Baby Bohdi Higginson became the first person in the world to join a clinical trial of a new drug for a rare form of epilepsy.
Bohdi, aged eight months, was diagnosed with KCNT1-related epilepsy in February, a rare and often fatal paediatric disease.
Mum Stephanie Higginson said he was having up to 70 seizures a day.
When he started the drug trial on April 21 with an antiseizure medication called ABS-1230, he was on two milligrams a day.
His seizures continued.
"I just hugged Bohdi and told him mumma was here," said Mrs Higginson, of Mannering Park, a suburb on Lake Macquarie's southern shore.
Three days later, doctors increased the medication to five milligrams twice a day.
"I held my boy and begged for this medication to work," Mrs Higginson said.
"Bohdi's last seizure was at 7.58pm that day. He has been seizure-free ever since.
"He's a changed little boy. He will not stop chatting and moving his legs. His head control is 100 times better."
Before Bohdi's rare epilepsy took hold, he was "kicking, babbling and smiling".
"Over two to three months, he stopped it all," Mrs Higginson said.
"He was just laying in bed. He wouldn't move or smile. He barely opened his eyes. He was sedated because the anti-epilepsy medication was so potent."
Mrs Higginson said receiving his diagnosis was "absolutely devastating".
"I was in pure shock. My husband Ian and I tried for 10 years to have a baby," she said.
Since the drug had worked, Bohdi was "a changed little boy".
"It's incredible. He will not stop chatting and moving his legs. His head control is 100 times better," she said.
"He's lost the ability to suck a bottle. He still has a nasal tube in, but he's starting to have puree food.
"He can sip a bit of milk out of a sippy cup."
The clinical trial includes a long-term extension for participants like Bohdi who benefit from the drug.
"He takes five milligrams twice a day every day. If it keeps working, he will continue that for the rest of his life," Mrs Higginson said.
Bohdi will need occupational, physio and speech therapy to help him recover further.
A GoFundMe titled "Bohdi's brave fight" has been established to help his recovery.
Before Bohdi participated in the drug trial, Stephanie and Ian Higginson tried 15 different medications for their son at Westmead Children's Hospital.
None of them worked.
Dr Kavita Kothur, his neurologist at Westmead, searched hard for any new treatments.
"She contacted professors and doctors around the world to try to see what worked for another child," Mrs Higginson said.
She discovered the clinical trial with ABS-1230, a drug developed by a San Diego-based biotech company called Actio Biosciences.
The Higginsons were eager to join the trial, with Bohdi becoming the first person to be administered this medication in the world.
"I was absolutely petrified for Bohdi, but the alternative was scarier. I don't want to lose my son," Mrs Higginson said.
The drug was accepted into a US Food and Drug Administration regulatory process to help develop therapies for ultra-rare genetic diseases.
It was also approved in Australia for Bohdi.
Actio Biosciences chief executive David Goldstein said in May that the drug "directly targets the underlying genetic driver of disease".
Pre-clinical data gave the company "confidence in its potential to meaningfully reduce seizure burden".
Justin West, co-founder and president of the KCNT1 Epilepsy Foundation, said the drug trial "represents real progress and renewed hope".
"For families in this community, including mine, the focus each day is simple and urgent: keeping our children alive," Mr West said.
