BioMarin Pharma Issues Updated Phase 1/2 Data On BMN 673 In Breast Cancer

(RTTNews) - BioMarin Pharmaceutical Inc. (BMRN) announced an update on the ongoing Phase 1/2 study for its poly ADP-ribose polymerase or PARP inhibitor, BMN 673, for the treatment of solid tumors.

In the most currently available data presented today at the European Cancer Congress 2013 from the ongoing Phase 1/2 study, among 14 gBRCA breast cancer patients treated at the dose of 1mg/day selected for the Phase 3 study, the confirmed RECIST response rate was 50% (7 confirmed objective responses: 1 complete and 6 partial). In addition, there were 5 patients with stable disease lasting at least 24 weeks for an overall clinical benefit response rate at this dose of 86% (12/14).

The company stated that median progression-free survival or PFS has not yet been reached for the gBRCA breast cancer patients. It is anticipated that the median PFS will exceed 6 months in this heavily pre-treated patient population.

In the complete cohort of 18 gBRCA breast cancer patients, which included 6 patients from the dose escalation cohort at doses ranging from 900 µg to 1100 µg and 12 patients from the dose expansion cohort at a dose of 1.0 mg, the RECIST response rate was 44% or 8 of 18 patients with 1 complete and 7 partial responses. The clinical benefit rate was 72% or 13 of 18 patients with 5 patients having stable disease in excess of 24 weeks. Treatment is ongoing in 9 of the 18 breast cancer patients in the study.

At all doses (n=18) there has been a best response of partial response or better in 12 patients, and four patients progressed prior to confirmation. Of the 14 patients treated at 1mg, there has been a best response of partial response or better in 8 patients, and one patient progressed prior to confirmation.

According to the company, BMN 673 was generally well-tolerated. The dose-limiting toxicity was thrombocytopenia. Myelosuppression was generally mild-to-moderate in severity. Greater than grade 1 anemia, thrombocytopenia and neutropenia occurred in 25%, 20% and 12.5% of patients, respectively, with chronic dosing. Fatigue, nausea and alopecia were observed in 26-29% of patients. Signs of activity were seen as low as 100 µg/day, and the maximum tolerated dose was 1.0 mg/day, which is the expected dose for further development. BMN 673 also has good bioavailability and a long half-life which supports once daily dosing.