GSK Moves to Acquire RAPT Therapeutics in $2.2 Billion Cash Deal

Pharmaceutical giant GSK has made a firm commitment to acquire the clinical-stage biotech firm RAPT Therapeutics. The all-cash transaction, valued at $58.00 per share, represents a total enterprise value of approximately $2.2 billion. Following the announcement, RAPT's stock price traded near the offer level, signaling strong market confidence in the deal's completion. This acquisition could mark a pivotal strategic shift for RAPT, which faced significant challenges in late 2024.

The driving force behind GSK's bid is the promising asset ozureprubart (formerly known as RPT904). This investigational anti-IgE antibody is currently in a Phase 2b clinical program named "prestIgE" for the prophylaxis of food allergies. Its key differentiator is an extended half-life, which could allow for dosing every 8 to 12 weeks. This offers a potential advantage over the existing therapy Xolair (omalizumab), which requires administration every 2 to 4 weeks. The market potential is substantial, with over 17 million people in the United States alone suffering from food allergies.

For RAPT Therapeutics, this agreement provides a clear path forward after a major setback at the end of 2024, when its prior lead drug program was halted due to safety concerns.

Deal Structure and Valuation

GSK, through a subsidiary, will initiate a tender offer to purchase all outstanding shares of RAPT for $58.00 each in cash. The offer price carries a significant premium of roughly 65% over RAPT's closing share price just before the deal was announced. GSK's net initial investment is estimated to be about $1.9 billion, accounting for the cash on RAPT's balance sheet that will be acquired.

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Any shares not tendered in the initial offer will be acquired later at the same price per share via a second-step merger, ensuring all shareholders receive the $58.00 valuation.

Expected Timeline and Conditions

GSK is obligated to commence the formal tender offer within ten business days of the signing, pointing to a launch in late January or early February. The companies anticipate closing the transaction in the first quarter of the year.

Completion is subject to customary closing conditions. These include the tender of a majority of RAPT's outstanding shares and the expiration of the mandatory waiting period under the Hart-Scott-Rodino Antitrust Improvements Act. Given the substantial all-cash premium, analysts view successful completion as highly probable.