NEW YORK, May 1, 2026, 15:06 EDT
- Summit shares slid as the HARMONi-3 update failed to deliver an early win for investors.
- The trial remains blinded; final progression-free survival results aren’t expected until the back half of 2026.
- The China-run survival readout set for ASCO on May 31 suddenly matters more.
Summit Therapeutics Inc. dropped roughly 23% Friday afternoon after the HARMONi-3 update disappointed—ivonescimab, the biotech’s high-profile lung cancer hopeful, didn’t deliver the early upside investors were hunting for. Shares last traded at $16.60. Merck & Co., running Keytruda as the trial comparator, moved up 3%.
The selloff packs a punch because ivonescimab sits at the heart of Summit’s pipeline. Known as SMT112 in Summit’s covered territories, this bispecific antibody targets both PD-1, an immune checkpoint, and VEGF, the signal for tumor blood vessel growth, within a single drug. Summit licenses the therapy from Akeso, holding rights across the Americas, Europe, Japan, and a range of other markets outside Akeso’s retained regions.
HARMONi-3 pits ivonescimab plus chemo against pembrolizumab (that’s Keytruda’s generic) plus chemo for patients getting their first round of treatment for metastatic non-small cell lung cancer. First-line, so this is the go-to regimen for advanced cases. Summit reported that after checking an early interim readout on progression-free survival, an independent data monitoring committee told them to keep the trial running as is—no safety issues flagged, double-blind stays intact.
Progression-free survival, or PFS, tracks how long patients go without their disease worsening. Leerink Partners analyst Daina Graybosch described the stock move as “reasonable,” but flagged “considerable uncertainty” ahead. Graybosch cited a potential hazard ratio between 0.75 and 0.60—meaning the risk of progression could be cut by 25% to 40%. Hazard ratios under 1 tip the balance in favor of the Summit regimen. Investors.com
That sharp jump? Chalk it up to the competitive stakes. In China, Akeso’s HARMONi-2 trial saw ivonescimab alone outperform Keytruda by 49% for PFS among PD-L1-positive NSCLC patients. Another study, HARMONi-6, found ivonescimab plus chemo delivered a 40% PFS edge over BeOne Medicines’ Tevimbra with chemo in squamous NSCLC.
The bar for global data climbed after that record. Next up for Summit: HARMONi-6 overall survival numbers from a China-based trial run by Akeso, set to be unveiled at the American Society of Clinical Oncology plenary on May 31. Overall survival tracks patient lifespans—a tougher benchmark, and the one that tends to draw the sharpest focus from both investors and regulators in late-stage cancer trials.
While waiting on more data, costs keep climbing. Summit posted a non-GAAP net loss of $116.6 million—more than double last year’s $51.8 million—using its own adjustments that strip out certain accounting items. As for liquidity, cash and short-term investments dropped to $598.7 million, down from $713.4 million at year-end, according to its first-quarter numbers.
The risk remains clear. Beyond HARMONi-3, Summit’s application for ivonescimab in EGFR-mutated lung cancer—targeting patients with that mutation—is under FDA review. According to Summit’s 10-Q, the agency signaled it expects to see a statistically significant overall-survival benefit for approval in this use; progression-free survival on its own might not meet the bar.
Friday’s update left HARMONi-3 rolling, but clarity? Not really. There’s still no unblinded data, no numbers on effect size, and investors don’t get the early PFS readout they wanted to settle the Keytruda comparison.
Summit’s stuck in a holding pattern, with both the global final data expected later this year and the China survival results set for ASCO. For now, shares aren’t reflecting a looming approval — instead, they’re behaving like there’s still plenty of trial risk on the table.
