- Email: [email protected]
G.P.130
Abstracts / Neuromuscular Disorders 24 (2014) 791–924 report on an arterial spin labeling (ASL) MRI study of the same boys, in whom brain perfusion was measured non-invasively. T1-weighted and pseudo continuous ASL scans were obtained on a 3T MR scanner from 27 boys with DMD and 20 age-matched healthy control boys (ages 8–18 years). The mean whole brain grey matter (GM) perfusion was quantified per individual, and voxelwise group analysis was performed to locate regions with different cerebral blood flow (CBF) using cluster-based multiple comparison correction. Group comparisons were made between DMD and controls using a t-test, and between DMD_Dp140+ and DMD_Dp140 and controls using ANOVA. DMD boys had significantly lower mean whole brain GM CBF (41.7 ± 7.8 versus 49.9 ± 8.7 mL/100 g/min in controls (p < 0.001)). No correlation with age or GM volume was found. Regional analysis of the perfusion showed lower CBF widespread throughout the GM in DMD boys compared to controls. DMD_Dp140- mean whole brain GM CBF was lower compared to controls, but differences in whole brain GM CBF were not significant between DMD_Dp140+ and controls or between DMD_Dp140+ and DMD_Dp140. DMD_Dp140 did show larger regions with more extensive CBF reductions compared to DMD_Dp140+. It is known that in muscle dystrophin interacts with neuronal nitric oxide synthase (nNOS) which plays a key role in vasoconstriction and dilation. Our findings further substantiate the vascular involvement in DMD and show that not only brain structure is altered, but also the CBF, which is frequently considered a proxy for glucose and oxygen delivery. http://dx.doi:10.1016/j.nmd.2014.06.157
G.P.128 Upper limb muscle MRI fat–water quantification and clinical functional correlation in non-ambulant Duchenne muscular dystrophy V. Ricotti 1, R.B. Evans 2, C.D.J. Sinclair 2, J.M. Morrow 2, J.W. Butler 1, R.L. Janiczek 3, M.G. Hanna 2, P.M. Matthews 3, T.A. Yousry 2, F. Muntoni 1, J.S. Thornton 2 1 UCL Institute of Child Health and Great Ormond Street Hospital, London, UK; 2 UCL Institute of Neurology, London, 3 UK; GlaxoSmithKline, London, UK Outcome measures in Duchenne muscular dystrophy (DMD) currently rely on invasive or functional but not very sensitive tests. Muscle MRI could offer a valuable alternative. A reliable evaluation of the upper limb could permit inclusion of non-ambulant DMD individuals not able to perform functional tests such as the 6-min walk test. 16 DMD boys and 10 age gender and age matched controls were included in this on-going study. Fat–water quantification was used to compare fat-infiltration in the forearm muscles of non-ambulant DMD patients and healthy controls. DMD individuals underwent 3T 3-point Dixon imaging of the dominant forearm to measure muscle fat-fraction (f.f.). Ten forearm muscles were segmented and mean f.f. and cross-sectional area recorded. Patients also underwent physiotherapy evaluation: Performance of Upper Limb (PUL) module; wrist extension myometry; and EK2 performance of tasks in daily life interview. Time to loss of ambulation (LOA) was recorded. To date, 8 non-ambulant DMD patients (mean age: 13.6 years; mean duration of non-ambulation 20 months) and 10 volunteers (mean age:14.6 years) have been imaged. Overall mean f.f (±SD) in DMD was significantly higher than healthy controls: (13.4 ± 11% vs 0.8 ± 0.1%, p = 0.002). Total mean area was reduced in DMD (1735 ± 331 mm2) compared to healthy controls (2398 ± 821 mm2, p = 0.04). Overall f.f. correlated with LOA (Spearman r = 0.8, p = 0.02) and wrist extension myometry (r = 0.8, p = 0.004) and less strongly with PUL (r = 0.6, p = 0.09) and with EK2 (r = 0.6, p = 0.09). Final analysis will include longitudinal change at one-year follow up. Initial results support MRI fat quantification as a potential objective biomarker to monitor disease progression in the upper limb in
DMD, showing significant correlation between putative pathological indices and clinically meaningful endpoints.
