Lecture Notes - Innovative Tumor Therapies - week 2

Module 4: Innovative Tumor Therapy (Week 2)
LECTURE: TARGETING METABOLISM (E. Giovannetti) Monday, 3/12/2018

Aerobic glycolysis is not an in vitro artefact as proven by
FDG-PET (PET is good at picking out malignant & fast growing
tumor/metastasis); tracking glucose uptake by tumor 
tumor uses much more glucose compared to normal cell

Why alter metabolism? (Gene expression alteration influence
metabolism)

1. Induce glycolytic enzyme (reduced number of
mitochondria)

2. Induce pyruvate dehydrogenase kinase

3. Downregulation of mitochondrial enzyme & reduced
number of mitochondria

Most common genetic alterations that lead to glycolytic switch: p53 inactivation, HIF1 alfa TF activation

P53 (guardian of genome) = most common cause of
cancer; inactivation impacts glycolytic flux (increased),
pyruvate oxidation (reduced), ATP production by oxphos
(reduced)

Normal P53: increase cytochrome oxidase activity 
more ATP produced  inhibit aerobic glycolysis,
downregulate pyruvate oxidase kinase 2 (PDK2) 
increase pyruvate dehydrogenase complex  no need for
ATP from glycolysis (reduce aerobic glycolysis rate)




HIF1 alfa

Normoxia v. Hypoxia state = see slide

HIF interact with HRE to activate target genes +
increase glucose metabolism in tumor cell

Hypoxia is driving force of several cancer (e.g.
pancreas = low oxygen drive metabolic switch, EMT,
invasion, clonal expansion)



Hypoxia affects proteins involved in glycolysis (GLUT1, HK1, MCT4, LDH-A)  upregulated = more pyruvate metabolized into
lactate

, Module 4: Innovative Tumor Therapy (Week 2)

Other metabolism altered in cancer cell: glutamine metabolism  along
with p53 mutation affect activity of C-myc (enhanced)

 Increase transporter expression
 Increase activity of glutaminase gene  production of kidney-
type glutaminase
 Stress-induced GLS2 expression

Glutamine is the main provider of nitrogen & carbon (cell cycle’s energy
source)




Altered metabolism and tumor behavior

Normal cells have optimal metabolism of glucose & glutamine, resulting in CO2, H2O, and ammonia + sufficient amount of ATP;
tumor cells have wasteful metabolism of glucose & glutamine, end product is CO2, H2O, lactate, pyruvate, etc. ATP
production = insufficient
Warburg effect is ADVANTAGEOUS for cancer cell’s survival (rapid ATP
production, basis for building blocks of cells, ROS protection, TME modulation)

 Produce ATP faster (competitive advantage in hypoxic/low nutrient state)

 Suppress immune cell activity & starve neighbouring cells (more space to
grow)

 Protect against killing by ROS (NADPH>>, mitochondrial ROS production
<<)

 Increase protein biosynthesis, promoting cell migration & metastasis

, Module 4: Innovative Tumor Therapy (Week 2)
Metabolism and tumor microenvironment

TME-derived exosomes may influence cancer cell
metabolism  analyse by exosomal metabolomics;
Interventions targeting tumor metabolism:

 Proper diet (less fatty acid) & physical
exercise (promote nutrient consumption)

 Reconsider current Tx: induction of
hypoxia; careful use because hypoxia may
drive tumor aggression

 New antiglycolytic agents (to be used in
combination to target genetic aberration &
metabolic switch)




LDH-targeting drugs

Other potential target: LDH inhibition  highly expressed in RES; important in glucose consumption & lactate production

Creating isoforms of LDH (most prevalent in tumor is LDH5) = comprised of LDH-A subunits, targetable; LDH5 is
overexpressed in pancreatic tumor tissue & in plasma, presence of LDH in CAF = maybe

Hereditary LDHA deficiency cause myopathy in patiemts following strenuous exercise d/t excessive lactate accumulation

Inhibit LDH (by siRNA): decrease cell proliferation, promote cell death d/t energy depletion (in hypoxic condition), other
molecules to inhibit LDH:

 FX11 (contains cathecol moiety)  beware of toxicity risk

 Azole-based molecules: small sized  questionable target selectivity

 NHI (N-hydroxyindole) compound: high selectivity for LDH5; NHI activity is enhanced by hypoxia  more cell
killed at lower NHI concentration when environment lacks oxygen; strong synergism (based on computational
software analysis) when NHI is combined w/ gemcitabine for pancreatic Ca

NHI increase DCK expression (DCK promoter is also a binding site fof HIF1 alfa = active promoter in hypoxic state
may enhance the effect of other compound combined to it)  proof of effectiveness by wound healing assay (scratch
test)

Tumor cells may use different metabolic pathways (glycolytic, lipogenic) = better understanding of metabolism leads to
better tx targeting, future perspectives: right target determination for better inhibition of deranged pathways, in vivo study
still hasn’t yielded results

, Module 4: Innovative Tumor Therapy (Week 2)
LECTURE: MOLECULAR IMAGING & THERAPY (O. Hoekstra) Monday, 3/12/2018

PET can be utilized to look for hotspots in the body that takes up more markers (glucose, lipids, etc) than normal cells, better
combined with CT/MRI  more sensitive than CT in detection of lesional size. PET is useful for re-staging prior to chemo w/
curative & palliative intents, as well as to reduce the risk of futile intervention (e.g. thoracotomy)

Things to consider when incorporating molecular imaging: feasibility, Dx accuracy, impact on Tx, cost-effectiveness

Not all tumor is FDG-AVID (solid tumor have low/variable uptake, e.g. low grade ER+/HER2- breast cancer has low
metabolic rate  low avidity of FDG, somehow impact outcome, low grade neuroendocrine tumor)

FES: different biodistribution from FDG, understanding tumor biology may help determine which tracer to use in PET

Developing molecular imaging agent:

 Proper targeting

Inject mice w/ anti CEA (mice has CRC, other mice has glioma) to see tracer uptake  Molecular imaging tracer should
be developed accordingly w/o altering pharmacokinetics of the molecule (e.g. biodistribution) & no toxicity of the
procedure, GMP-compliant

 Sufficient biodistribution

Prediction & evaluation of response by imaging

Aim: detect Tx failure as early as possible, avoid toxicity & more cost effective  require surrogate endpoint of drug
development (example: RECIST criteria of lymphoma & solid tumor)

Introduce biomarker for response (outcome-associated criteria of responsiveness, e.g. thresholds, need to be VALIDATED)

Example: GIST (befofe Tx = viable cell is in periphery, post tx = conversion of signals  marker expression is correlated with
outcome); lymphoma (showing partial metabolic response post Tx when there are lymphoma cells in the body 
complete/partial/no molecular response)

Solid tumor Tx response need to be quantified, e.g. using SUV (standardized uptake value) to reduce inter observer
variations




Total lesion glycolysis  prominent predictive marker, but all needs validation

Defining phenotypes for drug targeting

For tumors with variable phenotypes, PET tracer may be helpful to determine based on the molecular phenotype  see
where drug goes after being introduced

Challenges:

 Targeting tumor cells with monoclonal Ab: measurable biological half-life should match radiological half-ljfe;
example= opting for zirconium rather than others d/t Zr's shorter half-life (3 days), then soon do PET
 Fluorescent labelling process SHOULD NOT ALTER pharmacokinetics
Fluorescence penetration to tissue is variable, good for superficial lesions only & not feasible for tumors with
multimetastasis and high phenotype variations