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Modulation of the Immune System: Treatment Options and new Developments
PD Dr. Chris Rundfeldt
DrugConsult.Net
Magdeburg and Dresden, Germany
Diseases and conditions with (pathological) involvement of the immune system
Inflammatory conditions, associated with trauma, infection or tissue destruction
Chronic perpetuating inflammations: COPD, arthritis Allergic diseases: type I-IV Atopic diseases: atopic dermatitis, atopic rhinitis,
asthma Autoimmune related diseases: rheumatoid arthritis,
inflammatory bowl disease, colitis ulcerosa, morbus Crohn, psoriasis, multiple sclerosis, coeliac disease, Rasmussen's encephalitis, myasthenia gravis, ……
Organ / tissue transplantation and rejection reactions
Localized effects of the ubiquitous organ “Immune system”
The immune system is involved in numerous physiological and pathological processes
Each organ can be a disease target (CNS, skin, gut, muscle, soft tissue…..)
Often targeted tissues are limited and reasons for localized effects are not known
Potential reasons for localization are hidden in the complex nature of such multifactor diseases
A drug with immune modulator activity can be useful for diverse diseases
For example glucocorticoids are used for many conditions
Intervention options: well established drugs
Anti-inflammatory drugs Inhibitors of cyclooxygenases (Ibuprofen...) Inhibitors of lipoxygenases (Zileuton…) Leukotriene receptor antagonists ( Montelukast…)
Immune modulators Glucocorticoids
Selective cytokine blockers (Biologics) TNF inhibitor antibody / fusion protein (Infliximab,
Ethernacept…) IL-1 receptor antagonist (Ankarinra) Anti-T-cell fusion protein (Alefacept) …….
Intervention options: Immunosuppressives
Antimetabolites Purine synthesis inhibitors (Azathioprine …) Purine analog mimics adenosine, DNA synth. Inhibit. (Cladribine) Pyrimidine synthesis inhibitors (Leflunomide …) Antifolate (Methotrexate)
Calcineurin inhibitors (IL2 synthesis inhibitors) Cyclosporin Tacrolimus, Pimecrolimus
mTOR, kinase inhibitor, activation of T-cells inhibited Sirolimus (=Rapamycin)
TNFa-synthesis inhibitor (Thalidomide, Lenalidomide)(Thalidomide: teratogenic effect phocomelia, now used for Erythema nodosum leprosum, cancer, etc.
Limitations of pharmacological intervention
Immune suppressive agents can facilitate potentially life threatening infections Invasive aspergillosis Tuberculosis General infections
Unexpected adverse events include disturbance of learning and memory (Rapamycin)
Inhibition of rapidly dividing tissues Glucocorticoids lack a good separation of
pharmacologically active and toxic doses
Limitations of pharmacological intervention: Biologics
Biologics are thought to be selective but can induce: Flu-like symptoms, nausea, fatigue, loss of appetite Redness, rash, and/or pain at injection site Allergic reaction to mouse protein with monoclonal antibodies Increased risk of Hodgkin’s and non-Hodgkin’s lymphoma and
other types of cancer in children and teens taking TNF inhibitors Lupus-like syndrome Possible reactivation of latent tuberculosis infections with TNF
inhibitors Progressive Multifocal Leukoencephalopathy (PML), see
Natalizumab case (Tysabri) Induction of antibodies against therapeutics results in
loss of effect
New treatment options?
Novel treatment options should be:
Selective for pathological conditions (reduce over-activation of the immune system component)
Have a good separation of effects and adverse reactions
Be easy to handle, at best oral treatment
While no such drugs are readily available, a few interesting candidates can be discussed
Examples for new treatment options
Inhibitors of Phosphodiesterase 4
Stabilized cAMP analogues
Dimethylfumarate
Raft-modulators
Phosphodiesterase 4 inhibitors
Inhibitors of Phosphodiesterase 4 (PDE4)
Prototype: Rolipram Initial development as antidepressant Early investigation in multiple sclerosis indicate
pharmacological effect, but GI related side effects
Numerous development projects worldwide for diverse diseases
Currently only roflumilast marketed in EU for treatment of COPD
Other potential indications for roflumilast: Asthma, atopic dermatitis, psoriasis
Roflumilast (PDE4i)
Initial studies in patients with asthma
Roflumilast (PDE4i)
Significant effects in patients with COPD
But effect size lower than known for Theophyllin!
