Shares of ABL Bio plunged 22% in early trading on the 28th after news that "tobesimig," a bile duct cancer treatment being developed by ABL Bio's U.S. partner Compass Therapeutics, failed to meet the primary endpoint of overall survival (OS) in its phase 2/3 trial.
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 announced clinical results comparing the combination of tobesimig and the chemotherapy drug "paclitaxel" with paclitaxel monotherapy.
In the 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 group.
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, expectations for commercialization have dimmed. Kim Jun-young, an analyst at Meritz Securities, said, "The FDA tends to place more weight on OS improvement than PFS," adding, "While the PFS results are positive, the lack of clear evidence of an OS benefit due to the crossover design increases approval uncertainty."