Immunosuppresion for SLE

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Immunosuppressants
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Very, very powerful Immunosuppressants available

• Non-Pharmacological
• Irradiation
• Plasmapheresis ? removal of
• autoantibodies in diseases like MG

• Pharmacological
• deplete T cells or B cells completely with
  anti-CD3
• or anti-CD20 antibodies
• chemotherapy
• calcineurin inhibitors, steroids

Problem Immunosuppression (infections)
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Side-Effects of Immunosuppressants

• General Side Effect Immunosuppression
• Reactivation of latent viral infections
• (e.g. herpes, varicella, CMV, PML)
• Bacterial and fungal infections
• Bone marrow suppression
• Increased risk of cancer

• Specific Side Effects
• Nephrotoxicity of the calcineurin inhibitors
• Metabolic changes with steroids
• cytokine release syndrome with anti-CD3 Ab

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Corticosteroids

• broad anti-inflammatory effects
• High dose pulses of i.v. methylprednisolone
  (SOLU-MERDOL, A-METHAPRED) used to reverse acute
  transplant rejection and acute exacerbations of
  autoimmune diseases like MS or SLE
• also used to suppress allergic reactions to
  biologics (e.g. first-dose cytokine storm in
  transplantation with muromonad-CD3 or
  thymoglobulin)

Invaluable for short-term use!!!
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Cytotoxic Agents

• Are typically covered in Oncology.
• For this lecture it is sufficient you to know
  that all cytotoxic drugs that are used for cancer
  therapy also hit all fast dividing cells in the
  body
• immune system
• gut mucosa
• hair follicles

Cyclophosphamide and methotrexate often used in
RA and MS
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• Calcineurin Inhibitors
• Cyclosporine
• Tacrolimus
• Bind to immunophilins (cyclophilin or
  FK506-binding protein FKBP) forming a complex
  that inhibits calcineurin
• Calcineurin does not dephosphorylate NFAT
• NFAT does not translocate to the nucleus
• Inhibition of T cell proliferation and IL-2
  production

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Cyclosporine (Cyclosporin A)

• cyclic 11 amino acid polypeptide (very
  lipophilic, orally absorbed)
• very effective against T cell dependent
  responses, less effective against B cells

• Therapeutic uses
• kidney, liver, heart and other organ
  transplantation
• severe cases of RA
• severe disabling psoriasis where other therapies
  have failed
• Pharmacokinetics
• Administered i.v. (SANDIMMUNE Injection) or
  orally
• oral availability 20-50 Different formulations
  like SANDIMMUNE gelatine capsules and NEORAL
  microemulsion are NOT bioequivalent should not
  be freely substituted!!!
• plasma peak between 1.5 to 2 h t1/2 5-18 hours
• extensively metabolized through CYP3A4 excreted
  through bile
• ? Plasma drug levels must be monitored, drug
  interactions avoided and doses adjusted for
  hepatic insufficiency

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Drug Interactions with Cyclosporine

• any drug that is metabolized through CYP3A4
  affects CsA metabolism
• CYP3A4 blockers (ketoconazole, fluconazole,
  verapamil, idinavir, grape fruit juice) increase
  CsA plasma levels
• CYP3A4 inducers (phenobarbital, phenytoin)
  reduce CsA plasma levels

Cyclosporine Side Effects

• Nephrotoxicity occurs in nearly all patients ?
  cessation or modification of therapy
• Hypertension occurs in 50 of kidney and 100
  of heart transplant patients
• Hyperlipidemia
• Tremor
• Hirsutism and hypertrichosis
• Diabetogenic in combination with glucocorticoids

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Tacrolimus (FK506)

• macrolide antibiotic produced by Streptomyces
  tsukunaensis
• available for oral and i.v. administration
  (PROGRAF)
• t1/2 12 hours, PK variable. Metabolized through
  CYP3A4 (same interactions like CsA)
• Therapeutic Uses
• Similar to CsA but much less commonly used
• Rescue Therapy in patients who show rejection
• despite therapeutic CsA plasma levels
• Side Effects
• Same as CsA, nephrotoxicity is limiting