Roflumilast (PDE4i)
Significant effects: reduction of exacerbations
Novel PDE4i: how to test preclinically
In vitro tests: Cytokine release in PBMCs or whole blood Induction with LPS or anti-CD3/CD28 or similar
Ex vivo tests: Cytokine release from whole blood
In vivo tests: Ovalbumin induced eosinophilia in sensitized BN rats (asthma model)
LPS-induced neutrophilia in Lewis rats and in ferrets (COPD model)
Emesis in ferrets and domestic pigs
Example development strategy for PDE4i
CYP3A4 Induction
Stable in plasma,no or low turnover in liver preps.
Expl. kinetics in rat and dog(i.v. vs p.o.)
Dog: t 1/2 > 2 hBV > 30%
Side effect profile in- ferrets (emesis and CNS)- pigs (cardiovascular)- mice, rats (CNS)
TI > 10
Inhibition of cytokine release - PBMC‘s ; Maph(IL2, 4, 5, 13, IFN)(IL1, 6, 8, 12, 15, 17, MCP1)
Metabolic stability inplasma and liver prepar.,species comparison, metabolite profile
Quality Lead
IC50 < 100 nM
Effect on- LPS-induced neutrophilia in rats and ferrets- late phase eosinophilia in rats- bronchial hyperreactivity in mice
Equal or better than RoflumilastLTB4
(neutrophils)LTC(eosinophils)
IC50 < 100 nM
no induction
Preselection preclinical candidate
Example development strategy for PDE4i
Clinical Program
Identification of - major metabolites - metabolic pathways- involved enzymes
acceptable
Non-respiratory inflammation models- skin (mice)- other models (CRO)CNS diseases
Indication extension
PK / ME Safety
14C Pharmacokineticand metabolicprofiling
Tolerability- Irwin test (rat)- acute toxicity (rat, mice, dog)
Respiratory models- allergic rhinitis (rat)- LPS-induced neutrophilia ( ferrets and pigs)- allergen-induced broncho- constriction (guinea pigs)
Efficacy
Full 4-week tox package
Preclinical Candidate
Receptor screening
Selectivity > 100
Genotoxicity- Ames test - chromosome aberration test- micronucleus test
No effect
initiatedinitiated
Example data: Ovalbumin induced eosinophilia
Novel compound
Example data: LPS induced neutrophilia
Novel compound
Example data: Safety profile in experimenta animals
Rationale: clinical dose of roflumilast is limited by CNS side effects,not by emesis
Test Novel Roflumilast
LPS neutrophilia >50% 0.01mg/kg
0.01 mg/kg
Highest dose testedwithout emesis
3 mg/kg 0.1 mg/kg
Highest dose testedwithout CNS effects
0.3 mg/kg 0.01 mg/kgnot free of CNS effects
TI in relation to emesis p.o. ~300 ~10
TI in relation toCNS effects p.o.
~30 < 1, no separation
Compounds were administered to ferrets with gastric tube as a solutionor suspension
Translation of preclinical data in phase I
Phase I is dedicated to determination of safety Options to get insight in efficacy in phase I
LPS induced TNFa release from whole blood i.v. LPS induced hyperthermia and flu-like reaction in volunteers Intratracheal LPS administration followed by lung lobe lavage Local non-allergic or allergic skin irritation in sensitive patients,
with skin prick test or with Balsam of Peru Allergen induced late phase bronchoconstriction in volunteer-
patients with mild stable asthma Methacholine induced bronchoconstriction Local non-allergic or allergic skin irritation in sensitive patients,
with skin prick test or with Balsam of Peru
PDE4 inhibition, other options
Increased cAMP levels: cAMP substitution instead of PDE4 inhibition
Stable cAMP analogues can be active but activate also protein kinases
Clinically known stable analogue: Dibuturyl-cAMP (bucladesine) Bucladesine is a safe drug, no emesis Was developed as cardiotonic for i.v. administration Was developed as skin healing cream Failed for different reasons: Cardiotonic function
difficult to test, skin cream has strong odor (butyric acid is released)
Clinical data showing a homogenous clinical effect of cAMP level modulation
Goyarts et al., Skin Pharmacol Appl Skin Physiol 2000:13, 86-92
Dibuturyl-cAMP is active in arachidonic acid induced ear swelling in mice
vehicle ketoprofen0.00
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Drugs were administered onto the outer surface of the mouse ear 3 h before arachidonic acid challenge. Measurement of ear thickness. 60 min later the ear thickness was measured.
