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For personal use. Only reproduce with permission from The Lancet Publishing Group. THE LANCET Neurology Vol 1 July 2002 http://neurology.thelancet.com 142 Newsdesk A new drug has the potential to remove amyloid by binding to serum amyloid P component (SAP), a protein that makes amyloid fibrils resistant to degradation. “The low molecular weight drug changes the conformation of SAP so that it is very rapidly cleared from the circulation by the liver. If the drug can promote regression of amyloid deposits in humans, it should be readily applicable not only in systemic amyloidosis, but also in Alzheimer’s disease and type 2 diabetes,” comments lead author Mark Pepys (Royal Free and University Hospital Medical School, London, UK). Pepys and colleagues identified a specific inhibitor of SAP using a high- throughput assay against immobilised amyloid- fibrils. The low molecular weight compound was then dimerised to improve SAP-binding potency. The resulting drug, CPHPC, blocks ligand- binding sites on individual SAP protomers, preventing it from attaching to amyloid, and also crosslinks pairs of SAP molecules, leading to their rapid clearance by the liver. Infusion of CPHPC for 48 h in patients with systemic amyloidosis caused rapid and consistent depletion of circulating SAP in all seven patients. The patients with the most severe amyloidosis still showed a plasma SAP concentration below 25% of its original level 20 days after CPHPC infusion was stopped, suggesting, says Pepys, “that even a brief infusion of CPHPC had substantially depeleted the amyloid- associated SAP pool in the tissues.” Other results confirmed that the drug had substantially removed SAP from amyloid. Finally, the group carried out a longer-term open-label study in 19 patients, who were treated with 30–40 mg of CPHPC daily for 1 to 10 months. Most patients remained clinically stable during the treatment, despite all having end-stage disease that had not responded to other therapy (Nature 2002; 417: 254–59). “This study goes a long way to proving the concept that dissociating SAP from amyloid deposits can make them accessible to the body’s normal removal mechanisms”, comments Leslie Iversen (Wolfson Centre for Age Related Diseases, King’s College, London, UK) in an accompanying editorial (Nature 2002; 417: 232–33). In the current trial, the next phase will be to stop treatment after 6 or 12 months. “When plasma SAP returns to normal, indicating that SAP has fully re- equilibrated between the blood and amyloid pools, it will be possible to re- examine the patients using SAP scintigraphy to determine whether prolonged CPHPC treatment has actually promoted regression of amyloid deposit”, explains Pepys. A preliminary study of CPHPC in a small number of patients with Alzheimer’s disease is also about to start, in collaboration with Martin Rossor (UCL Institute of Neurology, London, UK). “We will examine drug tolerability and its effects on SAP, A, tau, and other markers in the CSF, whilst monitoring cognitive function and brain changes using quantitative MRI imaging”, reports Pepys. Kathryn Senior Drug with potential to clear amyloid US researchers have discovered a peptide that could help neurons to regenerate after CNS injury. It could be an “effective therapeutic agent in conditions characterised by failure of axonal regeneration”, such as spinal-cord injury, brain trauma, stroke, and multiple sclerosis, the investigators suggest. “Previous work has shown that white matter of the brain contains a protein, called Nogo, that is capable of limiting axon growth through a Nogo receptor on axons”, says lead researcher Stephen Strittmatter (Yale University, New Haven, CT, USA). A 66 amino acid residue (Nogo-66) within the molecule is responsible for preventing axonal regrowth. In the present study, Strittmatter and colleagues tested the efficacy of Nogo receptor antagonists, derived from fragments of Nogo-66, in rats with mid-thoracic spinal cord hemisection. They found that intrathecal administration of the antagonist NEP1 40 caused sig- nificant axonal sprouting and functional recovery (Nature 2002; 417: 547–51). “Therapeutically, this might have large implications”, says Strittmatter. “However, a number of steps remain. Optimisation of the Nogo receptor antagonist and assays for toxicity must still be performed in animals before it would be appropriate to consider a clinical trial.” Karim Fouad (University of Alberta, Canada) comments that these results are “very exciting”. However, he urged caution when speculating about the potential therapeutic effects of Nogo inhibition. “The role of Nogo in the human CNS is still unknown, and undesired side-effects of facilitated axonal sprouting and growth might occur.” Future studies using knockout or transgenic animal models, as well as long-term studies, will be essential to resolve these issues, he notes. Fouad adds that Nogo is just one of several obstacles preventing axonal regeneration after spinal-cord injury, and it is likely that a combination of therapies could be needed to treat spinal-cord damage effectively. These might include cellular grafts to bridge the lesion site, such as Schwann cells, olfactory ensheathing cells, or stem cells; application of neurotrophic factors to enhance axonal survival and growth; and degradation of chon- droitin sulphate proteoglycans with chondroitinase ABC (see The Lancet Neurology 2002; 1: 78). “Combina- tions with bridging techniques will definitely be required for treating severe or even anatomically complete spinal-cord injuries”, says Fouad, “since the neutralisation of Nogo by itself will not be sufficient to allow axonal growth through scar tissue and the lesion site”. Helen Frankish Peptide promotes axonal regrowth

Drug with potential to clear amyloid

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For personal use. Only reproduce with permission from The Lancet Publishing Group.