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Sirolimus (Rapamycin) RAPAMUNE

• Macrocyclic lactone produced by Streptomyces
  hygroscopicus (soil of Easter Islands)
• Originally developed by Wyeth as an antifungal
  when it was found to be an immunosuppressant

• Mechanism of Action
• Inhibits T cell activation downstream of the IL2
  receptor by binding to the immunophilin FKBP-12
• sirolismus-FKBP-12 complex inhibits the protein
  kinase mTOR (mammalian target of rapamycin),
  which is a key enzyme in cell-cycle progression
• cell cycle arrested in G1-S phase transition

• PK
• oral availability 15, plasma peak after 1-2
  hours, t1/2 62 h, metabolized by CYP3A4

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Sirolimus continued

• Therapeutic Uses (introduced in 1999)
• used in combination with calcineurin inhibitors
  and glucocorticoids for organ transplantation
  (Synergy!!)
• in patients experiencing or at high risk for
  calcineurin-inhibitor associated nephrotoxicity
  used with glucocorticoids and mycophenolate
  mofetil to avoid permanent renal damage
• also coated onto stents to prevent restenosis
  following angioplasty

• Side Effects
• increase in cholesterol and triglycerides
• delayed wound healing (? often started delayed
  after surgery)
• much less nephrotoxic than calcineurin
  inhibitors but carries warning about associated
  nephrotoxicity since Oct. 2008

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Cyclosporine and Sirolismus (rapamycin) are
synergistic ? Often combined to reduce CsA
toxicity
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Azathioprine (IMURAN)
Mechanism of Action (Antimetabolite) Cleaved by
nucleophiles like glutathione to
6-mercaptopurine ? Inhibits purine synthesis and
thus cell proliferation

• Therapeutic Uses
• in combination for organ transplantation
• severe RA

• Side Effects
• bone marrow suppression (leukopenia, sometimes
  thrombocytopenia)
• hepatotoxicity
• increased risk of infections and cancer

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Mycophenolate Mofetil (CELLCEPT)

• Prodrug (2-morpholinoethyl ester) that is
  rapidly hydrolyzed to mycophenolic acid (MPA),
  which is a reversible inhibitor of ionosine
  monophosphate dehydrogenase (IMPDH), an enzyme
  involved in guanine nucleotide synthesis
• T and B cells highly dependent on guanine
  nucleotide synthesis (? other cells can use other
  pathways) ? MPA inhibits T cell and B cell
  proliferation as well as antibody production

• Therapeutic Uses
• Prevention of transplant rejection (typically in
  combination with glucocorticoids and calcineurin
  inhibitors)
• approved for renal transplant in 1995, other
  transplants later indications might widen in the
  future

• Side Effects
• Leukopenia
• Increased incidence of infections (in June 2006
  Roche and FDA issued
• warning about PML 17 cases, 7 fatal)

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Progressive Multifocal Leukoencephalopathy (PML)

• PML is a rare demyelinating disease of the CNS
  that usually is fatal or leads to severe
  disability. PML is caused by reactivation of the
  JC virus, a polyomavirus that resides latently in
  70-90 of adults worldwide.
• PML presents with ataxia, hemiparesis,
  confusion, apathy, cognitive deficiencies and
  radiographic evidence of white matter disease.
• PML should be considered in any transplant or
  autoimmune disease patient who is on
  immunosuppression and who presents with
  neurological symptoms.
• Other than reducing the dose of
  immunosuppressant there are no interventions that
  can stop or treat PML.

see also Natalizumab for MS treatment
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FTY720

• Fingolimod (FTY720) is sphingosine-1-phosphate
  receptor 1 agonist that prevents egress of
  lymphocytes from lymph nodes
• was not superior to calcineurin inhibitors in
  Phase-3 clinical trial for kidney transplantation
  as a monotherapy
• Very encouraging effects in Phase-2 clinical
  trial for MS (relapse rate reduced by 80)
  various other trials going on

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Antithymocyte Globin (THYMOGLUBIN)

