High doses of biotin in chronic progressive multiple sclerosis: A pilot study

Open AccessPublished:January 23, 2015DOI:https://doi.org/10.1016/j.msard.2015.01.005

      Highlights

      • Biotin activates enzymes involved in energy production and myelin synthesis.
      • 91.3% of SPMS or PPMS patients improved clinically with high doses of biotin.
      • Improvement concerned chronic optic neuropathy, homonymous hemianopia or myelopathy.
      • In all cases improvement was delayed from 2 to 8 months following treatment׳s onset.
      • Two multi-centric double-blind placebo-controlled trials are currently underway.

      Abstract

      Background

      No drug has been found to have any impact on progressive multiple sclerosis (MS). Biotin is a vitamin acting as a coenzyme for carboxylases involved in key steps of energy metabolism and fatty acids synthesis. Among others, biotin activates acetylCoA carboxylase, a potentially rate-limiting enzyme in myelin synthesis.

      Objectives

      The aim of this pilot study is to assess the clinical efficacy and safety of high doses of biotin in patients suffering from progressive MS.

      Study design

      Uncontrolled, non-blinded proof of concept study

      Methods

      23 consecutive patients with primary and secondary progressive MS originated from three different French MS reference centers were treated with high doses of biotin (100–300 mg/day) from 2 to 36 months (mean=9.2 months). Judgement criteria varied according to clinical presentations and included quantitative and qualitative measures.

      Results

      In four patients with prominent visual impairment related to optic nerve injury, visual acuity improved significantly. Visual evoked potentials in two patients exhibited progressive reappearance of P100 waves, with normalization of latencies in one case. Proton magnetic resonance spectroscopy (H-MRS) in one case showed a progressive normalization of the Choline/Creatine ratio. One patient with left homonymous hemianopia kept on improving from 2 to 16 months following treatment׳s onset. Sixteen patients out of 18 (89%) with prominent spinal cord involvement were considered as improved as confirmed by blinded review of videotaped clinical examination in 9 cases. In all cases improvement was delayed from 2 to 8 months following treatment׳s onset.

      Conclusions

      These preliminary data suggest that high doses of biotin might have an impact on disability and progression in progressive MS. Two double-blind placebo-controlled trials are on going.

      Keywords

      1. Introduction

      In 85% of cases, multiple sclerosis (MS) initially evolves through relapses that resolve completely or incompletely (relapsing-remitting MS or RRMS). However, in about 50% of cases, patients who were initially presented with a relapsing-remitting course subsequently evolve towards a progressive form (secondary progressive MS or SPMS). In 15% of patients, the disease strikes with an immediate progressive setting without relapses (primary progressive MS or PPMS). It is possible to distinguish two components in the pathophysiology of multiple sclerosis: (1) an inflammatory component, responsible for the attacks, and (2) a degenerative component characterized by progression with few or less inflammation (
      • Noseworthy JH
      • Lucchinetti C
      • Rodriguez M
      • Weinshenker BG.
      Multiple sclerosis.
      ,
      • Compston A
      • Coles A.
      Multiple sclerosis.
      ). Among hypotheses that tend to explain the cause(s) of progressive MS, it has been proposed that progressive degeneration could be linked to a phenomenon of “virtual hypoxia” caused by a mismatch between increased energy demand by the demyelinated axon and decreased energy production because of mitochondria injury (
      • Luessi F
      • Siffrin V
      • Zipp F.
      Neurodegeneration in multiple sclerosis: novel treatment strategies.
      ,
      • Stys PK
      • Zamponi GW
      • van Minnen J
      • Geurts JJ.
      Will the real multiple sclerosis please stand up?.
      ,
      • Witte ME
      • Mahad DJ
      • Lassmann H
      • van Horssen J.
      Mitochondrial dysfunction contributes to neurodegeneration in multiple sclerosis.
      ).
      While immunosuppressive or immunomodulatory therapies reducing the inflammatory reaction are mainly effective at the relapsing-remitting phase of the disease, as they decrease the number or the duration of relapses and lesion accumulation on MRI, they only have poor efficacy on the long-term disability and only weak or no effectiveness in the progressive (primary or secondary) forms of the disease (
      • Hauser SL
      • Chan JR
      • Oksenberg JR.
      Multiple sclerosis: prospects and promise.
      ). With regards to permanent disability, fampridine is the only approved symptomatic drug that improves walking speed in a subgroup of patients (
      • Goodman AD
      • Brown TR
      • Krupp LB
      • Schapiro RT
      • Schwid SR
      • Cohen R
      • et al.
      Sustained-release oral fampridine in multiple sclerosis: a randomised, double-blind, controlled trial.
      ). Up to now, no drug has been found to have any impact on the disease׳s progressive phase (primary or secondary).
      Biotin (or vitamin H) is a ubiquitous water-soluble vitamin that is naturally found in many foods (
      • Zempleni J
      • Mock DM.
      Bioavailability of biotin given orally to humans in pharmacologic doses.
      ). In mammals, biotin acts as a coenzyme for carboxylases involved in key steps of energy metabolism and fatty acids synthesis.
      High doses of biotin have been found to be a therapeutic option in “biotin responsive basal ganglia disease” (BBGD; OMIM 607483), an orphan neuro-metabolic disease caused by mutations in the SLC19A3 gene coding for a thiamine transporter (
      • Tabarki B
      • Al-Shafi S
      • Al-Shahwan S
      • Azmat Z
      • Al-Hashem A
      • Al-Adwani N
      • et al.
      Biotin-responsive basal ganglia disease revisited: clinical, radiologic, and genetic findings.
      ). Patients with BBGD display severe episodes of Leigh-like encephalopathy leading to death or permanent disability and show dramatic improvement when high doses of biotin (5–10 mg/kg/day) and thiamine are administered (
      • Tabarki B
      • Al-Shafi S
      • Al-Shahwan S
      • Azmat Z
      • Al-Hashem A
      • Al-Adwani N
      • et al.
      Biotin-responsive basal ganglia disease revisited: clinical, radiologic, and genetic findings.
      ). In addition, we recently found that 5 patients suffering from optic neuropathies and leukoencephalopathy did respond clinically to high doses of biotin (
      • Sedel F
      • Challe G
      • Vignal C
      • Assouad R
      • Bellanger A
      • Galanaud D.
      A novel biotin sensitive leukodystrophy.
      ). Subsequently, we discovered that one of these 5 patients suffered from SPMS. From this starting point, high doses of biotin were tested in 22 additional patients with PPMS and SPMS. Results are reported here.

