Compass Therapeutics (CMPX) investor relations material

Study design and patient population

• COMPANION-002 was a randomized phase II/III trial in advanced biliary tract cancer patients who had received one prior line of therapy, comparing tovecimig plus paclitaxel to paclitaxel alone in a 2:1 ratio, with 168 patients enrolled.

• 111 patients were assigned to the combination arm, and 57 to the control arm; 54% of control patients crossed over to the combination after progression.

• Baseline prognostic variables, including tumor location, ECOG status, and disease extent, were well balanced between arms.

Endpoints and objectives

• Primary endpoint was overall response rate (ORR); key secondary endpoints included progression-free survival (PFS), overall survival (OS), and duration of response (DoR).

• Crossover was permitted after progression, with 54% of control patients receiving tovecimig.

Efficacy results

• The combination arm achieved a statistically significant improvement in ORR: 17.1% vs. 5.3% for paclitaxel alone (p=0.031), including one complete response.

• Median PFS was 4.7 months for the combination vs. 2.6 months for control (HR=0.44, p<0.0001), representing a 56% reduction in risk of progression.

• Median OS in the intent-to-treat analysis was confounded by crossover: 8.9 vs. 9.4 months (HR=1.05, p=0.78); pooled median OS for all patients receiving tovecimig was 8.9 months.

• Crossover patients had a median OS of 12.8 months vs. 6.1 months for non-crossover patients (HR=0.54, p=0.04).

• In crossover patients, median PFS improved from 1.9 months pre-crossover to 3.5 months post-crossover (HR=0.36, p=0.0016).