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Update on safety and efficacy of lentiviral hematopoietic stem cell gene therapy (HSC-GT) for metachromatic leukodystrophy (MLD)
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e u r o p e a n j o u r n a l o f p a e d i a t r i c n e u r o l o g y 2 1 ( 2 0 1 7 ) e 1 9 ee 2 1
encephalopathies it is important to test amino acid profiles during the episodes. Therapy is available, and in metabolic crises special attention should be paid to the fluid and electrolyte balance to avoid hyponatremia.
http://dx.doi.org/10.1016/j.ejpn.2017.04.985 OC40 Update on safety and efficacy of lentiviral hematopoietic stem cell gene therapy (HSC-GT) for metachromatic leukodystrophy (MLD) F. Fumagalli, V. Calbi, A. Zambon, F. Ciotti, L. Lorioli, M. Sessa, M. Sarzana, S. Canale, G. Antonioli, S. Medaglini, U. Del Carro, A. Quattrini, C. Baldoli, S. Martino, C. Di Serio, F. Ciceri, L. Naldini, M.G. Natali Sora, A. Biffi, A. Aiuti. Department of Neurology, San Raffaele Telethon Institute for Gene Therapy (SR-TIGET), Unit of Pediatric Immunohematology and BMT Program, IRCCS San Raffaele Scientific Institute, Milan, Italy Objective: MLD is a fatal demyelinating lysosomal disease due to Arylsulfatase A (ARSA) deficiency with no approved treatment. This is an updated ad hoc analysis of the first 21 early onset MLD patients treated with experimental HSC-GT. Methods: GT consists of autologous HSC engineered with a lentiviral vector encoding ARSA cDNA infused after Busulfan conditioning. Nine patients were Late Infantile (LI) and 12 were Early Juvenile (EJ), the latter including 1 patient classified as intermediate. Median age at treatment was 39.3 months (7.7e141.7); 8 LI and 4 EJ were treated before onset of overt disease ma manifestations. We compared the clinical outcomes to those in a cohort of 28 untreated MLD patients followed in a natural history (NH) study (16 LI and 12 EJ). Results: Nineteen patients are alive with median follow up (FU) of 29 mo (12.2e67.5); 2 EJ patients treated after onset of symptoms died due to disease progression. There was no treatment-related mortality, no evidence of abnormal clonal proliferation, and no treatment-related adverse events. We observed per persistent engraftment of gene corrected cells with a marked increase of ARSA act activity in peripheral blood and CSF. LI patients treated before symptom onset showed better motor and cognitive performance compared to the NH cohort. Prevention of progressive de demyelination on brain MRI, stabilization of nerve conduction velocities (NCV), and maturation of brainstem auditory evoked potentials (BAEP) were observed in the majority of LI subjects. Stabilization or improvement in NCV and BAEP were often preceded by a p period of deterioration in those parameters following GT. The 4 pre-symptomatic EJ patients show normal neurodevelopment to date. Conclusion: We confirm that HSC-GT continues to be well tolerated. Pre-symptomatic LI pts show a sustained clinical benefit. Prolonged FU will provide additional information on the long-term safety, clinical efficacy and factors predictive of outcome following HSC-GT.
http://dx.doi.org/10.1016/j.ejpn.2017.04.986 OC41 Development of treatment for Pelizaeus-Merzbacher disease: Drug-repositioning approach targeting a novel cellular pathology K. Inoue, H. Li, Y. Numata, H. Saya, Y. Goto. Dept. Mental Retardation and Birth Defect Research, National Institute of Neuroscience, NCNP, Kodaira, Japan Objective: Pelizaeus-Merzbacher disease (PMD) is the most common, but incurable inherited hypomyelinating leukodystrophy caused by various mutations in the PLP1 gene, which encodes a
myelin membrane protein. PLP1 amino acid substitutions often cause severe form of PMD. It has been suggested that the proapoptotic branch of unfolded protein response (UPR) triggered by accumulation of the mutant PLP1 in endoplasmic reticulum (ER) is the major cellular mechanism underlying the oligodendrocyte cell death. However, attenuation of this pathway doesn't ameliorate the cellular phenotypes, suggesting an involvement of other disease mechanisms. We have recently found that the mutant PLP1 also interfere with intracellular transport of other normal membrane and secretary proteins, possibly affecting the cellular homeostasis. We thus hypothesized that the mutant PLP1-induced dysfunction of secretary pathway may serve as another cellular mechanism for PMD and the drugs that can enhance the transport of secretary and membrane proteins may rescue the cellular phenotype caused by mutant PLP1. Methods: To identify such drugs, we have established a screening system using HeLa cells transiently co-expressing mutant PLP1 and secretable-form luciferase reporter. We screened a library of 1400 existing medicine, so that our findings are immediately applicable to the clinical study. We next tested if the selected compounds can also rescue the abnormal intracellular localization of KDEL receptor that is normally present in Golgi apparatus but is mislocalized in ER when co-expressed with mutant PLP1. Results: Using these screening systems, we have identified 20 compounds that can correct the reduced intracellular transport of normal secretary and membrane proteins. Of these, 6 were confirmed to correct the intracellular localization of KDEL receptor. Furthermore, two compounds successfully extended the life span of the PMD animal model, msd mouse. Conclusion: These findings suggest that these compounds may serve as novel candidate drugs for PMD with PLP1 point mutations.