      2. Methods

      Twenty-three consecutive patients with PPMS or SPMS were treated with high doses of biotin ranging from 100 mg to 600 mg/day (median=300 mg/day divided in three doses) in a compassionate use open-label trial. All patients were followed in French MS reference centers and fulfilled the McDonald criteria for Multiple Sclerosis (
      • Polman CH
      • Reingold SC
      • Banwell B
      • Clanet M
      • Cohen JA
      • Filippi M
      • et al.
      Diagnostic criteria for multiple sclerosis: 2010 revisions to the McDonald criteria.
      ) and Lublin revised criteria for progressive MS (
      • Lublin FD
      • Reingold SC
      • Cohen JA
      • Cutter GR
      • Sørensen PS
      • Thompson AJ
      • et al.
      Defining the clinical course of multiple sclerosis: the 2013 revisions.
      ). The term progressive disease refers to steadily increasing objectively documented neurologic dysfunction/disability without unequivocal recovery (fluctuations and phases of stability may occur,
      • Lublin FD
      • Reingold SC
      • Cohen JA
      • Cutter GR
      • Sørensen PS
      • Thompson AJ
      • et al.
      Defining the clinical course of multiple sclerosis: the 2013 revisions.
      ). All patients included in this study had a disease progressing for at least the last 12 months. None of the patients displayed any acute exacerbation within the 6 months prior to treatment׳s onset. The study has received review from an ethics committee. Seventeen patients were followed at Pitié-Salpêtrière Hospital by FS and CP; 3 patients were followed in Reims Academic Hospital by AT and 3 patients were followed in Nice Academic Hospital by CLF. Most of them had been treated with drugs usually proposed in progressive MS that failed to improve their neurological condition including monthly pulses of IV methylprednisolone (IVMP), cyclophosphamide, azathioprine or fampridine (Table 1 and Supplementary data). None of these drugs were introduced during the period of treatment with biotin except consecutive pulses of IVMP in case of MS relapses.
      Table 1Efficacy data in 23 patients with progressive MS treated with high doses of biotin.
      Case number (location)Age (yrs)MS formEDSS at onsetProg disease duration (yrs)Clinical formMax dose (mg)Total (mo)Delay (mo)MS RelapseQuant improvQual improvEfficacy: sustained (+), transient (+/−), no (−)Additional MS therapies at baselinePast MS treatments
      1 (PSL)74SP43ON600343VA (R: 0.1 (20/200)→0.3 (20/60); L: 0.2 (20/100)→0.5 (20/40)); VEPs, H-MRSPsychiatric signs+NoneMP pulses
      2 (PSL)26SP43ON300183+VA (R: 0.1 (20/100)→ 0.3 (20/60); L: 0.3 (20/60)→0.6 (20/30)), perimetry+/−IFNMP pulses
      3 (PSL)33PP49ON300153+VA (R: 0.07 (20/250)→ 0.12 (20/160); L: 0.06 (20/320)→0.1 (20/200)),perimetryCognition, ataxia+NoneMP pulses IFN
      4 (PSL)44SP44ON300123VA (R: 0.3 (20/60)→ 0.4 (20/50); L: 0.025 (20/400)→0.3 (20/60)), VEPs, perimetryUhthoff, fatigue, ataxia+NoneMP pulses IFN Fingo
      5 (PSL)29SP34LHH300162PerimetrySensory symptoms+NoneMP pulses
      6 (PSL)73SP8.512Tetra-paresis300122Muscle strength, EDSS: 8.5→8Video, swallowing, dysarthria, sensory signs+NoneMP pulses Cyclo
      7 (PSL)62PP78Para-paresis30063+EDSS: 7→6.5, TW25: −31.8%Video+/−NoneMP pulses MPM
      8 (PSL)53PP5.53Para-paresis30073EDSS: 5.5→4, TW25: −32.6%Video, dysuria+NoneMP pulses
      9 (PSL)73PP8.520Tetra-paresis30062Muscle strengthVideo, dysarthria, swallowing+NoneNA
      10 (PSL)47PP8.521Tetra-paresis3008Not improved+Not improvedNot improvedNoneMP pulses Cyclo Metho
      11 (PSL)49PP8.511Tetra-paresis30088Muscle strengthVideo, dysarthria, swallowing+NoneMP pulses IFNAza Cyclo
      12 (PSL)48PP8.510Tetra-paresis3007Not improvedNot improvedNot improvedNoneCyclo
      13(Reims)41SP8.515Tetra-paresis30063Noneswallowing, oscillopia, coordination+NoneIFN MP pulses Cyclo
      14 (Nice)60SP6.56Para-paresis30093EDSS: 6.5→6walking distance, fatigue+NoneMP pulses
