Download Overview: Macrophage Sodium Channels

Cellular Therapies for the
Treatment of Multiple Sclerosis
Michael Carrithers, MD, PhD
Wlliam Middleton Veterans Affairs Hospital and the
University of Wisconsin, Madison
Disclosures
• Biogen-Idec (investigator-initiated study)
• TEVA
Overview
• Gaps in existing treatments and need
for repair strategies
• Oligodendrocyte precursor (OPC) cell
therapy
• Immune-mediated cell therapy
• Challenges for clinical translation
Timeline of Treatments
• 1993: Betaseron (first interferon trial
funded in 1980).
• 1996: Avonex and Copaxone (Copolymer 1
first developed in 1970’s).
• 2002: Rebif.
• 2004/2006: Tysabri (first animal study
published in 1992).
• 2010: Gilenya (FTY-720 developed for
transplant patients, 1996).
• 2013: DMF (Tecfidera).
Survival in MS: A randomized cohort study 21 years after the start of the pivotal IFN-1b trial
Objective: To examine the effects of interferon beta (IFN)-1b on all-cause mortality over 21
years in the cohort of 372 patients who participated in the pivotal randomized clinical trial
(RCT),
retaining (in the analysis) the original randomized treatment-assignments.
Results: After a median of 21.1 years from RCT enrollment, 98.4% (366 of 372) of patients were
identified, and, of these, 81 deaths were recorded (22.1% [81 of 366]). Patients originally
randomly assigned to IFN-1b 250 mcg showed a significant reduction in all-cause mortality over
the 21-year period compared with placebo (p 0.0173), with a hazard ratio of 0.532 (95%
confidence interval 0.314–0.902). The hazard rate of death at long-term follow-up by KaplanMeier estimates was reduced by 46.8% among IFN-1b 250 mcg–treated patients (46.0% among
IFN-1b 50 mcg–treated patients) compared with placebo. Baseline variables did not influence
the observed treatment effect.
Conclusions: There was a significant survival advantage in this cohort of patients receiving early
IFN-1b treatment at either dose compared with placebo. Near-complete ascertainment,
together with confirmatory findings from both active treatment groups, strengthens the
evidence for an IFN-1b benefit on all-cause mortality.
Neurology® 2012;78:1315–1322
Model for MS Immunopathogenesis
1. Peripheral activation of
autoreactive T-cells, with
encephalitogenic potential
2. Homing to the CNS
3. Migration across the BBB (via
CAM attachment and MMP)
4. Reactivation of T-cell via
autoantigen (i.e. MBP, MOG,
MAG) on APCs
5. Secretion of pro-inflammatory
cytokines
6. Antibody & complement cascade
7. Macrophage-mediated myelin
destruction and oligodendrocyte
death
8. Axonal degeneration
Noseworthy et al. 2000 NEJM 343:938
Therapeutic Strategies for Repair
• Pharmacological neuroprotection: growth
factors, channel blockers.
• Cell-based therapies:
– embryonic stem cells
– oligodendrocyte precursors
– mesenchymal stem cells
– immune-mediated repair
The Oligodendrocyte Lineage
Adult Neural
Stem Cells
What is the target for repair?
Demyelinated plaque
Potential outcomes
No Treatment:
Demyelinated axons susceptible to damage
Chronic inflammation produces toxic mediators
Demyelinated axons lack trophic support
Following treatment:
Remyelination
Neuroprotection
Chronic axonal death leads to increasing loss
of function and disability
Axonal loss
Remyelination
Remyelination will:
1. Restore conduction to demyelinated axons
2. Protect axons against subsequent injury and loss
How can remyelination be achieved with stem cells?
What is the experimental evidence of
exogenous cell therapy success?
Eight Weeks Later:
Eight Weeks Later
Can cells be transplanted at
different levels of the CNS?
