The experiments were carried out by a British and American scientists, including scientists from the University of Leeds and University of Surrey.
The therapy switches off genes that fuel tumours known as glioblastomas (GBMs).
Fewer than half of sufferers survive beyond a year of being diagnosed.
The British and US team created a cocktail of chemicals that target the 'Hox' mutations.
Project leader Professor Hardev Pandha, of the University of Surrey, said: "People who suffer from glioblastomas have a five per cent survival rate over a five-year period - a figure that has not improved in decades.
"While we are still early in the process, our seven-year project offers a glimmer of hope for finding a solution to Hox gene dysregulation,which is associated with the growth of GBM and other cancers, and which has proven to be elusive as a target for so many years."
The peptide named HTL-001 contains short chain amino acids - the building blocks of proteins.
Ironically, Hox genes are responsible for the healthy growth of brain tissue. They are ordinarily silenced at birth after vigorous activity in the embryo.
If they are inappropriately 'turned on' again, it can lead to the progression of cancer. Hox gene dysregulation has long been recognised in GBM.
Brain tumours are rare. Glioblastomas affect an estimated one in 30,000 people. They develop when cells supporting nerves in the brain begin to divide uncontrollably.
Surgery is the main treatment. About 40 percent of patients survive beyond a year - and just 17 percent more than two years.
Co author Professor Susan Short, of the University of Leeds, said: "We desperately need new treatment avenues for these aggressive brain tumours.
"Targeting developmental genes like the HOX genes that are abnormally switched on in the tumour cells could be a novel and effective way to stop glioblastomas growing and becoming life threatening."
Hox genes have been linked to a host of common cancers ranging from bowel, breast, ovaroian and cervical to leukaemia.
The HTL-001 peptide is suitable for patient trials after passing safety tests, said the researchers. They are now being considered for glioblastomas and other cancers.
James Culverwell, CEO of University of Surrey start up HOX Therapeutics, said the breakthrough reported in BMC Cancer is exciting.
He added: "We hope with our continuing support, this research will eventually lead to novel and effective treatments for both brain and other cancers where HOX gene over-expression is a clear therapeutic target."