(electric music)
- So, thank you to the organizers at Abcam
for actually arranging this symposium
and giving us a chance to look backwards,
to look forwards, and to just think about
where the science is going and the areas
that we're really excited about.
And this is a picture I really like, because it really,
one, it's very beautiful, and two,
it illustrates for me a really interesting point
about epigenetics and the regulation of gene expression.
So if you think about a caterpillar and a butterfly,
they have exactly the same genomes,
but by very carefully and very precisely
regulating which genes they express,
you can actually produce totally distinct forms,
totally distinct functions and
absolutely different physiology.
So if you think about the power or the ability
to control gene expression, epigenetics
becomes really important, and what
we've learnt over the last few years is,
contrary to our expectations, epigenetics isn't
fixed during embryonic development.
So when a neuron forms, or a skin cell forms,
we'd always thought about epigenetics as being
really important in deciding cell lineage and cell fate.
What's been really interesting and exciting
over the last few years, is that we've learned that
epigenetics continues to be important throughout life,
it responds to the environment and it changes in disease,
and very importantly for us, it is actually
amenable to the use of small molecules
to alter epigenetic function, to potentially reverse
or impact on disease progression.
And so if you think about genes and the way they function
and how the different states they can be in,
and this is work taken from Ruslan Matatov,
and a number of his colleagues over a number of years,
they look at say, gene expression in the immune system,
you can think of genes in a number of different states.
You have those genes where the DNA is tightly wrapped around
the chromatin, in a locked position,
transcription factors can't get to it,
that gene is stably repressed and is off.
An the example there would be say,
the hemoglobin gene in dendritic cells.
You don't need to express that in those cells.
On the opposite end of the spectrum,
you've got genes that every cell needs to express,
and things like GAPDH, where the chromatin is open,
and the histone proteins of the DNA
is wrapped around, have already got the marks on it to say,
express this gene, keep it on, make it at high levels.
And the example there that I give is
GAPDH in dendritic cells.
Then you've got other sets of genes
where you actually want to respond very quickly.
So in response to a signal, you want
to be able to turn on these genes
within the matter of minutes.
And those are genes that say, allow you
in the immune system to respond
to a bacterial or viral infection.
So these genes are poised, the DNA is open,
some of the marks on those histone tails
are already there to say, in the event of a stimulus,
turn this gene on very rapidly.
And the examples there would be things like
interferon, betarin, plasmacytoid dendritic cells,
the cells that respond to viral infection very rapidly.
Then you've got another set of genes,
which turns out to be particularly interesting,
and I'll come back to these in a while again,
and these are called secondary response genes.
These are genes that encode factors
that when they're made, actually
produce dramatic biological effects.
You want to control the expression of these genes
very tightly, and these secondary response genes
actually require two things to happen.
You need, require, remodeling,
so you need to evict these histones,
you need these factors to come in,
and you need those factors to now start writing these marks,
almost histone tails, to say, turn this gene on.
And these genes then require the interaction
of a whole set of complexes to turn those genes on.
And the example there would be something like
IL6, or Interferon-beta in macrophages.
If you overexpress IL6, it's associated
with a lot of autoimmune disease,
so you really want to regulate that.
And this kind of illustrates to us
the importance of very precisely controlled gene expression.
And the immune system is one system
that allows us to explore that
very rapidly and very efficiently,
because unlike cancer cells, you haven't got
a lot of conflicting mutations,
and a lot of background of many changes across the genome.
These cells can be precisely formed,
can be precisely stimulated, and you can
look at these responses in vitro and in vivo.
So if you really think about the immune system,
it's actually perfect for epigenetics.
Every cell in the immune system
needs to know who it is, where it is,
what it's seen, and what it's going to need to see.
And if you think about that, that's going
to be epigenetically imprinted.
And you can see that from a lot of different people's work,
it's actually become very apparent
that at each of these cell decision points
there's a complex interaction between
transcription factors, epigenetic machinery,
and chromatin remodelers, to allow
the stable memory decisions to be made.
One of the other things that we've learned
is that much of the variation that's associated with disease
actually doesn't happen within coding regions.
As we've started to be able to map
enhancers and distal regulatory regions,
and this is work done by Murano and colleagues,
where they took genome-wide association studies and said,
where is the variation happening that's associated
with a predisposition to particular diseases.
More than 60% of it was actually happening
in enhancers very far away from the actual genes.
And what you see is that much of that variation
actually now starts to fall into these enhancer regions,
which are only active, which are
only open, in particular cell types.
So they are cell-type specific regulatory regions,
suggesting that immune cell identity is epigenetic,
and often immune cell dysfunction
is likely also to be epigenetic as well.
So there are many, many different mechanisms
associated with epigenetic regulation of gene expression,
and they range from everything from
modification of the DNA bases themselves,
like cytosine methylation, they involve
non-coding RNAs, but the area that
we've been focused on is really
the post-translational modification of these histone tails.
