Abstract
Hematopoietic cell transplantation (HCT) is a last resort, potentially curative treatment option for pediatric patients with refractory acute myeloid leukemia (AML). Cord blood transplantation (CBT) results in less relapses and less graft-versus-host disease when compared to other sources. Nevertheless, still more than half of the children die from relapses. We therefore designed a strategy to prevent relapses by inducing anti-AML immunity after CBT, using a CB-derived dendritic cell (CBDC) vaccine generated from CD34+ CB cells from the same graft. We here describe the optimization and validation of good manufacturing practice (GMP)-grade production of the CBDC vaccine. We show the feasibility of expanding low amounts of CD34+ cells in a closed bag system to sufficient DCs per patient for at least three rounds of vaccinations. The CBDCs showed upregulated costimulatory molecules after maturation and showed enhanced CCR7-dependent migration toward CCL19 in a trans-well migrations assay. CBDCs expressed Wilms’ tumor 1 (WT1) protein after electroporation with WT1-mRNA, but were not as potent as CBDCs loaded with synthetic long peptides (peptivator). The WT1-peptivator loaded CBDCs were able to stimulate T-cells both in a mixed lymphocyte reaction as well as in an antigen-specific (autologous) setting. The autologous stimulated T-cells lysed not only the WT1+ cell line, but most importantly, also primary pediatric AML cells. Altogether, we provide a GMP-protocol of a highly mature CBDC vaccine, loaded with WT1 peptivator and able to stimulate autologous T-cells in an antigen-specific manner. Finally, these T-cells lysed primary pediatric AML demonstrating the competence of the CBDC vaccine strategy.
Highlights
Acute myeloid leukemia (AML) is the second most prevalent leukemia (15%–20%) with a 5-year survival rate in children of ~50%–60% [1]
As a last treatment resort, patients with certain high-risk cytogenetic features (e.g. FMS-like tyrosine kinase 3 (FLT3)-ITD without concomitant NPM1) [2] and therapy-refractory patients or patients with relapsed AML who achieve CR2 after reinduction therapy are eligible for allogeneic hematopoietic cell transplantation [3]
Five test runs from five donors were performed to test for sufficient number of mature CB-derived dendritic cell (CBDC)
Summary
Acute myeloid leukemia (AML) is the second most prevalent leukemia (15%–20%) with a 5-year survival rate in children of ~50%–60% [1]. The reduced risk of developing graft versus host disease (GvHD) [10, 12, 13] and viral reactivation after HCT without serotherapy have supported the use of CB as a cell source for transplantation [10, 12, 14, 15]. This provides an autologous source for stem cell-derived DC for vaccination after HCT. The protocol generated CBDC in sufficient numbers as used in previous moDC vaccination studies (total dose in adults 0.1–20×10^6) [17,18,19]
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