DB-cAMP, water free ointment
Ketoprofen, commercial cream
2-deoxy-cAMP may be an interesting candidate for a topical anti-inflammatory ointment, but safety of this compound is not tested
No patent protection possible
Fumaric acid esters: old drugs with novel mode of action
Dimethyl fumarate: A novel old drug for oral treatment of immune diseases
Dimethyl fumarate (DMF) is marketed in Germany as main component of a first line oral drug for treatment of moderate to severe psoriasis (Fumaderm®)
Fumaric acid esters are an effective therapy in patient with moderate to severe psoriasis, even in those who have previously been intolerant of systemic therapy
The mode of action of DMF is not fully understood Problem: tolerability, GI irritation and flush, skin irritation Problem: Papilloma / carcinoma in forestomach rats Biogen Idec has developed a novel micro-tablet formulation
(immediate release) and tested positive for psoriasis and MS. Now in phase III for MS
Forward Pharma has solved the challenge of developing a modified release formulation. Now in phase II for Psoriasis
Fumaric acid ester (FAE) and Dimethylfumarate: Pharmacology
FAEs cause an increase of the intracellular calcium concentration FAEs inhibit the expression of the ICAM-1 T-cell receptor ligands The treatment of psoriatic patients with Fumaderm® results in a reduced
infiltration of the skin with granulocytes and T helper cells, followed by a reduction of the acanthosis and hyperkeratosis
Monomethyl fumarate increases the IL-4 and IL-5 production of activated T cells, in a dose-dependent manner
Dimethyl fumarate inhibits cytokine-induced E-selectin, VCAM-1 expression in human endothelial cells
Dimethyl fumarate inhibits cytokine-induced nuclear translocation of NF-kB. Dimethyl fumarate induces apoptosis in human monocyte-derived dendritic
cells. Monomethyl fumarate suppresses the FMLP-stimulated respiratory burst in
granulocytes
Fumaric acid ester (FAE) and Dimethylfumarate: Pharmacology (2)
In in vitro tests DMF is more potent than MMF In plasma samples, only MMF can be found (rapid
demethylation) In urine, DMF-conjugates with glutathione were
found Proposed MOA: Intracellular uptake in leukocytes Rapid conjugation with glutathione Dimethyl fumarate induces immune suppression
via glutathione depletion and subsequent induction of heme oxigenase
DMF pathways
Lumen -Gut wall- Blood streem
DMFTablet
ERY
ERY no
metabol.
ERYERY ERY
Plasma EsterasesDMF MMF
WBC:DMF
DMF-GSHActive Transp.
DMF-GSH Plasma EsterasesMMF-GSH
WBC:MMF
MMF-GSHActive Transp.
Mercapturic acid derivatives, excreted in urine
1
2
Glutathione depletion is immune suppressive
Top:PBMCs were stimulated with LPS/IFNg (1 mg/ml, 10 ng/ml) or PHA (100 mg/ml) in thepresence of DMFBottom: Mixed lymphocyte reaction to quantify dose response and reversibility
Substitution of reduced GSH abolishes the inhibition ofinflammatory cytokine secretion and alloreactive lymphocyte proliferation by DMF and DEF
FAEs are active in moderate to severe psoriasis
Mrowietz et al. Br. J. Dermatol. 1998138: 456-460
Effect of DMF in MS patients (Biogen)
Tabel from: Lee et al., The International MS Journal 2008; 15: 12–18
Figure from: Kappos et al., Lancet 2008; 372: 1463–72
Raft modulation as novel lipid chemistry target
Raft modulation: Innovation ahead?
Lipid Rafts are specific clusters of lipids and proteins regulating a wide range of biological and pathological processes
Lipid Rafts concentrate proteins to increase process efficacy
Rafts coordinate disease events at specific sites and times Signal transduction, virus entry & budding, bacterial entry,
receptor recycling, protein maturation are dependent on Lipid Rafts
Each process occurs in a Raft of unique composition
Rafts are novel pharmaceutical targets
Example: IgE receptor RAFT as drug target
IgE-receptor clustering drives RAFT formation Protein-driven (specificity) reaction is combined
with novel lipid chemistry target
RAFTlipids
IgE
FcRI kinase unrelatedRAFT receptor
multivalent allergen
Receptor clustering and RAFT coalescence
Signal cascade, release of immune modulators
Miltefosine is a clinically effective RAFT modulator
Skin-prick test on human volunteers; IgE-dependent allergic response Pretreatment with miltefosine (Miltex) or saline Skin-prick with allergen & positive control (histamine)
Weller et al. 2008 Miltefosine inhibits human mast cell activation in-vitro and in-vivo. J Invest Dermatol
Clinical effect back-translated in preclinical model: TDI induced ear swelling in mice
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Conclusion
Immune modulator drugs represent a diverse family of drugs
Despite the large number of marketed drugs, there is need for better drugs
Even among old drugs there are interesting new approaches to immune modulation
Recent data indicate the reduction in glutathione concentration can induce immune modulation
Raft modulation is a 2nd novel approach to immune modulation
Thank you for your attention
I am ready to take your questions