Pharmacology of Anti-CD3 Diphtheria Immunotoxin in CD3 Positive T-Cell Lymphoma Trials
Anti-CD3 recombinant diphtheria immunotoxin, A-dmDT390-bisFv(UCHT1), consists of the catalytic and translocation domains of diphtheria toxin fused to two single chain Fv fragments of an anti-CD3ɛ monoclonal antibody (UCHT1). A-dmDT390-bisFv(UCHT1) is capable of killing CD3+ T-lymphoma cells and normal T cells specifically in the femtomolar concentration range. To study pharmacology of A-dmDT390-bisFv(UCHT1) in patients with CD3+ T-cell lymphoma in a phase I clinical trial, (1) highly sensitive bioassay using Jurkat cells for measuring drug levels, (2) ELISA for measuring anti-DT antibody titer, and (3) 5-color FACS analysis method for measuring changes of subtype T-cell population were developed. In addition to evaluating drug efficacy and pharmacokinetics in patients, it is important to correlate pre-existing anti-DT antibody levels with maximum drug concentration in serum and extent of T-cell depletion because pre-existing anti-DT antibodies due to DPT (Diphtheria, Pertussis, and Tetanus) immunization can neutralize diphtheria immunotoxin. We observed that at the lowest treatment dose (2.5 μg/kg: twice daily for 4 days) A-dmDT390-bisFv(UCHT1) depletes greater than 99.0% of normal T cells in all six patients for a short period of time (2–3 days) and that there is no association of C max and extent of T-cell depletion with the pre-existing anti-DT antibody titer.
Key wordUCHT1 immunotoxin CD3 diphtheria toxin T-cell depletion pre-existing anti-DT antibodies
- 2.Hymes, K. B. (2007) Choices in the treatment of cutaneous T-cell lymphoma. Oncology (Williston Park) 21, 18–23.Google Scholar
- 4.Woo, J. H., Liu, J. S., Kang, S. H., Singh, R., Park, S. K., Su, Y., Ortiz, J., Neville, D. M., Jr., Willingham, M. C., Frankel, A. E. (2008) GMP production and characterization of the bivalent anti-human T cell immunotoxin, A-dmDT390-bisFv(UCHT1) for phase I/II clinical trials. Protein Expr Purif 58, 1–11.PubMedCrossRefGoogle Scholar
- 12.Hall, P. D., Virella, G., Willoughby, T., Atchley, D. H., Kreitman, R. J., Frankel, A. E. (2001) Antibody response to DT-GM, a novel fusion toxin consisting of a truncated diphtheria toxin (DT) linked to human granulocyte-macrophage colony stimulating factor (GM), during a phase I trial of patients with relapsed or refractory acute myeloid leukemia. Clin Immunol 100, 191–197.PubMedCrossRefGoogle Scholar
- 13.Kivisakk, P., Mahad, D. J., Callahan, M. K., Trebst, C., Tucky, B., Wei, T., Wu, L., Baekkevold, E. S., Lassmann, H., Staugaitis, S. M., Campbell, J. J., Ransohoff, R. M. (2003) Human cerebrospinal fluid central memory CD4+ T cells: evidence for trafficking through choroid plexus and meninges via P-selectin. Proc Natl Acad Sci U S A 100, 8389–8394.PubMedCrossRefGoogle Scholar
- 15.Soler, D., Chapman, T. R., Poisson, L. R., Wang, L., Cote-Sierra, J., Ryan, M., McDonald, A., Badola, S., Fedyk, E., Coyle, A. J., Hodge, M. R., Kolbeck, R. (2006) CCR8 expression identifies CD4 memory T cells enriched for FOXP3+ regulatory and Th2 effector lymphocytes. J Immunol 177, 6940–6951.PubMedGoogle Scholar