Compass Therapeutics Drops Sharply As Trial Crossover Complicates Survival Data In Bile Duct Cancer Patients

Compass Therapeutics Inc. (NASDAQ:CMPX) shares are tumbling on Monday as the company announced results from its COMPANION-002 study, which evaluated its drug tovecimig in patients with advanced biliary tract cancer. The stock is down 60% following the news. Overall Survival Results Cloud Interpretation Tovecimig did not meet the overall survival secondary endpoint due to high crossover from the control arm (31 of 57 patients, or 54%) and prolonged survival of those crossover patients after receiving tovecimig. As a result of this crossover, 85% (142 of 168) of patients in the study received tovecimig plus paclitaxel with a pooled overall survival in the study of 8.9 months. Tovecimig combination showed a median overall survival of 8.9 months compared to 9.4 months for the control arm, which included 26 patients (46%) who received paclitaxel alone and 31 patients (54%) who crossed over to receive tovecimig in combination with paclitaxel (p=0.78). In the rank-preserving structural failure time (RPSFT) OS analysis, the combination also had a median overall survival of 8.9 months compared to 9.4 months for paclitaxel alone (p=0.65). Though the RPSFT analysis is intended to adjust for crossover, its validity depends on certain assumptions that were not met in this study, and thus its results here are largely uninterpretable. Read Also: Also Read: Compass Therapeutics' Bile Duct Cancer Drug Seen As New Standard Of Care Progression-Free Survival Shows Statistically Significant Benefit The oncology-focused biopharmaceutical reported that tovecimig demonstrated a statistically significant improvement in progression-free survival (PFS) compared to paclitaxel alone, with a remarkable 56% reduction in the risk of disease progression. Tovecimig in combination with paclitaxel demonstrated a statistically significant improvement in median PFS of 4.7 months compared to 2.6 months for paclitaxel alone. The data showed an overall response rate of 17.1% for tovecimig in combination with paclitaxel (19 of 111 patients), including one complete response, compared to 5.3% for paclitaxel alone (3 of 57 patients), in patients with BTC in the second line setting. The 11.8% improvement in ORR for those receiving tovecimig was statistically significant (p=0.031). The company plans to engage with the U.S. Food and Drug Administration (FDA) regarding these findings ahead of a planned Biologics License Application (BLA) submission. Analyst View William Blair wrote, “This will raise questions on the approvability of this dataset, and while we believe the totality of the data shows that tovecimig provides clinical benefit in this patient population, it will clearly be a review issue at the FDA.” Analyst Matt Phipps notes the volatility as investors weigh the totality of the data and FDA uncertainty. CMPX Stock Price Activity: Compass Therapeutics shares were down 58.85% at $2.06 at the time of publication on Monday, according to Benzinga Pro data. Photo via Shutterstock Read Also: Read Next: SpaceX To RTX: Who's Building Trump's Golden Dome Missile Shield