TB Host-Directed Therapy (HDT)
Candidate Agents
December 2015 – Tuberculosis Clinical Research Branch, DAIDS, NIAID
TB HDT Rationale
 TB drug resistance continues to develop and HDT will be effective
despite resistance and may help to prevent increases
 Few new anti-TB drugs are in or entering clinical evaluation and
some have issues with safety and significant PKIs interactions
 MANY candidate HDT drugs await clinical evaluation for rapid
adaptation for TB – re-purposing avoids agent development costs
• If only a small % of potential new classes of HDT drugs are useful, the
number of available TB agents will be greatly expanded
 HDT agents for TB may also have therapeutic benefit for other
infections and also may serve as vaccine “potentiators”
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Rationale for Specific, Small Molecule
Adjunctive Immunomodulators in TB Rx
1. Improving TB-induced immune defects
– Particularly macrophages/other innate cells/autophagy
2. *Decreasing inflammatory tissue pathology/damage*
AND protected Mtb sanctuaries
– Less inflammation, necrosis, caseation, granulomas, lessened inhibitory molecules
• Improved immune cell access/function
• Improved anti-TB drug delivery to bacilli
• “NRP” TB may reactivate to be killed more quickly by TB drugs
3. Overall Effect  Improved TB clearance occurs in models
NIAID RFA - HDT for TB: New approaches
 Objective: Identify and characterize adjunctive host-directed
therapy agents to improve treatment outcomes
• Agents with evidence of therapeutic benefit in animal models
and have FDA approval or be in Phase II or III trials
 Mechanism: Phased UH2 / UH3 (5 yrs)
• UH2 – Pre-clinically identify/optimize specific agent and dosing regimen to
advance to POC clinical trial and trial preparation
• UH3 - Phase II POC Trial performance
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Four NIAID UH2/UH3 TB HDT Awards
• Autophagy Inducers (Deretic)
• Statins and other lipid-metabolism modulators (Karakousis)
• Imatinib (Kalman)
• Anakinra (Flynn) interleukin-1 receptor antagonist (IL-1Ra)
[Metformin grant application under review]
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Simvastatin increases the in vivo activity
of the first-line tuberculosis regimen
J Antimicrob Chemother 2014; 69: 2453–2457
Relative to the standard oral regimen of R/H/Z, addition of
25 mg/kg simvastatin in a BALB/c mouse model reduced
lung cfu by an additional 1 log10 at Day 28 (P=0.01) and by
a further 1.25 log10 at Day 56 (P=0.01)
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• In Mtb-infected mice, adjunctive metformin (MET) reduces the
intracellular growth of DS a DR Mtb in an AMPK–dependent manner
• MET increased production of mitochondrial reactive oxygen species and
facilitates phagosome-lysosome fusion
• MET reduced inflammation and lung pathology, and enhanced
specific immune responses and efficacy of conventional TB drugs
Collectively, these data indicate that MET is a promising
candidate host-adjunctive therapy for improving TB treatment
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Tyrosine Kinase Inhibition
Imatinib – abl and c-kit targets
• Myelomonocytic targets –
– Improved autophagy and phagosomal acidification
– Mobilization of myeloid progenitor cells
– Decreases the number and function of immune suppressor cells in some
malignancies
• Studies in NHP (Rhesus macaques) TB and TB-SIV models with
MDR Rx combinations are ongoing and appear promising
Planned BMGF Sponsored 5-arm Phase II Trial
• PDE-4 inhibitor - CC-11050
• Auranofin (complexed gold)
• Everolimus (mTOR inhibitor)
• Vitamin D
• Standard DS TB regimen
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Next Generation HDT?
First-generation HDT candidates were chosen as “antiinflammatory agents”, or empirically,
e.g., steroids, anti-TNF, statins, imatinib, metformin
Next generation HDT agents will be TARGETED agents chosen to
reverse specific abnormalities caused by Mtb in
• Cell regulatory pathways of infected/immune reactive cells
- “Precision Medicine”
• Immune effector functions of immune reactive cells
- “Immuno-oncology”
For BOTH innate and adaptive TREATMENT AND VACCINE Responses
Cell regulatory pathways - Precision Medicine Advances for TB
“Precision Medicine” Therapeutics
• Targeted HDTs have revolutionized cancer treatment by reversing effects of
“molecular drivers” subverting core cell regulatory pathways
• Some of the same cell pathways exploited by cancers are also disrupted by
Mtb to enhance survival/proliferation, e.g., altered cholesterol metabolism
AND to impair reactive immune cell function by disruption of cell metabolism
Many precision medicine agents now approved or in clinical trials can
be re-purposed for TB and other infections
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Precision Medicine and TB - Approaches
What research is needed?
