Compass Therapeutics (CMPX) Study update summary

Study design and patient population

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

• Crossover was permitted after centrally confirmed progression; 54% of control patients crossed over to combination therapy.

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

Efficacy results

• Primary endpoint (overall response rate) was met: 17.1% for tovecimig plus paclitaxel vs. 5.3% for paclitaxel alone (p=0.031).

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

• Crossover patients had improved PFS after switching to combination (3.5 months post-crossover vs. 1.9 months pre-crossover, HR=0.36, p=0.0016).

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

• Median OS in the combination arm was 8.9 months; intent-to-treat analysis showed no significant OS difference due to high crossover.

Safety and tolerability

• Safety profile was consistent with prior studies; no new safety signals identified.

• Most common adverse events in the combination arm included hypertension (69%), fatigue (67%), neutropenia, diarrhea, anemia, alopecia, and nausea.

• Grade ≥3 adverse events included hypertension (44%) and neutropenia (36%), but were manageable.

• Pulmonary hypertension occurred in 2.8% of patients, lower than in earlier studies.

• 3.7% discontinued due to hypertension.