Hindawi Publishing Corporation
`Iournal of Biomedicine and Biotechnology
`Volume 2010, Article ID 479364, 18 pages
`d0i:10.1155/2010/479364
`
`Review Article
`
`Molecular and Therapeutic Potential and Toxicity of Valproic Acid
`
`Sébastien Chateauvieux, Franck Morceau, Mario Dicato, and Marc Diederich
`
`Laboratoire de Biologie Moléculaire et Cellulaire du Cancer {LBMCC), “Fondation de Recherche Cancer ct Sang’:
`Hépital Kirchberg, Kirchberg 2540, Luxembourg
`
`Correspondence should be addressed to Marc Diederich, marc.diederich@lbmcc.lu
`
`Received 7 January 2010; Revised 3 May 2010; Accepted 6 June 2010
`
`Academic Editor: Ronald E. Baynes
`
`Copyright © 2010 Sébastien Chateauvieux et al. This is an open access article distributed under the Creative Commons Attribution
`License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly
`cited.
`
`Valproic acid (VPA), a branched short—chain fatty acid, is widely used as an antiepileptic drug and a mood stabilizer. Antiepileptic
`properties have been attributed to inhibition of Gamma Amino Butyrate (GABA) transaminobutyrate and of ion channels. VPA
`was recently classified among the Historic Deacetylase Inhibitors, acting directly at the level of gene transcription by inhibiting
`histone deacetylation and making transcription sites more accessible. VPA is a widely used drug, particularly for children suffering
`from epilepsy. Due to the increasing number of clinical trials involving VPA, and interesting results obtained, this molecule will be
`implicated in an increasing number of therapies. However side effects of VPA are substantially described in the literature whereas
`they are poorly discussed in articles focusing on its therapeutic use. This paper aims to give an overview of the different clinical-
`trials involving VPA and its side effects encountered during treatment as well as its molecular properties.
`
`1. Introduction
`
`Valproic acid (2—propylvaleric acid, 2—propylpentanoic acid
`or n—dipropylacetic acid)
`(see Figure 1(a)), derived from
`valeric acid (Figure 1(b)) (naturally produced by Valerian,
`Valericma oflicinalis) (see Figure 1(c)), was first synthesized
`in 1882 by Burton [1]. It is a branched short—chain fatty
`acid, forming a clear liquid at room temperature, and
`whose half—life is 9 to 16 hours. For nearly a century,
`this molecule was used as a “physiologically inert” solvent
`for organic compounds. It was in 1963, during a study
`focused on molecules with potential anti—convulsive activity,
`in which VPA was used as a molecular carrier, that the
`pharmacological activity of VPA was demonstrated: VPA
`prevented pentylenetetrazol—induced convulsions in rodents
`[2—4].
`In the human brain, VPA alters the activity of the neu-
`rotransmitter Gamma Amino Butyrate (GABA) by poten-
`tialising the inhibitory activity of GABA through several
`mechanisms,
`including inhibition of GABA degradation,
`inhibition of GABA Transaminobutyratre (ABAT), increased
`GABA synthesis, and decreased turnover [5]. Moreover, VPA
`attenuates N—Methyl—D—Aspartate—mediated excitation [6, 7]
`and blocks Na+ channels, Ca2+ channels (voltage—dependent
`
`L type CACNA1 type C, D, N, and F), and voltage—gated K+
`channels (SCN) [8].
`Besides its clinical use as an anticonvulsant and mood-
`
`stabilizing drug [9], VPA presents beneficial effects in clinical
`depression [10], absence seizures
`[11, 12],
`tonic—clonic
`seizures, complex partial seizures [13], juvenile myoclonic
`epilepsy [14], seizures associated with LennoX—Gastaut syn-
`drome [15], migraine headaches, and schizophrenia. VPA as
`a therapeutic agent is commercially available as Depakote,
`Depakote ER, Depakene, Depacon, Stavzor, Mylproin,
`Ergenyl, Dipropylacetic acid, Myproic Acid, Dipropylacetate,
`and Convulex.