839 MRI
http://dx.doi:10.1016/j.nmd.2014.06.158
G.P.129 Cine-MRI as a new tool to evaluate diaphragmatic dysfunction in Pompe disease S.C. Wens 1, P. Ciet 2, A. Perez-Rovira 2, K. Logie 3, E. Salamon 3, P. Wielopolski 2, M. Bruijne 2, M.E. Kruijshaar 1, H.W. Tiddens 2, N.A.M. van der Beek 1, P.A. van Doorn 1, A.T. van der Ploeg 1 1 Erasmus MC University Medical Center, Center for Lysosomal and Metabolic Diseases, Rotterdam, Netherlands; 2 Erasmus MC University Medical Center, Rotterdam, Netherlands; 3 Erasmus MC – Sophia Children’s Hospital University Medical Center, Rotterdam, Netherlands Severe pulmonary dysfunction is a serious threat to patients with Pompe disease, a treatable metabolic neuromuscular disorder caused by lysosomal acid a-glucosidase deficiency. This pulmonary dysfunction - which is particularly severe in the supine position – is mainly caused by diaphragmatic weakness. Standard pulmonary function tests provide only indirect information about diaphragmatic function, and they do not supply information about chest mechanics in detail. We therefore used cine-MRI to examine the dynamic performance of respiratory muscles, and compared these data with the results of simultaneously performed pulmonary function testing. Ten adult Pompe patients and six healthy volunteers participated. We performed two static scans at end-inspiration and end-expiration to evaluate lung anatomy and lung volumes. Three dynamic 3D acquisitions were performed to investigate overall respiratory dynamics. Using manual segmentation of the acquired images, three length ratios were calculated. Diaphragmatic displacement manifests itself by motion in cranio-caudal direction, while movement in antero-posterior and left–right directions reflects chest wall displacement. Pompe patients have a significantly reduced cranio-caudal length ratio compared to healthy volunteers (p < 0.001), indicating impaired diaphragmatic displacement. This ratio correlated strongly with forced vital capacity in supine position (r = 0.88), and severity of ’postural drop’ (FVCsitting–FVCsupine; r = 0.89). The difference in antero-posterior length ratio was less pronounced (p = 0.04), while there was no difference in left–right length ratio (p = 0.1). Cine-MRI is a promising technique to assess chest mechanics and to visualize the severely impaired diaphragmatic function in Pompe patients. It may allow us to detect respiratory weakness at an earlier stage. Early diagnosis of diaphragmatic weakness may prove important in deciding when to start enzyme treatment.
http://dx.doi:10.1016/j.nmd.2014.06.159
G.P.130 Tracking the brain in myotonic dystrophy: A 5-year longitudinal neuroimaging and neuropsychological follow-up study C. Merkel 1, M. Minnerop 2, S. Roeske 3, H. Gaertner 2, J.C. SchoeneBake 4, S. Adler 1, J.A. Witt 1, C. Anspach 1, C. Schneider-Gold 5, R.C. Betz 6, C. Helmstaedter 1, M. Tittgemeyer 7, K. Amunts 2, T. Klockgether 1, B. Weber 4, C. Kornblum 1 1 University Hospital of Bonn, Bonn, Germany; 2 Research Centre Juelich GmbH, Juelich, Germany; 3 German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany; 4 Life & Brain Research Center, Bonn, Germany; 5 Ruhr University Bochum, St Josef Hospital, Bochum, Germany; 6 University of Bonn, Bonn, Germany; 7 Max Planck Institute for Neurological Research, Cologne, Germany
840
Abstracts / Neuromuscular Disorders 24 (2014) 791–924
