Compass Therapeutics disclosed the primary and secondary results of its Phase 2/3 COMPANION‑002 study of the bispecific antibody tovecimig in combination with paclitaxel for patients with advanced biliary tract cancer. The study met its key secondary endpoint of progression‑free survival (PFS) and its primary endpoint of overall response rate (ORR), but failed to demonstrate a benefit in overall survival (OS).
The combination produced a 56% reduction in the risk of disease progression, with a median PFS of 4.7 months versus 2.6 months for paclitaxel alone. The overall response rate was 17.1% for the combination compared with 5.3% for paclitaxel alone, meeting the primary endpoint that was announced in April 2025.
Median OS was 8.9 months for the tovecimig‑paclitaxel arm and 9.4 months for paclitaxel alone, and the rank‑preserving structural failure time (RPSFT) analysis also showed no advantage. The company stated the RPSFT results were “largely uninterpretable” because the assumptions were not met.
A high crossover rate of 54%—31 of 57 patients in the control arm—complicated the OS analysis. The crossover patients survived a median of 12.8 months, similar to the median OS seen in front‑line studies. Including crossover, 85% of patients in the study received tovecimig in combination with paclitaxel, and the pooled median OS for all patients was 8.9 months, which is longer than the approximately six‑month benchmark for chemotherapy in this setting.
The mixed results have prompted a sharp market reaction, with analysts noting that the failure to meet the OS endpoint and the high crossover rate raise questions about the regulatory path forward. William Blair analysts said the OS miss “will raise questions on the approvability of this dataset,” while Leerink Partners reiterated an Outperform rating.
Compass remains in a spend‑to‑build phase, reporting a net loss of $15.7 million in the most recent quarter. The company has not issued new guidance following the trial results, but it plans to meet with the FDA to discuss the data ahead of a planned Biologics License Application submission.
Biliary tract cancer is an aggressive disease with limited second‑line options; gemcitabine and cisplatin are the standard first‑line therapy, and few approved agents exist beyond that. Tovecimig, a bispecific antibody targeting DLL4 and VEGF‑A, has shown promise in heavily pre‑treated patients. The company received Fast Track designation in April 2024 and Orphan Drug designation in April 2026, positioning it for potential accelerated review if the data can be interpreted favorably.
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