Scientists have developed a holy grail cancer drug that kills all solid cancer tumors while leaving other cells unharmed. The new molecule targets a protein present in most cancers that helps tumors grow and multiply in the body.

It is significant because this protein – the proliferating cell nuclear antigen (PCNA) – was previously thought to be ‘undruggable’. The drug was tested on 70 different cancer cells in the lab – including those derived from breast, prostate, brain, ovarian, cervical, skin, and lung cancer – and was effective against them all.

The pill is the culmination of 20 years of research and development by the City of Hope Hospital in Los Angeles, one of America’s largest cancer centers.

The medicine is codenamed AOH1996 after Anna Olivia Healy, who died in 2005 from a deadly childhood cancer aged nine. Dr Linda Malkas, who leads the research team, met Anna’s father just before she died and was inspired to find a cure in her memory.

It comes amid excitement that cancer will be curable within the coming decade, a claim that has been made by the scientists who invented the Pfizer Covid vaccine.

Curing cancer has also been a key goal of President Joe Biden — with his relaunched Cancer Moonshot operation in 2022 aiming to reduce the cancer death rate by half in the next 25 years.

But he was slammed last week for claiming that his administration had ‘ended cancer as we know it’ – even though there are signs death rates are slowing.

The latest study, published in the journal Cell Chemical Biology, revealed that the new drug had been tested on more than 70 cancer cell lines and several normal human cells that did not have cancer but were used as a control.

The molecule selectively killed cancer cells by disrupting their normal reproductive cycle, preventing cells with damaged DNA from dividing, and stopping the replication of faulty DNA. This combination of factors caused the cancer cells to die without harming healthy cells in the process.

The results will now need to be replicated in people. The drug is currently being tested on humans in a Phase 1 clinical trial at City of Hope.

Dr Linda Malkas, professor in City of Hope’s Department of Molecular Diagnostics and Experimental Therapeutics and the M.T. & B.A. Ahmadinia Professor in Molecular Oncology leads the team.

She explained how the molecule selectively disrupts DNA replication and repair in cancer cells, leaving healthy cells unaffected. She said: ‘Most targeted therapies focus on a single pathway, which enables wily cancer to mutate and eventually become resistant. ‘PCNA is like a major airline terminal hub containing multiple plane gates.