The US Food and Drug Administration (FDA) has granted Calliditas Therapeutics’ immunoglobulin A (IgA) nephropathy (IgAN) drug Tarpeyo (budesonide) a priority review for a decision on granting it a “full approval”.

The FDA previously granted the drug accelerated approval as the first therapy for the treatment of IgAN, in December 2021. The agency has now set a prescription drug user fee act (PDUFA) date for this supplemental new drug application (sNDA) application of 20 December 2023.

The FDA accepted Calliditas’s sNDA for the drug based on the full data set from the Phase III NefIgArd clinical study (NCT03643965). Patients treated for nine months with Tarpeyo showed a significant reduction of approximately 30%, in the urine protein-to-creatinine ratio compared with the placebo group.

The trial also met its primary endpoint of estimated glomerular filtration rate (eGFR), as the therapy demonstrated a significant kidney protective effect over the placebo.

Tarpeyo is an oral glucocorticoid anti-inflammatory agent that suppresses the gut immune system. This allows the drug to reduce proteinuria in adults with primary IgAN at risk of rapid disease progression. The drug was previously being developed under the brand name Nefecon, with the company renaming the novel targeted-release formulation of the drug as Tarpeyo. This formulation comprises a 4mg enteric-coated capsule, designed to remain intact until it reaches the patient’s ileum.

In the 18 August press release announcing the priority review, Calliditas’ CEO Renee Aguiar-Lucander said: “The significant eGFR treatment benefit observed across the entire study population provides further evidence that TARPEYO can be disease-modifying, potentially significantly delaying the need for dialysis or kidney transplantation for patients at risk.”

IgAN is a kidney disorder caused by a build-up of antibodies in the kidney tissue. This can cause the kidneys to gradually fail, requiring some patients to undergo dialysis, or in severe cases, kidney transplants. The condition mostly develops between the late teens and late 30s.

Calliditas is also working with its European partner, STADA Arzneimettel, to push a European Commission approval of the drug under the brand name Kinpeygo, following its 2022 European conditional authorisation. The Sweden-headquartered company also received conditional approval for the treatment from the UK’s Medicines and healthcare products regulatory agency (MHRA) in February 2023.