Compass Therapeutics reported encouraging clinical progress across its bispecific antibody pipeline, highlighted by positive efficacy signals from multiple programs and a strong financial position extending operations into 2027.
Tovecimig Shows Survival Promise in Biliary Tract Cancer
The company's lead candidate tovecimig, a DLL4 x VEGF-A bispecific antibody, met its primary endpoint in the randomized Phase 2/3 COMPANION-002 study in patients with biliary tract cancer. The combination of tovecimig plus paclitaxel significantly improved overall response rate compared to paclitaxel alone.
Notably, fewer deaths have been observed in the study than originally projected, which the company believes may suggest tovecimab could be affecting overall survival in the patient population. The pre-specified number of pooled overall survival events (80%) required to trigger secondary endpoint analyses has not yet been met, pushing the timeline for overall survival and progression-free survival analyses to Q1 2026.
"Following our previous announcement that the tovecimig Phase 2/3 trial met the primary endpoint of overall response rate, we are encouraged to see fewer deaths in the study than we originally modeled," said Thomas Schuetz, MD, PhD, Chief Executive Officer and Vice Chairman of the Board of Directors.
Deep Responses Observed with CTX-8371
The company's PD-1 x PD-L1 bispecific antibody CTX-8371 demonstrated notable efficacy in the post-checkpoint inhibitor setting. Within the first four dosing cohorts comprising 12 evaluable patients, one of five patients with non-small cell lung cancer achieved complete resolution of all measurable target tumor lesions, with baseline measurements of 59 mm reduced to zero. Additionally, one of three patients with triple-negative breast cancer achieved over 90% reduction in target tumor lesions, from 87 mm at baseline to 7 mm.
Based on these responses, Compass plans to initiate expansion cohorts focusing on non-small cell lung cancer and triple-negative breast cancer in Q4 2025. The Phase 1 dose-escalation study is currently enrolling its fifth and final dosing cohort, with CTX-8371 being generally well tolerated and no dose-limiting toxicities observed to date.
CTX-10726 Outperforms Competitor in Preclinical Studies
Compass's PD-1 x VEGF-A bispecific antibody CTX-10726 demonstrated superior performance compared to ivonescimab, a leading candidate in the class, across multiple preclinical models. In head-to-head studies using a human non-small cell lung cancer xenograft mouse model, CTX-10726-treated mice had significantly lower average tumor volume than those treated with ivonescimab.
The compound also showed superior PD-1 inhibition and tumor control in a mouse model of PD-1 blockade, along with more potent PD-1 blockade in in vitro studies compared to ivonescimab. CTX-10726 is designed to synergistically deliver VEGF-A blockade and checkpoint inhibition, with potential applications across multiple solid tumor indications.
"We are happy to share initial preclinical data suggesting superiority to ivonescimab, a leading candidate in the class, in both PD-1 inhibition and anti-tumor activity in relevant mouse models," Dr. Schuetz noted. The company expects to submit an IND for CTX-10726 in Q4 2025.
Financial Position and Pipeline Expansion
Compass ended the second quarter with $101 million in cash and marketable securities, compared to $127 million at year-end 2024, providing an anticipated cash runway into 2027. Research and development expenses increased 47% to $16.4 million for the quarter, primarily due to additional manufacturing expenses of $5.7 million related to tovecimig and CTX-10726.
The company is also advancing CTX-471, a CD137 agonist antibody that binds to a unique epitope of the co-stimulatory molecule 4-1BB. Compass expects to initiate a Phase 2 trial of CTX-471 in patients with tumors expressing NCAM (CD56) in the second half of 2025.
Additionally, preparations continue for a Phase 2 basket study of tovecimig in a broader set of DLL4+ cancers, including gastric, ovarian, renal, hepatocellular, and colorectal cancers, expected to begin following secondary endpoint analyses from the COMPANION-002 trial.
