Compass Therapeutics’ stock has dropped by more than 60% after a Phase II/III trial of its biliary tract cancer (BTC) combination therapy met one key secondary endpoint but missed another.
The COMPANION-002 study (NCT05506943) evaluated tovecimig, a bispecific antibody, plus paclitaxel versus paclitaxel alone in patients with unresectable advanced, metastatic or recurrent BTC as a second-line therapy.
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While the combination demonstrated a significant improvement in progression-free survival (PFS) of 4.7 months compared to 2.6 months for paclitaxel alone, overall survival (OS) was not statistically significant. Compass stated this was due to high crossover from the control arm (54%) and prolonged survival of those crossover patients after receiving tovecimig. As a result, the median OS in the combination cohort was 8.9 months compared to 9.4 months in the control arm, which included patients who received paclitaxel alone and patients who later crossed over to receive the combination after initially only receiving paclitaxel.
Tovecimig was generally well tolerated, and the safety profile was consistent with previously reported data. The most commonly reported treatment-emergent adverse events (TEAEs) were hypertension (69%) and fatigue (67%). TEAEs classified as Grade 3 or higher included hypertension (44%) and neutropenia (36%).
Compass’s stock, listed on the Nasdaq exchange, took a significant hit on the announcement, opening 64.8% down at $1.77 on 27 April compared to a $5.03 market close on 24 April.
Despite the OS miss, Compass still plans to meet with the US Food and Drug Administration (FDA) to discuss the data in advance of a planned Biologics Licence Application (BLA) submission. If approved, GlobalData predicts the drug to generate $570m in sales in 2031. GlobalData is the parent company of Clinical Trials Arena.
In April 2025, Compass announced that the study had met its primary endpoint of a 17.1% overall response rate (ORR) for tovecimig plus paclitaxel, compared to 5.3% for paclitaxel alone.
Dr Juan Valle, CMO of the Cholangiocarcinoma Foundation, said in a Compass press release: “Patients with advanced biliary tract cancer have an urgent need for better treatment options. These results are a significant step forward, and I anticipate that, if approved, it will meaningfully change the way physicians care for these patients.”
BTC is estimated to affect approximately 26,500 patients annually in the US. For the vast majority of patients with BTC whose tumours do not harbour an actionable mutation with an approved targeted therapy, there is currently no FDA-approved treatment in the second-line setting.
More data from COMPANION-002, including duration of response (DOR), will be reported at an undisclosed medical conference in 2026.
