Medical research using Angimmune's technology in a Phase I clinical trial of the anti-T cell bivalent immunotoxin Resimmune™ (IND No. 100712, clinical trial identifier NCT00611208) at Scott & White Memorial Hospital, Temple TX under the direction of Arthur Frankel M.D., is currently being investigated. Early results on the first 5 treated patients were reported in Current Drug Targets, 2009, 10, 104-109, Anti-CD3 Recombinant Diphtheria Immunotoxin Therapy of Cutaneous T Cell Lymphoma (CTCL).

Results from 30 patients in the Phase I trial was published in Haematologica, 2015 Jun;100(6):794-800. Resimmune, an anti-CD3ε recombinant immunotoxin, induces durable remissions in patients with cutaneous T-cell lymphoma3.

These results have not established safety or clinical efficacy. However, a number of interesting observations have been made that will guide future studies. Several of these observations and their relevance to mechanisms are described below. This page will be updated when additional study results are published.

Sustained Effect Theory

This immunotoxin kills both malignant and normal T cells, however the normal T cells begin to repopulate within ten days from the periphery. This process is known as homeostatic proliferation. T cells repopulated by homeostatic proliferation may have different clonal distributions and different activities compared to previous states.1 In the study, patient number two was treated and reported as follows:

"Patient 2 is a 78-year-old male who developed CTCL in 2003 with a maculopapular rash on his buttocks and a groin mass. Biopsy of both lesions showed T-cell lymphoma. CT scan showed diffuse adenopathy. He received six cycles of chemotherapy with cyclophosphamide, doxorubicin, vincristine, and methylprednisolone (CHOP chemotherapy), but after several years the rash recurred. Biopsy again showed CTCL. He did not have node or marrow involvement based on CT scans and bone marrow biopsies and was staged as IB. He was treated with A-dmDT390-bisFv(UCHT1) and achieved a PR lasting one month. Following recurrence of his skin lesions, he received no further therapy. His disease diminished spontaneously over six months."2 Further studies are being done to determine if this observation of a sustained effect is repeatable in a larger population of treated patients.

The most likely theory for a sustained effect is that the anti-T cell immunotoxin acts in addition to killing malignant T cells as an immunomodulator. The immunomodulation achieves a “resetting” of the immune system upon T cell repopulation that renders the body less hospitable to the tumor. Supporting evidence for this hypothesis is the fact that in mice homeostatic repopulated T cells lose self-tolerance toward tumor antigens (Klebanoff et al., Trends Immunol, 2005, 26(2), 111-117.) This raises the possibility that anti-T cell immunotoxin may be able to function as an immune modulator for malignancies that do not uniformly express surface CD3 such as T-ALL or even malignancies with no expression of CD3 such as metastatic melanoma.

T cells repopulated by homeostatic proliferation may have different clonal distributions and different activities compared to previous states. This raises the possibility that T cell depletion followed by homeostatic repopulation may induce remissions in some T cell driven autoimmune diseases.

In a monkey model of multiple sclerosis where foreign myelin basic protein induces T cells to enter the brain causing encephalomyelitis, treatment with anti-T cell immunotoxin eliminates brain and blood T cells. When T cells repopulate in the blood, they do not reenter the brain compartment indicating that the repopulated T cells have changed their pathological characteristics (Hu et al., 1997, Cellular Immunology, 177:26).