Compass Therapeutics (CMPX) Study update summary

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, using a 2:1 randomization of tovecimig plus paclitaxel versus paclitaxel alone, enrolling 168 patients.

• 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 17.1% ORR versus 5.3% for paclitaxel alone (p=0.031), including one complete response.

• Median PFS was 4.7 months for the combination versus 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 8.9 vs. 9.4 months (HR=1.05, p=0.78), confounded by high crossover rate.

• In crossover patients, post-crossover PFS improved to 3.5 vs. 1.9 months (HR=0.36, p=0.0016), and OS improved to 12.8 vs. 6.1 months (HR=0.54, p=0.04).

• The combination outperformed historical benchmarks for second-line chemotherapy.