A 13-year-old schoolgirl raised £92,000 in five days for her friend's life-saving cancer treatment.
Lillie Cotgrove, 13, was "devastated" when her best pal Lily Wythe, also 13, was diagnosed four months ago with the deadliest type of childhood cancer.
When treatment on the NHS ran out, Lily's family were told to "go home and make memories".
But they found two "promising" clinical trials in the United States to help treat Lily's cancer.
Determined Lillie then set up The One Pound Warriors - which has received a host of celebrity endorsements including Jonathan Ross, Rachel Riley, and Gemma Collins.
The One Pound Warriors has so far raised over half of the £300,000 needed to get Lily, from Benfleet, Essex, to the US, and pay for the clinical trials.
The fundraising page has raised £170,000 in total since it was set up nine weeks ago - with donations more than doubling since last Thursday alone, when the total stood at £78,000.
Lily's condition - a high-grade diffuse intrinsic pontine glioma (DIPG) - was diagnosed last year after a holiday in Malaga, where her parents noticed a change in her mood and she began slurring her words.
The survival prognosis for someone suffering Lily's brain tumour is just eight to 12 months.
Lily's mum, Diana Wythe, described her daughter's tumour as "unpredictable and aggressive".
But Diana said: "We had to do something, so we looked into promising clinical trials abroad.
"Our last chance to keep Lily alive is a pioneering clinical trial at Seattle Children's Hospital. But the medical costs will be at least £300,000.
"We started crowdfunding and by Thursday of last week the total stood at £78,000.
"Since Lillie's One Pound Warriors kicked in, the fundraising has gone crazy. Lily is blown away by it all. She can't believe that we're nearly there," Diana added.
And Lillie's mum, Sarah Cotgrove, added: "Lillie was devastated and heartbroken when she learnt that Lily had been told there was no more treatment for her after she had radiotherapy recently.
"She wanted to do something to help Lillie and I expected her to suggest something like a bake sale.
"But she came up with this idea to set up a Facebook group to help her young friend reach her crowdfunding goal, asking people to pay £1 to join."
Sarah added: "The ironic thing was that I had to set up the Facebook page for Lillie because she is too young to be on there."
The parents of both teenagers have been overwhelmed by the "phenomenal" response, which has included retweets and messages from celebrities including Jonathan Ross, Gemma Collins, and Keith Lemon.
And Gemma Collins shared the page on Sunday to her 1.3 million followers, writing: "Have a read, share and donate if you can."
Elsewhere, kind strangers have offered to donate their wages, a woman in Spain has given a villa holiday to be raffled, and a child undergoing cancer treatment has donated her Euro 50 birthday money.
Lillie's mum said: "The response was phenomenal with examples of people donating their wages.
"A scaffolder told us he would give what he earned that day and sent in £350.
"Children donated their birthday money or pocket money and we have had a number of touching stories from other brain tumour patients who have given what they can to help Lily (and Lillie).
"We never expected to be raising this kind of money from so many generous people."
She added: "Jonathan Ross's Tweet with all his followers retweeting caused my phone to crash!
"Lily is an absolute inspiration. If anyone can beat this horrible disease, she can."
And Lily's mum said: "Lily had a scan on Sunday and we will get the results in the next 10 days, which can then be sent to Seattle Children's Hospital to find out what the next move is.
"The money was originally going towards a trial called ONC201, a drug that suppresses the cancer and shrinks the tumour.
"But since Lily's diagnosis, a new trial has emerged called Brainchild03, which is Cart T Cells and is starting in March, price unknown at this time.
"This looks to be more promising than the drug ONC201, because Lily's own T Cells will recognise the cancer and keep it away.
"Depending on when we need to act, we will be joining one of these two trials."
National charity Brain Tumour Research are helping Lily and Lillie's family spread the word about The One Pound Warriors.
Hugh Adams, head of stakeholder relations at the charity, said: "It is just not acceptable that families who have loved ones affected by brain tumours are sent home and told to make memories.
"Parents like the Wythes are left having to resort to trawling the internet to find clinical trials to try to keep their children alive.
"We desperately need to increase the investment in research into brain tumours so that people don't have to resort to raising hundreds of thousands of pounds to access treatment abroad.
"It's only through research that we will find more effective treatments for brain tumour patients and ultimately a cure," he added.
To find out more about the campaign to fundraise for Lily's treatment, visit The One Pound Warriors page on Facebook, or go to: https://www.gofundme.com/f/help-lily-battle-brain-cancer.