Drug-regulated CD33-targeted CAR T cells control AML using clinically optimized rapamycin dosing
Jacob Appelbaum, … , Alexander Astrakhan, Michael C. Jensen
Jacob Appelbaum, … , Alexander Astrakhan, Michael C. Jensen
Published March 19, 2024
Citation Information: J Clin Invest. 2024;134(9):e162593. https://doi.org/10.1172/JCI162593.
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Drug-regulated CD33-targeted CAR T cells control AML using clinically optimized rapamycin dosing

Abstract

Chimeric antigen receptor (CAR) designs that incorporate pharmacologic control are desirable; however, designs suitable for clinical translation are needed. We designed a fully human, rapamycin-regulated drug product for targeting CD33+ tumors called dimerizaing agent–regulated immunoreceptor complex (DARIC33). T cell products demonstrated target-specific and rapamycin-dependent cytokine release, transcriptional responses, cytotoxicity, and in vivo antileukemic activity in the presence of as little as 1 nM rapamycin. Rapamycin withdrawal paused DARIC33-stimulated T cell effector functions, which were restored following reexposure to rapamycin, demonstrating reversible effector function control. While rapamycin-regulated DARIC33 T cells were highly sensitive to target antigen, CD34+ stem cell colony-forming capacity was not impacted. We benchmarked DARIC33 potency relative to CD19 CAR T cells to estimate a T cell dose for clinical testing. In addition, we integrated in vitro and preclinical in vivo drug concentration thresholds for off-on state transitions, as well as murine and human rapamycin pharmacokinetics, to estimate a clinically applicable rapamycin dosing schedule. A phase I DARIC33 trial has been initiated (PLAT-08, NCT05105152), with initial evidence of rapamycin-regulated T cell activation and antitumor impact. Our findings provide evidence that the DARIC platform exhibits sensitive regulation and potency needed for clinical application to other important immunotherapy targets.

Authors

Jacob Appelbaum, April E. Price, Kaori Oda, Joy Zhang, Wai-Hang Leung, Giacomo Tampella, Dong Xia, Pauline P.L. So, Sarah K. Hilton, Claudya Evandy, Semanti Sarkar, Unja Martin, Anne-Rachel Krostag, Marissa Leonardi, Daniel E. Zak, Rachael Logan, Paula Lewis, Secil Franke-Welch, Njabulo Ngwenyama, Michael Fitzgerald, Niklas Tulberg, Stephanie Rawlings-Rhea, Rebecca A. Gardner, Kyle Jones, Angelica Sanabria, William Crago, John Timmer, Andrew Hollands, Brendan Eckelman, Sanela Bilic, Jim Woodworth, Adam Lamble, Philip D. Gregory, Jordan Jarjour, Mark Pogson, Joshua A. Gustafson, Alexander Astrakhan, Michael C. Jensen

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Figure 4

DARIC33 stimulates T cell transcriptional responses in the presence of antigen and rapamycin and without hallmarks of tonic signaling.

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DARIC33 stimulates T cell transcriptional responses in the presence of a...
(A–D) DARIC33 cells derived from n = 4 healthy donors were incubated with 1 nM rapamycin or medium alone before culture alone or with CD33+ MV4-11 AML target cells. After coculture, CD4+ and CD8+ cells were sorted and evaluated by RNA-Seq. (A) Schema for the experiment. DARIC33 cells resting in the absence of rapamycin or antigen are considered “off,” whereas DARIC33 cells incubated in rapamycin without antigen and with antigen exposure are labeled “ready” and “active,” respectively. (B) Transcriptional responses among selected genes associated with early T cell activation. (C) Volcano plot of the magnitude of statistical significance (y axis) versus magnitude of rapamycin and antigen (e.g., “DARIC-active”) effect (x axis, labeled “Coef.” in the figure). GZMB, IL2RA, and TNFRSF9 are shown in red, and additional genes exhibiting significant “DARIC-active” regulation are shown in black, with more detail provided in a heatmap shown in Supplemental Figure 5. (D) Flow cytometric confirmation that transcriptional changes are reflected in protein abundance. MFI for each sample is shown.