BBC_Earth_Singapore_2017

“THIS VIRAL IMMUNOTHERAPY

APPEARS TO BE MORE POTENT THAN

OTHERS THAT HAVE BEEN BEFORE”

Update

THE LATEST INTELLIGENCE

PHOTOS: SCIENCE PHOTO LIBRARY X2 ILLUSTRATION: DAN BRIGHT

ABOVE: Immunotherapy uses

the body’s immune system to

tackle disease. Here, a T-cell

(purple) has been engineered

to attack a cancer cell (red)

Update

THE LATEST INTELLIGENCE

A team has created designer viruses that help the immune system target

tumours. One of the researchers, Prof Daniel Pinschewer, describes this new

approach to cancer therapy

What is ‘immunotherapy’?

Chemotherapy uses a chemical not normally

present that’s toxic and more deadly to cancer

cells than to other cells. Radiotherapy involves

dosing ionising radiation onto cancerous parts. In

contrast, immunotherapy describes any approach

that leverages the body’s own defence system in

combating cancer. There are several different

types of immunotherapy. The most commonly

known is antibodies that are injected – they

unleash the immune system. This takes the foot off

the brake, so the lukewarm response the body

usually mounts against cancers gets intensified.

But this is not specific, so any response is

strengthened, including responses that can make

you sick. That’s a downside.

How does your therapy work?

We haven’t yet trialled in humans, but the

approach we’re pursuing is to give a patient a virus

that causes an infection like a common cold. The

virus is equipped with a component of the tumour

that a patient – or in our case, the tumour-bearing

mouse – had. That creates awareness in the

defence system. Our immune defence has been

shaped over millions of years to fight viruses and

bacteria, and now it gets to see a piece of the

cancer in this context, so it will launch a fierce fight

against all the elements it sees as a virus. It treats

cancer cells as if they were virus-infected.

Which virus do you use?

We’re using lymphocytic choriomeningitis, a virus

that almost exclusively infects mice. It can be

accidentally transmitted to humans and normally

only causes a common cold-like illness, so

nothing serious. It’s not dangerous to an extent

that one could not justify giving it to a cancer

patient. However, we have engineered these

viruses to be ‘attenuated’, which means their

ability to make mice sick is reduced. Therefore, the

virus grows more slowly than the wild virus would.

Which cancers could you target?

In principle any cancer could be targeted, but for

each type you have to tailor-make a virus. You

need to identify a target, a molecular hallmark of

that cancer, then build it into your virus. We know

there are specific components that identify

cancers and would not be present in normal cells,

otherwise you would instruct your defence to

attack a healthy tissue of your body. Then we