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This is a talk about sugar and cancer.

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I became interested in sugar
when I was in college.

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Not this kind of sugar.

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It was the sugar that our biology
professors taught us about

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in the context of the coating
of your cells.

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Maybe you didn't know that your cells
are coated with sugar.

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And I didn't know that, either,

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until I took these courses in college,

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but back then --

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and this was in, let's just
call it the 1980s --

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people didn't know much about why
our cells are coated with sugar.

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And when I dug through my notes,
what I noticed I had written down

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is that the sugar coating on our cells
is like the sugar coating

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on a peanut M and M.

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And people thought
the sugar coating on our cells

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was like a protective coating

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that somehow made our cells
stronger or tougher.

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But we now know, many decades later,

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that it's much more complicated than that,

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and that the sugars on our cells
are actually very complex.

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And if you could shrink yourself down
to a little miniature airplane

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and fly right along
the surface of your cells,

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it might look something like this --

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with geographical features.

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And now, the complex sugars
are these trees and bushes --

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weeping willows that are
swaying in the wind

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and moving with the waves.

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And when I started thinking about
all these complex sugars

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that are like this foliage on our cells,

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it became one of the most interesting
problems that I encountered

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as a biologist and also as a chemist.

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And so now we tend
to think about the sugars

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that are populating
the surface of our cells

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as a language.

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They have a lot of information
stored in their complex structures.

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But what are they trying to tell us?

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I can tell you that we do know
some information

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that comes from these sugars,

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and it's turned out already
to be incredibly important

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in the world of medicine.

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For example, one thing
your sugars are telling us

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is your blood type.

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So your blood cells, your red blood
cells, are coated with sugars,

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and the chemical structures of those
sugars determine your blood type.

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So for example, I know
that I am blood type O.

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How many people are also blood type O?

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Put your hands up.

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It's a pretty common one,

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so when so few hands go up,
either you're not paying attention

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or you don't know your blood type,
and both of those are bad.

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(Laughter)

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But for those of you who share
the blood type O with me,

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what this means is that we have
this chemical structure

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on the surface of our blood cells:

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three simple sugars linked together
to make a more complex sugar.

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And that, by definition, is blood type O.

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Now, how many people are blood type A?

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Right here.

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That means you have
an enzyme in your cells

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that adds one more building block,

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that red sugar,

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to build a more complex structure.

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And how many people are blood type B?

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Quite a few.

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You have a slightly different enzyme
than the A people,

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so you build a slightly
different structure,

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and those of you that are AB

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have the enzyme from your mother,
the other enzyme from your father,

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and now you make both of these structures
in roughly equal proportions.

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And when this was figured out,

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which is now back in the previous century,

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this enabled one of the most important
medical procedures in the world,

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which, of course,
is the blood transfusion.

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And by knowing what your blood type is,

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we can make sure,
if you ever need a transfusion,

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that your donor has the same blood type,

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so that your body
doesn't see foreign sugars,

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which it wouldn't like
and would certainly reject.

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What else are the sugars on the surface
of your cells trying to tell us?

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Well, those sugars might be telling us
that you have cancer.

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So a few decades ago,

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correlations began to emerge
from the analysis of tumor tissue.

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And the typical scenario is a patient
would have a tumor detected,

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and the tissue would be removed
in a biopsy procedure

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and then sent down to a pathology lab

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where that tissue would be analyzed
to look for chemical changes

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that might inform the oncologist
about the best course of treatment.

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And what was discovered
from studies like that

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is that the sugars have changed

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when the cell transforms
from being healthy to being sick.

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And those correlations have come up
again and again and again.

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But a big question in the field
has been: Why?

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Why do cancers have different sugars?
What's the importance of that?

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Why does it happen, and what
can we do about it if it does turn out

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to be related to the disease process?

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So, one of the changes that we study

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is an increase in the density
of a particular sugar

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that's called sialic acid.

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And I think this is going to be
one of the most important sugars

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of our times,

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so I would encourage everybody
to get familiar with this word.

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Sialic acid is not
the kind of sugar that we eat.

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Those are different sugars.

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This is a kind of sugar
that is actually found

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at certain levels on all
of the cells in your body.

