Summit Therapeutics stock crashed Monday after the company's high-profile drug failed to meet the bar for overall survival in patients with advanced lung cancer.
The company tested a combination of its drug, ivonescimab, and chemotherapy. Ivonescimab targets the PD-1 protein that some cancer cells use to camouflage themselves from the immune system and VEGF. Blocking VEGF prevents the formation of new blood vessels. This cuts off the cancer's blood supply.
But, while the ivonescimab-containing combination showed promise on progression-free survival — the length of time patients live before worsening — overall survival missed its mark. Overall survival is how long patients live before dying of any cause. Those results weren't statistically significant.
"We believe it is unlikely FDA will grant approval based on (the study called) HARMONi nor that Summit will partner ivo at the substantial valuation expected by investors — greater than $15 billion with more than half up front," Leerink Partners analyst Daina Graybosch said in a report.
On the stock market today, Summit Therapeutics stock plummeted 25.2% to 19.44. Shares closed below their 50-day and 200-day moving averages. Shares of BioNTech, which is also working on a drug that blocks PD-1 and VEGF, tumbled 8.7% to 102.66. Merck stock fell nearly 1% to 84.10.
Safety Profile In Focus
Investors have closely watched the efforts to develop a PD-1/VEGF-blocking drug. The standard of care for a number of cancers remains Merck's PD-1 blocker, Keytruda. At this time last year, ivonescimab topped Keytruda in patients with non-small cell lung cancer. But overall survival was the real test.
At the time, Eliav Barr cautioned that blocking PD-1 and VEGF has proven difficult. While regimens have improved progression-free survival, none have led to a benefit on overall survival, he told Investor's Business Daily. Barr is the chief medical officer at Merck Research Laboratories.
"This is due to the toxicity of VEGF inhibition," he said. "We have an extensive program in this combination and found PFS benefit was observed and then toxicities caught up in the combo arm."
Summit noted Monday that 7.3% of patients who received ivonescimab and chemotherapy dropped out of the study due to side effects. That compares to 5% of placebo recipients. The placebo group was also given chemotherapy. Four patients in the ivonescimab died due to treatment-related side effects vs. five in the chemotherapy-alone group.
But Leerink's Graybosch says that looks safer than Avastin, a VEGF blocker from Roche. Still, she recommends BioNTech over Summit Therapeutics, noting the former is far more diversified and partnered with Bristol Myers Squibb.
Follow Allison Gatlin on X/Twitter at @AGatlin_IBD.
