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mTOR Inhibitors in Children: Current Indications and Future Directions in Neurology

  • Pediatric Neurology (WE Kaufmann, Section Editor)
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Abstract

The mammalian/mechanistic target of rapamycin (mTOR) pathway is a key signaling pathway that has been implicated in genetic epilepsy syndromes, neurodegenerative diseases, and conditions associated with autism spectrum disorder and cognitive impairment. The mTOR pathway has become an exciting treatment target for these various disorders, with mTOR inhibitors such as rapamycin being studied for their potential therapeutic applications. In particular, tuberous sclerosis complex (TSC) is a genetic disorder resulting from overactivation of the mTOR pathway, and pharmacologic therapy with mTOR inhibitors has emerged as a viable treatment option for the systemic manifestations of the disease. In this review, we discuss the approved indications for mTOR inhibitors in TSC, the potential future applications of mTOR inhibitors in TSC and other neurological conditions, and the safety considerations applicable to mTOR therapy in the pediatric population.

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References

Papers of particular interest, published recently, have been highlighted as: • Of importance •• Of major importance

  1. Rogeveen, J. The journal of Jacob Roggeveen, ed. A. Sharp. 1970: Oxford University Press.

  2. Vezina C, Kudelski A, Sehgal SN. Rapamycin (AY-22,989), a new antifungal antibiotic. I. Taxonomy of the producing streptomycete and isolation of the active principle. J Antibiot (Tokyo). 1975;28(10):721–6.

    Article  CAS  Google Scholar 

  3. Sehgal SN, Baker H, Vezina C. Rapamycin (AY-22,989), a new antifungal antibiotic. II. Fermentation, isolation and characterization. J Antibiot (Tokyo). 1975;28(10):727–32.

    Article  CAS  Google Scholar 

  4. Martel RR, Klicius J, Galet S. Inhibition of the immune response by rapamycin, a new antifungal antibiotic. Can J Physiol Pharmacol. 1977;55(1):48–51.

    Article  CAS  PubMed  Google Scholar 

  5. Houchens DP, Ovejera AA, Riblet SM, et al. Human brain tumor xenografts in nude mice as a chemotherapy model. Eur J Cancer Clin Oncol. 1983;19(6):799–805.

    Article  CAS  PubMed  Google Scholar 

  6. Heitman J, Movva NR, Hall MN. Targets for cell cycle arrest by the immunosuppressant rapamycin in yeast. Science. 1991;253(5022):905–9.

    Article  CAS  PubMed  Google Scholar 

  7. Sabatini DM, Erdjument-Bromage H, Lui M, et al. RAFT1: a mammalian protein that binds to FKBP12 in a rapamycin-dependent fashion and is homologous to yeast TORs. Cell. 1994;78(1):35–43.

    Article  CAS  PubMed  Google Scholar 

  8. Brown EJ, Albers MW, Shin TB, et al. A mammalian protein targeted by G1-arresting rapamycin-receptor complex. Nature. 1994;369(6483):756–8.

    Article  CAS  PubMed  Google Scholar 

  9. Zoncu R, Efeyan A, Sabatini DM. mTOR: from growth signal integration to cancer, diabetes and ageing. Nat Rev Mol Cell Biol. 2011;12(1):21–35.

    Article  CAS  PubMed  Google Scholar 

  10. Lipton JO, Sahin M. The neurology of mTOR. Neuron. 2014;84(2):275–91.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  11. Osborne JP, Fryer A, Webb D. Epidemiology of tuberous sclerosis. Ann N Y Acad Sci. 1991;615:125–7.

    Article  CAS  PubMed  Google Scholar 

  12. Bourneville DM. Sclerose tubereuse des circonvolutions cerebrales: idiotie et epilepsie hemiplegique. Arch Neurol. 1880;1:81–91.

    Google Scholar 

  13. Northrup H, Krueger DA, G. International Tuberous Sclerosis Complex Consensus. Tuberous sclerosis complex diagnostic criteria update: recommendations of the 2012 International Tuberous Sclerosis Complex Consensus Conference. Pediatr Neurol. 2013;49(4):243–54.

    Article  PubMed  PubMed Central  Google Scholar 

  14. Crino PB, Nathanson KL, Henske EP. The tuberous sclerosis complex. N Engl J Med. 2006;355(13):1345–56.

    Article  CAS  PubMed  Google Scholar 

  15. Chu-Shore CJ, Major P, Camposano S, et al. The natural history of epilepsy in tuberous sclerosis complex. Epilepsia. 2010;51(7):1236–41.