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It's actually quite common on your cells.

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But for some reason,

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cancer cells, at least in a successful,
progressive disease,

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tend to have more sialic acid

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than a normal, healthy cell would have.

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And why?

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What does that mean?

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Well, what we've learned

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is that it has to do
with your immune system.

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So let me tell you a little bit
about the importance of your immune system

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in cancer.

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And this is something that's, I think,
in the news a lot these days.

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You know, people are starting
to become familiar with the term

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"cancer immune therapy."

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And some of you might even know people

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who are benefiting from these very new
ways of treating cancer.

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What we now know
is that your immune cells,

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which are the white blood cells
coursing through your bloodstream,

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protect you on a daily basis
from things gone bad --

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including cancer.

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And so in this picture,

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those little green balls
are your immune cells,

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and that big pink cell is a cancer cell.

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And these immune cells go around
and taste all the cells in your body.

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That's their job.

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And most of the time, the cells taste OK.

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But once in a while,
a cell might taste bad.

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Hopefully, that's the cancer cell,

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and when those immune cells
get the bad taste,

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they launch an all-out strike
and kill those cells.

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So we know that.

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We also know that if you can
potentiate that tasting,

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if you can encourage those immune cells
to actually take a big old bite

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out of a cancer cell,

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you get a better job protecting
yourself from cancer every day

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and maybe even curing a cancer.

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And there are now a couple of drugs
out there in the market

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that are used to treat cancer patients

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that act exactly by this process.

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They activate the immune system

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so that the immune system
can be more vigorous

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in protecting us from cancer.

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In fact, one of those drugs

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may well have spared
President Jimmy Carter's life.

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Do you remember, President Carter
had malignant melanoma

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that had metastasized to his brain,

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and that diagnosis is one
that is usually accompanied by numbers

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like "months to live."

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But he was treated with one
of these new immune-stimulating drugs,

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and now his melanoma
appears to be in remission,

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which is remarkable,

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considering the situation
only a few years ago.

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In fact, it's so remarkable

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that provocative statements like this one:

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"Cancer is having a penicillin moment,"
people are saying,

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with these new immune therapy drugs.

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I mean, that's an incredibly bold thing
to say about a disease

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which we've been fighting for a long time

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and mostly losing the battle with.

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So this is very exciting.

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Now what does this have to do with sugars?

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Well, I'll tell you what we've learned.

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When an immune cell snuggles
up against a cancer cell to take a taste,

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it's looking for signs of disease,

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and if it finds those signs,

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the cell gets activated and it launches
a missile strike and kills the cell.

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But if that cancer cell has a dense forest
of that sugar, sialic acid,

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well, it starts to taste pretty good.

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And there's a protein on immune cells
that grabs the sialic acid,

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and if that protein
gets held at that synapse

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between the immune cell
and the cancer cell,

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it puts that immune cell to sleep.

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The sialic acids are telling
the immune cell,

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"Hey, this cell's all right.
Nothing to see here, move along.

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Look somewhere else."

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So in other words,

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as long as our cells are wearing
a thick coat of sialic acid,

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they look fabulous, right?

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It's amazing.

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And what if you could strip off that coat

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and take that sugar away?

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Well, your immune system

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might be able to see that cancer cell
for what it really is:

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something that needs to be destroyed.

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And so this is what we're doing in my lab.

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We're developing new medicines

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that are basically
cell-surface lawnmowers --

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molecules that go down
to the surface of these cancer cells

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and just cut off those sialic acids,

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so that the immune system
can reach its full potential

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in eliminating those cancer
cells from our body.

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So in closing,

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let me just remind you again:

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your cells are coated with sugars.

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The sugars are telling cells
around that cell

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whether the cell is good or bad.

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And that's important,

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because our immune system needs
to leave the good cells alone.

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Otherwise, we'd have autoimmune diseases.

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But once in a while,
cancers get the ability

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to express these new sugars.

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And now that we understand

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how those sugars mesmerize
the immune system,

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we can come up with new medicines
to wake up those immune cells,

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tell them, "Ignore
the sugars, eat the cell

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and have a delicious snack, on cancer."

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Thank you.

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(Applause)