Horizon Therapeutics has reported positive top-line data from the MIRROR randomised controlled trial (RCT) where Krystexxa (pegloticase injection) in combination with methotrexate met the primary endpoint.

The PEGylated uric acid specific enzyme Krystexxa is indicated to treat chronic gout in adults refractory to conventional therapy.

The Methotrexate to Increase Response Rates in Patients With Uncontrolled GOut Receiving Krystexxa trial (MIRROR RCT) was conducted in 152 subjects with chronic gout refractory to conventional therapies (uncontrolled gout).

It was designed to assess the use of Krystexxa in combination with methotrexate to help patients achieve a durable response to therapy.

During the trial, the participants were randomised and given methotrexate or a placebo for four weeks.

Later, they were treated with Krystexxa with the immunomodulator methotrexate or Krystexxa with placebo for 52 weeks.

The top-line data showed that the subjects treated with Krystexxa monotherapy have maintained serum uric acid (sUA) <6mg/dL at least 80% of the time in month six, the trial’s primary goal.

Horizon research and development executive vice-president Elizabeth Thompson said: “It is rare that you can improve a response rate so substantially for patients; by 30 percentage points in this case based on the results of our trial.

“These results reinforce what we have seen from published case series, as well as our open-label trial evaluating Krystexxa with methotrexate.

“Horizon has invested significantly over the last several years to ensure more uncontrolled gout patients are able to benefit from KRYSTEXXA and we continue to develop new approaches that target the underlying cause of gout.”

Based on significant improvement in response rate, the company plans to submit a supplemental biologics licence application to the US Food and Drug Administration in the first quarter of next year.