AstraZeneca’s hyperkalaemia treatment ZS-9 has suffered another setback on the path to US approval having been rejected by regulators for the second time.

The drug giant said the US Food and Drug Administration has issued a Complete Response Letter regarding the its resubmission for the condition, which is characterised by high potassium levels in the blood serum.

Specific reasons for the rejection were not revealed, but AZ did say that the CRL followed an inspection by the FDA of the ZS-9 (sodium zirconium cyclosilicate) manufacturing facility, and that it does not require the generation of any new clinical data.

The treatment, an insoluble, non-absorbed compound with a structure that was designed to preferentially capture potassium ions, was initially rejected by the FDA in May last year, on the back of certain manufacturing issues.

AZ said it remains dedicated to developing and commercialising ZS-9 for patients with hyperkalaemia, and is “confident in the profile of this potential medicine,” which it acquired through its acquisition of ZS Pharma for £2.7 billion in December 2015.

The medicine is yet to receive its first global approval; interactions with other health authorities in the European Union and Australia are ongoing, with decisions expected in the first half of 2017, the firm noted.

Circassia deal
Meanwhile, AZ also announced a strategic collaboration with respiratory biotech Circassia Pharmaceuticals for the development and commercialisation of chronic obstructive pulmonary disease (COPD) medicines Tudorza (aclidinium bromide) and Duaklir (formoterol/aclidinium) in the US.

Tudorza was approved and launched in the US in 2012, while Duaklir is expected to be submitted for US regulatory review some time next year.

Under the terms of the deal, Circassia will lead the promotion of Tudorza in the US and has been granted an option to gain the full commercial rights in the future, as well rights to Duaklir in the country.

In return, AZ stands to receive a minority equity stake in Circassia, and will complete ongoing development activities as well as manufacture and supply both medicines.

“Tudorza and Duaklir are important components of AstraZeneca’s respiratory franchise globally and this collaboration will support their commercialisation in the US for the benefit of the millions of COPD patients,” said Mark Mallon, executive vice president, Global Product & Portfolio Strategy at AZ, explaining the strategy behind the move. “It also further sharpens our focus on Symbicort, Bevespi Aerosphere, benralizumab and other respiratory development programmes”.