Culture of CNP-EGFP oligospheres: label mature
oligodendrocyte and Schwann cells
Transplantation
Brain (corpus callosum, bilateral)
Spinal cord (thoracolumbar, dorsal column)
Shi mice
(n=14)
P0-1
P21
Histology
P120
Widespread migration of CNP-EGFP
cells in the shi brain
EGFP/MBP
Widespread CNP-EGFP grafts
in the shi spinal cord
dorsal
ventral
CNP-EGFP
CNP-EGFP
MBP
control cervical cord (same animal)
Merge
Propose
d Trial:
Asterias
OPC1
Challenges to OPC Transplant in MS
• Delivery to disseminated regions
• Remyelination requires intact axons
• Chronic inflammation within lesions and cell
survival
Immune-mediated Repair:
T Regulatory Cells and
Anti-inflammatory
Macrophages
Pharmacological vs Cell-based
Treatments
MS DMT’s
Wang et al., 2011
Current Treg Clinical Trials
Wang et al., 2011
Treg Therapy in MS
• Can they enhance existing treatments?
• Do they have a role in non-responders
to existing immune treatments?
• Is there a subset of Tregs that mediate
repair in addition to inflammatory cell
suppression?
Immune-mediated Repair:
Anti-inflammatory Macrophages
Axonal Degeneration: Acute and Chronic
Injury
Bjarmatar et al, 2001
Macrophage-Microglia in Axonal
Degeneration
Bjartmar, 2001
Stem Cell Studies in Experimental
Autoimmune Encephalomyelitis
(EAE)
• Embryonic and mesenchymal stem
cells improve clinical EAE outcomes.
• Capable of migration into the CNS.
• Differentiate into CD11b positive cells.
• Protection is likely mediated by
alternatively activated macrophages.
Immune-Mediated Repair: Macrophages
Murray & Wynn, 2011
Overview: Macrophage SCN5A Channel
• Identified as differentially expressed in immune-activated
human macrophages by microarray analysis.
• Human macrophages express intracellular, novel splice
variants of a sodium channel gene, SCN5A (NaV1.5).
• Macrophage SCN5A regulates endosomal function and
anti-inflammatory signaling pathways.
• The macrophage SCN5A splice variant is expressed in
human and primate macrophages.
Generation of Human Macrophage
NaV1.5 Transgenic Mice
Transfer of hSCN5A+ Macrophages into Mice
with Severe EAE Leads to Clinical Recovery
Transferred hSCN5A+ Macrophages
Home to Regions of Injury and Express
Anti-Inflammatory Markers
Macrophage-mediated Immune Repair of
the CNS
• Formation of nodules of phagocytic
cells may limit CNS tissue injury.
• hSCN5A-expressing macrophages may
be protective and useful in cell-based
treatments.
• Neuroprotective strategies that block
sodium channels may have proinflammatory effects.
Therapeutic Development
• Cytometric: Cell selection
• Genomic:
– Microarray expression analysis
– Promoter binding analysis
• Proteomic: Protein-protein interactions
• Broad Institute Connectivity Map (Cmap)
SCN5A Signaling Network
Lead Compound Identification
Cell-based Immune Therapies:
Advantages
• Cells can have multiple actions as
compared to pharmacologic
approaches.
• Transplants can be autologous.
• Less tumorigenic and fewer regulatory
issues as compared to stem cells.
Cell-based Therapies:
Challenges
• Safety/Donor rejection.
• Expansion of cells in vitro.
• Does the approach clearly demonstrate
enhanced efficacy?
• FDA IND review and approval.
• On-site GMP (Good Manufacturing Practice)
facilities.
• Patent issues/prior disclosures.
Acknowledgements
• Ian Duncan
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Elise Wojcik
Matthew Subramani
Kusha Rahgozar
Erik Wright
Casey Bresser
Alexis Jones
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VA Merit Award
Biogen-Idec
TEVA
NMSS
MMRRC/UC-Davis
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“The contents do not represent the
views of the Dept. of Veterans
Affairs or the United States
Government”