`
`More recently VPA has been described as an HDAC
`inhibitor, resulting in an increased interest for its use in
`cancer therapy. Chromatin is formed of DNA packaged in
`nucleosome structures, constituted by 146 base—pair DNA
`sequence winding around an octamere of histones (two
`copies of each histone: H2A, H2B, H3, and H4) held in
`place by histone H1. The condensed form of chromatin
`(heterochromatin)
`is inactive in terms of transcription
`whereas the decondensed form (euchromatin) corresponds
`to an active form. The transition between euchromatin
`
`and heterochromatin is dependent upon two families of
`proteins: histone acetyl transferases (HATS), and histone
`
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`
`deacetylases (HDACs). It has been established that histone
`acetylation leads to relaxation of the nucleosome structure,
`releasing the DNA and allowing transcription. Inhibition of
`HDAC promotes decondensed chromatin formation, thereby
`promoting the expression of genes.
`VPA, as well as other HDAC inhibitors (HDACi), is able
`to alter expression of many genes. Corresponding proteins
`were described to play important roles in cellular activity and
`could influence several important pathways such as cell cycle
`control, differentiation, DNA repair, and apoptosis [16—19].
`VPA specifically targets 2 of the 4 classes of HDACs:
`class I, subclasses Ia and Ib, and class II, subclass IIa. Within
`
`subclass IIa, HDAC9 is an exception to this modulation,
`being activated by VPA, which is also true for HDAC11 [20].
`HDAC 6, 8, and 10 are not modulated. It is interesting to
`mention that HDAC classes I and II have been reported to
`be strongly implicated in neuronal function, which could
`partially explain the action of VPA in neural pathologies.
`DNA methylation also contributes to the regulation of
`gene expression. Hypermethylation of the promoter, usually
`corresponding to inhibition of gene expression,
`is con-
`trolled by DNA methytransferase (DNMT). Demethylation
`of nucleic acid has been commonly associated with pas-
`sive processes corresponding to inhibition of maintenance
`methylation during S—Phase of the cell cycle. The existence
`of DNA demethylase was shown a decade ago, resulting
`in a demethylated active DNA form [21, 22]. HDACi have
`been associated with demethylation of DNA, and since 2001,
`were associated with the active demethylated form. The
`exact mechanism is not yet known, but it seems that VPA
`does not directly enhance the enzymatic activity of DNA
`demethylase. However, through HDACi activity, VPA enables
`methylated DNA to be more accessible, which is confirmed
`by the observation that inhibition of HAT diminishes the
`demethylation effect triggered by VPA [23, 24]. In addition, it
`has been shown that valproic acid downregulates expression
`of proteins essential for chromatin maintenance: SMCs 1-
`6 (Structural Maintenance of chromatin 1 to 6), DNMT1
`(DNA methyl transferase—1), and HP1 (Heterochromatin
`Protein—1) [25]. The effects upon transcription are observed
`after less than 24 hours, while 48 hours are needed to see
`the effects upon protein levels, which correlates with DNA
`decondensation (shown in breast cancer cell lines).
`Recently,
`it has been shown that VPA is also able to
`induce mono—, di—, or tri—methylation of histone 3, particu-
`larly at lysine 9 (H3K4) [20, 26-28]. Methylation of histones
`at this lysine is associated with increased transcriptional
`activity. However, this phenomenon and its purpose are not
`currently clear, considering the specific site of methylation,
`and the fact that it only occurs on already hyperacetylated
`histones, and near—demethylated genes. It is assumed that
`this modification could serve to stabilize the transiently
`released form of chromatin, mediated by histone acetylation
`[28].
`Among many drugs named as “molecular therapies,”
`epigenetic drugs are between the most encouraging, because
`in contrast to other drugs that target the expression of a
`molecule or a family of molecules, they target chromatin
`through associated proteins (HDAC, DNMT, HP1, and
`
`Iournal of Biomedicine and Biotechnology
`
`HO
`
`OH
`
`photo by Maarten.@2007 Erowid.org
`
`111111 o_fj‘lL.11zail5 flower
`
`.
