Key Moments
- RAPT Therapeutics Inc (NASDAQ:RAPT) surged 63.6% after GSK plc (LON:GSK) agreed to purchase the company for $58 per share in an all-cash deal valuing RAPT at $2.2 billion.
- The acquisition centers on RAPT’s anti-IgE antibody ozureprubart, now in Phase IIb development for prophylaxis against multiple food allergens, with Phase IIb prestIgE data expected in 2027.
- Separately, GSK said Shionogi & Co will buy Pfizer’s 11.7% stake in ViiV Healthcare for $2.125 billion, lifting Shionogi’s interest to 21.7% while GSK retains a 78.3% holding.
RAPT Shares Jump on Premium Takeover Offer
RAPT Therapeutics Inc (NASDAQ:RAPT) saw its stock price soar 63.6% on Tuesday after GSK plc (LON:GSK) unveiled an agreement to acquire the biotechnology company. Under the terms of the proposed transaction, GSK will pay $58 per share in cash, assigning RAPT an equity value of $2.2 billion.
After factoring in RAPT’s cash position, the net value of the deal is estimated at approximately $1.9 billion.
Strategic Rationale: Expanding in Food Allergy Treatments
The contemplated acquisition is designed to give GSK control of RAPT’s food allergy portfolio, led by its anti-IgE antibody ozureprubart. This asset is currently being evaluated in a Phase IIb program aimed at preventing reactions to multiple food allergens, including peanut, milk, egg, cashew, and walnut.
GSK emphasized potential advantages of ozureprubart relative to currently approved options such as Xolair. According to the company, ozureprubart may allow for less frequent administration, with dosing every 8-12 weeks instead of every 2-4 weeks as with Xolair. In addition, GSK noted that ozureprubart can be used in patients with high IgE levels or higher body weight who do not qualify for Xolair therapy.
The company also stated that ozureprubart has four times higher affinity than Xolair and is capable of removing bound IgE.
Clinical Development and Market Opportunity
Ozureprubart’s Phase IIb prestIgE trial is expected to deliver results in 2027. Beyond food allergy, the antibody has generated supportive clinical data in Chronic Spontaneous Urticaria. Phase II results from China indicated numerically higher response rates versus Xolair after a single dose.
The food allergy space is described as a substantial commercial opportunity. The article noted that more than 17 million people in the U.S. have been diagnosed with food allergies, including about 6 million children. Roughly 40% of individuals with food allergies are allergic to more than one food, and around half have experienced severe reactions.
Geographic Scope and Deal Structure
The proposed transaction does not encompass rights to ozureprubart and related programs in several territories. Rights for mainland China, Macau, Taiwan, and Hong Kong are specifically excluded from the acquisition.
| Transaction Component | Detail |
|---|---|
| Offer price per RAPT share | $58 |
| Implied equity value | $2.2 billion |
| Approximate net deal value (after RAPT cash) | $1.9 billion |
| RAPT share price reaction | 63.6% increase on Tuesday |
| Key asset | Anti-IgE antibody ozureprubart (Phase IIb) |
| Expected timing of Phase IIb prestIgE results | 2027 |
| Excluded territories | Mainland China, Macau, Taiwan, Hong Kong |
Details on Ozureprubart and Competitive Positioning
Within its food allergy strategy, GSK underscored specific attributes of ozureprubart that may help differentiate it from established therapies. In addition to the extended dosing interval of 8-12 weeks, the company pointed to the drug’s ability to target a broader patient population by including those with high IgE levels or higher body weight who are not candidates for Xolair.
GSK further highlighted that ozureprubart exhibits four times higher affinity than Xolair and can eliminate bound IgE, which the company views as a meaningful mechanistic feature.
Separate Deal: Shionogi Increases Stake in ViiV Healthcare
In a separate disclosure, GSK reported that Shionogi & Co has agreed to purchase Pfizer’s 11.7% holding in ViiV Healthcare for $2.125 billion. Following completion of this transaction, Shionogi’s interest in ViiV Healthcare will rise to 21.7%.
Despite the change in minority ownership, GSK will continue to hold a 78.3% majority stake in ViiV Healthcare.
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