• Identification of therapeutic targets - Precise determination of the
immune cell regulatory pathways disrupted by Mtb to cause
immunopathogenesis
• Screening - A wide variety of clinically available precision medicine
agents for effect on TB infection in improved in vitro “granuloma
model” systems
Animal models (as appropriate)  POC clinical Trials
Molecular Targets of Precision Medicine Agents
of Relevance for TB HDT
Evidence for PG role or benefit
NOT YET EXPLORED for PG or benefit
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AMPK
P13K-AKT-mTOR
MAPKs – JNK, ERK
Protein kinases: abl, c-kit,
VEGF, EGFR, JAK/STAT
Mevalonate pathway
Autophagy inducers
Rho/ROCK
Ras
Cathelicidin/AMPs –
HDACs as inducers
Wnt/beta-catenin
MMPs
PARPS
Sirtuins – STACs/inhibitors
Hedgehog
Notch
HIF-1α
Other kinases – SIK, FAK-Src, S6…
Inflammasomes
DPP-4
ERS/UPR reduction
Angiotensin II receptors
Bcl-2
GSK-3
Many more
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Reversing TB immunosuppressive Mechanisms
1) Immune checkpoint modifications (Directly on Mtb-reactive cells)
Immune cell co-receptor checkpoints
• Prevent inhibitory T-cell co-receptor/ligand signaling
– AGENTS - PD-1, CTLA-4, LAG-3, A2aR blockers (OX40* is stimulatory)
Immunometabolic checkpoint modifications
• Regulate immune cell differentiation and function by pathway controlled cellular
metabolism, e.g., to enhance Th1/TH17 and memory CD8+ T cell responses
- AGENTS - AMPK, sirtuin1/HIF-1α, mTOR inhibition*  VACCINE potentiation
* Used in combination for vaccine potentiation - animals
2) Block Suppressor cell induction (Indirect effect on Mtb-reactive cells)
• Tregs, MDSCs, M2 polarized macrophages induced by Mtb and BCG vaccination
- AGENTS – IDOi, ATRA, TKIs, PDE-5i, bisphosphonates, others
Leveraging the exciting advances in precision medicine for the
development of innovative next-generation HDTs may lead to
entirely new paradigms for treatment and prevention of
tuberculosis and other infectious diseases.
BACK-UPS
Targeting Immunometabolic Cell Regulatory Pathways
to improve Vaccine Responses
AMPK Stimulation
• Regulates CD4 T cell responses to infection by control of a glucose-sensitive metabolic
checkpoint for Th1 and Th17 development
• Controls metabolic transition of active/glycolytic effector CD8 T lymphocytes to
quiescent T cells to support CD8 T-cell memory development
Sirtuin1/HIF1a signaling
• Sirtuin1 inhibition enhances HIF1a activity in DCs to improve Th1 T cell differentiation
and to decrease Tregs
• HIF1a activity stabilizing agents improve Th1 responses by inhibiting HIF-PHs (HypoxiaInducible Factor prolyl hydroxylases – PHDs)
mTORC inhibition – including with BCG vaccination
• Improves memory CD8+ T cell generation in animal models – see “Beyond Adjuvants:
Immunomodulation Strategies to enhance T-cell immunity” Vaccine 33S (2015) B21-28.
