Stockholm-based biopharma company Calliditas Therapeutics AB (NASDAQ: CALT) (NASDAQ Stockholm: CALTX) (Calliditas) disclosed on Tuesday that it has entered into an exclusive license agreement with Viatris Pharmaceuticals Japan Inc, a subsidiary of Viatris Inc (NASDAQ: VTRS), to register and commercialise Nefecon, a specialty drug to treat chronic autoimmune kidney disease Immunoglobulin A Nephropathy (IgAN) in Japanese patients.

Calliditas added that Nefecon was recently approved in Europe and the US for the treatment of IgAN, which is also known as Berger's disease. This is a rare and serious progressive autoimmune disease in which results in up to 50% of patients at risk of developing end stage renal disease and then requiring dialysis or a kidney transplant.

According to the terms of the agreement, Calliditas is entitled receive an initial upfront payment of USD20m upon signing and up to an additional USD80m in pre-defined development and commercialisation milestones.

In addition, Viatris will pay mid-teens percentage royalties on net sales.