New Scientist - USA (2019-10-05)

6 | New Scientist | 5 October 2019

IF STANDARD treatments for

cancers fail, doctors sometimes

prescribe drugs that haven’t been

approved for that particular

cancer type. In the Netherlands,

this is now being done as part of

a new kind of trial, so we can get a

better idea of which drugs work for

what cancers – and which don’t.

The results from the first

215 people show that a third of

them saw some benefit from the

“off-label” use of drugs. One or two

had a complete remission, says

Emile Voest at the Netherlands

Cancer Institute in Amsterdam.

Knowing about failures is just as

important, because then we can

prevent people who may not have

long to live from being given drugs

that won’t help them and could

have nasty side effects.

A new drug goes through an

approval process for treating a

specific disease, such as a certain

kind of breast cancer. Once a

drug is approved for one purpose,

doctors can prescribe it for

another, although often insurers

won’t pay for off-label use.

This is typically done on an

ad-hoc basis. One doctor will

decide which drug, if any, might

help a patient who has run out

of other options. But there is no

systematic way of reporting the

outcomes to help other doctors

in similar situations.

The approach can help some

people, but it can also go horribly

wrong. In the 1980s, some heart

drugs were widely used off-label in

the US. Later trials suggest that this

caused 50,000 premature deaths.

So Voest and his colleagues

have set up a more rational way of

using off-label drugs for cancers.

The starting point is to sequence

the whole genomes of tumours

in people for whom standard

treatments have failed, and to

use that information to identify

drugs that might help them.

For example, several drugs have

been approved to treat breast

cancers with a mutation that

makes them produce excessive

amounts of a growth factor called

HER2. Some other cancer types

also produce lots of HER2, so these

drugs might work for them too.

In the trial, a person with a

particular tumour type is assigned

a drug that might help. Similar

patients are assigned the same

drug, until eight people have tried

it. If no one benefits, no more

people with that tumour type

will be given that drug. If at least

one benefits, more patients are

enrolled to see if others benefit

too (Nature, doi.org/db5z).

In the Netherlands, the trial

has been set up with the help

of hospitals, charities and

pharmaceutical companies,

which are donating the drugs

free of charge. The number of

patients now exceeds 1000.

Several other countries are

adopting the protocol, including

Canada, Denmark and Italy.

The findings of the trial

should still be checked by proper

randomised controlled trials,

says Voest. But the results have

already led to health insurers

in the Netherlands agreeing to

pay for an off-label use of one

drug even though this hasn’t

been approved by the European

Medicines Agency. ❚

“In recent years, false

rumours on WhatsApp

have spread at an

alarming speed”

Michael Le Page

CA

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News

Trying drugs intended for

other cancers can extend

a person’s life

Social media

WhatsApp limits

slow, but don’t stop,

spread of fake news

LIMITS on the number of times

a WhatsApp message can be

forwarded to other people slow

the spread of fake news, but the

restrictions don’t seem to curtail

the most shareable content.

More than 60 billion messages

are sent on WhatsApp daily, and

in recent years false rumours have

spread at an alarming speed. These

have included conspiracy theories,

anti-vaccination misinformation

and rumours about child abductors.

Fabrício Benevenuto at the

Federal University of Minas Gerais,

Brazil, and his colleagues looked at

the spread of information in public

groups in Brazil, India and Indonesia

dedicated to political discussions.

The researchers tracked how

784,000 unique images were

shared by users in the 60 days

before and 15 days after the recent

general elections in each of the three

countries. They found that 80 per

cent of the images stopped being

shared after two days, but some

continued to crop up more than two

months after their first appearance.

In January, WhatsApp introduced

a limit that meant content could

only be forwarded to five users

or groups at a time. By running

simulations, Benevenuto and his

team found that the five-forward

limit slowed the spread of content

by one order of magnitude. For

example, if a piece of content would

ordinarily take five days to reach

an entire network, the limit would

slow the spread to 50 days.

But this delay depended on the

virality of the content – how likely

users were to share an image after

seeing it. For highly viral content,

the limits weren’t effective in

preventing it from quickly reaching

a large portion of the network

(arxiv.org/abs/1909.08740).

WhatsApp told New Scientist that

the five-forward limit has cut the

number of forwarded messages

on the platform by 25 per cent. ❚

Donna Lu

Medicine

Repurposing cancer drugs

Treating cancers with medicines for other tumours sometimes works