Calliditas Therapeutics has received full approval from the US Food and Drug Administration (FDA) for Tarpeyo (budesonide) delayed-release capsules in adult patients with primary immunoglobulin A nephropathy (IgAN).

The approval pertains to the use of the drug to mitigate the loss of kidney function in primary IgAN patients at risk of disease progression, regardless of their proteinuria levels.

Calliditas Therapeutics CEO Renee Aguiar-Lucander said: “We are thrilled that adult IgAN patients at risk for progression in the United States can now have access to this pioneering treatment option that could help preserve their kidney function and, hence, impact the progression of their disease.”

Based on the surrogate marker of proteinuria, the FDA had first approved Tarpeyo under accelerated approval in December 2021. In August 2023, the B-cell immunomodulator was given priority review for the full approval.

Tarpeyo, a delayed-release oral formulation of budesonide at 4mg, is engineered to stay intact until it reaches the ileum. Featuring coated beads of budesonide, each capsule selectively targets mucosal B-cells in the ileum, including those in the Peyer’s patches, responsible for producing galactose-deficient IgA1 antibodies (Gd-Ag1) associated with IgA nephropathy.

Its standard FDA approval has been driven by data from the Phase 3 NefIgArd clinical trial conducted by Calliditas Therapeutics. This randomised, double-blind, multicentre study evaluated the efficacy and safety of Tarpeyo, administered at 16mg once daily.

The drug was compared to a placebo in adult patients with primary IgAN, alongside optimised renin-angiotensin system inhibitor (RASi) therapy.

In the trial, Tarpeyo demonstrated a statistically significant and confirmed benefit over placebo in estimated glomerular filtration rate (eGFR) during a two-year period, encompassing nine months of treatment with the B-cell immunomodulator plus optimised RASi or placebo, followed by optimised RASi, with a 15-month off-drug follow-up.

The substantial reduction in proteinuria achieved with Tarpeyo plus RASi at nine months proved durable and was maintained throughout the 15-month off-drug period.