Hutchmed, the Hong Kong-based drug developer, said the US Food and Drug Administration has granted orphan drug designation to sovleplenib for primary immune thrombocytopenia (ITP).
ITP is an autoimmune disorder in which the immune system destroys platelets, the blood cells that help clotting, raising the risk of bleeding and bruising.
Sovleplenib is an oral, once-daily drug that blocks spleen tyrosine kinase (Syk), a protein involved in the immune process that destroys platelets.
What orphan status means
The FDA gives orphan status to treatments for rare diseases, defined as those affecting fewer than 200,000 people in the US.
If the drug is approved for the designated condition, it becomes eligible for seven years of US market exclusivity, which blocks rivals from selling the same drug for the same use.
Orphan status also brings tax credits for qualifying clinical trials, waivers of FDA user fees and specialist regulatory guidance during development.
The designation does not mean the drug has been approved, and it does not signal any view by the FDA on whether it works.
Patient numbers and next steps
Hutchmed estimates that about 110,000 people in China have primary ITP, along with 56,000 in the US, Germany, France, Italy, Spain, the UK and Japan.
It said many patients develop resistance to existing treatments and relapse, leaving a significant group in need of new options.
In China, regulators are reviewing applications for sovleplenib in primary ITP and in warm antibody autoimmune haemolytic anaemia, a condition in which the immune system destroys red blood cells.
The applications are backed by positive results from two pivotal trials, ESLIM-01 and ESLIM-02.
Hutchmed retains all worldwide rights to the drug.
The announcement gave no timetable for US trials or a filing.