It is unknown whether brain affection in myotonic dystrophy type 1 (DM1) and 2 (DM2) is due to neurodevelopmental defects, neurodegeneration or both. Longitudinal imaging studies are missing to date. We performed a longitudinal study to compare changes in cognitive functioning and brain morphology including 16 DM1 (m/f: 6/ 10, age at baseline 42.48 ± 6.46 years/y, disease duration/DD 13.4 ± 7.5 y), 16 DM2 patients (m/f: 9/7, age 48.49 ± 8.36 y, DD 11.4 ± 9.1 y), and 17 healthy controls (m/f: 9/8, age 50.54 ± 9.78 y). At baseline and 5.45 ± 0.41 y follow-up all subjects underwent neurological and neuropsychological (NP) examinations and 3T-brain magnetic resonance imaging using the identical hard- and software. Diffusion tensor imaging (DTI, Tract Based Spatial Statistics) was conducted to analyse white matter (WM) affection with respect to fractional anisotropy (FA), axial, radial, and mean diffusivity. We used 2-sample t-tests (TT) for group comparisons between patients and controls, and paired t-tests (PT) for longitudinal analyses within each group (p < 0.05, corrected for multiple comparisons). DTI group comparisons (TT) showed almost identical FA reduction patterns at baseline and follow-up. In DM1 compared to controls, FA was reduced along the corpus callosum (CC), association (AF), and projection fibres. In DM2, we found mild affection of CC and forceps minor, and minor additional changes at follow-up. At follow-up, the number of voxels showing FA reduction was particularly increased in DM1 indicating progressive WM disintegrity. Analysing longitudinal differences within each group (PT), we found significant FA changes only in DM1 affecting frontal and posterior AF. These findings were accompanied by a decline in motor tasks in DM1, and a mild deterioration of NP performance in DM1 more than DM2 over time. Our data indicate a mild -however significant-progress of WM affection predominantly in DM1 which might point towards a neurodegenerative component of WM changes. http://dx.doi:10.1016/j.nmd.2014.06.160
DMI + MYASTHENIA + CHANNEL DISEASES G.P.131 Cell membrane integrity in myotonic dystrophy type 1: Implications for therapy A. Gonza´lez-Barriga 1, J. Kranzen 1, H.J.E. Croes 1, W.J.A. van den Broek 1, B.G.M. van Engelen 2, J.C.T. van Deutekom 3, B. Wieringa 1, S.A.M. Mulders 3, D.G. Wansink 1 1 Radboud Institute for Molecular Life Sciences, Nijmegen, Netherlands; 2 Donders Centre for Neuroscience, Radboud University Medical Center, Nijmegen, Netherlands; 3 Prosensa Therapeutics B.V., Leiden, Netherlands Myotonic Dystrophy type 1 (DM1) is a multisystemic disease caused by toxic RNA from a DMPK gene carrying an expanded (CTG*CAG) n repeat. Promising strategies for treatment of DM1 patients are currently being tested. These include antisense oligonucleotides and drugs for elimination of expanded RNA or prevention of aberrant binding of this RNA to RNP proteins. A significant hurdle for preclinical development along these lines is efficient systemic delivery of compounds across endothelial and muscle and brain cell membranes. It has been reported that DM1 patients show elevated levels of muscular markers in their serum and that splicing of dystrophin, an essential protein for muscle membrane structure, is abnormal. Therefore, we studied cell membrane integrity in DM1 mouse models commonly used for preclinical testing. We found that membranes in skeletal muscle, heart and brain were impermeable to Evans Blue Dye. Creatine kinase levels in serum were similar to those in wild type mice and expression of dystrophin protein was unaffected. Also in patient muscle biopsies cell surface distribution of dystrophin was normal. Combined, our findings
show that cells in DM1 tissues have a normal functional membrane, which forms a barrier that must be overcome in future work towards effective drug delivery. http://dx.doi:10.1016/j.nmd.2014.06.161
