Assessment of the allergenic and immunotoxic properties of the recombinant non-immunogenic staphylokinase in preclinical and clinical trials

The aim. To study possible allergenic and immunotoxic properties of the recombinant non-immunogenic staphylokinase molecule with the amino acids replacement Lys₇₄, Glu₇₅ and Arg₇₇ with alanine in preclinical and clinical studies.

Materials and methods. The allergenic and immunotoxic properties of the recombinant non-immunogenic staphylokinase drug were studied using standard methods in accordance with the Guidelines for the Preclinical Study of New Substances in guinea pigs (n=15) and mice (n=45) at doses 5, 10 and 20 times higher than therapeutic (for humans). A clinical study was conducted in 100 patients with acute ST-segment elevation myocardial infarction after a single intravenous injection of the drug. The study included the determination of titers of specific antibodies to recombinant non-immunogenic staphylokinase and the study of plasma neutralizing activity.

Results. During the complete set of preclinical studies, it was found that the drug does not affect the cellular and humoral immune response in guinea pigs and mice at doses many times higher than therapeutic doses for humans. It was found that the drug did not cause an immediate-type of hypersensitivity reaction (Weigle index 0) and a delayed type IV (0 points according to S.V. Suvorov) in guinea pigs, did not affect the cellular capacity of popliteal lymph nodes (reaction index 0.91), did not affect the number of nucleated and antibody-forming cells in the spleen of mice. As a result of a clinical study of recombinant non-immunogenic staphylokinase, no allergic reactions were registered. Assessment of the neutralizing activity of the plasma of patients who were administered recombinant non-immunogenic staphylokinase showed that 70% samples did not have neutralizing activity: 30% of the patients’ samples were characterized by a minimum neutralizing activity of 0.33±0.02 μg/mL, which is 30–310 times lower than after the use of native staphylokinase. These values are 7.8 times lower than the determined concentration of recombinant non-immunogenic staphylokinase  in the blood (2.59 μg/mL). Thus, the drug does not lead to the anti-staphylokinase neutralizing antibodies formation capable to neutralize its effect upon repeated administration.

Conclusion. According to the results of the trials, the absence of allergenic and immunotoxic properties of the recombinant non-immunogenic staphylokinase and its safety in relation to the immune system have been proven.

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