http://dx.doi.org/10.1016/j.ejpn.2017.04.987
OC42 Osteogenic transdifferentiation as ideal in vivo model for inherited hypomyelination with spondylometaphyseal dysplasia (H-SMD) Ferdy Cayamia,b,c, Noriko Miyakea,b,c, Dimitra Michaa,b,c, Joanna Crawforda,b,c, Alex Conanta,b,c, Zoya Kingsburya,b,c, Annette Bleya,b,c, Andreas Hahna,b,c, Deborah Sivala,b,c, Shihoko Kimura-Ohbaa,b,c, Andrea Superti-Furgaa,b,c, Karen W. Grippa,b,c, Dorothy Bulasa,b,c, Ryan J. Tafta,b,c, Keiichi Ozonoa,b,c, Naomichi Matsumotoa,b,c, Bernd A. Neubauera,b,c, Cas Simonsa,b,c, Adeline Vandervera,b,c, Nicole I. Wolfa,b,c. aDepartment of Child Neurology, VU University Medical Center, Amsterdam, The Netherlands. b Department of Clinical Genetics, VU University Medical Center, Amsterdam, The Netherlands. cCenter for Biomedical Research, Diponegoro University, Semarang, Indonesia Objective: To identify the responsible gene for hypomyelination with spondylometaphyseal dysplasia (H-SMD) and to prove pathogenicity of selected mutations using transdifferentiated osteoblasts. Methods: In a collaborative effort, we identified 12 patients with similar clinical, radiological and neuroradiological characteristics. They underwent comprehensive examination and genetic testing by Whole Exome Sequencing (WES). Patientderived fibroblasts were transdifferentiated to osteoblasts with human platelet lysate to investigate the expression of the target gene. Results: Twelve patients from 6 families, all male, presented between age 12e24 months with growth delay and delayed motor development. Bone X-rays were diagnostic for spondylometaphyseal dysplasia, brain MRI showed hypomyelination. Other
e u r o p e a n j o u r n a l o f p a e d i a t r i c n e u r o l o g y 2 1 ( 2 0 1 7 ) e 1 9 ee 2 1
encephalopathies it is important to test amino acid profiles during the episodes. Therapy is available, and in metabolic crises special attention should be paid to the fluid and electrolyte balance to avoid hyponatremia.
http://dx.doi.org/10.1016/j.ejpn.2017.04.985 OC40 Update on safety and efficacy of lentiviral hematopoietic stem cell gene therapy (HSC-GT) for metachromatic leukodystrophy (MLD) F. Fumagalli, V. Calbi, A. Zambon, F. Ciotti, L. Lorioli, M. Sessa, M. Sarzana, S. Canale, G. Antonioli, S. Medaglini, U. Del Carro, A. Quattrini, C. Baldoli, S. Martino, C. Di Serio, F. Ciceri, L. Naldini, M.G. Natali Sora, A. Biffi, A. Aiuti. Department of Neurology, San Raffaele Telethon Institute for Gene Therapy (SR-TIGET), Unit of Pediatric Immunohematology and BMT Program, IRCCS San Raffaele Scientific Institute, Milan, Italy Objective: MLD is a fatal demyelinating lysosomal disease due to Arylsulfatase A (ARSA) deficiency with no approved treatment. This is an updated ad hoc analysis of the first 21 early onset MLD patients treated with experimental HSC-GT. Methods: GT consists of autologous HSC engineered with a lentiviral vector encoding ARSA cDNA infused after Busulfan conditioning. Nine patients were Late Infantile (LI) and 12 were Early Juvenile (EJ), the latter including 1 patient classified as intermediate. Median age at treatment was 39.3 months (7.7e141.7); 8 LI and 4 EJ were treated before onset of overt disease ma manifestations. We compared the clinical outcomes to those in a cohort of 28 untreated MLD patients followed in a natural history (NH) study (16 LI and 12 EJ). Results: Nineteen patients are alive with median follow up (FU) of 29 mo (12.2e67.5); 2 EJ patients treated after onset of symptoms died due to disease progression. There was no treatment-related mortality, no evidence of abnormal clonal proliferation, and no treatment-related adverse events. We observed per persistent engraftment of gene corrected cells with a marked increase of ARSA act activity in peripheral blood and CSF. LI patients treated before symptom onset showed better motor and cognitive performance compared to the NH cohort. Prevention of progressive de demyelination on brain MRI, stabilization of nerve conduction velocities (NCV), and maturation of brainstem auditory evoked potentials (BAEP) were observed in the majority of LI subjects. Stabilization or improvement in NCV and BAEP were often preceded by a p period of deterioration in those parameters following GT. The 4 pre-symptomatic EJ patients show normal neurodevelopment to date. Conclusion: We confirm that HSC-GT continues to be well tolerated. Pre-symptomatic LI pts show a sustained clinical benefit. Prolonged FU will provide additional information on the long-term safety, clinical efficacy and factors predictive of outcome following HSC-GT.
