Poster Session
Title
In Vivo Protection with Human Monoclonal Antibody S315 following Challenge with Diphtheria Toxin
Date
2017-05-16
Document Type
Poster Abstract
Description
Background: Morbidity and mortality from Corynebacterium diphtheriae is reduced by prompt administration of equine-derived diphtheria anti-toxin (DAT), which is in short supply worldwide. MassBiologics has developed a human monoclonal antibody (S315) to diphtheria toxin to provide a safer alternative to DAT and address critical supply issues. S315 prevents toxin binding to its putative host receptor and S315 pre-mixed with toxin increased survival in a guinea pig model of intoxication. To further evaluate the ability of S315 to provide in vivo protection, we established a post-exposure treatment model.
Methods: Female Hartley guinea pigs (300-350g) were challenged subcutaneously with diphtheria toxin (0.03 to 0.09 Lf, limit of flocculation) to identify the minimum lethal dose. To evaluate anti-toxin efficacy, DAT or S315 was administered five hours post-toxin challenge and animals monitored for 30 days for signs of illness (lethargy, dehydration, weak limbs). Serum anti-diphtheria toxin antibodies were measured by ELISA and Vero cell toxin neutralization assays.
Results: The minimum lethal toxin dose was 0.09 Lf. To determine the protective dose of DAT, 0.2 IU, 1.0 IU or 5.0 IU was administered intravenously post-toxin challenge (n=4/cohort). All 0.2 IU or 1.0 IU DAT-treated animals died, while one animal treated with 5.0 IU survived. DAT was subsequently evaluated at 5.0 IU, 10 IU, and 20 IU and compared to a cohort receiving 3.5 mg of S315. All untreated animals died within 72 hours and all antibody-treated animals survived. Dehydration was observed more frequently in the 5 IU and 10 IU DAT cohorts compared to the 20 IU and S315 cohorts.
Conclusions: Treatment with S315 after diphtheria toxin exposure is protective; further studies will define a minimum effective dose of S315. This model mimics the route and timing of anti-toxin treatment in humans and provides a rigorous preclinical evaluation of a human antibody replacement for equine DAT.
Keywords
diphtheria toxin, human monoclonal antibody
DOI
10.13028/bfkd-6954
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Repository Citation
Smith HL, Lobikin M, Gao W, Saia G, Wang Y, Leney M, Molrine DC. (2017). In Vivo Protection with Human Monoclonal Antibody S315 following Challenge with Diphtheria Toxin. UMass Center for Clinical and Translational Science Research Symposium. https://doi.org/10.13028/bfkd-6954. Retrieved from https://escholarship.umassmed.edu/cts_retreat/2017/posters/74
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Bacterial Infections and Mycoses Commons, Immunology and Infectious Disease Commons, Translational Medical Research Commons
In Vivo Protection with Human Monoclonal Antibody S315 following Challenge with Diphtheria Toxin
Background: Morbidity and mortality from Corynebacterium diphtheriae is reduced by prompt administration of equine-derived diphtheria anti-toxin (DAT), which is in short supply worldwide. MassBiologics has developed a human monoclonal antibody (S315) to diphtheria toxin to provide a safer alternative to DAT and address critical supply issues. S315 prevents toxin binding to its putative host receptor and S315 pre-mixed with toxin increased survival in a guinea pig model of intoxication. To further evaluate the ability of S315 to provide in vivo protection, we established a post-exposure treatment model.
Methods: Female Hartley guinea pigs (300-350g) were challenged subcutaneously with diphtheria toxin (0.03 to 0.09 Lf, limit of flocculation) to identify the minimum lethal dose. To evaluate anti-toxin efficacy, DAT or S315 was administered five hours post-toxin challenge and animals monitored for 30 days for signs of illness (lethargy, dehydration, weak limbs). Serum anti-diphtheria toxin antibodies were measured by ELISA and Vero cell toxin neutralization assays.
Results: The minimum lethal toxin dose was 0.09 Lf. To determine the protective dose of DAT, 0.2 IU, 1.0 IU or 5.0 IU was administered intravenously post-toxin challenge (n=4/cohort). All 0.2 IU or 1.0 IU DAT-treated animals died, while one animal treated with 5.0 IU survived. DAT was subsequently evaluated at 5.0 IU, 10 IU, and 20 IU and compared to a cohort receiving 3.5 mg of S315. All untreated animals died within 72 hours and all antibody-treated animals survived. Dehydration was observed more frequently in the 5 IU and 10 IU DAT cohorts compared to the 20 IU and S315 cohorts.
Conclusions: Treatment with S315 after diphtheria toxin exposure is protective; further studies will define a minimum effective dose of S315. This model mimics the route and timing of anti-toxin treatment in humans and provides a rigorous preclinical evaluation of a human antibody replacement for equine DAT.