      15 (Nice)50PP8.520Tetra-paresis30093Muscle strengthtrunk hypotonia+NTZAza MPM Cyclo Mito
      16 (Nice)53SP913Tetra-paresis30093Muscle strengthtrunk hypotonia+IgIVIgIV Cyclo MPM Aza
      17 (PSL)75SP65Para-paresis30064TW25: −42% EDSS: 6→5.5Video+NoneMP pulses Stem cells
      18 (PSL)46PP6.530Para-paresis30022NoneFatigue, walking+NoneMP pulses Aza
      19 (PSL)59PP610Para-paresis30064TW25: −33.8%, Muscle strengthVideo+NoneCyclo
      20 (PSL)52PP3.55Para-paresis30063TW25: −17.6%,Video,urgent mictions+/−NoneNA
      21(Reims)49PP8.56Tetra-paresis20022NoneFatigue+FampridineMP pulses Cyclo
      22 (PSL)63PP8.510Tetra-paresis20052Muscle strengthNone+NTZNA
      23 (Reims)57PP8.513Tetra-paresis30044Muscle strengthVideo, fatigue+NoneMP pulses
      TotalMean=52.8PP=60%Mean=10.5Med=300Mean=9.2Mean=3.14 /23 (17.4%)(+): 78.3% (+/−): 13% (−): 8.7%
      Age: age at last follow-up; AZA: azathioprine; Cyclo: cyclophosphamide; Delay: treatment duration before first signs of improvement; Fingo: fingolimod; HH: homonymous hemianopia; H-MRS: proton magnetic resonance spectroscopy; IFN: β-interferon; IgIV: intravenous immunoglobulins, Max dose: maximum dose received per day; Med: median; Metho: methotrexate; MP: methylprednisolone; MPM: mycophenolate mofetil; Mito: mitoxantrone; Mo: months; MS relapse: any relapse of multiple sclerosis during treatment, NA: not available; NR: not relevant; NT: not tried, NTZ: natalizumab; ON: optic neuropathy; PP: primary progressive, Prog disease duration: duration of the progressive disease before treatment׳s onset; PSL: Pitié-Salpêtrière Hospital; Quant improve: quantitative measures improved; Qual improve: qualitative improvement; SP: secondary progressive, Spinal: spinal cord involvement; Sustained: sustained efficacy at last follow-up; Total: total treatment duration at last follow-up; VA: visual acuity expressed in decimals units and US Snellen equivalent before and after treatment (best recorded values) for right (R) and left (L) eye, VEPs: visual evoked potentials, Video: filmed clinical examination follow-up.
      Assessment of biotin׳s efficacy varied according to the clinical situation and the center. In the four patients with chronic optic neuropathies, efficacy was assessed using visual acuity (VA), Goldmann perimetry and/or visual evoked potentials (VEP). In the patient with homonymous hemianopia, efficacy was assessed using Humphrey automated perimetry. In the 18 patients with spinal cord involvement, efficacy was assessed using walking distance, EDSS, TW25, muscle strength testing and videotaped clinical examination in a subset of patients. In addition, clinicians collected the following clinical symptoms: fatigue, swallowing difficulties, dysarthria, Uhthoff׳s phenomenon and urinary dysfunction.
      For 9 patients, videotaped clinical examinations were reviewed blindly by an independent examiner from a center not participating in the study and specialized in the evaluation of motor disability in multiple sclerosis and related neurodegenerative diseases (Dr. Kathleen Zackowski, Kennedy Krieger Institute/Johns Hopkins School of Medicine, Baltimore, USA). Before and after treatment videos were mixed up and numbered 1 or 2. No visual or auditory details in the video could help identify if the patient was filmed before or after treatment initiation. The blinded examiner was asked to rate the muscular movements and walking exercises, to select a video where the patient was eventually improved and the degree of improvement, based on clinical global impression. Two videos were reviewed per patients corresponding to (1) the first available video before or soon after treatment׳s onset when the pre- treatment video was lacking and (2) the latest available video after treatment׳s onset. The examiner who performed the rating was aware of the uncontrolled open label nature of the study. Capsules containing 100 mg of biotin each were prepared by the pharmacy of Pitié-Salpêtrière Hospital (Patent Application WO/2011/124571).

