A Melbourne-led research team is reporting a 25 per cent success rate in preliminary trials of a new cancer drug.

Melbourne mother Catherine Ringwood felt like she was staring down the barrel of a gun when told her leukaemia was back more savage than before.

The only thing the doctors could say was that they were sorry. There was no cure.

Two years later the proportion of her bone marrow with leukaemia present has fallen from 85 per cent to five per cent.

The 63-year-old former nurse feels as if she has been touched by a miracle.

She is not the only one.

Melbourne-led clinical trials of a drug to treat chronic lymphocytic leukaemia (CCL) are being hailed as unprecedented.

Almost a quarter of participants, all of whom had been told there was no cure for their disease, have had all traces of leukaemia eradicated from their system.

A further 61 per cent have experienced some remission, despite having failed an average of four previous treatment regimes, and there is hope for further improvement.

Ms Ringwood’s doctors believe she may be able to achieve full remission.

“Even if I don’t get a complete remission, getting rid of us much disease as possible can only benefit me,” she says.

“We could be very lucky.”

The drug, ABT-199, is a non-toxic oral pill that patients could potentially take indefinitely.

Peter MacCallum Cancer Centre consultant haematologist Constantine Tam said it targeted the cancer cells’ “death machinery”.

“It’s better than anything else that we’ve tried in recent memory,” Dr Tam said.

“We don’t like to use the word terminal but that’s essentially what they are; all of a sudden we’ve got 84 per cent responding and responding well.

“They go back to normal life.”

The successful trial, led by researchers at the Peter MacCallum Cancer Centre, The Royal Melbourne Hospital and the Walter and Eliza Hall Institute for Medical Research, has implications for other cancer treatments.

Haematology Service chair at the Peter MacCallum Cancer Centre John Seymour said there had been “extremely exciting effectiveness” of the ABT-199 compound in laboratory models when combined with other cancer treatments.

“We certainly feel there is potential for therapies similar to this to enter clinical development as complementary therapies for these diseases,” Prof Seymour said.