PAMP or
DAMP
PRR
RTK
β-AR
Adenylate
Cyclase
cAMP
PI3K
PKA
SR
ROS
ATP
ERK
PTEN
AKT
OxLDL
JNK
Oxidative
Stress
mTOR
OxLDL
ER
STRESS
PDE
Autophagy
AMPK
DAMPs
PARP
Foamy
Macrophage
M2
NF-κB
Antiinflammatory
SIRT
PRO-inflammatory
And Cell Death
Metformin
• Decreases glycolation (pyridoxamine and buformin
may be better) reacts with dicarbonyls
• Decreased TNF and other inflammatory CKs by
inhibiting ERK/EGR-1 pathway and suppressing
scavenger receptors (CD36 and SR-A)
• AMPK activation
– Inhibits mTOR – enhances autophagy in TB infected
macrophages mediated by PPAR-gamma
– Inhibits PARP activation and activates Bcl-6
– Decreases effects of RAGE signaling on some cells and
inhibits HMGB1 release
– Decreases NF-kB expression/Suppresses ROS formation
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Statins
HIGHLY PLEIOTROPHIC EFFECTS
• AGE/RAGE effects
– Decrease MPO-dependent AGE generation
– Control AGE-mediated histone modification
– Displaces RAGE from membrane
– Decrease RAGE expression by inhibition of Rac-1
• Decreases LOX-1 effects
• Enhance Efflux pumps for lipids
• Matrix metalloproteinase down-regulation
And Others - Will all of these be sufficiently additive
to significantly impact TB-DM treatment outcomes?
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Metabolic pathways in T cell fate and function
Immunometabolism: linking metabolism and immune function
Trends in Immunology April 2012, Vol. 33, No. 4
T-cell Activation Immune Checkpoints
Checkpoints for development of effective cellular immunity
T cell Co-receptors
• Blocking PD-1 and CTLA-4 checkpoints with antibodies improves antigenspecific T cell functions – reverses senescence
• The next generation of immune checkpoint blockade for clinical evaluation will
include oral A2aR antagonists. Some are in trials (e.g., oral istradefylline) to
increase immune responses to tumors (by T-cells, macrophages, NK cells)
• TB connection - Journal of Infectious Diseases 2014;210:824–33
“… a role for the purinergic pathway in the host response to M. tuberculosis.
Dampening inflammation through signaling via the adenosine A2A receptor may
limit tissue damage but may also favor bacterial immune escape.”
Myeloid-derived Suppressor Cells (MDSCs)
MDSCs are immunosuppressive lesion-infiltrating cells
• Tumor-associated MDSCs are being targeted in cancer vaccine and other
immunotherapies to improve host immune responses
• Large numbers of MDSCs develop during active TB in humans and BCG infection
recruits MDSCs
• In a mouse model, BCG-induced MDSCs blocked T cell proliferation and dampened
Ag-specific priming in lymph nodes
Interventions - MDSC suppression or conversion to improve cancer immunoRx by
• Sirtuin1 inhibition directs a switch to a M1 lineage by glycolytic activation of
cells through enhanced HIF1a function
• All-trans retinoic acid, PDE-5 and c-KIT inhibition (sunitilib), bisphosphonate…
Innovative New Research Tools for Use at Single Cell Level
High through-put assays to define effects of molecular drivers of disease on
individual cell regulation and to identify intervention targets
• Epigenomic assays – defining the regulome
• ChIP (Chromatin Immunoprecipitation)-based assays (acetyl, methyl, TF binding, etc.)
• Chromatin accessibility assays (ATAC-seq, FAIRE-seq, …)
• DNA methylation sequencing – bisulfite methylation sequencing (BMS)
• Advanced proteomics, metabolomics…
• Combined for simultaneous use – interactomes
• DNA + RNAseq, CHiP + DNAseq, ChIP + BMS, Chip+proteomics, etc.