• Purified gamma globulin fraction from the serum
  of rabbits immunized with human thymocytes
• contains cytotoxic Abs that bind to CD2, CD3,
  CD4, CD8, CD11a, CD18, CD25, CD45 and MHC class I
  and II (and probably a lot more!!)
• Abs deplete circulating lymphocytes by direct
  cytotoxicity (complement and cell mediated) and
  block cell surface receptors

• Therapeutic Uses
• Approved for acute renal transplant rejection
• Often used immediately after kidney transplant
  if graft function is delayed to avoid early use
  of nephrotoxic calcineurin inhibitors

• Toxicity
• Polyclonal rabbit Ab ? xenogenic protein elicits
  acute allergic reactions (fever, chill,
  hypotension) ? premedication with
  glucocorticoids, acetaminophen and antihistamines
• Anti-ATG Abs develop but do not limit repeated
  use

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Anti-CD3 Monoclonal Antibodies

• Antibodies directed against the e chain of the T
  cells receptor CD3
• ?? treatment induces rapid internalization of the
  TCR and is followed by depletion and
  extravasation of T cells from the blood and
  lymphoid organs (redistribution to the lungs)
• Muromonab-CD3 (OKT3) original mouse IgG2a
  introduced in 1986
• Fully humanized Ab hOKTg1 less cytokine release

• Therapeutic Uses
• Mouse Ab still used to reverse glucocorticoid
  resistant rejection episodes (repeated use
  results in neutralizing Abs)
• Humanized Ab for treatment and prevention of
  acute rejection
• Phase-2/3 clinical trials for prevention of T1DM

• Side Effects
• cytokine release syndrome typically 30 min
  after infusion (TNFa, IL2, IL6, INFg from
  activated T cells and macrophages) ? high fever,
  chills, tremor (worst on first dose)
• Glucocorticoid administration on first dose is
  now standard

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Rituximab (RITUXAN)

• monoclonal anti-CD20 Ab approved in 1997 for the
  treatment of B-cell non-Hodgkin lymphomas
• binds to CD20 on the surface of B cells and
  seems to induce apoptosis of CD20 cells and/or
  induce complement and cell mediated cytotoxicity
  (ADCC), drastically reduces number of circulating
  B cells

• Therapeutic Uses
• Leukemia, lymphoma see Hem/Onc
• In combination with methotrexate for severe RA
• Clinical trials ongoing for various autoimmune
  diseases including idiopathic autoimmune
  hemolytic anemia, MS, T1DM, Sjogren's syndrome,
  SLE

• Side Effects
• Infusion reactions similar to anti-CD3 Abs
• Immunosupppression carries Box Warning about
  PML

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Anti-CD25 (Anti-IL-2 Receptor)

• Daclizumab (ZENAPAX) humanized chimeric
  monoclonal Ab
• Basiliximab (SIMULET) murine-human chimeric
  monoclonal Ab
• both Abs seem to inhibit activated T cells
  without significant depletion

• Therapeutic Uses
• Prophylaxis of acute transplant rejection
  (pre-operatively and afterwards in biweekly
  intervals)
• Combination for maintenance therapy with other
  immuno-suppressants (azathioprine,
  glucocorticoids, cyclosporine)

• Side Effects
• no cytokine release syndrome
• anaphylaxis can occur

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Abatacept (ORENCIA)

• fusion protein composed of human immunoglobulin
  fused to the extra-cellular domain of CTLA-4

• Costimulation of CD28 through B7-1/2 (CD80/CD86)
  is necessary for full activation of naïve T
  cells Engagement of the related receptor CTLA-4
  inhibits/reduces T cell activation
• ? Abatacept prevents co-stimulation and can
  potentially induce tolerance

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Abatacept continued

• Therapeutic Uses
• Currently approved for RA patients who have
  failed methotrexate and anti-TNF reagents
• Currently in clinical trials for T1DM
  prevention, colitis, psoriasis and transplant
  rejection

• Side Effects
• usual risk of increased infections and
  malignancies
• should not be used in combination with
  TNF-antagonist (no additional benefit and greatly
  increased risk of infections)

