Thousands of potential stem cell donors have come forward after musicians including Ed Sheeran encouraged people to sign up to the register.
Blood cancer charity DKMS said around 4,000 additional people had signed up to its registry since the star and others backed an appeal for a seven-year-old cancer patient who is desperately searching for a matching donor.
In July, the musician posted a picture of himself holding a piece of paper with the phrase "#JoinforJasmi" to encourage people to sign up to the registry.
Adam 'Ad Rock' Horovitz from the Beastie Boys, musician Frank Turner and former Nizlopi duo John Parker and Luke Concannon - who rose to fame when their JCB song topped the charts in 2005 - have also backed the campaign.
Jasmi Lindberg Cooke, from Bury St Edmunds, Suffolk, has been battling acute lymphoblastic leukaemia for three years.
Following a relapse she is in hospital receiving chemotherapy and radiotherapy.
Charity DKMS said the youngster "urgently" needs to find a matching blood stem cell donor to give her the best chance of survival.
Despite an influx of potential donors, a match for Jasmi has still not been found.
Sheeran, who grew up in Suffolk, said: "Each year around 2,000 people living with a blood cancer are searching for a lifesaver. It only takes a few minutes to sign-up as a potential blood stem cell donor.
"That's why I'm supporting the #JoinForJasmi appeal. Please register for your home swab kit at dkms.org.uk and you'll go on standby to give someone like Jasmi a second chance of life."
Jasmi's mother, Rena Cooke, said: "We are so grateful to everyone that has supported the #JoinForJasmi campaign.
"It's fantastic that so many people have registered to become a potential blood stem cell donor for Jasmi and others affected by blood cancer and in need of a transplant.
"It's heartbreaking to watch your child go through something like this but all the love and support has helped to keep us strong.
"We hope that we find her matching donor soon - if you haven't registered please do so today."
Joe Hallet, senior donor recruitment manager at DKMS, added: "The #JoinForJasmi campaign has given us a great platform to raise awareness of blood cancer and Jasmi's urgent search plus increase the numbers on the registry.
"If you are aged between 17-55 and in general good health please register online today for a home swab kit at dkms.org.uk and go on standby to help save someone living with a blood cancer."
:: To find out more visit: dkms.org.uk or call 020 8747 5620.