'Targeted' breast and ovarian cancer drug could have far wider application
Canadian researchers have shown that the 'targeted' cancer drug olaparib, which was developed to treat cancers caused by inherited faulty versions of the BRCA1 or BRCA2 genes, can also reduce the size of tumours in a substantial minority of ovarian cancer patients who do not carry these gene faults.
The study, published in Lancet Oncology, seems to suggest that the drug can be used to treat certain women with the more common 'sporadic' (non-inherited) form of ovarian cancer. In total, the disease affects about 6,500 women in the UK every year.
The drug blocks the activity of a protein called Poly (ADP-ribose) polymerase, or PARP, which along with the proteins made by the BRCA genes is involved in DNA repair.
Inhibiting PARP in a tumour cell that already lacks a BRCA gene prevents cancer cells from repairing their DNA, which boosts the effectiveness of chemotherapy and causes them to die.
The phase 2 drug trial was designed to find out how effective it is in treating those breast and ovarian cancer patients who do not carry the BRCA gene fault.
A total of 65 ovarian cancer and 26 breast cancer patients were prescribed 400mg of olaparib twice daily for four weeks. They were also sub-divided according to whether their tumours had faulty BRCA genes.
Approximately 41 per cent of ovarian cancer patients with BRCA faults experienced a significant reduction in the size of their tumour. This compared with 24 per cent of patients who&aposs cancers did not contain BRCA faults.
None of the breast cancer patients whose tumours had intact BRCA genes showed any response to the drug.
Henry Scowcroft, Cancer Research UK's science communication manager, said: "Since they were first developed, PARP inhibitors have shown increasing and expanding potential to treat cancer. These results suggest they may be useful as a treatment for women with ovarian cancer - but this was just an early-phase trial involving a relatively small number of patients so there&aposs still work to do.
"Thanks to the generous support of the public, Cancer Research UK scientists are playing a key role in the development of PARP inhibitors, and we're extremely encouraged to see them chalk up more experimental successes."
Copyright Press Association 2011