    Article  PubMed  Google Scholar 

  16. van Slegtenhorst M, de Hoogt R, Hermans C, et al. Identification of the tuberous sclerosis gene TSC1 on chromosome 9q34. Science. 1997;277(5327):805–8.

    Article  PubMed  Google Scholar 

  17. European Chromosome 16 Tuberous Sclerosis Consortium. Identification and characterization of the tuberous sclerosis gene on chromosome 16. Cell. 1993;75(7):1305–15.

    Article  Google Scholar 

  18. Tee AR, Fingar DC, Manning BD, et al. Tuberous sclerosis complex-1 and -2 gene products function together to inhibit mammalian target of rapamycin (mTOR)-mediated downstream signaling. Proc Natl Acad Sci U S A. 2002;99(21):13571–6.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  19. Laplante M, Sabatini DM. mTOR signaling in growth control and disease. Cell. 2012;149(2):274–93.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  20. Inoki K, Li Y, Xu T, et al. Rheb GTPase is a direct target of TSC2 GAP activity and regulates mTOR signaling. Genes Dev. 2003;17(15):1829–34.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  21. Sarbassov DD, Ali SM, Sengupta S, et al. Prolonged rapamycin treatment inhibits mTORC2 assembly and Akt/PKB. Mol Cell. 2006;22(2):159–68.

    Article  CAS  PubMed  Google Scholar 

  22. Goh S, Butler W, Thiele EA. Subependymal giant cell tumors in tuberous sclerosis complex. Neurology. 2004;63(8):1457–61.

    Article  PubMed  Google Scholar 

  23. Roth J, Roach ES, Bartels U, et al. Subependymal giant cell astrocytoma: diagnosis, screening, and treatment. Recommendations from the International Tuberous Sclerosis Complex Consensus Conference. Pediatr Neurol. 2012;49(6):439–44.

    Article  Google Scholar 

  24. Adriaensen ME, Schaefer-Prokop CM, Stijnen T, et al. Prevalence of subependymal giant cell tumors in patients with tuberous sclerosis and a review of the literature. Eur J Neurol. 2009;16(6):691–6.

    Article  CAS  PubMed  Google Scholar 

  25. de Ribaupierre S, Dorfmuller G, Bulteau C, et al. Subependymal giant-cell astrocytomas in pediatric tuberous sclerosis disease: when should we operate? Neurosurgery. 2007;60(1):83–9. discussion 89–90.

    Article  PubMed  Google Scholar 

  26. Franz DN, Leonard J, Tudor C, et al. Rapamycin causes regression of astrocytomas in tuberous sclerosis complex. Ann Neurol. 2006;59(3):490–8.

    Article  CAS  PubMed  Google Scholar 

  27. Koenig MK, Butler IJ, Northrup H. Regression of subependymal giant cell astrocytoma with rapamycin in tuberous sclerosis complex. J Child Neurol. 2008;23(10):1238–9.

    Article  PubMed  PubMed Central  Google Scholar 

  28. Krueger DA, Care MM, Holland K, et al. Everolimus for subependymal giant-cell astrocytomas in tuberous sclerosis. N Engl J Med. 2010;363(19):1801–11.

    Article  CAS  PubMed  Google Scholar 

  29. •• Franz DN, Belousova E, Sparagana S, et al. Efficacy and safety of everolimus for subependymal giant cell astrocytomas associated with tuberous sclerosis complex (EXIST-1): a multicentre, randomised, placebo-controlled phase 3 trial. Lancet. 2013;381(9861):125–32. Randomized, placebo-controlled trial demonstrating efficacy of everolimus in the treatment of subependymal giant cell astrocytomas in TSC.

    Article  CAS  PubMed  Google Scholar 

  30. Franz DN, Belousova E, Sparagana S, et al. Everolimus for subependymal giant cell astrocytoma in patients with tuberous sclerosis complex: 2-year open-label extension of the randomised EXIST-1 study. Lancet Oncol. 2014;15(13):1513–20.

    Article  CAS  PubMed  Google Scholar 

  31. Krueger DA, Northrup H. Tuberous sclerosis complex surveillance and management: recommendations of the 2012 International Tuberous Sclerosis Complex Consensus Conference. Pediatr Neurol. 2013;49(4):255–65.