`
`structure of
`(b)
`(a) Structure of Valproic acid,
`FIGURE 1:
`(c) valeriana officinalis
`(valeriana officinalis
`in
`valeric acid,
`an early stage of flowering,
`[Belgium] Photo by Maarten. ©
`2007 Erowid.org: http://WWW.erowid.org/herbs/show_image.php?i=
`valerian/valeriana_officinalis_flower__i2005e1334_disp.jpg).
`
`SMCs). Thus, epigenetic drugs affect the expression of many
`proteins and therefore may be applicable to a wide range of
`pathologies, especially cancer, where multiple antioncogens
`are repressed during carcinogenesis. Epigenetic drugs could
`particularly target these repressed tumor suppressor genes.
`Moreover, given that
`the balance of acetylation and
`deacetylation, under the control of HAT and HDAC,
`is
`not restricted to histones [29], it can be hypothesized that
`VPA, like other HDACi, could modulate molecular activity
`in addition to transcription. Targeted genes could be Ku
`(releasing BAX), STAT3, HSP90, p53, and various transcrip-
`tion factors. Candidates have already been mentioned in a
`preliminary study in 2005 [30].
`it has not
`For all the signaling pathways modulated,
`been established if VPA acts through epigenetic regulation,
`inhibition of acetylation of molecules other than histones, or
`by other molecular mechanisms.
`
`

`
`Iournal of Biomedicine and Biotechnology
`
`2. VPA Targets a Wide Range of Pathologies
`
`Valproic acid used in therapy is available in many formu-
`lations: syrup, suppositories, tablets, or locale injection; the
`different formulations can affect the bioavailability and rate
`of absorption of the molecule. Classically age or weight
`has no influence in VPA serum concentration. There is no
`
`proportional relationship between the dose administrated
`and the serum concentration [31]. Diet plays also a role in the
`rate of absorption as VPA is more rapidly bioavailable when
`ingested before feeding. Finally,
`the serum concentration
`can be strongly influenced by combination with pheny-
`toin (49.5%), carbamazepine (66.2%), or phenobarbital
`(76.3%) than when given alone (100%). On average, 250 mg
`VPA ingested induce a serum concentration of 54.6 ug/mL
`(0.34 mM) [32]. Overdosage of VPA results in somnolence,
`heart block or deep coma.
`
`2.1. Neurological Diseases. Many of the neurodegenerative
`diseases identified to day have genetic causes. Spinal muscular
`atrophy (SMA) is caused by the homozygous loss of the
`SMN1 gene (survival motor neuron protein). The effects of
`the loss of this gene could be modulated by expression of
`the Fl—SMN2 protein (Full Length), which determines the
`severity of the disease [33]. VPA is a promising candidate
`for Fl—SMN2—overexpression therapies, because it has been
`shown that it is able to increase both SMN transcript and
`protein levels in SMA patients. However, the specificity of
`target of several HDACi members decreases their effective-
`ness and could lead to the choice of less specific molecules,
`such as SAHA [28].
`Parkinson’s disease (PD) is caused by the degeneration of
`nigrostriatal dopaminergic neurons. To date, several scien-
`tific papers have shown no effect of VPA on PD. However,
`recent in vitro studies have shown positive effects of VPA
`in models mimicking PD at different levels: VPA treatment
`prevents apoptosis induced by rotenone (inducing PD—like
`neurodegeneration); protects neurons from dopaminergic
`toxin 1—methyl—phenylpyridinium (MPP+) by stimulating
`the release of trophic substances from glia; protects cul-
`tured dopaminergic neurons from over—activated microglia—
`induced degeneration by promoting microglia apoptosis and
`protects neurons by increasing oc—synuclein expression and
`preventing its monoubiquitination and nuclear transloca—
`tion [34—37]. In rodents, experiments show that selective
`alterations of 0c—synuclein caused by rotenone (decrease of
`the native protein and an increase in monoubiquitination in
`substantia nigra and striatum) are counteracted by long—term
`administration of VPA [38].