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Anti-TNF Reagents

• Infliximab (REMICADE) chimeric anti-TNF-a
  monoclonal Ab containing a human constant and a
  murine variable region binds with high affinity
  to TNF-a and prevents it from binding to its
  receptor
• Etanercept (ENBREL) Fusion protein of Fc
  portion of human IgG1 and ligand binding portion
  of TNF-a receptor
• Adalimimab (HUMIRA) fully humanized recombinant
  monoclonal anti-TNF-a antibody for i.v. use

• Therapeutic Uses
• Infliximab and Adalimimab approved for
  psoriasis, Crohn's disease, ankylosing
  spondylitis, psoriatic arthritis, rheumatoid
  arthritis, sarcoidosis and ulcerative colitis
• Etanercept (various formulations including
  autoinjector pen) approved for RA 4.3 billion
  sales in 2006!! (7th top selling drug)

• Side Effects
• Increase incidence of lymphomas and infections
  Black box warning
• Rare cases of demylelination (contra-indicated
  in MS)

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Other Biologics
Recently introduced or in Development

• Efalizumab (RAPTIVA) targets LFA-1 and blocks T
  cell adhesion and activation
• Anakinra (KINERET) IL-1 receptor antagonist
  approved for RA
• Alefacept (AMEVIVE) Fusion protein that targets
  CD2, approved for moderate to severe psoriasis
• Campath-1H (ALEMTUZUMAB) humanized anti-CD52 Ab
  ? depletes T cells, B cells, macrophages and NK
  cells approved for renal transplantation
• Anti-IL-12/IL23 antibody clinical trials for MS
  and RA

There will be many more new immunosuppressants in
future as we understand the immune system better.
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Therapy of Organ Transplantation

• For solid organs like heart and kidney it is
  rarely possible to achieve perfect HLA matching
  because of limited supply of organs (exception
  live kidney donation from identical twin)
• ? Strong immunosuppression necessary

• At most transplant centers intensive biologic
  induction therapy followed by maintenance therapy
• Induction Therapy (delays use of nephrotoxic
  agents)
• Anti-CD3 Abs (? anti-CD25)
• Antithymocyte globin
• plasmapheresis if high titers of anti-HLA
  antibodies
• Maintenance Therapy (typically triple therapy at
  low doses for synergy)
• calcineurin inhibitor glucocorticoid
  mycophenolate mofetil
• sirolimus glucocorticoid mycophenolate
  mofetil
• calcineurin inhibitor sirolimus third agent

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Therapy of Organ Transplantation

• Therapy of Established or Acute Rejection
• High dose methylprednisolone
• Anti-CD3 Abs (? anti-CD25)
• Antithymocyte globin

• Calcineurin Inhibitors and kidney transplants
• Ultrasound guided biopsy best way to
  differentiate nephro-toxicity (too much CsA) from
  rejection (too little CsA)

Future?? Currently a lot of research going on
into the possibility of achieving tolerance with
sirolimus (spares Tregs in contrast to CsA)
and/or abatacept
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Therapy of Autoimmune Diseases

• Typically milder immunosuppression used than
  for prevention of transplant rejection
• Choice of therapy should be guided by
• Knowledge about specific pathology of autoimmune
  disease
• Careful weighing of benefits of therapy versus
  side effects since treatment is typically for the
  rest of the patients life

Example of a bad strategy In the late 1980s
and early 1990s cyclosporine was used to prevent
T1DM during the honeymoon period ? very
effective at preventing T1DM but abandoned
because of nephrotoxicity
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Example Rheumatoid Arthritis
American College of Rheumatology recommends that
treatment should be chosen based on

• how long a patient has had rheumatoid arthritis
• the severity of rheumatoid arthritis symptoms
• potential for side effects
• tuberculosis screening (required before starting
  
• biologic DMARDs)
• cost of treatment (real issue with biologics!!)
• patient preference regarding treatment options

DMARD disease modifying anti-rheumatic drugs
(as opposed to NSADs like aspirin that purely
treat the symptoms)
29

