Summit Therapeutics PLC's (SMMT) stock plummeted 5.04% in the pre-market trading session on Tuesday after the company provided updates on its key clinical trials involving Ivonescimab, its lead investigational candidate targeting PD-1 and VEGF.

During the company's fourth quarter and full-year 2024 earnings call, Summit shared details on the progress of its ongoing global Phase III trials for Ivonescimab. While the company highlighted several milestones achieved, including completing enrollment for the HARMONi trial in advanced non-small cell lung cancer (NSCLC) and initiating the HARMONi-7 trial in first-line metastatic NSCLC patients, the updates failed to impress investors.

One key disappointment was the lack of clarity on the timing for the top-line data readout from the pivotal HARMONi-3 trial, which is evaluating Ivonescimab in combination with chemotherapy as a first-line treatment for metastatic NSCLC. The company stated that it had recently started enrolling non-squamous patients in the U.S. and would initiate site activations in other regions during the second quarter of 2025, but did not provide a concrete timeline for completion of enrollment or data readout.