      3. Results

      Twenty-three patients aged from 26 to 75 years (mean=52.8 years) were treated with high doses of biotin from 2 to 36 months (mean treatment׳s duration=9.2 months). Fourteen patients suffered from PPMS and 9 from SPMS. Four patients (1–4) had permanent visual loss following optic nerve involvement; one patient (patient 5) had progressive lateral hemianopia caused by involvement of optic radiations and 18 patients (patients 6–23) had progressive paraparesis or tetraparesis related to spinal cord involvement. Results are summarized in Table 1, Fig. 1, Fig. 2, Fig. 3 and are detailed in Supplementary data.
      Figure thumbnail gr1
      Fig. 1Evolution of visual evoked potentials in patient 4 (whole field, 24×32, mean curves). On the left side, although no individualized P100 wave could be observed on the left before treatment (M0), a P100 wave was well confirmed after 9 months (M9) with a normal latency of 104 ms. On the right side, a P100 was obtained before treatment with an increased latency (167 ms). At M9, the latency of the P100 was in the normal range (103 ms).
      Figure thumbnail gr2
      Fig. 2Evolution of NMR spectroscopy at short echo time in the diseased brain white matter of patient 1. Note the progressive decrease in the choline/creatine ratio (materialized by a dotted square) starting after 6 months of treatment (M6) and normalization after 9 months (M9). Serial brain H-MRS were performed on a 3 T MR unit (General Electric, WI) with a single voxel acquisition using the PRESS sequence at short (TR=1500 ms, TE=28 ms) and long (TR=1500 ms, TE=135 ms) echo times in the white matter of the centrum ovale. The volume of interest was similarly located in all acquisitions and measured 40 mm×16  mm×20 mm (x,y,z axes).
      Figure thumbnail gr3
      Fig. 3Patient 5. (A) Follow-up of visual fields measured by Humphrey automated perimetry before treatment (between Apr 2008 and Jan 2012) and after treatment with 300 mg/day of Biotin (June 2012 to september 2013). Treatment was started on Apr 2012. Note the progressive left homonymous hemianopia (Black color) between Apr 2008 and Jan 2012 that improves (becoming progressively brighter) after two months of treatment (Jun 2012). Improvement was even more pronounced at M4, M7, M11, M13 and M16. (B) Location of the lesion involving the right optic radiations on brain MRI using a T2-weighted sequence. (C) Evolution of mean deviations of the visual field defects (MD) during the 48 months preceding treatment׳s onset and during the 16 months following treatment׳s onset. The progressive improvement of the MD values confirms the qualitative improvement shown in A. R: right eye; L: left eye.

      3.1 Patients with prominent optic nerve involvement (1–4)

      The 4 patients with chronic visual loss related to involvement of optic nerves exhibited improvement of VA after a delay of 3 months following treatment׳s onset. The 8 diseased eyes improved by a mean of 0.18 decimal units (sd=0.11) a threshold considered beyond a possible test–retest effect (
      • Rosser DA
      • Cousens SN
      • Murdoch IE
      • Fitzke FW
      • Laidlaw DA.
      How sensitive to clinical change are ETDRS logMAR visual acuity measurements?.
      ). In all cases, improvement was observed with the dose of 300 mg/day. Improvement was maintained over time except in patient 2 who exhibited worsening after a MS relapse (supplementary data). Improvement of VA was associated with improvement of Goldmann perimetry in patients 2–4 (not shown). In addition, VEP were performed in patients 1 and 4. In both cases, P100 waves, although not recordable or very delayed at baseline were clearly observable after 9 months of treatment with normalization of latencies in patient 2 (Fig. 1).
      H-MRS was performed every 3 months from treatment׳s onset in patient 1 (Fig. 2). A progressive normalization of the Choline/Creatine ratio, a myelin marker, was observed over time. After 9 months of treatment, this ratio had returned to normal values.

      3.2 Patient with homonymous hemianopia (patient 5)

      Patient 5 had progressive left homonymous hemianopia worsening over 4 years, related to a lesion involving optic radiations (Fig. 3). Humphrey perimetry was observed to continuously improve from M2 (2 months after treatment׳s initiation) up to M16 (last follow-up). This was confirmed by Visual field defect׳s quantification showing better mean deviation (MD) values reached after 7 months of treatment compared to those obtained during the 4 years of the pre-treatment follow-up (Fig. 3). Despite functional improvement, no change in the size or aspect of the right occipital white matter lesion was noted on brain MRIs performed after treatment׳s onset.

