Around 200 low-paid NHS workers have seen their rent nearly double since their accommodation was sold to developers.
Barts and the London Charity sold part of its staff quarters in 2012 to developers who raised the rent for a one bed flat from £565 to £675 and in July will raise it again to £900.
Hospital administrator Silvia de Vanna says the sharp increase will leave her struggling to afford food after she's paid her bills and travel costs but a lack of housing in the area will make it hard to find alternative and affordable accommodation.
Around 400 people have signed a petition urging the landlord to stagger the rent increase.
They fear a long-term problem for NHS workers who will continue to struggle as living costs rise and their wages remain frozen.
The landlord intends to redevelop Claire Alexander House, Kent House and Dawson House next to the Royal London Hospital in Tower Hamlets in 2016.
Silvia is a coordinator in a cancer unit and like other people who live in the flats she is on a low wage.
Previously she was able to manage because the rent was subsidised by the charitable Trust which owned the property.
Then two years ago everything changed - the block of flats Silvia lives in and other properties were sold by the charity to a private developer.
Soon afterwards the rent went up by £110 but the real shock came with a second increase a year later.
Silvia and the other tenants were due to pay the increase from next month.
Now the managing agent has come up with a deal - which the owners still have to ratify -where the rent will stay at the current rate until July to give them time to look for more affordable housing.
The flats are on prime land close to Canary Wharf and the tenants feel they are being priced out of the capital and away from their jobs: an issue which will be raised increasingly more often as rents in the capital continue to rise.