`Past clinical trials had showed a lack of VPA activity in
`patients with Huntington’s disease (HD) [39], which is sur-
`prising given that the molecular explanation for this disease
`involves excitotoxicity and reduced gene transcription due
`to decreased levels of histone acetylation. However, a recent
`study showed that using high doses of VPA (100 mg/kg/ days)
`is capable of prolonging life expectancy and improving
`traction [40]. This study, based on tests conducted on the
`N171—82Q transgenic mouse model of HD, showed that
`following chronic intraperitoneal daily administration, VPA
`
`significantly improved the condition of mice, increasing the
`number of the surviving mice and reducing the decrease in
`motor activity, and this without exerting any noteworthy side
`effects upon behavior or striatal dopamine content at the
`dose administered. This study therefore recommends further
`clinical trials, based on increasing doses of VPA administered
`in mono— or polytherapy.
`
`2.2. Addiction. The GABAergic system is involved in psy-
`chostimulant sensitization, and VPA can modulate central
`
`GABAergic neurotransmission. An initial study, conducted
`on mice, showed that multiple injections of VPA, admin-
`istered consecutively after methamphetamine, could reduce
`the addictive behavior induced by this drug. However,
`this effect is not reproducible for cocaine—induced behavior
`[41]. These initial results indicated that
`these forms of
`addiction should not involve the same neural mechanisms.
`
`A clinical study of VPA use in treating addiction to various
`substances particularly targeted the stage of detoxification
`prior to treatment and rehabilitation. It was shown that
`a combination of Buprenorphine and VPA seems to be
`the most appropriate for detoxification, compared to the
`traditional combination Clonidine and Carbamazepine [42].
`Several addictions, obsessive—compulsive disorders, and
`compulsive sexual behaviors have similarities in their pro-
`cesses, and, in the use of VPA, may find a possible therapeutic
`treatment.
`
`(HDAC1) has
`2.3. HIV Infection. Histone deacetylase 1
`been implicated in maintaining HIV in infected cells. The
`inhibitory action of VPA upon this protein makes it a
`good candidate for AIDS therapy. A study published in
`2005 undertaken with four patients, showed that
`three
`of them treated with valproic acid in addition to highly
`active antiretroviral therapy (HAART), showed a reduction
`in latent HIV infection [43]. However, a subsequent study
`showed that VPA, alone and in a long—term treatment, is not
`sufficient to reduce the size of the HIV-1 reserve [44].
`
`2.4. Other Pathologies. The possibility of using VPA in
`treatment of Duchenne Muscular Dystrophy, a skeletal
`muscle degeneration disease, was recently demonstrated in
`vitro and in vivo on mice mdx/utrn’/’ [45]. This study
`showed that VPA is able to induce the Akt/mTOR/p70S6K
`pathway, through the induction of phosphatidylinositol 3-
`OH kinase (PI3K), resulting in lower collagen content and
`fibrosis, a decrease of hind limb contractures, an increase of
`
`sarcolemmal integrity, a decrease of CD8—positive inflamma-
`tory cells and higher levels of activated Akt in muscles.
`
`3. VPA Targets Signaling Pathways in
`Cancer Cells
`
`Epigenetic processes, such as histone deacetylation and DNA
`methylation, are known to contribute to the cancerous
`transformation of cells by silencing critical genes, leading
`to chemotherapy resistance. It has been hypothesized that
`HDACi act
`through a derepression or a stimulation of
`
`

`
`[46—48]. Several data
`silenced tumor suppressor genes
`demonstrate the ability of these epigenetic drugs to modulate
`global gene expression in tumors (Figure 2).
`VPA modulates expression of p21WAF1/CDKNIA [49],
`a CDK (cyclin dependent kinase) generally associated with
`cell cycle arrest
`in G1/S phase. VPA appears to induce
`an increase in the amount of p21WAF1 protein over 48
`hours in AML cells, which is independent of p53 levels
`(whose expression is not modulated by VPA), but appears
`to be dependent on c—myc, whose mRNA and protein levels
`decrease in a dose—dependent manner during VPA treatment.
