Fig. 9. mLPA-antigen cellular immunization sustains the in vivo anti-leukemia efficacy of DN4.99 TCR-T cells against CD1c+ acute leukemia MOLM-13.
a DN4.99 TCR-transduced T (DN4.99 TCR-T) cells restrict MOLM-13 leukemia progression in vivo. NOD.Cg-Prkdcscid IL- 2rgtm1Wjl/SzJ (NSG) mice (n = 10) received intravenous (i.v.) injection of 5 × 104 MOLM-13-CD1c cells co-expressing secreted LUCIA luciferase. After 17 days, mice were sub-lethally irradiated, followed 24 h later by the transfer of 107 DN4.99 TCR-T cells (red lines/dots) or vehicle (gray lines/triangles). n = 5 mice/group. After 2 weeks, all mice received i.v. 5 × 105 monocyte-derived Dendritic Cells (moDCs) loaded with methyl-lysophosphatidic acid (mLPA), followed, only in the mice the had originally received the first T cell transfer, by two subsequent transfers of 107 DN4.99 TCR-T cells one week apart. b Tumor progression was monitored in peripheral blood by a bioluminescence assay. RLU, Relative Light Unit. c DN4.99 TCR-T cell expansion upon i.v. injection of mLPA-loaded moDCs into MOLM-13-CD1c tumor-bearing mice, determined as the percentage of human T cells in the peripheral blood of mice by flow cytometry labeling with anti-mouse CD45 and anti-human CD3 monoclonal antibody. T cell frequency was normalized based on the percentage of mouse CD45- cells. Data are represented as mean ± SD. *P = 0.0467; ***P = 0.0002 determined by Ordinary one-way ANOVA followed by Tukey’s multiple comparison test. n = 5 mice at day +21, +26, and +37; n = 2 mice at day +42. d Kaplan–Meier survival curves show a significant increase in the survival of mice receiving DN4.99 TCR-T cells compared to control groups. **P = 0.002 determined by log-rank (Mantel–Cox) test. Results are representative of 2 independent experiments with independent T cell lines giving comparable results.