So when DNA is tightly wrapped
around the histones, these tails stick out
and they can be chemically modified with tags,
which can either be acetylation,
phosphorylation, methylation, etc.
Those chemical tags essentially function
to form mechanisms to allow the marking of sets of genes,
to essentially tell them when they should be on,
when they should be repressed,
or when they need to be expressed
in response to particular stimuli.
And those marks are added by what we call the writers,
they're removed by sets of enzymes
that we call the erasers, and they're read
by proteins that recognize those marks,
and then assemble particular transcriptional complexes
in response to the stimuli that I mentioned before.
The really interesting thing in the whole area
of epigenetics is the degree of progress
that's been made in identifying and progressing
molecules into clinical development.
And you know that there are pan-DNMT inhibitors
that are licensed for the treatment
of a number of different leukemias.
These are non-selective DNMT1, 2 and 3 inhibitors.
Very recently there's been the exciting approval
of the IDH2 selective inhibitor for,
again, for the treatment of different leukemias.
And you'll know that there are a number
of pan-HDAC inhibitors that are approved, again,
for the treatment of different
myeloid leukemias and lymphomas.
So that first generation of molecules
were characterized by being non-selective,
pan-DNMT or pan-HDAC inhibitors.
What we're starting to see, and we've been
involved with this, is actually the generation
of the second generation of epigenetic inhibitors,
which show greater selectivity,
and therefore are associated with better tolerability.
And one of the most dramatic observations
and learnings that we've had over the last few years is,
almost as you'd predict, as we make
more selective inhibitors, the sets of genes
that you regulate are much more defined.
And many people's expectations on epigenetics
have been based actually on an understanding
of these non-selective inhibitors.
And what we're seeing with these new inhibitors is,
as we make them better, as we target them better,
as we make them more selective,
we're actually starting to see
very precise sets of genes being modulated.
And GSK and Horizon have taken the first
LSD1 inhibitors into the clinic,
epitherapeutics have generated
the first inhibitors of the JARIDs,
we generated the first JmjD3/Utx inhibitors,
which show very nice and selective
modulation in the immune system.
We've actually been able to use
this targeting technology that allows us
to deliver HDAC inhibitors just into
monocytes and macrophages, that's allowed us
to take a pan-HDAC into patients
with rheumatoid arthritis, and we generated
the first-ever PAD4 selective inhibitors
that we've partnered with BMS via Padlock.
In terms of the writers, Episyme
have made some great progress in taking
the first DOT1L inhibitors into the clinic.
GSK, Epizyme and Constellation have taken the first
DZH2 inhibitors into the clinic,
and there's some really impressive efficacy data
being reported in patients with mutant follicular lymphomas.
And GSK has taken the first PRMT5 inhibitor,
in the next few weeks you're going to hear
some news about another PRMT inhibitor
that's just about to move into the clinic.
In terms of the readers, I'll talk a little bit
about some of the work that we've done
with BET, but there's also been a whole range
of different reader inhibitors
that have been generated,
have started to be characterized, and again,
are showing really surprisingly
selective effects on gene transcription.
So I've talked a bit about the readers,
so lysine residues on histone tails can be
post-translationally modified,
and if we think about the acetyl code,
those acetylation marks are added
by histone acetyletranferases,
they're removed by the histone deacetylases,
and those post-translational marks are read
by these bromodomain-containing proteins.
Contrary to everybody's expectations,
we were actually able to develop and identify
very selective BET bromodomain inhibitors
that just inhibited BRD2, 3 and 4,
and T actually had no effect across the whole family
of bromodomain-containing proteins,
which many people had not anticipated,
given that they were just recognizing
a very simple post-translational modification.
We were able to show that those inhibitors
bound into the binding pocket,
where the acetyl lysine residue would normally sit,
and actually function as a competitive antagonist.
And a result of that, actually we've characterized
in cancer cells and taken the first of those inhibitors
into Phase 2 studies in breast cancer and prostate cancer.
And we'll come back and talk about
the data in the next few years.
I'm going to talk today more about the work
we've been doing, as I mentioned,
in the immune system using these.
And we've been able to show that
BET proteins turn out to be really important
in modulating immune cell dysfunction, and we've shown this,
and other people have now confirmed this.
I'm going to talk a bit about the work
we've done in macrophages.
So working with Sasha Tarakhovsky at the Rockefeller,
we take mouse bone marrow-derived macrophages,
differentiate them in vitro, and treat them
with LPS, which is a TRL4 agonist,
which makes those cells think there's an infection going on.
They turn on about 800 genes after four hours,
and to our surprise, what we saw
was that actually only 150 of those genes
were regulated by the presence of the compound.
If you look to see where the BET proteins are,
across the genome, it's present on thousands of genes.
And the knockouts had told us that
it was going to affect thousands of genes,
and everybody's expectation was that inhibiting
these proteins would have global
catastrophic effects on transcription.