    Article  PubMed  PubMed Central  Google Scholar 

  32. Bissler JJ, Kingswood JC. Renal angiomyolipomata. Kidney Int. 2004;66(3):924–34.

    Article  PubMed  Google Scholar 

  33. Rakowski SK, Winterkorn EB, Paul E, et al. Renal manifestations of tuberous sclerosis complex: incidence, prognosis, and predictive factors. Kidney Int. 2006;70(10):1777–82.

    Article  CAS  PubMed  Google Scholar 

  34. Shepherd CW, Gomez MR, Lie JT, et al. Causes of death in patients with tuberous sclerosis. Mayo Clin Proc. 1991;66(8):792–6.

    Article  CAS  PubMed  Google Scholar 

  35. Ewalt DH, Diamond N, Rees C, et al. Long-term outcome of transcatheter embolization of renal angiomyolipomas due to tuberous sclerosis complex. J Urol. 2005;174(5):1764–6.

    Article  PubMed  Google Scholar 

  36. Moss J, Avila NA, Barnes PM, et al. Prevalence and clinical characteristics of lymphangioleiomyomatosis (LAM) in patients with tuberous sclerosis complex. Am J Respir Crit Care Med. 2001;164(4):669–71.

    Article  CAS  PubMed  Google Scholar 

  37. Costello LC, Hartman TE, Ryu JH. High frequency of pulmonary lymphangioleiomyomatosis in women with tuberous sclerosis complex. Mayo Clin Proc. 2000;75(6):591–4.

    Article  CAS  PubMed  Google Scholar 

  38. Bissler JJ, McCormack FX, Young LR, et al. Sirolimus for angiomyolipoma in tuberous sclerosis complex or lymphangioleiomyomatosis. N Engl J Med. 2008;358(2):140–51.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  39. •• Bissler JJ, Kingswood JC, Radzikowska E, et al. Everolimus for angiomyolipoma associated with tuberous sclerosis complex or sporadic lymphangioleiomyomatosis (EXIST-2): a multicentre, randomised, double-blind, placebo-controlled trial. Lancet. 2013;381(9869):817–24. Randomized, placebo-controlled trial demonstrating efficacy of everolimus in the treatment of renal angiomyolipomas in TSC.

    Article  CAS  PubMed  Google Scholar 

  40. Haemel AK, O’Brian AL, Teng JM. Topical rapamycin: a novel approach to facial angiofibromas in tuberous sclerosis. Arch Dermatol. 2010;146(7):715–8.

    Article  PubMed  Google Scholar 

  41. Song MG, Park KB, Lee ES. Resurfacing of facial angiofibromas in tuberous sclerosis patients using CO2 laser with flashscanner. Dermatol Surg. 1999;25(12):970–3.

    Article  CAS  PubMed  Google Scholar 

  42. Boixeda P, Sanchez-Miralles E, Azana JM, et al. CO2, argon, and pulsed dye laser treatment of angiofibromas. J Dermatol Surg Oncol. 1994;20(12):808–12.

    Article  CAS  PubMed  Google Scholar 

  43. Hofbauer GF, Marcollo-Pini A, Corsenca A, et al. The mTOR inhibitor rapamycin significantly improves facial angiofibroma lesions in a patient with tuberous sclerosis. Br J Dermatol. 2008;159(2):473–5.

    Article  CAS  PubMed  Google Scholar 

  44. Koenig MK, Hebert AA, Roberson J, et al. Topical rapamycin therapy to alleviate the cutaneous manifestations of tuberous sclerosis complex: a double-blind, randomized, controlled trial to evaluate the safety and efficacy of topically applied rapamycin. Drugs R D. 2012;12(3):121–6.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  45. Curatolo P, Bombardieri R, Jozwiak S. Tuberous sclerosis. Lancet. 2008;372(9639):657–68.

    Article  CAS  PubMed  Google Scholar 

  46. Weiner HL, Carlson C, Ridgway EB, et al. Epilepsy surgery in young children with tuberous sclerosis: results of a novel approach. Pediatrics. 2006;117(5):1494–502.

    Article  PubMed  Google Scholar 

  47. Ma TS, Elliott RE, Ruppe V, et al. Electrocorticographic evidence of perituberal cortex epileptogenicity in tuberous sclerosis complex. J Neurosurg Pediatr. 2012;10(5):376–82.

    Article  PubMed  Google Scholar 

  48. Ruppe V, Dilsiz P, Reiss CS, et al. Developmental brain abnormalities in tuberous sclerosis complex: a comparative tissue analysis of cortical tubers and perituberal cortex. Epilepsia. 2014;55(4):539–50.