`Under VPA treatment, transcription of c—myc is dependent
`upon INK/SAPK, and ectopic expression of c—myc, leading to
`more resistant cells in cell cycle arrest, shows the importance
`of this protein in VPA—mediated activity. In addition to this,
`while VPA treatment in the cell lines is followed by a decrease
`of c—myc and an induction of p21, it has been observed that
`in primary AML cells, only the systematic decrease of c—myc
`is maintained, without upregulation of p21 expression.
`VPA—induced apoptosis, via the extrinsic pathway involv-
`ing engagement of the caspase—8—dependent cascade, sensi-
`tizes cells to TRAIL/Apo2L—mediated apoptosis by increasing
`expression of DR4 and DR5 by 3- and 14-fold, respectively.
`In the absence of TRAIL/Apo2L, VPA is able to reduce the
`expression of antiapoptotic factors acting on both extrinsic
`and intrinsic apoptotic pathways, including c—FLIPs, proteins
`associated with DISC and Bcl—2/Bcl—X(L). When applied
`with TRAIL/Apo2L, VPA increased cell death and caspase-
`3 activity. These results were reproduced in AML, CLL,
`thoracic cancers, and hepatocellular carcinoma [50—53].
`VPA induces Caspase—11 and FAS —L at the transcriptomic
`level, and Caspase—3 at the proteomic level during exposition
`[54]. Long treatment periods result in enhancement of Fas-
`dependent apoptosis associated with an overexpression of
`Fas and Fas ligand, and a central role in Bcl—2 inhibition [55].
`It has been reported that VPA increased fi—catenin levels
`through concentration—dependent
`inhibition of glycogen
`synthase kinase 3—fi (and 30:) activity, and tau phosphory—
`lation [56]. On one hand, this resulted in the inhibition of
`ubiquitination of fi—catenin and on the other hand, in the
`inhibition of c—jun phosphorylation leading to an increase
`in the DNA binding activity of AP—1. Inhibition of fi—catenin
`ubiquitination led to its translocation into the nucleus, and
`resultant upregulation of c—myc transcription.
`The PI3—kinase/Akt pathway and Sp1 are involved in
`HSP70 induction by HDAC inhibitors, and induction of
`HSP70 by VPA in cortical neurons may contribute to its
`neuroprotective and therapeutic effects [57].
`In medullary thyroid cancer (MTC) cells, VPA is able
`to modify the expression of Notchl, by increasing its
`expression, resulting in inhibition of the growth of these cells
`and the induction of apoptosis. These results along with the
`apparent tolerance of patients to VPA treatment have led to
`the suggestion to involve VPA being in future clinical trials
`on advanced medullary thyroid cancer [58].
`PPAR signaling is involved in several biochemical regula-
`tion processes, including lipidic metabolism, differentiation,
`insulin sensitivity, and cell survival. VPA appeared to be
`a pan—activator of PPAR (both PPARoc, also PPAR5 and
`
`Iournal of Biomedicine and Biotechnology
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`[59, 60]. This mechanism could be one factor
`PPAR)/)
`favoring the teratogenic effect of VPA [60]. In contrast, it
`was reported that in neuronal cells VPA induced a significant
`decrease in PPARy signaling [61]. These results highlight
`potential tissue—specific effects of VPA, as observed in several
`publications, and the difficulties in predicting its effects prior
`to clinical trials.
`
`In similar fashion, HDAC3 is involved in inhibition
`of STAT3 phosphorylation [62]. This inhibition led to a
`decrease in the dimerisation of STAT3 and its translocation
`
`into the nucleus for transcriptional activation of many genes
`in a wide range of biological processes, including induction
`of immune response, oncogenesis, cell cycle control, develop-
`ment, cell adhesion, and differentiation [63]. HDAC3 is one
`of the direct targets of VPA, but until now no papers present
`data concerning the effect of VPA on the STAT3 pathway.
`
`4. Clinical Trials with VPA
`
`As previously mentioned, several reports have demonstrated
`the ability of epigenetic drugs to modulate global gene
`expression in tumors. In many cases, such drugs have moved
`into the first or second phase of clinical trials for treatment
`of various solid cancers or leukemia, and in cotreatment with
`
`several chemotherapeutic agents (Table 1).