We were really surprised to see
a really select set of genes being modulated
by these inhibitors, and we were able to show
at the promoters of those genes,
that those compounds were preventing
the recruitment of these proteins
to those enhancers and promoters,
and that inhibition was a correlating
with our ability to regulate that gene expression.
It turns out that that subset of genes
that we were affecting actually
turn out to be really important.
If you give a high enough dose of LPS
to mice, you induce a sepsis-like syndrome.
Those mice develop a massive cytokine storm,
their temperature drops, their fur ruffles,
and then within about 24-48 hours
all of those mice are dead.
What we found was that a single dose
of the I-BET compound given either
90 minutes before LPS, or even more remarkably,
90 minutes after LPS, after the primary
response genes had already started
to be induced, we were able to keep
all of those mice alive, suggesting that
the subset we were affecting was actually
a really physiologically important set of genes.
So what were they?
So if you look at the genes that are induced,
what we saw, as I mentioned earlier,
when you see all these primary response genes
come on very rapidly in response to LPS,
none of those were affected by the presence of the compound.
In the same cells, the same concentration of compound,
was selectively affecting 95% of these
secondary response genes.
And those secondary response genes
turn out to be really important,
because many of these, that we know from studies
in the immune system, turn out to be
really important for driving autoimmunity
and pathological immune cell function.
So we've actually accidentally discovered
that inhibitors of BET proteins can modulate
sets of genes that turn out to be
important in the immune system.
And now you can actually do some reverse translation.
You can actually now take some of these molecules
that we've developed to take into the clinic,
to start to explore fundamental aspects of biology.
Can you use these now to start to dissect
aspects of gene transcription?
So again, now looking at macrophages,
if you stimulate them with this TLR4 ligand,
you can actually look genome-wide to see
all of the enhancers that are being turned on
in response to that stimulation,
and what you see is that this mark,
this dimethyl mark is being added
as those enhancers are being stabilized and formed.
There are a number of genes that are being turned off,
where that mark disappears, and what you see,
what we found was that actually
that enhancer formation and stabilization
actually required transcription of those enhancers.
If we blocked the transcription with these BET inhibitors,
you could actually stop these enhancers being formed.
There was a beautiful correlation
of the enhancer RNA expression, and the distal genes
that are regulating, suggesting that these
distal enhancers were actually coordinating
transcription of the enhancer and the gene body.
And that inhibition of transcriptional elongation
prevents enhancer stabilization.
So you can start to explore new aspects of biology.
As you'd hope, if we then go into in vivo models
of immune cell activation, if we take
an I-BET compound and put it into a rat
collagen-induced arthritis model,
what you do is you inject an adjuvant
plus collagen protein, you activate
the immune system and then the rat's immune system,
now starts attacking the joints.
You get inflammation in the joints and bone damage.
You can then measure that clinical score,
and what we found was actually just treating
the compound for the first ten days,
was actually able to epigenetically reset,
and those rats never go on to develop disease.
We also found that if you waited 10 days,
and then started treatment once the immune activation
had already started, that was also able
to completely reverse the development of arthritis,
and also worked in a different model of arthritis,
where you do a serum transfer model.
Consistent with that exciting pre-clinical
biology, I'm pleased to say we've now
been able to take a BET inhibitor
that we can target to monocytes and macrophages.
So in addition to the molecules we've got
progressing in oncology studies,
we've been able to take the first BET inhibitors
in to patients with rheumatoid arthritis,
psoriasis, and lupus, using this targeting technology.
And we'll be able to come back in a few years
and tell you about the progress in that space there.
So I hope I've been able to share with you
some of the excitement, and how
epigenetics, which started in cancer,
where cancer cells forget who they are,
and when to stop dividing, to the immune system,
where immune cells who normally need to know
who they are and what they need to fight
actually forget what self is versus foreign is,
and how actually that's a huge new frontier
for the application of epigenetics.
Can we use epigenetics to retrain the immune system
to actually fight autoimmunity and inflammatory diseases?
And we're starting to see actually,
probably the next frontiers are going to be
metabolic disease, and neuroscience,
again, cells that need to remember who they are,
and where they are, and just remember.
And those are the areas that we think
epigenetics is moving in to.
We think epigenetic mechanisms are going to be important
in allowing the very precise control of gene expression.
I've shown how some of these epigenetic inhibitors,
as well as being able to progress into the clinic,
actually allow us to identify exciting
therapeutic opportunities for modulating gene biology.
Those compounds actually allow us
to dissect new areas of biology,
to start to understand epigenetic mechanisms
at the cell, the gene, and the tissue level.
And as I'll have mentioned at the beginning,
since we started our epigenetics effort in 2012,
we've now been able to advance seven different
epigenetic molecules into clinical development.
And that is quite exciting for a whole new era of science,
to actually translate fundamental scientific
research into clinical exploration.
And with that I will stop, and thank you.
(audience applauding)