    Article  CAS  PubMed  Google Scholar 

  49. Zeng LH, Xu L, Gutmann DH, et al. Rapamycin prevents epilepsy in a mouse model of tuberous sclerosis complex. Ann Neurol. 2008;63(4):444–53.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  50. •• Krueger DA, Wilfong AA, Holland-Bouley K, et al. Everolimus treatment of refractory epilepsy in tuberous sclerosis complex. Ann Neurol. 2013;74(5):679–87. Case series describing the efficacy of everolimus for refractory epilepsy in TSC. The findings in this trial allowed for the development of a randomized, placebo-controlled trial of everolimus in TSC.

    Article  CAS  PubMed  Google Scholar 

  51. •• French JA, Lawson JA, Yapici Z, et al. Adjunctive everolimus therapy for treatment-resistant focal-onset seizures associated with tuberous sclerosis (EXIST-3): a phase 3, randomised, double-blind, placebo-controlled study. Lancet. 2016. doi:10.1016/S0140-6736(16)31419-2. A randomized, placebo-controlled trial of everolimus for refractory epilepsy in TSC, which demonstrated superiority of everolimus versus placebo.

    Google Scholar 

  52. Ehninger D, Silva AJ. Rapamycin for treating tuberous sclerosis and autism spectrum disorders. Trends Mol Med. 2011;17(2):78–87.

    Article  CAS  PubMed  Google Scholar 

  53. Numis AL, Major P, Montenegro MA, et al. Identification of risk factors for autism spectrum disorders in tuberous sclerosis complex. Neurology. 2011;76(11):981–7.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  54. Vignoli A, La Briola F, Peron A, et al. Autism spectrum disorder in tuberous sclerosis complex: searching for risk markers. Orphanet J Rare Dis. 2015;10:154.

    Article  PubMed  PubMed Central  Google Scholar 

  55. Richards C, Jones C, Groves L, et al. Prevalence of autism spectrum disorder phenomenology in genetic disorders: a systematic review and meta-analysis. Lancet Psychiatry. 2015;2(10):909–16.

    Article  PubMed  Google Scholar 

  56. Jeste SS, Varcin KJ, Hellemann GS, et al. Symptom profiles of autism spectrum disorder in tuberous sclerosis complex. Neurology. 2016;87(8):766–72.

    Article  PubMed  Google Scholar 

  57. • Ehninger D, Han S, Shilyansky C, et al. Reversal of learning deficits in a Tsc2+/− mouse model of tuberous sclerosis. Nat Med. 2008;14(8):843–8. Study in an animal model of TSC showing that affected mice demonstrate deficits in learning and memory, and that brief treatment with rapamycin may ameliorate the cognitive dysfunction and behavioral deficits seen in affected mice. This study shows promise for similar applications of rapamycin derivatives in humans, and the potential for the treatment of cognitive and behavioral symptoms in affected patients.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  58. Sato A, Kasai S, Kobayashi T, et al. Rapamycin reverses impaired social interaction in mouse models of tuberous sclerosis complex. Nat Commun. 2012;3:1292.

    Article  PubMed  PubMed Central  Google Scholar 

  59. Poduri A, Evrony GD, Cai X, et al. Somatic activation of AKT3 causes hemispheric developmental brain malformations. Neuron. 2012;74(1):41–8.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  60. Orlova KA, Parker WE, Heuer GG, et al. STRADalpha deficiency results in aberrant mTORC1 signaling during corticogenesis in humans and mice. J Clin Invest. 2010;120(5):1591–602.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  61. Lim JS, Kim WI, Kang HC, et al. Brain somatic mutations in MTOR cause focal cortical dysplasia type II leading to intractable epilepsy. Nat Med. 2015;21(4):395–400.

    Article  CAS  PubMed  Google Scholar 

  62. Lee JH, Huynh M, Silhavy JL, et al. De novo somatic mutations in components of the PI3K-AKT3-mTOR pathway cause hemimegalencephaly. Nat Genet. 2012;44(8):941–5.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  63. Cheung KM, Lam CW, Chan YK, et al. Atypical focal cortical dysplasia in a patient with Cowden syndrome. Hong Kong Med J. 2014;20(2):165–7.

    Article  CAS  PubMed  Google Scholar 

  64. Baulac S, Ishida S, Marsan E, et al. Familial focal epilepsy with focal cortical dysplasia due to DEPDC5 mutations. Ann Neurol. 2015;77(4):675–83.

