Summit Therapeutics stock plunged Friday after its highly-watched cancer drug slowed progression, but failed to significantly improve overall survival in lung cancer patients.
Patients treated with Summit's drug, ivonescimab, and chemotherapy were 48% less likely to progress or die than patients who received chemo alone. But the drug failed to make a statistically significant difference in overall survival, a metric that measures how long patients live before dying of any cause. Rather, the results "showed a positive trend" for overall survival.
In response, Summit Therapeutics stock dropped 30.5%, closing at 18.22. Shares of Merck, its chief rival, rose a fraction to 76.82.
Summit's drug works by simultaneously blocking proteins called PD-1 and VEGF. Cancer cells use PD-1 to camouflage themselves from the immune system. Ivonescimab latches onto PD-1, unveiling the hidden cancer cell. VEGF is a signaling protein that plays a role in forming new blood vessels. This is important in how the cancer grows. Cutting off VEGF cuts off cancer's blood supply.
There's a long history of anti-PD-1 and anti-VEGF drugs showing promise in lengthening the amount of time patients live before their cancer worsens. But overall survival is trickier. So far, none in this combination class have been able to improve overall survival. Summit noted as much in its release.
Can Summit Take On Merck?
Analysts have suggested Summit's approach could threaten Merck. Merck sells Keytruda, a PD-1 blocker that treats numerous cancer types. Keytruda is often used in combination with chemo. But the Street has been looking at ivonescimab as a Keytruda replacement for some cancers.
Summit says the positive trend in overall survival "provides further support" for using ivonescimab to treat patients with previously treated non small-cell lung cancer, or NSCLC, who have a mutation in their EGFR gene.
But Summit Therapeutics stock undercut both its 50-day and 200-day moving averages, according to MarketSurge. Shares rocketed to a record high on April 24, but had pulled back nearly 29% from that point, as of Thursday's close.
Still, shares have a best-possible Relative Strength Rating of 99, according to IBD Digital.
Follow Allison Gatlin on X/Twitter at @AGatlin_IBD.