• Sensitive detection of histone-altering gene polymorphisms (acetylation ChiP-DNAseq to find haQTL
SNPs) – on a genome-wide basis using cohorts < 100, MAF ’s < 1%
Results:
Correlating changes in specific cell’s signaling (and influence of genetics, epigenetics)
 gene expression (transcription/translation/post-translational modifications)
 effects on cell metabolism and defense functions (phenotype)
“Signaling Network Modeling” for Outcomes
Single cell methods are key to this modeling
• With a sufficient signaling database for a specific cell type – develop
mathematical modeling for effects of signaling changes on cellular outcomes
-- gene expression  cell metabolism/function
• Adaptive – modify model as new data becomes available
• In silico study of network dynamics to predict “network nodes” of most
vulnerability to intervention
• Modeling can predict effect of targeted drug interventions and if combination
therapy would be significantly more effective
• After drug intervention – include dosing effects to determine minimal effective
dose for a drug
 The future of therapeutic development for most diseases
Immune Protection vs. Inflammatory Damage
Immune reaction regulation will need to change over the time course
of an evolving immune reaction to pathogens
Initially • Enhance robust and usually highly inflammatory reaction to first control and then
kill and begin to remove the pathogen -- or react to vaccine
• HDT’s best use may be to reverse pathogen immune disruptive effects
Later - ? Exactly when
• Inflammatory down-regulation must INCREASE as the immune process evolves in
order to limit tissue damage and implement tissue repair
• NOW- HDT role may be to help modulate inflammation/damage – also to improve
access and function of immune cells and antibiotics
 Timing/context of use of different HDTs may be crucial
Key Cellular Regulatory Signaling Pathways
Core pathways
• PARP family
• mTOR
• Sirtuin family
• AMPK
Other key pathways – with known links to TB pathogenesis
• Cellular Kinase networks (and Phosphatases)
• MAPK and cascades
• Kinases – TKs – (e.g., abl, c-kit, VEGF, JAK/STAT) and MANY more classes
• Small molecule GTPases
• Wnt/beta-catenin family
• Hedgehog, Notch1/SOCS3….
Implicated in BCG-induced suppression of immune responses
Drug Class/Target
Tyrosine kinase inhibitors
c-abl, c-kit
JAK/STAT
VEGF
Src/FAK
Ser-thr Kinase
SIK inhibition
AMPK activators
MAPK Cascade inhibitors
RAF-B
MEK
ERK
JNK
PI3K-, AKT-, mTOR Pathway mTOR
Small GTPase inhibitors
Ras (-RAF-MEK-ERK)
Rho/ROCK
PARP inhibitors
Examples
*
Imatinib and others
Tofactinib* Ruxolitinib*
Pazopanib* Bevacizumab
Dasatinib*, Bosutinib*
Metformin*, AICAR and AZD-769662
Berberine* ,Resveratrol* ASA*
Vemurafenib*, Dabrafenib
Trametinib*
SCH772984. VTX11e (pre)
CC-930
Idelalisib*, Hispidulin, Afuresertib, Perifosine, MK-2206,
Triciribine, Ridaforolimus
Oxidative Stress Reduction
Tipifarnib+Statin, Salirasib
Fasudil# Statins, metformin
NAM*, NR*, NMN*,
Tetracylcines*,
Olaparib*
Resveratrol*
Statins* Metformin
Berberine Disulfiram
Silymarin Tanshinone
Angiotensin II receptors
telmisartan*
Sirtuin activators
* US FDA-approved or available OTC
Drug Class/Target
Examples
Inflammasome inhibitors
Phenylbutyrate*
Ursolic acid*
Fasudil#
Tauroursodeoxycholic acid
Βeta-hydroxybutyrate, MCC950
Dipeptide dipeptiase-4 inhibitors
Sitagliptin*
GSK-3β Inhibitors
CHIR98014, KICG1338
Cathelicidin Inducers
Vitamin D, Phenylbuturate, Lithocholic acid,
curcumin, nicotinamide, reseveratrol, pterostilbene
Curcumin*, Imatinib*/TKIs,, Metformin*, Statins*,
Verapamil*, SRIs*, Carbamazepine*, Berberine*,
rapalogues
ERS/UPR Reduction
Autophagy Inducers (46)
Mevalonate metabolism modulation ERK signaling inhibition through RAS
farnesylation
γδ T cell activation
Highly Pleiotropic
CombinationsVEGFR Inhibitors
# Approved in other countries with stringent regulatory authorities
Tipifarnib+Statin
Amino-bisphophonates*
Metformin, statins, phenylbutyrate, telmisartan, fasudil#,
berberine, dimethyl fumatate*
Benfotiamine
Fasudil and Statins (ROCK)
Vitamin D and Phenylbutyrate (AMPs)
Metformin and disulfiramPazopanib
Bold: Preclinical testing against MTB being performed
HDT CAVEATS
• May not work
– PK/PD issues - delivery to site of action in active form
with sufficient exposure
– Extrapolation from different disease models/states
– In vitro and animal model (rodent) data not translating
– Actions depend on “tissue/cellular context”
– Complexity of regulation/signaling – counter-reactions
– ETC.
• Could cause harm
– Worsen TB disease course
– Increase lung damage
– Impact on HIV co-infection