Randomized, Double-Blind, Phase I Pharmacokinetic Study of Subcutaneous Recombinant Human Superoxide Dismutase (rhSOD) in Healthy Volunteers

Background: Excessive production of reactive oxygen species (ROS), particularly superoxide anion (O⋅−2), is a key mechanism in diseases such as cancer, inflammatory disorders, neurodegenerative conditions, and metabolic diseases. Evidence also suggests that microgravity-induced oxidative stress, primarily driven by elevated O⋅−2 levels, may contribute to the adverse physiological effects observed in astronauts during extended space missions. Superoxide dismutase (SOD) is critical for mitigating oxidative stress, and exogenous SOD supplementation offers a potential therapeutic strategy. Methods: This randomized, double-blind, placebo-controlled Phase I study evaluated the safety, tolerability, and pharmacokinetics of recombinant human Cu/Zn-SOD (rhSOD, SOD1) following subcutaneous administration of 40 mg every 12 hours in 16 healthy volunteers. Eight subjects were enrolled each in the single-dose (SD) and multiple-dose (MD) cohorts. Study assessments, including pharmacokinetic sampling, were performed for 72 (SD) or 92 hours (MD). Injection site erythema was objectively assessed using the innovative Standardized Erythema Value (SEV*) method, derived from photographs taken with Scarletred®Vision software (SCARLETRED Holding GmbH). Results: No serious adverse events occurred, and all treatment-related adverse events were mild. Injection site erythema was objectively assessed using the innovative standardized erythema value (SEV*) method, derived from photographs taken with Scarletred® Vision software (SCARLETRED Holding GmbH). The Visual Analog Scale scores and SEV* assessments were comparable between the rhSOD and placebo groups. Beyond safety and tolerability, pharmacokinetic analysis revealed that the volume of distribution, clearance, and half-life at presumed steady state were 129 ± 66.3 L, 5.97 ± 1.25 L/h, and 15.0 ± 6.69 h, respectively. Compared with the rapid systemic elimination after intravenous administration of SOD, subcutaneous administration resulted in a favorable plasma concentration-time profile. Conclusions: These findings suggest that subcutaneous rhSOD may be a promising therapeutic candidate for conditions characterized by excessive O⋅−2 exposure or diminished endogenous SOD activity. Further clinical studies are warranted to assess its anti-inflammatory potential in relevant patient populations. EudraCT Number: 2022-000173-11.