`VPA is used for many years in the treatment of convulsive
`seizures and in chronic treatment of epilepsy. Highlighting its
`HDAC inhibitory property and therefore its potential action
`on some cancers has made this molecule, already well known,
`a top candidate in new clinical trials.
`Valproic acid has been implicated in more than two
`hundred clinical trials, sometimes in association with other
`
`ranging from
`drugs and involving various pathologies,
`mood disorders to cancers, through treatment of narcotic
`addictions, muscle disorders, and the ability to reduce viral
`load in AIDS patients (http://clinicaltrials.gov/).
`However, concerning cancer prevention and therapy, a
`recent study on a population taking VPA over a long period
`(minimum 1500 g in the last 5 years) demonstrated that it
`had no significant effect upon prevention of cancer develop-
`ment [64] and thus is not eligible for chemoprevention.
`
`4.1. Clinical Trial in Noncomcerous Disorders. VPA has been
`
`used for many years as a treatment against epilepsy and
`convulsive disorders. Today, the majority of clinical trials
`involving VPA relate to neural pathology, applying to more
`than thirty different pathologies.
`One clinical study aims to compare the antiaggressive
`efficacy of risperidone monotherapy versus risperidone
`in combination with valproate in patients suffering from
`schizophrenia. The random blind test, including 33 patients
`(16 with risperidone and 17 with polytreatment), was unable
`to show any significant difference between the treatments,
`except a higher capacity of patients under combination ther-
`apy to complete the study [65]. The use of valproic acid was
`investigated for its ability to improve mood stabilization. The
`blind clinical trial aimed to assess the capacity of lamotrigine
`or VPA to increase mood stabilization for patients with
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`Iournal of Biomedicine and Biotechnology
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`FIGURE 2: Pharmacological activity of VPA described in the literature. Schematic representation of direct and indirect targets of VPA.
`Principal direct targets known for VPA are ionic channels and ABAT (in green). Epigenetic action of VPA (in violet) as HDACi activity:
`VPA targets the transcriptomic system and principally directly inhibits HDAC class 1 (subcategories 1, 2, and 3), and less strongly class
`II/a (subcategories 4, 5, and 7), but induces HDAC 9 and 11, and indirectly inhibits the function of SMC and DNMT. Probably due to
`its epigenetic properties, or interactions not yet established, VPA alters, directly or indirectly, expression of many molecules involved in
`molecular pathways such as apoptosis, inflammation, differentiation, and proliferation (in red).
`
`

`
`schizophrenia who are both stabilized and partially respon-
`sive [66]. Efficiency assessment was evaluated using the Pos-
`itive and Negative Syndrome Scale, Calgary Depression Scale
`for Schizophrenia, Demoralization Scale, Clinical Global
`Impression severity and improvement scores and Lehman
`quality of life improvement scale to assess quality of life
`and social functioning. The increase of antipsychotics usage
`with mood stabilizers like lamotrigine or VPA for partially
`responsive patients with chronic schizophrenia seems to be
`an inefficient treatment strategy for improving the residual
`symptoms.
`A clinical trial to establish the difference between VPA
`
`in the treatment of pediatric migraine
`and Propranolol
`prophylaxis was undertaken on a population of 120 patients
`aged from 3 to 15 years. The results showed no significant dif-
`ference in all therapeutic effects between the two molecules,
`with a mean of 70% response and a reduction of >50% in
`headache frequency [67].
`A clinical trial concerning agitation of older people with
`dementia was based upon the use of VPA as a treatment over
`several years, without any conclusive clinical trials able to
`show the effects. The results presented were based on the
`compilation of three incomplete clinical studies and show
`that VPA does not induce any improvement in pathology but
`does present an unacceptable rate of side effects [68].
