After word spread that Tovetumab, a bile duct cancer treatment in development by Compass Therapeutics, the U.S. subsidiary of ABL Bio, failed to meet the primary endpoint of overall survival (OS) in a phase 2/3 trial, ABL Bio plunged 22% in early trading on the 28th.
As of 9:32 a.m. on the 28th, on the KOSDAQ market, ABL Bio was trading at 133,200 won, down 39,500 won (22.87%) from the previous session.
On the 27th (local time), Compass Therapeutics released clinical results comparing the combination of Tovetumab and the chemotherapy "paclitaxel" with paclitaxel monotherapy.
In these results, OS, which shows how much longer patients actually lived, was 8.9 months for the combination therapy and 9.4 months for monotherapy, showing little difference and failing to meet the secondary endpoint. The company said survival data were diluted due to crossover in the control arm.
By contrast, progression-free survival (PFS) showed a statistically significant improvement at 4.7 months for the combination therapy versus 2.6 months for monotherapy.
Based on these results, Compass Therapeutics plans to hold a meeting with the U.S. Food and Drug Administration (FDA) regarding a biologics license application (BLA).
However, with the failure to improve the key metric of OS, some say commercialization prospects have dimmed. Kim Jun-young, an analyst at Meritz Securities, said, "The FDA tends to view OS improvement as more important than PFS," adding, "While the PFS results are positive, the lack of clear proof of an OS advantage due to the crossover design increases approval uncertainty."