      3.3 Patients with spinal cord involvement (6–23)

      Eighteen patients had prominent involvement of the spinal cord with progressive tetraparesis (11 cases) or paraparesis (7 cases). Sixteen out of 18 patients (89%) displayed clinical improvement after a delay ranging from 2 to 8 months. Seven patients (6, 7, 8, 13, 14, 15, 16) started to improve with 100 mg/day of biotin; 5 of them (6, 8, 14, 15, 16) improved even more after increasing the dosage to 300 mg/day. In the 9 remaining patients, improvement started at the dose of 200 mg (patients 21 and 22) or 300 mg/day (patients 9, 11, 17, 18, 19, 20, 23). In 9 cases (50%), improvement was documented by blinded review of videotaped clinical examinations (Table 2). In all cases, the blinded examiner recognized that the latest video (after the longest period of treatment) corresponded to the best examination.
      Table 2Results of blinded evaluation of videos.
      Patient numberInitial videoLast videoTestScore at initial visitScore at last visitBest examination in the opinion of examinerCGI at best examinationComments from the examiner
      6M4M12Deltoid (L)44M123In video number 2 movements in right brachialis and extensor digitorum were more apparent
      Flexor digitorum profundis (L)11
      Brachialis (R)02+
      Extensor digitorum (R)02+
      Quadriceps femori (R)12−
      Quadriceps femori (L)12−
      7M0M3Time to make the same distance101 s41 sM33
      8M0M7Time to make the same distance14 s9 sM73Walk was faster in video 2
      9M0M6Flexor digitorum profundis (R)2−2M63
      Extensor digitorum (R)22
      Brachialis (R)2−2−
      Triceps (R)12−
      11M3M8Flexor digitorum profundis (L)02−M83
      Extensor digitorum (L)02−
      Brachialis (L)2−2−
      Triceps (L)2−
      Extensor carpi (L)02−
      Flexor carpi (L)02−
      17M0M7Time to make the same distance2815M73The walking path in video 2 (M0) is more cluttered than the path in video 1 (M7), this will affect the speed of walking in the trial
      19M2M6Time to make the same distance20 s13 sM62
      Deltoid (R)2−2
      20M0M3Time to make the same distance44 s35 sM33
      23M0M3Deltoid (L)2−2+M33
      CGI (clinical global impression): Rate total improvement whether or not, in your judgement, it is due entirely to drug treatment. Compared to the worst video, how much has he changed? 0=Not assessed; 1=Very much improved; 2=Much improved; 3=Minimally improved; 4=No change; 5=Minimally worse; 6=Much worse; 7=Very much worse.
      In the sub-group of 11 patients with tetraparesis, 9 patients improved after a delay of 2–8 months. The longest period of observation in this group was 12 months (patient 6). Two patients (10 and 12) did not respond at all to treatment despite increasing the dosage to 300 mg/day. In patient 21, treatment׳s withdrawal for 15 days was followed by a marked worsening leading to the reintroduction of the treatment.
      In the sub-group of 7 patients with paraparesis, all patients improved after a delay ranging from 2 to 5 months. The TW25 test was performed in 5/7 cases and best improvement compared to baseline ranged from 17.6% to 33.8%, which can be considered as clinically relevant (
      • Goodman AD
      • Brown TR
      • Krupp LB
      • Schapiro RT
      • Schwid SR
      • Cohen R
      • et al.
      Sustained-release oral fampridine in multiple sclerosis: a randomised, double-blind, controlled trial.
      ,
      • Schwid SR
      • Goodman AD
      • McDermott MP
      • Bever CF
      • Cook SD.
      Quantitative functional measures in MS: what is a reliable change?.
      ). In patients 7 and 20, although some improvement was observed after 3 months of treatment, the positive effect was not maintained overtime. Worsening occurred following a MS relapse in patient 7 and without any explanation in patient 20.

      3.4 Other symptoms improvement

      Neurologists considered that the following symptoms and signs also improved: fatigue (5 cases), swallowing difficulties (4 cases), dysarthria (3 cases), sensory signs (2 cases), gait ataxia (2 cases), urinary dysfunction (2 cases), cognition (1 case), psychiatric signs (1 case), oscillopia (1 case) motor coordination (1 case) and Uhthoff׳s phenomenon (1 case). Overall, the EDSS score significantly improved in 4/23 patients (22%) with a decrease of at least 1 point (for initial EDSS between 4 and 5.5) or of at least 0.5 (for initial EDSS between 6 and 8.5).

      3.5 Effect on relapses

      Four patients (2, 3, 7 and 10) out of 23 (13%) receiving high doses of biotin experienced at least one MS relapse. This frequency was similar to that observed before treatment in these patients.

      3.6 Safety data

      No adverse effects were reported in 20 cases. Transient diarrhea was noted in 2 patients. Patient 1 died from cardiac failure 36 months after treatment׳s onset. Mild aortic valvulopathy with dilatation of the ascending aorta together with a first-degree atrio-ventricular block was discovered during the patient׳s follow-up. No relation was established between treatment׳s onset, mild cardiac abnormalities and death: no change in ECG or cardiac ultrasonography could be noted in this patient (Supplementary data). Patient 15 died one year after treatment׳s onset from a pneumopathy few days after sigmoid volvulus surgery. No relation could be established between death and treatment.

