FIG. 4.

(A) There is little difference among RNA CAR constructs in survival, though CTX is required for multiple infusions to have efficacy. NSG mice (n=5 per experiment, repeated twice) were given 10⁶ Nalm-6 CBG on day 0 followed by the 3 infusion schedule of 10⁷ mRNA CAR T cells or a single infusion of 10⁷ stably transduced CAR T cells. All anti-CD19 CARs have statistically superior improved median overall survival (p<0.0001) to saline alone, CTX alone, a mesothelin CAR, and the 19–BBz CAR with no interval CTX. There was no significant difference between 19–z, 19–28z, 19–BBz, or 19–28BBz in survival. (B) In this experiment, NSG mice received 10⁶ of a primary pediatric high-risk leukemia modified to express the CBG luciferase. Constructs compared include CARs with unmodified sequence cassettes within the CAR or codon optimized versions to reduce internal open reading frames. While the 19–BBz wild type produced the most rapid initial disease response by bioluminescence, the effect was not sustained at the third infusion possibly because too much time had elapsed allowing leukemia to progress. (C) Survival was followed for 126 days, and no statistically significant differences in median overall survival could be appreciated between mRNA constructs (p=0.22). Stably modified CARs were superior in overall survival, with five mice both clearing leukemia and not developing lethal xenogenic GVHD. (D) Day 100 image of mice from the lentiviral CAR groups, demonstrating the jaw/tooth harbor site and the appearance of locoregional relapse.