`Acute mania is a behavioral disorder outcome of bipolar
`disorder, also known as manic—depressive disorder, manic
`depression, or bipolar affective disorder. Compilation of
`data provided by European Mania in Bipolar Evaluation
`of Medication (EMBLEM) concerning the comparison of
`olanzapine and valproic acid treatments on a panel of over
`600 patients (rz : 107 valproate, n : 514 olanzapine),
`demonstrated that olanzapine monotherapy seems to be
`more effective than valproate monotherapy in the treatment
`of acute mania [69].
`In contrast, a recent systematic review about the effect
`of VPA upon 142 patients with acute bipolar depression
`shows a significant effect of this molecule for the reduction
`of depressive symptoms of acute bipolar depression, as well
`as high patient tolerance [70]. The outcomes investigated
`were depression, anxiety, hypomania, attrition, and adverse
`events, and the study analyzed existing randomized control
`trial data for the efficacy and tolerability of valproate.
`Results are particularly conclusive for depression (50%
`improvement, for 22% of patients), but inconclusive for
`anxiety, and there was no evidence for an increased risk
`of mania, as
`it also induces long—term antidepressant
`effects.
`
`VPA was investigated for clinical therapy of amyotrophic
`lateral sclerosis (ALS). This prognostic neuropathy was
`studied in 163 patients who received either VPA (1500 mg)
`or placebo, daily. The end points targeted were survival and
`progression of the disease. This study concluded that VPA
`had no beneficial effect upon survival or disease progression
`in patients with ALS [71].
`A phase II study of the effect of VPA upon spinal
`muscular atrophy (SMA), with a panel of 2 SMA type I
`(ages 2-3 years), 29 SMA type II (ages 2-14 years), and
`11 type III (ages 2-31 years) was recently published. The
`
`Iournal of Biomedicine and Biotechnology
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`investigation focused upon several factors, such as assess-
`ment of gross motor function (via the modified Hammer-
`smith Functional Motor Scale: MHFMS), electrophysiologic
`measures of innervations (with maximum ulnar compound
`muscle action potential amplitudes: CMAP) and motor unit
`number estimation (MUNE), body composition, and bone
`density via dual—energy X—ray absorptiometry (DEXA), and
`quantitative blood SMN mRNA levels, as well as carnitine
`depletion, hepatotoxicity, and increased weakness (for the
`side effects). Results revealed a trend of weight gain but
`also an increase of gross motor function in 27 patients,
`all of them with SMA type II and younger than five years
`old. There was no variation in expression of SMN protein
`(survival motor neuron protein), but bone mineral density
`and innervations increased significantly (P S .0001). In
`conclusion, the results presented by this preliminary study
`highlight
`the strengths and limitations of using a large
`cohort of patients for such a trial, as opposite results were
`obtained as functions of age and type of SMA. As such,
`no final conclusion was made concerning VPA, but it was
`suggested that additional controlled clinical trials with VPA
`targeting more restricted cohorts of subjects were needed
`[72].
`
`A phase II clinical trial, principally investigating the
`effect of glyceryl trinitrate, and incidentally that of VPA,
`on pain caused by diabetic peripheral neuropathy, showed
`that these two molecules induce significant improvement,
`whether used alone or in combination [73]. This study,
`undertaken upon 83 patients divided into four groups,
`compared visual analogue score (VAS) and present pain
`intensity (PPI) at
`the beginning of the study and after
`three months, with motor and sensory nerve conduction
`velocities measured using electrophysiological tests. These
`results show significant improvements with both drugs indi-
`vidually and in combination, except for electrophysiological
`test results with VPA treatment, which show no significant
`modification.
`
`Kaposi sarcoma (KS) is a cutaneous tumor caused by
`Human herpesvirus 8 (HHV8) and is often associated
`with coinfection by HIV (AIDS—associated Kaposi sarcoma),
`especially in African populations. Valproate stimulates HIV
`replication in some HIV—infected cell lines in culture [74, 75],
`and in the case of HHV8—infected cells, valproate induces
`expression of multiple HHV8—encoded transcripts that are
`associated with entry into the lytic phase of replication [76].