G.P.132 Pre-clinical development of peptide-conjugated antisense oligonucleotides for myotonic dystrophy type 1 (DM1) S.A.M. Mulders 1, B. Aguilera 1, A. Gonzalez-Barriga 1, J. van de Giessen 1, W.J.A. van den Broek 2, D.G. Wansink 2, J.C.T. van Deutekom 1, N.A. Datson 1 1 Prosensa Therapeutics, Leiden, Netherlands; 2 Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, Nijmegen, Netherlands Myotonic dystrophy type 1 (DM1) is a multisystemic neuromuscular 0 disorder caused by an expanded CTG repeat in the 3 UTR of the DM protein kinase (DMPK) gene, resulting in formation of toxic RNA aggregates that interfere with RNA splicing and dysregulate normal cell function. RNA-modulation by antisense oligonucleotides (AONs) represents an interesting therapeutic approach for DM1 and is currently in pre-clinical development. We have previously obtained molecular proof-of-concept for a panel of AONs that target the CUG expansion and result in efficient knockdown of toxic RNA in DM1 patient myoblasts with different repeat expansion lengths and in cultured muscle cells derived from DM500 mice. To facilitate systemic AON delivery and uptake, we used a 7-amino acid linear muscle targeting peptide (PP08) and conjugated this to different CUG-targeting AONs. We have shown that these peptide-conjugated AONs are well tolerated and do not result in complement activation in human and monkey plasma or induce cytokine release in human whole blood in vitro safety assays. Subcutaneous administration of peptide-conjugated AONs in different DM1 mouse models (DM500, HSALR) resulted in enhanced tissue PK levels in several tissues of relevance for DM1 such as skeletal muscle and brain, indicating that the peptide-AON displayed efficient tissue uptake and was even able to pass the blood–brain-barrier. The higher tissue levels were accompanied by an increased knockdown of mutant RNA compared to non-conjugated AONs. Besides inducing a significant RNA knockdown, peptide-conjugated AONs resulted in a mild but statistically significant reduction of myotonia in gastrocnemius and tibialis muscles of HSALR mice, as determined by EMG analysis. These data demonstrate that peptide-AONs targeting the CUG-repeat have potential in a multisystemic therapeutic approach for DM1. http://dx.doi:10.1016/j.nmd.2014.06.162
G.P.133 Ankle muscle weakness but not balance trouble account for walking disability in patients with myotonic dystrophy type 1 G. Ollivier 1, V. Decostre 1, I. Ledoux 1, L. Servais 1, T. Gidaro 1, A. Behin 2, T. Stojkovic 2, B. Eymard 2, G. Bassez 3, J.Y. Hogrel 1 1 Institut De Myologie, Paris, France; 2 Universite´ Pierre et Marie Curie, Assistance Publique-Hoˆpitaux de Paris, Hoˆpital La Pitie´ Salpetrie`re, Institut De Myologie, Paris, France; 3 Department of Pathology, Henri Mondor University Hospital, Creteil, France Myotonic dystrophy type 1 (DM1) is an autosomal dominant disease for which treatments are being developed. There is a need to define reliable and reproducible criteria to evaluate neuromuscular function in order to assess their effects. The main aim of our study consists of a follow-up of the natural history of DM1 patients over 3 years. Here, baseline values for the 6-min walk distance (6MWD), the lower limb
G.P.128 Upper limb muscle MRI fat–water quantification and clinical functional correlation in non-ambulant Duchenne muscular dystrophy V. Ricotti 1, R.B. Evans 2, C.D.J. Sinclair 2, J.M. Morrow 2, J.W. Butler 1, R.L. Janiczek 3, M.G. Hanna 2, P.M. Matthews 3, T.A. Yousry 2, F. Muntoni 1, J.S. Thornton 2 1 UCL Institute of Child Health and Great Ormond Street Hospital, London, UK; 2 UCL Institute of Neurology, London, 3 UK; GlaxoSmithKline, London, UK Outcome measures in Duchenne muscular dystrophy (DMD) currently rely on invasive or functional but not very sensitive tests. Muscle MRI could offer a valuable alternative. A reliable evaluation of the upper limb could permit inclusion of non-ambulant DMD individuals not able to perform functional tests such as the 6-min walk test. 16 DMD boys and 10 age gender and age matched controls were included in this on-going study. Fat–water quantification was used to compare fat-infiltration in the forearm muscles of non-ambulant DMD patients and healthy controls. DMD