Incyte (Incyte (INCY)) is making a big bet on a rare bleeding disorder. The company announced Monday it will acquire Vega Therapeutics, a wholly owned subsidiary of Star Therapeutics, for $1.25 billion upfront. If certain sales milestones are hit, the total deal value could reach $2 billion.

The centerpiece of the acquisition is VGA039, a novel monoclonal antibody designed to modulate Protein S and improve hemostasis—basically, it helps the body control bleeding. The drug is currently in Phase 3 development for von Willebrand disease (VWD), the most common inherited bleeding disorder. About 135,000 people in the U.S. have been diagnosed with VWD, which can cause excessive bleeding that varies in severity and frequency, significantly affecting quality of life.

VGA039 has the potential to be the first subcutaneous (under-the-skin) prophylactic treatment for VWD patients. That's a big deal because existing therapies often require frequent intravenous infusions, which are less convenient. If approved, VGA039 could offer a much more patient-friendly option.

Incyte CEO Bill Meury said the drug fits perfectly with the company's strategy of building a long-term growth business. He called VGA039 a first-in-class Phase 3 program with encouraging early data, a manageable development pathway, and the potential to become a meaningful growth contributor within Incyte's hematology franchise.

The drug has already received Breakthrough Therapy, Fast Track, orphan drug, and rare pediatric disease designations from the FDA, which signals regulatory support and could speed up development. VGA039 is now in the Phase 3 VIVID-6 study, a global single-arm crossover trial evaluating its safety and efficacy as a prophylactic treatment for bleeding in patients with all forms of VWD.

Analysts are bullish on the deal. William Blair wrote that VGA039 fits well into Incyte's hematology franchise and offers a relatively de-risked Phase 3 asset with blockbuster commercial potential in the 2030s. Analyst Matt Phipps noted that even with conservative assumptions around pricing and market penetration, VGA039 has a clear path to a more than $1 billion market opportunity.

Investors seem to agree. Incyte shares were up 3.01% at $103.67 on Tuesday, reflecting optimism that this deal could pay off handsomely down the road.