• The 2008 ACR Recommendations for Rheumatoid
  Arthritis Treatments
• Initiating treatment with methotrexate or
  leflunomide for most RA patients
• Methotrexate plus Plaquenil (hydroxychloroquine)
  for RA patients with moderate to high disease
  activity
• Treatment with TNF-a antagonist (etanercept,
  infliximab, adalimumab) plus methotrexate for
  patients with early rheumatoid arthritis
  (symptoms for less than 3 months) and high
  disease activity
• For RA with moderate to long disease duration,
  TNF-a antagonists for those who failed to get a
  satisfactory response from methotrexate therapy
• Abatacept and rituximab should be reserved for
  patients with at least moderate disease activity
  and inadequate treatment response to other agents
• Treatment with methotrexate or the biologics
  should not be resumed or started during an active
  bacterial or viral infection
• Severe flair-ups CsA or methylprednisolone

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Example Multiple Sclerosis

Chronic, immune-mediated demyelinating disease of
the CNS that is characterized by inflammation,
gliosis and axonal damage

Most common neurological disease in young adults
(age of onset 15-50 years) affects 400 000
people in the US and about 2.5 million worldwide
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MS is a T cell mediated disease

• myelin-antigen specific T cells with a Th1
  profile can be isolated both from the blood and
  the CSF of MS patients
• Although myelin-antigen specific T cells are
  also present in the blood of healthy controls and
  occur with the same frequency, their activation
  state in MS patients is different.
  Myelin-reactive MS patients T cells secrete
  larger amounts of IL-2, IFN-g and TNF-a than T
  cells from controls, and are predominantly of a
  Th1/Th0 memory phenotype

Extravasating T cells in a postmortem brain
section from a MS patient
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FDA APPROVED TREATMENT OPTIONS FOR MS

• Immunomodulatory drugs
• IFN-b
• Copaxone (Glatiramer acetate)
• Natalizumab
• Immunosuppressive drugs
• Acute severe attack methylprednisolone
• Cyclophosphamide and mitoxantrone for secondary
  progressive and primary progressive MS

Diagnosis and symptoms of MS will be covered in
Neurology
33
Interferon-b

• naturally occurring cytokine with still unknown
  mechanism of action
• - suppresses T cell proliferation
• - reduces T cell migration into the CNS
• - changes cytokine profile from Th1 to Th2
  (?)
• like most proteins interferons are potentially
  immunogenic (especially when produced
  recombinantly ? altered glycosylation) and
  neutralizing Abs appear in many patients ? still
  hotly debated whether these antibodies reduce
  efficacy of INF-b

34
Glatiramer Acetate (Copaxone)

• random polymer of glutamic acid, lysine, alanine
  and tyrosine (which compose MBP) with unclear
  mechanism
• induction of tolerance to MBP (?)
• induces a population of GA-reactive Th2-type
  regulatory T cells that secrete Th2 cytokines
  in the brain and create an anti-inflammatory
  milieu either spontaneously or after
  cross-stimulation with myelin antigens (?)
• long-term treatment also seems to induce serum Abs

35
Phase III Trials Reduction in Annual Relapse Rate
INF-b
INF-b
For patients who had been in the study for 2
years. Jacobs et al. Ann Neurol. 199639285
IFNB MS Study Group. Neurology. 199343655
IFNB MS Study Group and University of British
Columbia MS/MRI Analysis Group. Neurology.
1995451277 Johnson et al. Neurology.
1995451268 PRISMS Study Group. Lancet.
19983521498
36
Natalizumab (Tysabri)Anti-VLA-4 Monoclonal
Antibody

• 66 reduction in relapses
• 92 reduction in active MRI lesions
• Monthly IV administration
• 2/1200 patients treated developed PML and died
• ? Tysabri removed from the market in early
  2005

• March 2006 an FDA advisory committee
  recommended that it should return to the market
  (massive pressure from MS patients and NMSS)

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Symptom Management of MS

• Primary
• Caused by actual demyelination within the CNS
• Fatigue, tremor, incontinence, spasticity,
  depression
• ? antidepressants, anti-spastics
• Secondary
• Caused by failure to manage the primary
• Contractures, decubiti, fractures, muscle atrophy
• ? physiotherapy
• Tertiary
• Psychological, social, marital, vocational,
  personal
• ? antidepressants, Viagra, Life-style changes