The US Food and Drug Administration (FDA) has accepted a design change of part B of Calliditas Therapeutics’ NefIgArd trial evaluating Nefecon in IgA Nephropathy (IgAN), a chronic autoimmune kidney disorder.

Nefecon is a two-step, locally acting formulation that combines a time lag effect involving the concentrated release of budesonide, the active substance, in a specific target area.

The pivotal Phase III NefIgArd study is comparing the drug’s effect on proteinuria to that of placebo in IgAN patients at around 140 sites across 19 countries.

The FDA’s acceptance of the change to the confirmatory part B of the trial includes a two-year eGFR-based endpoint. It cuts the study duration from six to approximately three and a half years.

“We are extremely pleased with the outcome of our interactions with the FDA.”

In addition, the trial size decreases from a total of 450 participants across parts A and B to 360, in turn positively affecting overall costs and enrolment time.

The acceptance from the US regulator also provides Calliditas with an option to launch a rollover for a repeat-dosing study after patients complete the NefIgArd study.

Calliditas Therapeutics CEO Renée Aguiar-Lucander said: “We are extremely pleased with the outcome of our interactions with the FDA, which will have a very positive impact on the conduct of our pivotal study.

“This is great news for patients as well, as it will enable us to complete the confirmatory part of the trial in a timely manner without potential impact on patient access to the marketed drug. It also has a significant benefit with regards to the overall cost and timelines of the programme.”

The first patient in the NefIgArd study was dosed last November. Top-line results from 200 dosed participants are expected to be available in the second half of next year.

If the trial yields positive data, the company plans to obtain regulatory approvals for Nefecon.