individuals underwent 3T 3-point Dixon imaging of the dominant forearm to measure muscle fat-fraction (f.f.). Ten forearm muscles were segmented and mean f.f. and cross-sectional area recorded. Patients also underwent physiotherapy evaluation: Performance of Upper Limb (PUL) module; wrist extension myometry; and EK2 performance of tasks in daily life interview. Time to loss of ambulation (LOA) was recorded. To date, 8 non-ambulant DMD patients (mean age: 13.6 years; mean duration of non-ambulation 20 months) and 10 volunteers (mean age:14.6 years) have been imaged. Overall mean f.f (±SD) in DMD was significantly higher than healthy controls: (13.4 ± 11% vs 0.8 ± 0.1%, p = 0.002). Total mean area was reduced in DMD (1735 ± 331 mm2) compared to healthy controls (2398 ± 821 mm2, p = 0.04). Overall f.f. correlated with LOA (Spearman r = 0.8, p = 0.02) and wrist extension myometry (r = 0.8, p = 0.004) and less strongly with PUL (r = 0.6, p = 0.09) and with EK2 (r = 0.6, p = 0.09). Final analysis will include longitudinal change at one-year follow up. Initial results support MRI fat quantification as a potential objective biomarker to monitor disease progression in the upper limb in
DMD, showing significant correlation between putative pathological indices and clinically meaningful endpoints.
839 MRI
http://dx.doi:10.1016/j.nmd.2014.06.158
G.P.129 Cine-MRI as a new tool to evaluate diaphragmatic dysfunction in Pompe disease S.C. Wens 1, P. Ciet 2, A. Perez-Rovira 2, K. Logie 3, E. Salamon 3, P. Wielopolski 2, M. Bruijne 2, M.E. Kruijshaar 1, H.W. Tiddens 2, N.A.M. van der Beek 1, P.A. van Doorn 1, A.T. van der Ploeg 1 1 Erasmus MC University Medical Center, Center for Lysosomal and Metabolic Diseases, Rotterdam, Netherlands; 2 Erasmus MC University Medical Center, Rotterdam, Netherlands; 3 Erasmus MC – Sophia Children’s Hospital University Medical Center, Rotterdam, Netherlands Severe pulmonary dysfunction is a serious threat to patients with Pompe disease, a treatable metabolic neuromuscular disorder caused by lysosomal acid a-glucosidase deficiency. This pulmonary dysfunction - which is particularly severe in the supine position – is mainly caused by diaphragmatic weakness. Standard pulmonary function tests provide only indirect information about diaphragmatic function, and they do not supply information about chest mechanics in detail. We therefore used cine-MRI to examine the dynamic performance of respiratory muscles, and compared these data with the results of simultaneously performed pulmonary function testing. Ten adult Pompe patients and six healthy volunteers participated. We performed two static scans at end-inspiration and end-expiration to evaluate lung anatomy and lung volumes. Three dynamic 3D acquisitions were performed to investigate overall respiratory dynamics. Using manual segmentation of the acquired images, three length ratios were calculated. Diaphragmatic displacement manifests itself by motion in cranio-caudal direction, while movement in antero-posterior and left–right directions reflects chest wall displacement. Pompe patients have a significantly reduced cranio-caudal length ratio compared to healthy volunteers (p < 0.001), indicating impaired diaphragmatic displacement. This ratio correlated strongly with forced vital capacity in supine position (r = 0.88), and severity of ’postural drop’ (FVCsitting–FVCsupine; r = 0.89). The difference in antero-posterior length ratio was less pronounced (p = 0.04), while there was no difference in left–right length ratio (p = 0.1). Cine-MRI is a promising technique to assess chest mechanics and to visualize the severely impaired diaphragmatic function in Pompe patients. It may allow us to detect respiratory weakness at an earlier stage. Early diagnosis of diaphragmatic weakness may prove important in deciding when to start enzyme treatment.
