A Combinatorial Approach with Monoclonal Antibodies to SerpinB13 and CD3 Is Therapeutically Superior to Single Antibody Use in Autoimmune Diabetes

A successful approach to autoimmune diabetes therapy may require simultaneous insulin-producing cell regeneration and T-cell mediated autoimmunity resolution in pancreatic islets. While CD3 antibody has been proved to reduce islet inflammation, the monoclonal antibody (mAb) to serpinB13 protease inhibitor, developed in our laboratory, was shown to cause regenerative changes in beta cells. Whether a combination of both antibodies is superior to single antibody use in the treatment of autoimmune diabetes is unclear. To address this non-obese diabetic (NOD) female mice at late pre-diabetic stage were injected with serpinB13 mAb (clone B29, 10, 40 or 200 micrograms/animal) and CD3 mAb (clone 145-2C11; at a suboptimal dose of 10 micrograms). All experimental injections were controlled with nonspecific hamster IgG and mouse IgG (clone HB-158). After the last antibody injection, random blood glucose levels were assessed for 20 weeks, and mice were declared diabetic after two measurements of glucose exceeding 300 mg/dL. We found that the combination of 40 micrograms of serpinB13 mAb with CD3 mAb offered a significant level of protection from diabetes (p=0.0027, Kaplan-Meyer with log rank test), while the combination with 10 micrograms of serpinB13 mAb had no effect. The higher dose of 200 micrograms of serpinB13 mAb showed a trend in favor of diabetes inhibition. Interestingly, at 6 to 7 weeks after completing the treatment with 40 micrograms of serpinB13 mAb alone, NOD mice showed a strong tendency to remain healthy, and separated from the double-negative control, which continued to progress to diabetes. Our results indicate that a combinatorial approach with mAbs to serpinB13 and CD3 is beneficial in autoimmune diabetes. The observations also suggest that an intermediate dose of serpinB13 mAb, and a sufficient time following administration of this mAb, is critical for its positive impact on diabetes prevention. Disclosure B.Szepietowska: None. S.V.Avdulov: None. Y.Kryvalap: None. J.Czyzyk: None. Funding JDRF (2-SRA-2022-1215-S-B)