A new drug that targets a cancer cell’s ability to repair its DNA has shown “encouraging” results in its first patient trial.
In a study designed to asses the safety of the medicine, researchers found cancer to stop growing in half of the patients who were given berzosertib, which belongs to a new class of drugs known as ATR inhibitors.
ATR inhibitors work by blocking the function of a protein called ATR, which helps cancer cells fix damaged DNA.
The team also found tumours to disappear completely in two of the patients.
The researchers said it is unusual to see a clinical response at early stage of the trial, the findings of which are published in the Journal of Clinical Oncology.
Study author Professor Johann de Bono, head of drug development at The Institute of Cancer Research, London, and The Royal Marsden NHS Foundation Trust, said: “Our new clinical trial is the first to test the safety of a brand new family of targeted cancer drugs in people, and it’s encouraging to see some clinical responses even in at this early stage.”
While damage to the DNA in cells is thought to be the main cause of cancer, finding ways to prevent cancer cells from bring able to repair their DNA can stop the disease from spreading.
In the phase I trial, the scientists at The Institute of Cancer Research, London, and The Royal Marsden NHS Foundation Trust, gave berzosertib, either on its own or with chemotherapy, to 40 patients with very advanced tumours.
They were able to establish the doses at which the drug was safe for use in further clinical trials, and discovered berzosertib on its own caused only mild side effects.
The scientists also found berzosertib stopped tumours growing in half of patients given the drug, either on its own, or with chemotherapy.
The drug’s benefit was even more marked in patients who also received chemotherapy, with 15 of 21 patients seeing their disease stabilise, the researchers said.
One patient with advanced bowel cancer saw his tumours disappear and was able to stay cancer free for more than two years after taking berzosertib on its own.
Another woman with advanced ovarian cancer, whose disease had come back after treatment with another drug, saw her tumours shrink after receiving berzosertib alongside chemotherapy.
Professor Paul Workman, chief executive of The Institute of Cancer Research, said: “Targeting a cancer’s ability to repair its DNA is a fundamentally important avenue of cancer research which has delivered some of the most important advances against the disease in recent years.
“It’s exciting to see the first clinical trial of a drug targeting a key player in the DNA repair process have such promising results, and I look forward to the results of further studies testing the benefit of this new family of targeted treatments.”
The drug is now moving forward in further trials and the researchers hope it can be developed into a new targeted treatment for patients.