http://dx.doi:10.1016/j.nmd.2014.06.159
G.P.130 Tracking the brain in myotonic dystrophy: A 5-year longitudinal neuroimaging and neuropsychological follow-up study C. Merkel 1, M. Minnerop 2, S. Roeske 3, H. Gaertner 2, J.C. SchoeneBake 4, S. Adler 1, J.A. Witt 1, C. Anspach 1, C. Schneider-Gold 5, R.C. Betz 6, C. Helmstaedter 1, M. Tittgemeyer 7, K. Amunts 2, T. Klockgether 1, B. Weber 4, C. Kornblum 1 1 University Hospital of Bonn, Bonn, Germany; 2 Research Centre Juelich GmbH, Juelich, Germany; 3 German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany; 4 Life & Brain Research Center, Bonn, Germany; 5 Ruhr University Bochum, St Josef Hospital, Bochum, Germany; 6 University of Bonn, Bonn, Germany; 7 Max Planck Institute for Neurological Research, Cologne, Germany
840
Abstracts / Neuromuscular Disorders 24 (2014) 791–924
It is unknown whether brain affection in myotonic dystrophy type 1 (DM1) and 2 (DM2) is due to neurodevelopmental defects, neurodegeneration or both. Longitudinal imaging studies are missing to date. We performed a longitudinal study to compare changes in cognitive functioning and brain morphology including 16 DM1 (m/f: 6/ 10, age at baseline 42.48 ± 6.46 years/y, disease duration/DD 13.4 ± 7.5 y), 16 DM2 patients (m/f: 9/7, age 48.49 ± 8.36 y, DD 11.4 ± 9.1 y), and 17 healthy controls (m/f: 9/8, age 50.54 ± 9.78 y). At baseline and 5.45 ± 0.41 y follow-up all subjects underwent neurological and neuropsychological (NP) examinations and 3T-brain magnetic resonance imaging using the identical hard- and software. Diffusion tensor imaging (DTI, Tract Based Spatial Statistics) was conducted to analyse white matter (WM) affection with respect to fractional anisotropy (FA), axial, radial, and mean diffusivity. We used 2-sample t-tests (TT) for group comparisons between patients and controls, and paired t-tests (PT) for longitudinal analyses within each group (p < 0.05, corrected for multiple comparisons). DTI group comparisons (TT) showed almost identical FA reduction patterns at baseline and follow-up. In DM1 compared to controls, FA was reduced along the corpus callosum (CC), association (AF), and projection fibres. In DM2, we found mild affection of CC and forceps minor, and minor additional changes at follow-up. At follow-up, the number of voxels showing FA reduction was particularly increased in DM1 indicating progressive WM disintegrity. Analysing longitudinal differences within each group (PT), we found significant FA changes only in DM1 affecting frontal and posterior AF. These findings were accompanied by a decline in motor tasks in DM1, and a mild deterioration of NP performance in DM1 more than DM2 over time. Our data indicate a mild -however significant-progress of WM affection predominantly in DM1 which might point towards a neurodegenerative component of WM changes. http://dx.doi:10.1016/j.nmd.2014.06.160
DMI + MYASTHENIA + CHANNEL DISEASES G.P.131 Cell membrane integrity in myotonic dystrophy type 1: Implications for therapy A. Gonza´lez-Barriga 1, J. Kranzen 1, H.J.E. Croes 1, W.J.A. van den Broek 1, B.G.M. van Engelen 2, J.C.T. van Deutekom 3, B. Wieringa 1, S.A.M. Mulders 3, D.G. Wansink 1 1 Radboud Institute for Molecular Life Sciences, Nijmegen, Netherlands; 2 Donders Centre for Neuroscience, Radboud University Medical Center, Nijmegen, Netherlands; 3 Prosensa Therapeutics B.V., Leiden, Netherlands Myotonic Dystrophy type 1 (DM1) is a multisystemic disease caused by toxic RNA from a DMPK gene carrying an expanded (CTG*CAG) n repeat. Promising strategies for treatment of DM1 patients are currently being tested. These include antisense oligonucleotides and drugs for elimination of expanded RNA or prevention of aberrant binding of this RNA to RNP proteins. A significant hurdle for preclinical development along these lines is efficient systemic delivery of compounds across endothelial and muscle and brain cell membranes. It has been reported that DM1 patients show elevated levels of muscular markers in their serum and that splicing of dystrophin, an essential protein for muscle membrane structure, is abnormal. Therefore, we studied cell membrane integrity in DM1 mouse models commonly used for preclinical testing. We found that membranes in skeletal muscle, heart and brain were impermeable to Evans Blue Dye. Creatine kinase levels in serum were similar to those in wild type mice and expression of dystrophin protein was unaffected. Also in patient muscle biopsies cell surface distribution of dystrophin was normal. Combined, our findings