    Article  CAS  PubMed  Google Scholar 

  65. Ishida S, Picard F, Rudolf G, et al. Mutations of DEPDC5 cause autosomal dominant focal epilepsies. Nat Genet. 2013;45(5):552–5.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  66. Hernandez RN, Feinberg RL, Vaurio R, et al. Autism spectrum disorder in fragile X syndrome: a longitudinal evaluation. Am J Med Genet A. 2009;149a(6):1125–37.

    Article  PubMed  PubMed Central  Google Scholar 

  67. Gross C, Hoffmann A, Bassell GJ, et al. Therapeutic strategies in fragile X syndrome: from bench to bedside and back. Neurotherapeutics. 2015;12(3):584–608.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  68. Hagerman PJ, Stafstrom CE. Origins of epilepsy in fragile X syndrome. Epilepsy Curr. 2009;9(4):108–12.

    Article  PubMed  PubMed Central  Google Scholar 

  69. Darnell JC, Van Driesche SJ, Zhang C, et al. FMRP stalls ribosomal translocation on mRNAs linked to synaptic function and autism. Cell. 2011;146(2):247–61.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  70. • Hoeffer CA, Klann E. mTOR signaling: at the crossroads of plasticity, memory and disease. Trends Neurosci. 2010;33(2):67–75. Study demonstrating increased phosphorylation of the mTOR substrates S6K1 and eIF4E in brain tissue and peripheral blood lymphocytes of patients with fragile X syndrome (FXS). This study provides a mechanistic link between FXS and disorders such as TSC and also provides new therapeutic targets for FXS.

    Article  CAS  PubMed  Google Scholar 

  71. Verkerk AJ, Pieretti M, Sutcliffe JS, et al. Identification of a gene (FMR-1) containing a CGG repeat coincident with a breakpoint cluster region exhibiting length variation in fragile X syndrome. Cell. 1991;65(5):905–14.

    Article  CAS  PubMed  Google Scholar 

  72. Sharma A, Hoeffer CA, Takayasu Y, et al. Dysregulation of mTOR signaling in fragile X syndrome. J Neurosci. 2010;30(2):694–702.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  73. Hoeffer CA, Sanchez E, Hagerman RJ, et al. Altered mTOR signaling and enhanced CYFIP2 expression levels in subjects with fragile X syndrome. Genes Brain Behav. 2012;11(3):332–41.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  74. Querfurth HW, LaFerla FM. Alzheimer’s disease. N Engl J Med. 2010;362(4):329–44.

    Article  CAS  PubMed  Google Scholar 

  75. Li X, Alafuzoff I, Soininen H, et al. Levels of mTOR and its downstream targets 4E-BP1, eEF2, and eEF2 kinase in relationships with tau in Alzheimer’s disease brain. FEBS J. 2005;272(16):4211–20.

    Article  CAS  PubMed  Google Scholar 

  76. Davies SW, Turmaine M, Cozens BA, et al. Formation of neuronal intranuclear inclusions underlies the neurological dysfunction in mice transgenic for the HD mutation. Cell. 1997;90(3):537–48.

    Article  CAS  PubMed  Google Scholar 

  77. Ravikumar B, Vacher C, Berger Z, et al. Inhibition of mTOR induces autophagy and reduces toxicity of polyglutamine expansions in fly and mouse models of Huntington disease. Nat Genet. 2004;36(6):585–95.

    Article  CAS  PubMed  Google Scholar 

  78. Williams A, Sarkar S, Cuddon P, et al. Novel targets for Huntington’s disease in an mTOR-independent autophagy pathway. Nat Chem Biol. 2008;4(5):295–305.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  79. Rensing N, Han L, Wong M. Intermittent dosing of rapamycin maintains antiepileptogenic effects in a mouse model of tuberous sclerosis complex. Epilepsia. 2015;56(7):1088–97.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

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Correspondence to Michael Wong.

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Anna Jeong declares no conflict of interest.

Michael Wong is a site PI for a Novartis-sponsored clinical trial on the effects of everolimus on refractory seizures in tuberous sclerosis patients.

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This article does not contain any studies with human or animal subjects performed by any of the authors.

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This article is part of the Topical Collection on Pediatric Neurology

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Jeong, A., Wong, M. mTOR Inhibitors in Children: Current Indications and Future Directions in Neurology. Curr Neurol Neurosci Rep 16, 102 (2016). https://doi.org/10.1007/s11910-016-0708-8

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