Disc Medicine has reported positive initial data of 15 subjects enrolled in an ongoing Phase II trial of bitopertin for the treatment of erythropoietic protoporphyria (EPP) and X-linked protoporphyria (XLP).

The parallel-arm, randomised, open-label Phase II BEACON study is designed for evaluating changes in levels of protoporphyrin IX (PPIX) in patients with EPP or XLP.

It has also assessed the safety and tolerability of bitopertin, quality of life of patients and their tolerance to sunlight.

Up to 22 patients were enrolled from sites in Australia and randomised to receive either bitopertin 20mg or 60mg given once daily for 24 weeks.

They also have an option to continue in an open-label extension of the study lasting for an additional 24 weeks.

At both dose levels, bitopertin was found to be well-tolerated and no serious adverse events were reported.

Disc Medicine chief medical officer Will Savage said: “We are excited to share these initial data from the BEACON trial, where we observed consistent and sustained suppression of PPIX, the disease-causing metabolite in EPP, in patients treated with bitopertin.

“Importantly, this reduction translated into significant improvements in the time that patients can spend in sunlight without reporting pain or symptoms related to their disease.

“We’re encouraged by the data and plan to present additional data at the end of the year.”

Bitopertin inhibits glycine transporter 1 (GlyT1) that modulates heme biosynthesis and supports erythropoiesis.

Disc is also investigating bitopertin in EPP patients in an ongoing placebo-controlled, randomised, double-blind Phase II AURORA trial.