Shares of RAPT Therapeutics surged sharply on Tuesday after the biopharmaceutical company said it had agreed to be acquired by British drugmaker GSK in a deal valued at about $2.2 billion, giving the larger group access to a late-stage food allergy treatment.
RAPT stock jumped 64% to $57.41 in premarket trading, approaching the agreed offer price.
The shares had already gained strongly over the past year and were more than three times higher than a year ago through Friday’s close, reflecting growing investor optimism around its pipeline.
Terms of the deal
Under the terms of the agreement, GSK will pay $58 per RAPT share, representing an aggregate equity value of approximately $2.2 billion.
The transaction includes an upfront cash payment of $1.9 billion and is expected to close in the first quarter of 2026, subject to customary regulatory approvals and closing conditions.
The acquisition comes as large pharmaceutical companies increasingly seek to bolster pipelines through targeted acquisitions, particularly in areas with well-defined biological pathways and significant unmet medical needs.
RAPT, which was founded in 2015 and listed on Nasdaq in 2019, had a market capitalisation of about $972.7 million before the deal was announced, highlighting the premium GSK is willing to pay for its lead asset.
Food allergy drug at the centre of acquisition
The deal gives GSK control of ozureprubart, an antibody under development for the prevention of food allergies.
The drug targets immunoglobulin E, or IgE, a validated pathway in allergic disease, and could offer a more convenient alternative to existing treatments.
Current anti-IgE therapies typically require injections every two to four weeks.
Ozureprubart has the potential to reduce dosing frequency to once every 12 weeks, which could significantly ease the treatment burden, particularly for children.
It may also expand access to treatment for around 25% of patients who are currently ineligible for existing therapies.
“The addition of ozureprubart brings another promising new, potential best-in-class treatment to GSK’s pipeline,” said Tony Wood, GSK’s chief scientific officer.
Clinical progress and next milestones
The US Food and Drug Administration cleared RAPT’s investigational new drug application for ozureprubart in September, allowing the company to advance the treatment into a phase IIb food allergy trial.
In October, RAPT launched the prestIgE study, a randomised, double-blind, placebo-controlled trial evaluating ozureprubart as a standalone therapy.
Phase IIb data from the prestIgE trial are expected in 2027, with phase III studies planned in both adult and paediatric populations.
Food allergies affect more than 17 million people in the United States alone and lead to more than 3 million hospital and emergency visits each year, underscoring the commercial and clinical potential of new therapies.
Strategic fit for GSK
The acquisition strengthens GSK’s respiratory, immunology and inflammation pipeline, a key strategic focus for the company.
While the deal still carries development and regulatory risks, analysts see it as a calculated bet.
“This is exactly the sort of risk that GSK should be taking,” said Russ Mould, investment director at AJ Bell.
He added that a more convenient treatment could generate substantial returns if it succeeds.
In the nine months to September 30, 2025, RAPT reported losses of $52.4 million, down from $76.6 million a year earlier, as research and development spending fell sharply.
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