Figure 7. Transient High Affinity FRβ mRNA CAR T cells retain anti-tumor activity against disseminated AML.

HA-Z and HA-28Z CAR mRNA was introduced into resting T cells by electroporation. CAR expression (a) and THP1 lysis (b) was measured on day 1 (left panels), day 5 (middle panels), and day 8 (right panels) following electroporation. “No RNA” (black) represents T cells electroporated in the absence of mRNA. (c) Bioluminescence of disseminated THP1 tumor growth in mice treated with mRNA or lentiviral (Lenti) CAR T cells. Mice were inoculated with 5×10⁶ fLuc-THP1AML cells via IV injection. Mice received 5×10⁶ HA-Z or CD19-Z Lenti CAR T cells on days 6 and 11, or 10×10e⁶ HA-Z or CD19-Z mRNA CAR T cells on days 6, 11, and 18 post tumor injection via IV delivery. mRNA CAR T cells were injected 18h post-electroporation. Mice receiving mRNA CAR T cells also received 60mg/kg Cyclophosphamide (Cy) IP between T cell doses (days 10 and 17) to eliminate CAR-negative T cells between doses. Error bars represent mean ± SEM of n=5 mice per group. IV– intravenous, IP– intraperitoneal, SEM– standard error, HA – high affinity FRβ. (* P < .05, ** P < .01, *** P < .001)