Summit Therapeutics PLC (SMMT) experienced an after-hours plunge of 6.03% on Thursday, following the release of its second-quarter financial results and operational update.

The decline came after the company reported a GAAP net loss of $215.7 million, or $0.28 per share, which narrowed from $565.7 million a year ago. However, this improvement was primarily driven by a significant decrease in stock-based compensation expense. On a non-GAAP basis, which excludes stock-based compensation, the net loss widened to $147.0 million, or $0.19 per share, from $86.9 million in the prior-year quarter. Non-GAAP operating expenses surged to $151.8 million from $89.6 million, driven by the expansion of clinical studies and development costs related to its lead candidate, ivonescimab.

The company highlighted continued clinical momentum for ivonescimab, including positive overall survival data from the HARMONi-6 study and an updated HARMONi analysis showing consistent efficacy across patient populations. Summit ended the quarter with $690.7 million in cash and investments, having raised $230.8 million through its at-the-market facility during the period. The U.S. FDA has set a target action date of November 14, 2026, for its Biologics License Application for ivonescimab in EGFR-mutated non-small cell lung cancer.