Incubation of Immune Cell Grafts With MAX.16H5 IgG1 Anti-Human CD4 Antibody Prolonged Survival After Hematopoietic Stem Cell Transplantation in a Mouse Model for Fms Like Tyrosine Kinase 3 Positive Acute Myeloid Leukemia

Abstract

Despite the constant development of innovative therapeutic options for hematological malignancies, the gold-standard therapy regimen for curative treatment often includes allogeneic hematopoietic stem cell transplantation (HSCT). The graft-vs.-leukemia effect (GVL) is one of the main therapeutic goals that arises from HSCT. On the other hand, graft-vs.-host disease (GVHD) is still one of the main and most serious complications following allogeneic HSCT. In acute myeloid leukemia (AML), HSCT together with high-dose chemotherapy is used as a treatment option. An aggressive progression of the disease, a decreased response to treatment, and a poor prognosis are connected to internal tandem duplication (ITD) mutations in the Fms like tyrosine kinase 3 (FLT3) gene, which affects around 30% of AML patients. In this study, C3H/HeN mice received an allogeneic graft together with 32D-FLT3ITD AML cells to induce acute GVHD and GVL. It was examined if pre-incubation of the graft with the anti-human cluster of differentiation (CD) 4 antibody MAX.16H5 IgG1 prevented the development of GVHD and whether the graft function was impaired. Animals receiving grafts pre-incubated with the antibody together with FLT3ITD AML cells survived significantly longer than mice receiving untreated grafts. The observed prolonged survival due to MAX.16H5 incubation of immune cell grafts prior to transplantation may allow an extended application of additional targeted strategies in the treatment of AML.

Humanized mouse model: Hematopoietic stemcell transplantation and tracking using short tandem repeat technology

“…After a minimum of 4 hours of recovery time, 2 × 10 5 or 4 × 10 5 CD34 + HSC were injected intrahepatically. The transplantation of PBMC was carried out by intravenous injection of 2 × 10 7 cells (preincubated with or without anti-human CD4 antibody MAX.16H5 IgG 4 to suppress the graft-vs-host reaction potentially mediated by the graft, a concept which we already described earlier 4,13,14 ). PB samples were obtained by retrobulbar bleeding under anesthesia.…”

The Epitope-Specific Anti-human CD4 Antibody MAX.16H5 and Its Role in Immune Tolerance

“…So far, no therapy manages HSCT or donor lymphocyte infusion without the need for conventional systemic immunosuppressive drugs. Promising in vivo data were obtained regarding the feasibility and effectivity of ex vivo graft incubation with MAX.16H5 IgG 1 and the antibody's influence on GVHD down modulation after allogeneic full-mismatch immune stem cell transplantation if the graft from TTG mice was preincubated with the antibody (70–72). Of note, removing unbound antibody molecules from the graft did not reduce its effectiveness (70–72).…”

“…Promising in vivo data were obtained regarding the feasibility and effectivity of ex vivo graft incubation with MAX.16H5 IgG 1 and the antibody's influence on GVHD down modulation after allogeneic full-mismatch immune stem cell transplantation if the graft from TTG mice was preincubated with the antibody (70–72). Of note, removing unbound antibody molecules from the graft did not reduce its effectiveness (70–72). The graft's unresponsiveness to allogeneic BALB/c wt antigens was even preserved if immune and stem cells from transplanted GVHD-free mice were transferred to new BALB/c wt mice without MAX.16H5 preincubation—a phenomenon called “infectious tolerance” (71).…”

“…It was shown that graft preincubation with the murine MAX.16H5 IgG 1 antibody did not influence the GVL effect which was induced by the transplanted immune cells (70, 71). In another murine model, the murine MAX.16H5 IgG 1 also prolonged the survival of recipient C3H/HeN mice (receiving a TTG immune cell graft to induce GVHD) even if they were co-transplanted with myeloblast-like murine cell line 32D Clone 3 (32D) expressing human Fms like tyrosine kinase 3 with the internal tandem repeat duplication (FLT3 ITD ), which constitutes an aggressive acute myeloid leukemia (AML) cell line model (72).…”