Compass Therapeutics Shares Plunge 64.8% After Biliary Tract Cancer Trial Misses OS Endpoint
Compass Therapeutics shares plunged over 60% after its Phase II/III COMPANION-002 trial in unresectable biliary tract cancer failed to meet the overall survival endpoint despite a PFS gain of 4.7 months versus 2.6 months for paclitaxel alone. High control-arm crossover (54%) likely confounded OS results.
1. Clinical Trial Results
Compass Therapeutics’ Phase II/III COMPANION-002 study evaluated tovecimig plus paclitaxel versus paclitaxel alone in second-line biliary tract cancer. The combination achieved median PFS of 4.7 months versus 2.6 months but recorded median OS of 8.9 months compared with 9.4 months in the control arm due to 54% crossover.
2. Stock Market Reaction
Shares opened down 64.8% at $1.77 on April 27 after closing at $5.03 on April 24, reflecting investor concern over the OS miss despite the PFS gain. The sharp decline underscores market sensitivity to secondary endpoint outcomes in oncology trials.
3. Safety Profile
Tovecimig plus paclitaxel was generally well tolerated with hypertension in 69% of patients (44% Grade ≥3), fatigue in 67% and neutropenia in 36% of patients. The safety profile remained consistent with prior data and showed no new adverse signals.
4. Regulatory Path Forward
Compass plans a meeting with the US FDA to discuss COMPANION-002 data ahead of a planned BLA submission. If approved, tovecimig is forecast to generate $570 million in 2031 sales, following a prior report of a 17.1% ORR versus 5.3% for paclitaxel alone.