Summit Therapeutics Plunge 25.15% as $330M Surge in Volume Drives Stock to 366th in Market Activity Amid Divergent Trial Data

, 2025, , . The selloff followed the release of underwhelming long-term follow-up data from a global trial of its experimental lung cancer therapy, ivonescimab. Updated results showed divergent outcomes between Chinese and North American/European patient populations, with potential overall survival risks observed in Western cohorts. This discrepancy raised significant regulatory hurdles for the drug’s approval pathway.

Analysts highlighted the implications of the data split. Leerink’s Daina M. Graybosch maintained an underperform rating, emphasizing the degradation of survival signals from China to Western markets and doubting the FDA’s approval likelihood. Truist’s , despite a buy rating, described the outcome as a "narrow miss" and underscored the regulatory uncertainty. Conversely, Citizens Bank’s Reni J. Benjamin viewed the results as confirmation of cross-regional efficacy, suggesting the selloff could present a buying opportunity. Summit has yet to engage with the FDA regarding these findings, leaving the drug’s regulatory future in limbo.

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