Mucoadhesive recombinant human catalase for dry eye disease: From protein engineering to first-in-human study.

BACKGROUND: Oxidative stress caused by excess reactive oxygen species (ROS) plays a key role in the progression of dry eye disease (DED), yet no approved DED therapy directly eliminates ROS. Here, we develop an antioxidant biologic with enhanced ocular-surface retention by thiol engineering of recombinant human catalase (hCAT) as a new ROS-scavenging eye drop therapy for DED. METHODS: Thiolated hCAT (hCAT-SH) was characterized for activity, stability, mucin interaction, and ocular retention. Efficacy, mechanism, and safety were evaluated in mouse, rabbit, and rat studies, followed by a randomized, double-blind, placebo-controlled first-in-human trial in 30 patients with DED. FINDINGS: With formulation optimization, hCAT-SH maintained enzymatic activity and formulation stability, while exhibiting enhanced mucin binding and prolonged corneal retention. In mouse DED models, hCAT-SH reduced oxidative stress, accelerated epithelial repair, restored tear secretion, and modulated inflammatory and barrier-repair pathways distinct from cyclosporine. In rabbits, exposure remained predominantly ocular with favorable repeated-dose tolerability. Clinically, 0.1 mg/mL hCAT-SH significantly improved corneal fluorescein staining, reduced tear cytokine levels and corneal dendritic cell density versus placebo, and raised no treatment-related safety concerns. CONCLUSIONS: hCAT-SH is a carrier-free, long-retained H2O2-scavenging biologic, with integrated preclinical and first-in-human evidence supporting further development as a new DED drug. FUNDING: National Natural Science Foundation of China; National Technology Innovation Center for Biopharmaceuticals; Jiangsu Key R&D Program; National Key R&D Program of China; Shanghai "Dawn" Program; Shanghai Science and Technology Innovation Action Plans; Shanghai Municipal Commission of Health; Shanghai High-Quality Development Plan for Science and Technology Industry; and Macao FDCT.