A new chemotherapy drug has been found to “annihilate” solid tumours, leaving healthy cells intact, in early research.
The “cancer-killing pill” attacks a protein which encourages tumours to grow by aiding DNA replication and the repair of cancerous cells.
That protein, called proliferating cell nuclear antigen (PCNA), was once considered too challenging to target.
The drug, called AOH1996, was named after a child – Anna Olivia Healy, born in 1996 – who died when she was only nine after being diagnosed with a rare childhood cancer neuroblastoma.
The breakthrough was made by researchers at the City of Hope in California, one of the largest cancer research and treatment organisations in the US.
Professor Linda Malkas and her team, who spent two decades developing the drug, said targeted chemotherapy appears to “annihilate” all solid tumours in preclinical research.
She said: “PCNA is like a major airline terminal hub containing multiple plane gates.
“Data suggests PCNA is uniquely altered in cancer cells, and this fact allowed us to design a drug that targeted only the form of PCNA in cancer cells.
“Our cancer-killing pill is like a snowstorm that closes a key airline hub, shutting down all flights in and out only in planes carrying cancer cells.”
It was tested in more than 70 cancer cell lines and found to selectively kill cancer cells by disrupting the normal cell reproductive cycle, according to the research centre.
It works by preventing cells with damaged DNA from dividing and replicating, causing the death of cancer cells, but it does not affect healthy stem cells.
The professor called the results “promising” but made clear that research has found AOH1996 can suppress tumour growth in cell and animal models, and the first phase of a clinical trial in humans is under way.
The first patient received the potentially cancer-stopping pill in October with the phase one clinical trial still continuing and expected to last for at least two years.
Patients are still being recruited for the trial.
Researchers are also still examining mechanisms that make the drug work in animal studies.
Lead author of the study, Long Gu, said: “No one has ever targeted PCNA as a therapeutic because it was viewed as 'undruggable', but clearly City of Hope was able to develop an investigational medicine for a challenging protein target.”
“We discovered that PCNA is one of the potential causes of increased nucleic acid replication errors in cancer cells.
“Now that we know the problem area and can inhibit it, we will dig deeper to understand the process to develop more personalised, targeted cancer medicines.”
The study – titled “Small Molecule Targeting of Transcription-Replication Conflict for Selective Chemotherapy” – was published in the Cell Chemical Biology journal.