THE LANCET Neurology Vol 1 July 2002 http://neurology.thelancet.com142

Newsdesk

A new drug has the potential to removeamyloid by binding to serum amyloid Pcomponent (SAP), a protein that makesamyloid fibrils resistant to degradation.“The low molecular weight drugchanges the conformation of SAP sothat it is very rapidly cleared from thecirculation by the liver. If the drug canpromote regression of amyloid depositsin humans, it should be readilyapplicable not only in systemicamyloidosis, but also in Alzheimer’sdisease and type 2 diabetes,” comments

lead author Mark Pepys (Royal Freeand University Hospital MedicalSchool, London, UK).

Pepys and colleagues identified aspecific inhibitor of SAP using a high-throughput assay against immobilisedamyloid-� fibrils. The low molecularweight compound was then dimerisedto improve SAP-binding potency. Theresulting drug, CPHPC, blocks ligand-binding sites on individual SAPprotomers, preventing it from attachingto amyloid, and also crosslinks pairs of

SAP molecules, leading to their rapidclearance by the liver. Infusion ofCPHPC for 48 h in patients withsystemic amyloidosis caused rapid andconsistent depletion of circulating SAPin all seven patients. The patients withthe most severe amyloidosis stillshowed a plasma SAP concentrationbelow 25% of its original level 20 daysafter CPHPC infusion was stopped,suggesting, says Pepys, “that even abrief infusion of CPHPC hadsubstantially depeleted the amyloid-associated SAP pool in the tissues.”

Other results confirmed that thedrug had substantially removed SAPfrom amyloid. Finally, the groupcarried out a longer-term open-labelstudy in 19 patients, who were treatedwith 30–40 mg of CPHPC daily for 1 to10 months. Most patients remainedclinically stable during the treatment,despite all having end-stage disease thathad not responded to other therapy(Nature 2002; 417: 254–59).

“This study goes a long way toproving the concept that dissociatingSAP from amyloid deposits can makethem accessible to the body’s normalremoval mechanisms”, commentsLeslie Iversen (Wolfson Centre for AgeRelated Diseases, King’s College,London, UK) in an accompanyingeditorial (Nature 2002; 417: 232–33). Inthe current trial, the next phase will beto stop treatment after 6 or 12 months.“When plasma SAP returns to normal,indicating that SAP has fully re-equilibrated between the blood andamyloid pools, it will be possible to re-examine the patients using SAPscintigraphy to determine whetherprolonged CPHPC treatment hasactually promoted regression ofamyloid deposit”, explains Pepys.

A preliminary study of CPHPC in asmall number of patients withAlzheimer’s disease is also about tostart, in collaboration with MartinRossor (UCL Institute of Neurology,London, UK). “We will examine drugtolerability and its effects on SAP, A�,tau, and other markers in the CSF,whilst monitoring cognitive functionand brain changes using quantitativeMRI imaging”, reports Pepys.Kathryn Senior

Drug with potential to clear amyloid

US researchers have discovered apeptide that could help neurons toregenerate after CNS injury. It couldbe an “effective therapeutic agent inconditions characterised by failure of axonal regeneration”, such asspinal-cord injury, brain trauma,stroke, and multiple sclerosis, theinvestigators suggest.

“Previous work has shown that white matter of the braincontains a protein, called Nogo, thatis capable of limiting axon growththrough a Nogo receptor on axons”,says lead researcher StephenStrittmatter (Yale University, NewHaven, CT, USA). A 66 amino acid residue (Nogo-66) within the molecule is responsible forpreventing axonal regrowth. In thepresent study, Strittmatter andcolleagues tested the efficacy ofNogo receptor antagonists, derivedfrom fragments of Nogo-66, in ratswith mid-thoracic spinal cord hemisection. They found thatintrathecal administration of theantagonist NEP1 40 caused sig-nificant axonal sprouting andfunctional recovery (Nature 2002;417: 547–51).

“Therapeutically, this might havelarge implications”, says Strittmatter.“However, a number of stepsremain. Optimisation of the Nogoreceptor antagonist and assays for toxicity must still be performedin animals before it would be appropriate to consider a clinical trial.”

Karim Fouad (University ofAlberta, Canada) comments thatthese results are “very exciting”.However, he urged caution whenspeculating about the potentialtherapeutic effects of Nogoinhibition. “The role of Nogo in thehuman CNS is still unknown, andundesired side-effects of facilitatedaxonal sprouting and growth mightoccur.” Future studies usingknockout or transgenic animalmodels, as well as long-term studies,will be essential to resolve theseissues, he notes.

Fouad adds that Nogo is just oneof several obstacles preventingaxonal regeneration after spinal-cordinjury, and it is likely that acombination of therapies could beneeded to treat spinal-cord damageeffectively. These might includecellular grafts to bridge the lesionsite, such as Schwann cells, olfactoryensheathing cells, or stem cells;application of neurotrophic factorsto enhance axonal survival andgrowth; and degradation of chon-droitin sulphate proteoglycans withchondroitinase ABC (see The LancetNeurology 2002; 1: 78). “Combina-tions with bridging techniques willdefinitely be required for treatingsevere or even anatomically completespinal-cord injuries”, says Fouad,“since the neutralisation of Nogo byitself will not be sufficient to allowaxonal growth through scar tissueand the lesion site”.Helen Frankish

Peptide promotes axonal regrowth