      4. Discussion

      Our results based on clinical, electrophysiological and H-MRS data suggest that high doses of biotin have some impact on disease progression and permanent disability in patients with progressive MS. Overall, 21/23 patients (91.3%) exhibited some qualitative or quantitative clinical improvement with high doses of biotin. Similar positive results were noted in patients with SPMS and PPMS suffering from optic neuropathies, homonymous hemianopia or spinal cord involvement. In all cases, clinical improvement was delayed by 2–8 months (mean=3 months) following treatment׳s onset. Only 2 patients with severe tetraparesis did not show any response to treatment, probably related to its short duration (8 and 7 months respectively). Indeed, in patient 11 with a severe tetraparesis, treatment׳s benefit only started 8 months after treatment׳s initiation. The range of dose was determined empirically after having observed some clinical improvement in a single patient with 300 mg/day of biotin. Several attempts to decrease or increase the dosage were performed. Increasing the dose to 600 mg/day in one patient was not associated with additional benefit whereas decreasing the dose to 100 mg/day in one patient was associated with worsening. In 5 cases, increasing the dosage from 100 to 300 mg/day was followed by an additional improvement. From these observations, the dose of 300 mg/day was thought to be associated with the best clinical response. In addition, the treatment appeared to be safe: transient diarrhea, the only minor adverse effect, was noted in 2 patients. Two patients died in the course of the trial but in both cases, death could not be attributed to the treatment.
      Although these data rely on an open label study with the possibility of a placebo effect, they are in marked contrast with the natural history of progressive forms of MS where almost no spontaneous or sustained improvement occurs (
      • Confavreux C
      • Vukusic S
      • Moreau T
      • Adeleine P.
      Relapses and progression of disability in multiple sclerosis.
      ). Furthermore, clinical treatment׳s efficacy was confirmed in few patients by unbiased quantitative measures such as VEP and H-MRS that both showed continuous improvement during the first year of treatment. The normalization of VEP latencies and of the choline/creatine ratio suggests the possibility of myelin repair that would also account for the delayed efficacy. In contrast, the treatment is unlikely to be associated with an anti-inflammatory effect. Indeed, biotin did not prevent from inflammatory attacks as observed in 4 patients who displayed relapses while on treatment. On the other hand, the question whether high doses of biotin could favor attacks of the disease still remains. Of note, in our study, the rate of relapses did not significantly change before and after treatment but more data are still needed.
      To our knowledge, high doses of biotin have never been hypothesized as a potential treatment for MS. The discovery that this might represent a therapeutic option in chronic progressive MS both in its secondary and primary forms relies on a serendipity. However a posteriori, the observed effects do rely on a strong rational. Progression in MS (either secondary or primary) is often considered as a consequence of both demyelination and energy failure (
      • Luessi F
      • Siffrin V
      • Zipp F.
      Neurodegeneration in multiple sclerosis: novel treatment strategies.
      ,
      • Stys PK
      • Zamponi GW
      • van Minnen J
      • Geurts JJ.
      Will the real multiple sclerosis please stand up?.
      ). A large proportion of ATP produced in the nervous system is used by the NA/K ATPase to restore the membrane resting potential. In the normal condition, myelin insulation reduces the energy demand during impulse propagation because only the nodes of Ranvier are excited. In contrast, in unmyelinated fibers where the entire membrane is involved, much more ATP is needed for ion pumping. As a consequence, it has been estimated that an unmyelinated axon may use up to 5000 times more energy than a myelinated axon (
      • Quarles RH
      • Wendy B
      • Macklin WB.
      Myelin formation, structure and biochemistry.
      ). In MS, in addition to the fact that demyelinated fibers increase their energy demand, energy production may be compromised because of mitochondrial injury (
      • Witte ME
      • Mahad DJ
      • Lassmann H
      • van Horssen J.
      Mitochondrial dysfunction contributes to neurodegeneration in multiple sclerosis.
      ). The resulting mismatch between increased energy demand for nerve conduction and decreased supply by impaired mitochondria could bias demyelinated axons towards a state of ‘virtual hypoxia’ culminating in degeneration (
      • Luessi F
      • Siffrin V
      • Zipp F.
      Neurodegeneration in multiple sclerosis: novel treatment strategies.
      ,
      • Stys PK
      • Zamponi GW
      • van Minnen J
      • Geurts JJ.
      Will the real multiple sclerosis please stand up?.
      ).
      Biotin is a water-soluble vitamin that serves as an essential coenzyme for carboxylases catalyzing the transfer of a carboxyl (COOH) group to targeted substrates (
