleeding rates, few adverse events and no induction of FVIII inhibitors. The drug is FDA approved as a prophylactic agent and for on-demand treatment to control bleeding including during operative procedures.

Trastuzumab emtansine for the treatment of HER2-positive metastatic breast cancer.

Trastuzumab emtansine is an antibody-drug conjugate comprised of the receptor tyrosine-protein kinase erbB-2 (HER2) antibody trastuzumab, and a derivative of the cytostatic agent maytansinoid DM1, covalently linked by a thiol linker. The drug was developed in an attempt to overcome trastuzumab resistance in patients with HER2-positive breast carcinoma, but it is also of potential use in other HER2-positive cancers. The preclinical antitumor activity of trastuzumab emtansine was established in HER2-positive breast cancer cell lines and murine xenograft models. Preclinically, trastuzumab emtansine was efficacious in HER2-positive cells that were resistant to trastuzumab or lapatinib. Clinically, the drug is well tolerated in most patients, with a predictable pharmacokinetic profile and minimal systemic exposure to free cytotoxic DM1. Unlike with trastuzumab, cardiac toxicity has not been seen in patients receiving trastuzumab emtansine and less adverse events have been reported than with other chemotherapy regimens. Results from a number of phase II studies and early results from a phase III investigation (EMILIA) demonstrated response rates of 25-35% in patients with breast cancer who had previously received trastuzumab. Several phase II and III studies are under way investigating trastuzumab emtansine in combination with other regimens in patients with HER2-positive cancers.

Alipogene tiparvovec for the treatment of lipoprotein lipase deficiency.

Alipogene tiparvovec is the first adeno-associated virus (AAV)-mediated gene therapy to be approved for the treatment of a metabolic disorder. Lipoprotein lipase (LPL) deficiency (LPLD) is a rare autosomal-recessive disorder in which gene mutations cause the production of a catalytically inactive enzyme required for plasma triglyceride hydrolysis. The resultant hypertriglyceridemia causes frequent abdominal pain, fatty deposits in the skin and retina, and can lead to potentially fatal pancreatitis. In addition, patients with LPLD can develop diabetes and cardiovascular disease. Past therapies to lower plasma triglycerides in these patients have been ineffective. Intramuscular injection of alipogene tiparvovec delivers a natural gain-of-function LPL gene variant, LPLS447X, to muscle tissue and has demonstrated efficacy in animal models of LPLD. In phase I/II and phase II/III clinical evaluations, alipogene tiparvovec significantly lowered plasma triglycerides and increased LPL activity, resulting in a reduction in plasma chylomicron and a decrease in the frequency of pancreatitis episodes. The therapy is well tolerated in animals and humans and produces no serious treatment-related adverse effects.

Taliglucerase alfa for the treatment of Gaucher's disease.

Gaucher's disease is a rare inherited inborn error of metabolism caused by mutations in the gene encoding the lysosomal enzyme glucocerebrosidase, GBA. Glucocerebrosidase is involved in the metabolism of the lipid metabolism-derived substrate, glucocerebroside. Accumulation of glucocerebroside substrate in macrophages, as a result of loss of enzyme function, leads to the formation of Gaucher cells causing hypertrophy of the spleen and liver, hematological disorders, skeletal malformations and the neurological symptoms characteristic of Gaucher's disease. The disease is subdivided into three types that differ in their symptoms, severity and prognosis. Patients of any age can be affected but those of a younger age have a poor prognosis often dying in infancy. As a genetic disorder the incidence of the disease is variable on a global scale. Enzyme replacement therapy is the therapy of choice and has demonstrated good efficacy in treating the visceral and skeletal symptoms of Gaucher's disease. A cost-effective plant-cell-derived human recombinant glucocerebrosidase, taliglucerase alfa, has been developed that demonstrated a promising safety and efficacy profile in phase I clinical trials and is currently in phase III and IV trials for the treatment of pediatric and adult patients with Gaucher's disease.

Brentuximab vedotin: its role in the treatment of anaplastic large cell and Hodgkin's lymphoma.