http://dx.doi.org/10.1016/j.ejpn.2017.04.986 OC41 Development of treatment for Pelizaeus-Merzbacher disease: Drug-repositioning approach targeting a novel cellular pathology K. Inoue, H. Li, Y. Numata, H. Saya, Y. Goto. Dept. Mental Retardation and Birth Defect Research, National Institute of Neuroscience, NCNP, Kodaira, Japan Objective: Pelizaeus-Merzbacher disease (PMD) is the most common, but incurable inherited hypomyelinating leukodystrophy caused by various mutations in the PLP1 gene, which encodes a
myelin membrane protein. PLP1 amino acid substitutions often cause severe form of PMD. It has been suggested that the proapoptotic branch of unfolded protein response (UPR) triggered by accumulation of the mutant PLP1 in endoplasmic reticulum (ER) is the major cellular mechanism underlying the oligodendrocyte cell death. However, attenuation of this pathway doesn't ameliorate the cellular phenotypes, suggesting an involvement of other disease mechanisms. We have recently found that the mutant PLP1 also interfere with intracellular transport of other normal membrane and secretary proteins, possibly affecting the cellular homeostasis. We thus hypothesized that the mutant PLP1-induced dysfunction of secretary pathway may serve as another cellular mechanism for PMD and the drugs that can enhance the transport of secretary and membrane proteins may rescue the cellular phenotype caused by mutant PLP1. Methods: To identify such drugs, we have established a screening system using HeLa cells transiently co-expressing mutant PLP1 and secretable-form luciferase reporter. We screened a library of 1400 existing medicine, so that our findings are immediately applicable to the clinical study. We next tested if the selected compounds can also rescue the abnormal intracellular localization of KDEL receptor that is normally present in Golgi apparatus but is mislocalized in ER when co-expressed with mutant PLP1. Results: Using these screening systems, we have identified 20 compounds that can correct the reduced intracellular transport of normal secretary and membrane proteins. Of these, 6 were confirmed to correct the intracellular localization of KDEL receptor. Furthermore, two compounds successfully extended the life span of the PMD animal model, msd mouse. Conclusion: These findings suggest that these compounds may serve as novel candidate drugs for PMD with PLP1 point mutations.
http://dx.doi.org/10.1016/j.ejpn.2017.04.987
OC42 Osteogenic transdifferentiation as ideal in vivo model for inherited hypomyelination with spondylometaphyseal dysplasia (H-SMD) Ferdy Cayamia,b,c, Noriko Miyakea,b,c, Dimitra Michaa,b,c, Joanna Crawforda,b,c, Alex Conanta,b,c, Zoya Kingsburya,b,c, Annette Bleya,b,c, Andreas Hahna,b,c, Deborah Sivala,b,c, Shihoko Kimura-Ohbaa,b,c, Andrea Superti-Furgaa,b,c, Karen W. Grippa,b,c, Dorothy Bulasa,b,c, Ryan J. Tafta,b,c, Keiichi Ozonoa,b,c, Naomichi Matsumotoa,b,c, Bernd A. Neubauera,b,c, Cas Simonsa,b,c, Adeline Vandervera,b,c, Nicole I. Wolfa,b,c. aDepartment of Child Neurology, VU University Medical Center, Amsterdam, The Netherlands. b Department of Clinical Genetics, VU University Medical Center, Amsterdam, The Netherlands. cCenter for Biomedical Research, Diponegoro University, Semarang, Indonesia Objective: To identify the responsible gene for hypomyelination with spondylometaphyseal dysplasia (H-SMD) and to prove pathogenicity of selected mutations using transdifferentiated osteoblasts. Methods: In a collaborative effort, we identified 12 patients with similar clinical, radiological and neuroradiological characteristics. They underwent comprehensive examination and genetic testing by Whole Exome Sequencing (WES). Patientderived fibroblasts were transdifferentiated to osteoblasts with human platelet lysate to investigate the expression of the target gene. Results: Twelve patients from 6 families, all male, presented between age 12e24 months with growth delay and delayed motor development. Bone X-rays were diagnostic for spondylometaphyseal dysplasia, brain MRI showed hypomyelination. Other