show that cells in DM1 tissues have a normal functional membrane, which forms a barrier that must be overcome in future work towards effective drug delivery. http://dx.doi:10.1016/j.nmd.2014.06.161
G.P.132 Pre-clinical development of peptide-conjugated antisense oligonucleotides for myotonic dystrophy type 1 (DM1) S.A.M. Mulders 1, B. Aguilera 1, A. Gonzalez-Barriga 1, J. van de Giessen 1, W.J.A. van den Broek 2, D.G. Wansink 2, J.C.T. van Deutekom 1, N.A. Datson 1 1 Prosensa Therapeutics, Leiden, Netherlands; 2 Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, Nijmegen, Netherlands Myotonic dystrophy type 1 (DM1) is a multisystemic neuromuscular 0 disorder caused by an expanded CTG repeat in the 3 UTR of the DM protein kinase (DMPK) gene, resulting in formation of toxic RNA aggregates that interfere with RNA splicing and dysregulate normal cell function. RNA-modulation by antisense oligonucleotides (AONs) represents an interesting therapeutic approach for DM1 and is currently in pre-clinical development. We have previously obtained molecular proof-of-concept for a panel of AONs that target the CUG expansion and result in efficient knockdown of toxic RNA in DM1 patient myoblasts with different repeat expansion lengths and in cultured muscle cells derived from DM500 mice. To facilitate systemic AON delivery and uptake, we used a 7-amino acid linear muscle targeting peptide (PP08) and conjugated this to different CUG-targeting AONs. We have shown that these peptide-conjugated AONs are well tolerated and do not result in complement activation in human and monkey plasma or induce cytokine release in human whole blood in vitro safety assays. Subcutaneous administration of peptide-conjugated AONs in different DM1 mouse models (DM500, HSALR) resulted in enhanced tissue PK levels in several tissues of relevance for DM1 such as skeletal muscle and brain, indicating that the peptide-AON displayed efficient tissue uptake and was even able to pass the blood–brain-barrier. The higher tissue levels were accompanied by an increased knockdown of mutant RNA compared to non-conjugated AONs. Besides inducing a significant RNA knockdown, peptide-conjugated AONs resulted in a mild but statistically significant reduction of myotonia in gastrocnemius and tibialis muscles of HSALR mice, as determined by EMG analysis. These data demonstrate that peptide-AONs targeting the CUG-repeat have potential in a multisystemic therapeutic approach for DM1. http://dx.doi:10.1016/j.nmd.2014.06.162
G.P.133 Ankle muscle weakness but not balance trouble account for walking disability in patients with myotonic dystrophy type 1 G. Ollivier 1, V. Decostre 1, I. Ledoux 1, L. Servais 1, T. Gidaro 1, A. Behin 2, T. Stojkovic 2, B. Eymard 2, G. Bassez 3, J.Y. Hogrel 1 1 Institut De Myologie, Paris, France; 2 Universite´ Pierre et Marie Curie, Assistance Publique-Hoˆpitaux de Paris, Hoˆpital La Pitie´ Salpetrie`re, Institut De Myologie, Paris, France; 3 Department of Pathology, Henri Mondor University Hospital, Creteil, France Myotonic dystrophy type 1 (DM1) is an autosomal dominant disease for which treatments are being developed. There is a need to define reliable and reproducible criteria to evaluate neuromuscular function in order to assess their effects. The main aim of our study consists of a follow-up of the natural history of DM1 patients over 3 years. Here, baseline values for the 6-min walk distance (6MWD), the lower limb