Summit Therapeutics stock tumbles as FDA filing for ivonescimab hits tape, GSK trial tie-up follows
12 January 2026
2 mins read

Summit Therapeutics stock tumbles as FDA filing for ivonescimab hits tape, GSK trial tie-up follows

New York, Jan 12, 2026, 14:55 EST — Regular session

  • Summit shares dropped steeply in afternoon trading following the announcement of a U.S. FDA biologics license application for ivonescimab.
  • The company also entered a clinical trial collaboration with GSK to test a combination regimen in solid tumors.
  • Investors await the FDA’s upcoming procedural move and new insights from conference presentations.

Shares of Summit Therapeutics Inc dropped roughly 11% to $17.46 Monday afternoon, after fluctuating between $20.30 and $16.51. The move came following the company’s announcement that it filed a U.S. biologics license application for its lung cancer drug ivonescimab. 1

Summit’s filing marks its first attempt to introduce ivonescimab to the U.S. market, targeting a challenging segment of non-small cell lung cancer (NSCLC). This involves patients with EGFR-mutated tumors whose disease has advanced despite treatment with a newer EGFR drug. The biologics license application (BLA) is the formal FDA submission needed to gain approval for marketing a biologic medicine in the U.S. 2

Summit reported that its submission relies on the overall data from the global Phase III HARMONi trial. If accepted as filed, the company anticipates a regulatory decision by Q4 2026. It also revealed preliminary unaudited cash, cash equivalents, and short-term investments totaled roughly $710 million as of December 31, 2025. 3

On Monday, the company revealed a clinical trial partnership with GSK to test ivonescimab alongside GSK’s B7-H3 antibody-drug conjugate, risvutatug rezetecan, targeting multiple solid tumors, including small cell lung cancer. Summit expects patient dosing to begin in mid-2026. Co-CEOs Robert W. Duggan and Maky Zanganeh described the deal as part of a larger strategy focused on combination therapies. 4

The stock’s decline coincided with a tough day for biotech shares at the start of the annual J.P. Morgan Healthcare Conference, a major investor event where deal buzz typically sets the tone early in the week. The SPDR S&P Biotech ETF fell on the day, according to Barron’s. 5

Summit announced ahead of time that it would present Monday morning at the conference, with Duggan and Zanganeh set to provide a corporate overview and update on ivonescimab’s development plan. 6

Ivonescimab is a PD-1/VEGF bispecific antibody, engineered to merge immune checkpoint inhibition with anti-angiogenesis in a single treatment. Summit notes the drug has yet to secure regulatory approval outside China. 7

Summit highlighted the commercial potential in Monday’s BLA announcement, noting that over 14,000 U.S. patients annually might qualify for second-line or later treatment in the EGFR-mutated NSCLC segment they’re targeting. 8

An immediate procedural point: the FDA usually takes up to 60 days to decide if it will “file” an application, which then triggers the official review timeline. 9

The path isn’t straightforward. The FDA can reject an application it finds incomplete, and even after filing, concerns about the clinical data, labeling, or manufacturing processes can delay approval or shift the odds. 10

Traders are eyeing further details from management presentations throughout the J.P. Morgan Healthcare Conference, which continues until Jan. 15. They’ll also watch closely for any FDA news on whether Summit’s application has been accepted for review. 11

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