Brentuximab vedotin is being developed in a joint collaboration between Seattle Genetics and Millennium: The Takeda Oncology Company. In August 2011, it was approved by the FDA for the treatment of patients with Hodgkin's lymphoma (HL) and anaplastic large cell lymphoma (ALCL). Brentuximab vedotin is an antibody-drug conjugate that specifically targets the TNF receptor superfamily member 8 (CD30) antigen on the surface of cancer cells to induce cell death. Brentuximab vedotin has shown efficacy in inducing apoptosis in HL and ALCL cell lines that express CD30 and reducing tumor size in preclinical models. Brentuximab vedotin is under clinical evaluation for the treatment of relapsed or refractory HL and ALCL in both adults and children. It is being investigated for use as a combination agent with pre-existing frontline chemotherapies and as a stand-alone salvage therapy for use prior to autologous stem cell transplant. Treatment with brentuximab vedotin is generally well tolerated although it is associated with grade 1-2 adverse reactions such as neutropenia and there have been reports of grade 3-4 serious adverse events. In particular its use with chemotherapy regimens that include bleomycin is contraindicated because of adverse pulmonary effects.

Behavioural genetics of the serotonin transporter.

The serotonin transporter is a key regulator of the bioavailability of serotonin and therefore any modulation in the expression or action of the transporter would be expected to have consequences on behaviour. The transporter has therefore become a target for pharmaceutical intervention in behavioural and mood disorders. The search for polymorphic variants in the transporter that would associate with neurological disorders has been extensive but has become focused on two domains which are both termed variable number tandem repeat (VNTR)polymorphisms. Both of these VNTRs are in non-coding DNA and therefore proposed to be mechanistically involved in a disorder through their ability to modulate transcriptional or post-transcriptional regulation of the transporter. The most extensively studied is in the promoter and is a bi-allelic insertion/deletion found in the 50 promoter region of the gene 1.2 kb upstream of the transcriptional start site. This VNTR, termed, 5-HTTLPR was initially identified as two variants containing either, 14 (short/deletion) or 16 (long/insertion) copies of a 22 bp repeat. A second widely studied VNTR found in the non-coding region of the transporter is located within intron 2 and comprises 9, 10 or 12 copies of a16­17 bp repeat termed, STin2.9, STin2.10 and STin2.12, respectively. These VNTR polymorphisms have been associated with a range of behavioural and psychiatric disorders including depression, OCD, anxiety and schizophrenia, however often the lack of reproducibility in different cohorts has led to debate on the actual association of the polymorphisms with this extensive range of neurological conditions. Here we review these two polymorphic VNTRs in depth and relate that to pharmaceutical response, their ability to regulate differential transporter expression, their core involvement in gene-environment interaction and their genetic association with specific disorders.

Mipomersen sodium: a new option for the treatment of familial hypercholesterolemia.

In collaboration with Genzyme, Isis Pharmaceuticals has developed mipomersen sodium (ISIS-310312), a synthetic second-generation 20-base phosphorothioate antisense oligonucleotide (ASO) that targets messenger RNA encoding apolipoprotein B-100 (Apo B-100). Elevated cholesterol levels, in particular low-density lipoprotein cholesterol (LDL-C) which contains a single apolipoprotein B (ApoB) molecule, have been directly correlated with the incidence of cardiovascular events. Preclinical investigations in transgenic mice have demonstrated that lowering LDL-C or ApoB can reduce aortic plaque formation associated with atherosclerosis. Mipomersen pharmacokinetics showed a wide and rapid tissue distribution and a slow prolonged elimination phase of several days in a range of species. Mipomersen displayed dose-dependent efficacy in lowering LDL-C, ApoB, triglycerides, total cholesterol and other low-density lipoproteins in healthy volunteers with mild hyperlipidemia. Similar decreases were observed in patients on stable lipid-lowering therapy for familial hypercholesterolemia with baseline LDL-C levels declining towards clinically desirable concentrations of 70 mg/dL. The efficacy of mipomersen in treating patients with severe heterozygous or homozygous familial hypercholesterolemia with cardiovascular complications has been recently assessed. There have been no serious adverse events noted with treatment and mipomersen can be administered in combination with other lipid-lowering therapies. One concern noted was an elevation in liver transaminase concentrations, although these increases were reversible.

The human neurokinin B gene, TAC3, and its promoter are regulated by Neuron Restrictive Silencing Factor (NRSF) transcription factor family.

