Compass Therapeutics (CMPX) Study Update summary

Study design and background

• The randomized phase 2/3 study enrolled 111 patients in the combination arm and 57 in the paclitaxel-only arm for advanced biliary tract cancer after one prior therapy, with 2:1 randomization and crossover allowed after progression.

• Primary endpoint was overall response rate (ORR) by Blinded Independent Central Review; secondary endpoints include progression-free survival (PFS), overall survival (OS), and duration of response (DOR).

• Hierarchical testing method was used to control for alpha spending across endpoints.

Mechanism of action and rationale

• Tevesemig (also called tovecimig) is a bispecific antibody targeting VEGF-A and DLL4, designed to disrupt tumor angiogenesis and overcome resistance to anti-VEGF therapies.

• Demonstrates monotherapy activity in colorectal and gastric cancer, anchoring in the tumor microenvironment.

Efficacy and safety results

• ORR was 17.1% in the combination arm versus 5.3% in the control arm (p=0.031); complete response in 0.9% and partial response in 16.2% of the combination arm.

• Stable disease observed in 44.1% (combination) vs 33.3% (monotherapy); progressive disease in 16.2% vs 42.1%.

• Waterfall plots showed most patients in the combination arm had tumor burden reduction, with four patients achieving 100% decline.

• Safety profile has been consistent with prior studies, with no new safety signals identified to date; independent committee recommended continuation without modification.

• Interim safety looks suggest fewer DLL4-type toxicities than previously observed, but full safety data are pending.