The Japanese Pharmaceuticals and Medical Device Agency (PMDA) has granted approval for Partner Therapeutics’ Leukine (sargramostim) for inhaled use in treating autoimmune pulmonary alveolar proteinosis (aPAP).

This is the first regulatory approval of an inhaled recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) product for this indication.

In Japan, Leukine is branded as Sargmalin and was licensed to Nobelpharma in 2022 for certain indications.

Leukine is a glycosylated recombinant human GM-CSF produced by recombinant DNA technology in yeast.

Partner Therapeutics will execute the manufacturing of Sargmalin for Nobelpharma at its facility in Lynnwood, US.

The approval is based on the findings from the multicentre, randomised, double-blind, placebo-controlled Phase II PAGE study.

It assessed Leukine in 64 subjects with mild to moderate aPAP.

Subjects were randomised in a 1:1 ratio to receive either Leukine 125μg or a placebo twice a day for seven days, followed by seven days off, over 12 cycles of two weeks.

The trial demonstrated a significant improvement on the primary endpoint, which was the improvement in the alveolar-arterial oxygen gradient from baseline to week 25.

Subjects treated with Leukine also showed greater improvements in serum biomarker secondary endpoints, including KL-6, CEA and monocyte chemoattractant protein-1.

Partner Therapeutics CEO Robert Mulroy stated: “We are grateful to Nobelpharma for their partnership, as well as their deep commitment to making this treatment available to aPAP patients in Japan.

“It has been a pleasure working with their team and we look forward to ensuring the availability of Sargmalin. We also deeply appreciate the commitment of the many patients and doctors who participated in the investigator-initiated clinical trial led by Dr Nakata of Niigata University.”