      • Zempleni J
      • Mock DM.
      Bioavailability of biotin given orally to humans in pharmacologic doses.
      ). The five biotin-dependent carboxylases are: pyruvate carboxylase (PC), propionly-CoA carboxylase (PCC), β-methylcrotonyl-CoA caboxylase (MCC), and acetyl-CoA carboxylase (ACC), with the latter enzyme existing in two distinct isoforms one of which is in the cytosol (ACC1) and the other is attached to the outer mitochondrial membrane (ACC2,
      • Tong L.
      Structure and function of biotin-dependent carboxylases.
      ). PC, PCC and MCC are expressed in astrocytes and neurons (
      • Hassel B.
      Carboxylation and anaplerosis in neurons and glia.
      ,
      • Ballhausen D
      • Mittaz L
      • Boulat O
      • Bonafé L
      • Braissant O.
      Evidence for catabolic pathway of propionate metabolism in CNS: expression pattern of methylmalonyl-CoA mutase and propionyl-CoA carboxylase alpha-subunit in developing and adult rat brain.
      ) and are involved in the production of oxaloacetate, succinyl- CoA and acetyl CoA CoA that are key intermediates for the tricarboxylic acid (Krebs) cycle which plays a central role in neuronal energy production (Fig. 4). Activation of the Krebs cycle by very high doses of biotin may therefore increase the energy production in axons, thus avoiding the “virtual hypoxia phenomenon”. On the other hand, ACC1 (and ACC2) is involved in the synthesis of malonyl CoA from acetyl CoA and citrate (Fig. 4). The synthesis of Malonyl CoA represents the rate-limiting and committed step of long-chain fatty acid biosynthesis. In the nervous system, ACC immunoreactivity is high in oligodendrocytes (
      • Tansey FA
      • Thampy KG
      • Cammer W.
      Acetyl-CoA carboxylase in rat brain. II. Immunocytochemical localization.
      ), and its activity is detected in purified myelin (
      • Chakraborty G
      • Ledeen R.
      Fatty acid synthesizing enzymes intrinsic to myelin.
      ), suggesting that ACC (either ACC1 or ACC2) might be a key regulator for myelin synthesis. Furthermore, studies in cell cultures have shown that lactate, the main energetic substrate in the central nervous system, is oxidized in the Krebs cycle to produce ATP in neurons, whereas oligodendrocytes use lactate in part to produce membrane lipids presumably for myelin (
      • Sanchez-Abarca LI
      • Tabernero A
      • Medina JM.
      Oligodendrocytes use lactate as a source of energy and as a precursor of lipids.
      ,
      • Rinholm JE
      • Hamilton NB
      • Kessaris N
      • Richardson WD
      • Bergersen LH
      • Attwell D.
      Regulation of oligodendrocyte development and myelination by glucose and lactate.
      ). Overall, high doses of biotin, could target the main metabolic processes related to progressive MS by (1) activating the Krebs cycle in demyelinated axons to increase energy production; (2) activating the Krebs cycle in oligodendrocytes to increase the production of citrate required for lipids synthesis and; (3) activating ACC1 and ACC2, the rate-limiting enzymes in the synthesis of long chain fatty acids required for myelin synthesis (Fig. 4).
      Figure thumbnail gr4
      Fig. 4Potential mechanisms of action of high doses of biotin. Targets of biotin are: (1) PC: pyruvate carboxylase, (2) PCC: propionyl CoA carboxylase, (3) MCC: methylcrotonyl CoA carboxylase, (4) ACC: acetylCoA carboxylases. Activation of PC, PCC, MCC may lead to increase ATP production in neurons (and astrocytes) whereas activation of ACC may lead to myelin synthesis by oligodendrocytes. Adapted from
      • Tong L.
      Structure and function of biotin-dependent carboxylases.
      and from
      • Rinholm JE
      • Hamilton NB
      • Kessaris N
      • Richardson WD
      • Bergersen LH
      • Attwell D.
      Regulation of oligodendrocyte development and myelination by glucose and lactate.
      (see also text).
      The adequate daily intake of biotin in adults is 30 μg and the dose used in this study was 10,000 more. Oral biotin is completely absorbed, urinary excretion of biotin and its metabolites being similar after intravenous and oral administration (
      • Wang KS
      • Kearns GL
      • Mock DM.
      The clearance and metabolism of biotin administered intravenously to pigs in tracer and physiologic amounts is much more rapid than previously appreciated.
      ). Biotin is transported across the blood–brain barrier by a saturable system; the apparent Km being about 100 μmol/L, a value several orders of magnitude greater than the concentration of free biotin in plasma even after administration of very high doses (
      • Zempleni J
      • Mock DM.
      Bioavailability of biotin given orally to humans in pharmacologic doses.
      ,
      • Spector R
      • Mock D.
      Biotin transport through the blood-brain barrier.
      ). Accordingly, it is expected that high doses of biotin administered orally will reach the brain to be incorporated into apocarboxylases in fine (
      • Spector R
      • Mock DM.
      Biotin transport and metabolism in the central nervous system.
      ).

