Overview

• In a Phase I study published in Cancer Cell, 7 of 20 pet cats with head and neck squamous cell carcinoma achieved stable disease or tumor shrinkage after six intravenous doses over about a month.
• The cyclic double-stranded DNA decoy (CS3D) inhibits STAT3 by mimicking its target DNA sequence, enabling systemic delivery with improved stability versus earlier intratumoral versions.
• Responders lived a median 161 days from first dose versus 57 days for non‑responders, with no treatment‑attributed toxicities beyond mild anemia reported across the cohort.
• Tumor and blood analyses showed biological activity, including increased PD‑1 and distinct immune and gene‑expression patterns in responders, yielding candidate biomarkers for future trials.
• Investigators from UCSF and UC Davis are pursuing further feline studies, exploring combinations, and working with a small biotech to prepare an early‑phase human trial.