We have previously shown that one of the major determinants directing the expression of the preprotachykinin-A (TAC1) gene, which encodes the neuropeptide substance P, is the transcription factor Neuronal Restrictive Silencer Factor (NSRF), which is also termed Repressor Element-1 Silencing Factor (REST). In rodent models of epilepsy, NRSF and its truncated isoform short NRSF (sNRSF), also termed REST4, are increased as an immediate response to seizure. In similar models the neurokinin B (NKB) gene (TAC3) is also induced and NKB has also been shown to be proconvulsant. In this communication we have demonstrated that both the TAC3 endogenous gene and its promoter are regulated, directly or indirectly, by the NRSF transcription factors resulting in both the increased expression of the endogenous gene and increased reporter gene activity. We demonstrate by chromatin immunoprecipitation analysis that NRSF and sNRSF will bind to the NKB promoter in vivo. Consistent with a model in which NRSF modulation of TAC3 gene expression is a mechanism that operates during epilepsy, the observed increases in both the level of the endogenous gene and the activity of the NKB promoter by these NRSF variants, were diminished by the action of the anticonvulsant drug, carbamazepine.

Molecular genetics of monoamine transporters: relevance to brain disorders.

We have demonstrated in both the human serotonin transporter gene (5HTT) and the dopamine transporter gene (DAT1) that specific polymorphic variants termed Variable Number Tandem Repeats (VNTRs), which correlate with predisposition to a number of neurological and psychiatric disorders, act as transcriptional regulatory domains. We have demonstrated that these domains can act as both tissue-specific and stimulus-inducible regulators of gene expression. As such they can act to be mechanistically associated with the progression or initiation of a behavioural disorder by altering the level of transporter mRNA, which in turn regulates the concentration of transporter in specific cells or in response to a challenge; chemical, environmental or physiological. The synergistic actions of such transcriptional domains will modulate gene expression. Our hypothesis is that these VNTR variants are one mechanism by which nurture can modify concentrations of neurotransmitters in a differential manner.

Generation of a transgenic model to address regulation and function of the human neurokinin 1 receptor (NK1R).

We have generated mouse transgenic lines using yeast artificial chromosome (YAC) technology which demonstrate expression from the human NK1 receptor (NK1R) locus. We introduced a 380 kb fragment encompassing the human NK1R gene and flanking regions which we hoped would recapitulate the expected endogenous expression of the human gene. To visualise this expression the NK1 locus co-expresses the green fluorescence protein gene (GFP) under the control of an internal ribosome entry site (IRES) sequence. We have generated five mouse lines that express the human NK1 receptor gene with and without the marker gene. All the lines incorporating the marker gene appear to exhibit the same expression pattern in analysis of selected anatomical regions throughout the mouse. The lack of a human specific NK1R antibody determined that we could not distinguish between expression of the transgene and endogenous NK1R. Our analysis has shown transgene expression in brain areas known to express NK1R in human such as the hippocampus and caudate putamen. The majority of these cells were also positive for GFP fluorescence. These transgenic lines may prove a good pre-clinical model as drugs can be addressed against both the human receptor and modulators of its expression in vivo.

Regulation and role of REST and REST4 variants in modulation of gene expression in in vivo and in vitro in epilepsy models.

Repressor element-1 silencing transcription factor (REST) is a candidate modulator of gene expression during status epilepticus in the rodent. In such models, full-length REST and the truncated REST4 variant are induced and can potentially direct differential gene expression patterns. We have addressed the regulation of these REST variants in rodent hippocampal seizure models and correlated this with expression of the proconvulsant, substance P encoding, PPT-A gene. REST and REST4 were differentially regulated following kainic acid stimulus both in in vitro and in vivo models. REST4 was more tightly regulated than REST in both models and its transient expression correlated with that of the differential regulation of PPT-A. Consistent with this, overexpression of a truncated REST protein (HZ4, lacking the C-terminal repression domain) increased expression of the endogenous PPT-A gene. Similarly the proximal PPT-A promoter reporter gene construct was differentially regulated by the distinct REST isoforms in hippocampal cells with HZ4 being the major inducer of increased reporter expression. Furthermore, REST and REST4 proteins were differentially expressed and compartmentalized within rat hippocampal cells in vitro following noxious stimuli. This differential localization of the REST isoforms was confirmed in the CA1 region following perforant path and kainic acid induction of status epilepticus in vivo. We propose that the interplay between REST and REST4 alter the expression of proconvulsant genes, as exemplified by the PPT-A gene, and may therefore regulate the progression of epileptogenesis.