A Wellington teenager with inoperable brain cancer has lost consciousness, just as a major fundraising effort has come to an end. 

Jemima Gazley, 15, was diagnosed with stage 4 brain cancer in February. 

She underwent months of treatment, including radiotherapy and an experimental drug from Germany, before the cancer was found to be growing again. 

Eternally optimistic and resourceful, Jemima suggested a Givealittle page to support research in the field of her specific cancer. 

"I'm not smart enough to find a cure myself but I am smart enough to advocate for it," she said. 

The page was accepting donations for one week, and had raised a total of $358,369 when it closed at midnight on Sunday. 

The money raised will be going towards the work of Dr Matt Dun, Associate Professor at Newcastle University in Australia. 

But at 9pm Sunday, just hours before the Givealittle page stopped accepting donations, Jemima's family posted an update, saying the teenager's health had taken an unexpected turn that morning. 

Her dad Oliver Gazley said she was unconscious at home, surrounded by her family, and supported by doctors and nurses from Mary Potter Hospice. 

'While she's not in pain, we don't expect her to see Matt receive the funds — however, she is aware of the rough amount that has been raised and has read almost every message that was sent. 

"Thank you for every kind word, thought, prayer, dollar and cent. You've helped this girl change the world. She was both flying and floored at the energy you've all shared with her. What a special gift we have shared this week. 

"We are deeply grateful to each of you, and as many of you have said; well and truly proud of what Jemima has achieved with her 'work on earth'." 

Gazley said the fundraising effort had given Jemima a legacy she didn't know was waiting for her. 

"It's given meaning to the senseless. Power and hope where there wasn't much before."