`Because valproate is sometimes used in individuals who
`might be infected with HHV8 and HIV, a recent study aimed
`to identify the effect of VPA in cases of AIDS—associated
`Kapo si sarcoma [77]. Their results show that treatment with
`VPA was associated with low toxicity, and that KS clinical
`response and herpesvirus lytic induction were not high
`enough to be associated with significant induction of virus
`replication.
`
`The clinical trials mentioned to date concerning treat-
`ment of nonmalignant diseases show few real benefits
`associated with use of VPA in mono— or polytreatment, and
`this despite the very encouraging preclinical data obtained so
`far.
`
`

`
`Iournal of Biomedicine and Biotechnology
`
`TABLE 1: Ongoing clinical studies implicating valproic acid in
`monotherapies.
`
`Dependences
`Alcohol abuse or dependence
`Alcoholism
`
`Cocaine dependence
`Marijuana abuse
`Substance abuse or dependence
`Substance withdrawal syndrome
`Cancer
`
`Autoimmune lymphoproliferative syndrome
`Brain and central nervous system tumor
`Breast cancer
`CLL
`
`HTLV—I associated myelopathy
`MDS risk; AML
`
`Nasopharyngeal carcinoma
`Prostate cancer
`Sarcoma
`
`Neurological disorders
`Alzheimer disease
`
`Amyotrophic lateral sclerosis
`Attention deficit hyperactivity disorder
`Autism
`
`Bipolar disorder
`Borderline personality disorder
`Cluster headache
`Dementia
`
`Depression
`Disruptive behavior
`Epilepsy
`Mania
`
`Migraine
`Mood disorder
`
`Neuralgia
`Phosphosensitive epilepsy
`Post traumatic stress disorder
`
`Progessive supranuclear palsy
`Resistant bipolar depression
`Schizophrenia
`Spinal muscular atrophy type 1
`Others
`Asthma
`
`Hypersplenism; lymphadenopathy
`Hyp oalbunemia
`Insulin resistance
`
`4.2. Clinical Trial in Solid Tumors and Leukemia
`
`4.2.1. VPA in Myeloid and Lymphoid Malignancies. The use
`of VPA in monotherapy or polytherapy seems promising for
`leukemia diseases. It has already been established that VPA
`
`exerts different effects in different cell types, and probably in
`the function of these cell types. It can induce proliferation
`in early stem cells and can inhibit angiogenesis, production
`of TNF—oc and IL-6, and activation of NF—KB. Taken together
`these properties could be beneficial in the treatment of MDS
`or leukemic pathologies.
`While HDACi are emerging as valuable new agents in the
`treatment of acute myeloid leukaemia (AML), the efficiency
`rates of these compounds in isolation are low, which requires
`them to be used in cotreatment with other anticancer
`
`drugs. Research into predictive markers of the efficiency
`of cotreatment with VPA gave rise to a study published
`in 2009, comparing results obtained by coprocessing using
`all
`trans retinoic acid (ATRA) and theophylline on 20
`patients and several cell lines, and a microarray study on
`primary AML cells and cell
`lines. Comparison between
`results obtained with cotreatment (one Complete Remission
`(CR), two Partial Remission (PR)) and those obtained in
`treatment of primary cells and cell lines allowed the authors
`to conclude that similar factors determine both in vivo and in
`
`vitro sensitivity and identified elevated FOSB—expression as a
`potential marker of VPA sensitivity [78].
`Hematological
`improvement was reported in many
`patients with different
`types of cancer
`following VPA
`treatment, with favorable responses; in patients with MDS
`(myelodystrophy syndromes) and MP8 (myeloproliferative
`syndromes)
`[79];
`in patients with AML developed from
`MPD (myeloproliferative disorders) [80]; in patients with
`myelofibrosis in myeloid metaplasia [81]. Clinical studies on
`the use of VPA have shown the beneficial effect of this drug
`especially on MDS [82, 83].
`In 2007, a phase I/II study investigated the use of a
`tritherapy combination of 5—azacitidine (5—AZA), VPA, and
`ATRA in patients with acute myeloid leukemia or high-
`risk MDS. A total of 53 patients were tr