Some children with cancer are receiving a new type of drug treatment that is much less toxic than chemotherapy, the BBC reported.
11-year-old Arthur was one of the first to try it at London's Great Ormond Street Hospital to treat blood cancer.
His family calls the therapy "a little sunshine" because it works without making Arthur feel much worse.
And because it can be applied on the go, not just in the hospital, he spends more time at home with his family, enjoying more of what he loves.
He carried it with him in his backpack.
After chemotherapy fails to clear all of his cancer and leaves him very weak, blinatumomab or blina is the only real option for Arthur.
Blina is already licensed to treat adults with cancer, and experts hope to prove it can safely help children as well.
About 20 centers in the UK use it off-label to treat children with B-cell acute lymphoblastic leukemia (B-ALL).
The drug is an immunotherapy that seeks out cancer cells so the body's immune system can recognize and destroy them.
And this hunt is precisely targeted - healthy cells are not affected, unlike chemotherapy.
Blina comes in a bag of liquid that is administered through a thin plastic tube that remains in a vein in the patient's arm for many months.
A battery-powered pump controls how quickly the drug enters the bloodstream—one bag can last for days.
The entire set can be carried in a backpack smaller than an A4 textbook, making it completely portable.
For Arthur, this means he can do other things, like play on the swings at the local park, while the treatment takes place.
And unlike intense chemotherapy, which stopped working anyway, it didn't make him too weak.
Like other patients undergoing blina, before the start of the infusion, Arthur was given drugs that reduce the chance of serious reactions or side effects.
Initially, he had several bouts of fever and had to stay in the hospital for follow-up examinations.
But soon after, he managed to get home.
The rucksack stays with Arthur at all times, including in bed - and despite the noise of the pump, he manages to sleep soundly.
Chemotherapy has been tough on Arthur and switching to blina has been a relief, says his mother Sandrine.
"It was completely out of his control - we were living in a constant state of challenge as his body was being hit by the drugs," she said.
"We treated him by making him feel worse - that's very hard to take."
Around 450 children a year in the UK are diagnosed with Arthur's type of cancer.
Lead researcher and consultant pediatric haematology, Professor Ajay Vora, said: "Chemotherapies are poisons that kill leukemia cells, but they also kill and damage normal cells - and this is the reason for their side effects.
"Blinatumomab is a milder and gentler treatment."
Another drug for targeted immunotherapy has recently become available - chimeric antigen receptor T-cell therapy (CAR-T).
But it is more expensive and the patient's own cells must be taken and then changed in a laboratory before being given back as a drug, which takes time.
Thanks to all the treatment, Arthur's cancer is now gone.
Sandrine said: "We found out on New Year's that blina had worked and there was no cancer left - and that was just amazing and so we celebrated doubly." /BGNES