Dive Brief:
- A Phase 2 study has shown "clinically meaningful" platelet count improvements for a variety of of primary immune thrombocytopenia (ITP) patients treated with Argenx's investigational therapy efgartigimod.
- Based on those topline results, Argenx is moving efgartigimod for ITP into Phase 3 development, and intends to start a Phase 2 trial testing subcutaneous administration of the drug for ITP. Another mid-stage trial is pegged for the first half of 2019 and will evaluate efgartigimod in chronic inflammatory demyelinating polyneuropathy, the drug's fourth tested indication.
- In a Monday statement, Argenx also announced an underwritten U.S. public offering of American Depositary Shares (ADS), with an offering in Europe only to qualified investors, worth around $300 million.
Dive Insight:
When Argenx released topline Phase 1/2 data for efgartigimod for generalized myasthenia gravis (gMG) last December, along with Phase 1/2 data for cusatuzumab in leukemia and lymphoma, its share price shot up to an all-time high of $43.25.
The biotech's stock trading at prices more than twice that now. Following news of the fresh Phase 2 data, shares rose 5% to $98.65 apiece by market's open Monday — though they fell back down to around $90 apiece by late morning Tuesday.
Primary immune thrombocytopenia (ITP) is a chronic and progressive autoimmune disorder affecting around 16,000 patients in the U.S. Current therapies include corticosteroids, plasmapheresis and TPO-receptor agonists, but there is still a need for better therapies.
"The variability seen across patients makes a one-size-fits-all treatment approach very difficult and current therapies come with significant side effects," said Adrian Newland, a principal investigator of the Phase 2 proof-of-concept trial for efgartigimod in ITP, in a statement.
Efgartigimod is the fragment crystallization region of an antibody known as IgG1, and is being developed for the treatment of IgG-mediated autoimmune diseases like ITP. Though Argenx has been quick to tout the drug's "differentiating features," there are several other new ITP therapies to contend with.
Rigel Pharmaceutical has Tavalisse (fostamatinib), which gained Food and Drug Administration approval in April. There's also Dova Pharmaceutical's Doptelet (avatrombopag), which is pending an additional approval for ITP, and Protalex's PRTX-100, which is in Phase 1/2 in Europe and the U.S.