On the day of Brunton's third wedding anniversary in January he discovered a hard lump on his abdomen.
With no prior health concerns, the 41-year-old decided to take no risks and booked an appointment with his doctor that afternoon.
Brunton was diagnosed with an aggressive stage 4 diffuse large B-cell non-Hodgkin lymphoma, a type of blood cancer.
Initially his prognosis was positive, with doctors giving him a 90 per cent chance of beating the disease but eight months down the track his survival rate has dropped to 10 per cent.
Brunton's body rejected chemotherapy and stem cell treatment was no longer an option.
"The only chance we have left is an immuno-therapy trial in the US but we are in a race against time," Brunton-Rennie said.
Father's Day had been extra difficult this year, Brunton-Rennie explained.
"He just opened his Father's Day gifts and we were all just crying because part of us is scared and the other part of us is just extremely hopeful."
On Wednesday their baby daughter Sage will turn 1.
"She's daddy's girl, and deserves to grow up with her Dad," friend Emma Mildon wrote on the Givealittle page.
The ground-breaking CAR-T treatment is yet to surface in New Zealand but clinical trials are being held in Boston in the United States.
The way the treatment works is the immune cells - known as the T cells - are taken out and are genetically engineered into "killer cells" which takes around three weeks before they are inserted back into the blood.
Next week Brunton will fly to Boston with his mother while his wife stays home to look after Sage.
"Given we get the green light from the consultation, I will join him for two weeks of the treatment while my mum looks after Sage here," Brunton-Rennie said.
Brunton-Rennie said she wanted to tell her story because in the short time-frame since her husband had been diagnosed she had meet so many other families going through the same thing.
