Compass Therapeutics presents biomarker data related to CTX-471

Compass Therapeutics (CMPX) announced its poster presentation entitled “Pharmacodynamic and Response Biomarkers in the Monotherapy Arm of a Phase 1 Trial of CTX-471, a Novel Anti-CD137 Agonist Antibody” at the 39th Society for Immunotherapy of Cancer Annual Meeting, from November 6-10, 2024 in Houston, TX. These data arise from Compass’s Phase 1 open-label, first-in-human study that evaluated CTX-471 as a monotherapy in patients with metastatic or locally advanced malignancies that have progressed while receiving an approved PD-1 or PD-L1 inhibitor. Exploratory data reported here complement safety and efficacy data previously published at ASCO 2024. Biopsy specimens and blood samples from patients treated with CTX-471 were analyzed by multi-parameter immunofluorescence, flow cytometry, and a panel of cytokines using the Neogenomics Multi-omyx platform. To measure pharmacodynamic effects, comparisons were made between samples collected before and after CTX-471 treatment. To survey response biomarkers, values from baseline samples obtained from patients with tumors showing complete or partial responses as well as stable disease were compared with tumors showing progressive disease. Further, the authors propose a mechanism by which NCAM facilitates CTX-471 response. Specifically, tumor cell NCAM appears to enrich activated NK cells in the tumor microenvironment that express the CTX-471 target, CD137. The dataset shows these effects to be specific for NCAM expressing lymphocytes such as NK cells and is not observed in other lymphocyte subsets such as CD8+ T cells. These findings are novel in a clinical setting and support the potential use of NCAM as a selection marker for future clinical trials. Data highlights from the poster presentation include: CTX-471 pharmacodynamic biomarker changes were consistent with immune stimulation. CTX-471 disease control is associated with measurable baseline biomarkers. Baseline tumor cell expression of NCAM/CD56 is associated with response and disease control. A novel baseline circulating cell phenotype is associated with partial responses to CTX-471.