Bupa sponsored it for 22 years before pulling out in 2014. Supermarket Morrisons stepped in last year.
Chief Executive at The Great Run Company, Mark Hollinshead, said he was confident of finding a sponsor and was in talks with some "ambitious" brands.
The annual half marathon will take place on 11 September.
The 13.1-mile (21km) race, which is thought to be the second largest for participation in the world, takes place between Newcastle and South Shields.
Mr Hollinshead said: "We have several interesting conversations underway with some very ambitious brands but we are not in a position to announce anything."
Leah Gillooly, a lecturer in marketing at Manchester University, said there were a lot of events competing for sponsors and event organisers had to choose carefully to avoid being associated with "undesirable" brands.
In 2013, Newcastle United caused controversy when it named pay-day loans company Wonga as its sponsor.
Ms Gillooly said: "The run is a fantastic event, but the sponsorship landscape is tricky with a lot of events competing for brands.
"Organisers are commercial so they do have an eye on profit, but it's important when selecting a sponsor that they don't just choose the one offering the most cash."
She also said events can go ahead without sponsors, but they would not make as much money to put towards future events.
Morrisons said the company had been glad to back the run, but it was "focusing on other ways to reach customers".
The Great North Run, which attracts more than 50,000 runners, is without a sponsor less than three months before the 2016 event takes place.