The author Michael Rosen has backed a campaign to "save" Stratford Circus.
Newham Council is planning to use the venue in Theatre Square as a base for its flagship arts centre for young people.
Stratford Arts Trust - which used to run Stratford Circus - lost its fight to remain at the site in November.
Now the council is tendering for new management to provide opportunities for young people in culture, creativity and the arts.
When run by the trust, Stratford Circus offered a broader range of professional and community arts projects, alongside a youth arts programme.
Mr Rosen said: "I support this campaign to save Stratford Circus. I’ve read and performed there many times, providing theatre and readings for adults and schoolchildren.
"Stratford Circus offers people a fantastic range of cultural events and must not be taken away from them."
A town hall spokesperson said: "Over the last decade the council has seen its funding from central government halved whilst dealing with the most serious public health emergency in living memory.
"An expectation [it] will reverse a decision made last year using funds it does not have is unrealistic."
A protest is to be held at Theatre Square from 1pm on Saturday, August 28. It is part of a campaign led by the north and east London general branch of Equity, the performing arts practitioner s' union.
Blue Sky Actors - a theatre company for actors with learning disabilities and difficulties who were based at Stratford Circus - also backs the action.
Its artistic director, Ray Downing, said: "We and our communities have lost our home but not our hope. We will continue to fight for our right and tell our truth."
Campaigners say the council's focus on youth provision will reduce access to the arts for older people who are working class, disabled or members of the black, Asian and minority ethnic communities.
Equity is calling on Newham Council to make a fully functioning arts centre with a broad range of professional, community and youth arts part of the official bid requirements.
It wants the venue reopened and all displaced arts projects, including Blue Sky Actors, rehomed.
An online petition organised by Equity has gained more than 1,000 signatures.
The council spokesperson said it wants to increase capacity for local arts organisations "wherever possible".
He added a partnership with Theatre Royal Stratford East and any future operator will strengthen that ambition.
He said Newham is talking with arts organisations on using space at the venue and the mayor has offered to meet Equity.
"We have exciting plans for the future of performing arts as we wish to ensure all residents benefit from vibrant cultural programmes," he added.
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