      5. Conclusion

      These data suggest that high doses of biotin may impact disease׳s progression and improve clinical sequelae in primary and secondary progressive MS. They rely on a case reports series and need to be confirmed. Two multi-centric double-blind placebo-controlled trials are currently underway.

      Conflicts of interest

      Frédéric Sedel is currently CEO and shareholder of medDay pharmaceuticals. Other authors have no conflict of interest related to this study. This study received no funding.

      Acknowledgments

      We thank Dr. Kathleen Zackowski (Kennedy Krieger Institute/Johns Hopkins School of Medicine, Baltimore, USA) for the blinded review of patients videos.

      Appendix A. Supplementary materials

      References

        • Ballhausen D
        • Mittaz L
        • Boulat O
        • Bonafé L
        • Braissant O.
        Evidence for catabolic pathway of propionate metabolism in CNS: expression pattern of methylmalonyl-CoA mutase and propionyl-CoA carboxylase alpha-subunit in developing and adult rat brain.
        Neuroscience. 2009; 64: 578-587
        • Chakraborty G
        • Ledeen R.
        Fatty acid synthesizing enzymes intrinsic to myelin.
        Brain Res Mol Brain Res. 2003; 112: 46-52
        • Compston A
        • Coles A.
        Multiple sclerosis.
        Lancet. 2008; 372: 1502-1517
        • Confavreux C
        • Vukusic S
        • Moreau T
        • Adeleine P.
        Relapses and progression of disability in multiple sclerosis.
        N Engl J Med. 2000; 343: 1430-1438
        • Goodman AD
        • Brown TR
        • Krupp LB
        • Schapiro RT
        • Schwid SR
        • Cohen R
        • et al.
        Sustained-release oral fampridine in multiple sclerosis: a randomised, double-blind, controlled trial.
        Lancet. 2009; 373: 732-738
        • Hassel B.
        Carboxylation and anaplerosis in neurons and glia.
        Mol Neurobiol. 2000; 22: 21-40
        • Hauser SL
        • Chan JR
        • Oksenberg JR.
        Multiple sclerosis: prospects and promise.
        Ann Neurol. 2013; 74: 317-327
        • Lublin FD
        • Reingold SC
        • Cohen JA
        • Cutter GR
        • Sørensen PS
        • Thompson AJ
        • et al.
        Defining the clinical course of multiple sclerosis: the 2013 revisions.
        Neurology. 2014; 83: 278-286
        • Luessi F
        • Siffrin V
        • Zipp F.
        Neurodegeneration in multiple sclerosis: novel treatment strategies.
        Expert Rev Neurother. 2012; 12: 1061-1076
        • Noseworthy JH
        • Lucchinetti C
        • Rodriguez M
        • Weinshenker BG.
        Multiple sclerosis.
        N Engl J Med. 2000; 343: 938-952
        • Polman CH
        • Reingold SC
        • Banwell B
        • Clanet M
        • Cohen JA
        • Filippi M
        • et al.
        Diagnostic criteria for multiple sclerosis: 2010 revisions to the McDonald criteria.
        Ann Neurol. 2011; 69: 292-302
        • Quarles RH
        • Wendy B
        • Macklin WB.
        Myelin formation, structure and biochemistry.
        in: Brady S Siegel G Albers RW Basic neurochemistry: molecular, cellular and medical aspects. Elsevier, Inc., 2006: 51-71
        • Rinholm JE
        • Hamilton NB
        • Kessaris N
        • Richardson WD
        • Bergersen LH
        • Attwell D.
        Regulation of oligodendrocyte development and myelination by glucose and lactate.
        J Neurosci. 2011; 31: 538-548
        • Rosser DA
        • Cousens SN
        • Murdoch IE
        • Fitzke FW
        • Laidlaw DA.
        How sensitive to clinical change are ETDRS logMAR visual acuity measurements?.
        Investig Ophthalmol Visual Sci. 2003; 44: 3278-3281
        • Sanchez-Abarca LI
        • Tabernero A
        • Medina JM.
        Oligodendrocytes use lactate as a source of energy and as a precursor of lipids.
        Glia. 2001; 36: 321-329
        • Schwid SR
        • Goodman AD
        • McDermott MP
        • Bever CF
        • Cook SD.
        Quantitative functional measures in MS: what is a reliable change?.
        Neurology. 2002; 58: 1294-1296
        • Sedel F
        • Challe G
        • Vignal C
        • Assouad R
        • Bellanger A
        • Galanaud D.
        A novel biotin sensitive leukodystrophy.
        J Inherit Metab Dis. 2011; 34: S267
        • Spector R
        • Mock D.
        Biotin transport through the blood-brain barrier.
        J Neurochem. 1987; 48: 400-404
        • Spector R
        • Mock DM.
        Biotin transport and metabolism in the central nervous system.
        Neurochem Res. 1988; 13: 213-219
        • Stys PK
        • Zamponi GW
        • van Minnen J
        • Geurts JJ.
        Will the real multiple sclerosis please stand up?.
        Nat Rev Neurosci. 2012; 13: 507-514
        • Tabarki B
        • Al-Shafi S
        • Al-Shahwan S
        • Azmat Z
        • Al-Hashem A
        • Al-Adwani N
        • et al.
        Biotin-responsive basal ganglia disease revisited: clinical, radiologic, and genetic findings.
        Neurology. 2013; 80: 261-267
        • Tansey FA
        • Thampy KG
        • Cammer W.
        Acetyl-CoA carboxylase in rat brain. II. Immunocytochemical localization.
        Brain Res. 1988; 471: 131-138
        • Tong L.
        Structure and function of biotin-dependent carboxylases.
        Cell Mol Life Sci. 2013; 70: 863-891
        • Wang KS
        • Kearns GL
        • Mock DM.
        The clearance and metabolism of biotin administered intravenously to pigs in tracer and physiologic amounts is much more rapid than previously appreciated.
        J Nutr. 2001; 131: 1271-1278
        • Witte ME
        • Mahad DJ
        • Lassmann H
        • van Horssen J.
        Mitochondrial dysfunction contributes to neurodegeneration in multiple sclerosis.
        Trends Mol Med. 2013; 20: 179-187
        • Zempleni J
        • Mock DM.
        Bioavailability of biotin given orally to humans in pharmacologic doses.
        Am J Clin Nutr. 1999; 69: 504-508