BioMarin Pharmaceutical has reported preliminary data from an ongoing Phase I/II trial that seeks to evaluate poly ADP-ribose polymerase (PARP) inhibitor BMN 673 for the treatment of solid tumours.
Exhibiting substantial single-agent anti-tumour activity in deleterious germline BRCA ovarian and breast cancers, BMN 673 was well-tolerated in the trial.
The RECIST response rate was 44%, the CA-125 response rate was 70% and the clinical benefit response rate was 82% in the 28 gBRCA ovarian cancer patients, according to the data.
Around a 39% RECIST response rate and 67% clinical benefit rate were observed in the 18 gBRCA breast cancer patients.
The Royal Marsden NHS Foundation Trust honorary consultant in medical oncology, the Institute of Cancer Research, London, experimental cancer medicine professor Johann de Bono said there are no targeted treatment options for patients with germline BRCA-associated tumours.
"We have seen excellent anti-tumor activity in some of our patients treated with BMN 673," de Bono said.
Demonstrating Grade 3 thrombocytopenia as the dose-limiting toxicity, the study is continuing treatment in 12 of 18 breast cancer patients.
During the trial, six partial responses with three unconfirmed and one complete response were observed among the patients, while four ongoing patients demonstrated stable disease for less than 12 weeks.
With good bioavailability and a long half-life, BMN 673's signs of activity were seen with as low as 100µg/day and 1.0mg/day as maximum tolerated dose.
BioMarin chief medical officer Dr Hank Fuchs said; "We look forward to initiating a Phase III trial in metastatic gBRCA breast cancer patients to pursue a safe and effective therapy in a once-daily, oral dose that meets an unmet medical need in this aggressive form of cancer."
Given the positive preliminary data, a Phase III trial in metastatic gBRCA breast cancer is scheduled to commence in the fourth quarter of 2013.