Germline mutations of either BRCA1 or BRAC2 are particularly associated with an increased risk for breast and ovarian cancer. The initial results of a Phase I/II trial reported at the annual meeting of the American Society of Clinical Oncology indicate that a new drug, BMN-673, developed by BioMarin Pharmaceuticals in the United States, might be useful in the treatment of these often aggressive tumours.

There are 70 patients with various solid tumours that have or that are suspected of having BRCA mutations taking part in the clinical trial. The data so far indicate that the drug is well tolerated. Of the 25 patients with ovarian cancer taking part, 11 have had 30% or greater tumour shrinkage, according to response evalutation criteria in solid tumours, and 82% have shown clincial benefit (stable disease or better). Of the 18 patients with breast cancer, 12 have experienced clinical benefit, and seven have shown tumour shrinkage.

BMN-673 is an inhibitor of poly(ADP-ribose) polymerase (PARP), and as Johan De Bono of the Institute of Cancer Research, London, UK, a lead scientist on the study, said “Patients with germline BRCA-associated tumours have no targeted treatment options ... and PARP inhibitors offer that potential” ( Medical Daily , 3 Jun 2013).

Professor Nicola Curtin from the the Northern Institute for Cancer Research, Newcastle University, UK, added “BMN-673 is the most potent PARP inhibitor in clinical development. We saw evidence of PARP inhibition in samples from patients on very low doses of BMN-673” ( MedicalXpress.com , 6 Jun 2013).

As ever, a note of caution is required and this was provided by Dr Safia Danovi, from Cancer Research UK, who stated that “These early-stage results are encouraging, but we've got a long way to go before we know whether these drugs can be used to [effectively] treat cancer patients.” ( The Telegraph , 4 Jun 2013).