Mrs Maynard said the group had been set up after she had attended an all-party parliamentary group, where she had heard stories from people with brain cancer or those who had lost loved ones to the disease.
She said in 2015/2016, 120,000 people signed a petition and the government at the time “was very supportive” of it.
“But has that change happened? No, and the funding hasn’t materialised yet,” she said.
“There are a lot of people who are deeply frustrated.”
Mrs Maynard was diagnosed with glioblastoma – one of the hardest brain tumours to treat. The survival rate remains stubbornly low and the standard treatment in the UK has not changed in decades.
Much of that is due to a lack of research, which Mrs Maynard and her brother, Witney MP Charlie Maynard, are trying to change.
She has been to see research at the Centre for Medicines Discovery at Oxford University. and said she was “hopeful” there would be some significant new treatments in the next five years.