Pharmacologic control of CAR-T cell function using dasatinib

Abstract

Key Points Dasatinib potently and reversibly suppresses CAR-T cell cytotoxicity, cytokine secretion, and proliferation. Dasatinib could be repurposed as a safety switch to mitigate CAR-mediated toxicity in patients.

Transient “rest” induces functional reinvigoration and epigenetic remodeling in exhausted CAR-T cells

“…We and others recently demonstrated that dasatinib, an FDA-approved tyrosine kinase inhibitor, suppresses CAR-T cell activation via rapid and reversible antagonism of proximal T cell receptor (TCR) signaling kinases (Mestermann et al, 2019;Weber et al, 2019). Consistent with our previous findings, dasatinib-treated HA.28z CAR-T cells exhibited undetectable phosphorylation of CAR CD3z and ERK1/2 compared to those treated with vehicle ( Figure S6A), indicating that dasatinib potently suppresses tonic signaling in CAR-T cells.…”

“…Similarly, transient rest in a population that had already acquired functional, transcriptional and epigenetic hallmarks of exhaustion, but not aPD-1 blockade, induced impressive functional reinvigoration that was associated with global transcriptional and epigenetic reprogramming. We observed similar phenotypic and functional reinvigoration following transient exposure to dasatinib, a Src kinase inhibitor that potently and reversibly inhibits TCR and CAR signaling (Lee et al, 2010;Mestermann et al, 2019;Schade et al, 2007;Weber et al, 2019). Collectively, these results challenge the paradigm that exhaustion is an epigenetically fixed state (Pauken et al, 2016;Philip et al, 2017) and reveal that transient cessation of CAR signaling may provide a new strategy for augmenting the function of exhausted human CAR-T cell populations.…”

“…To determine which of these factors was responsible for the incomplete reinvigoration observed in DasatinibD11-15 cells, we sought to interrogate exhaustion reversibility using a more protracted in vitro time course, wherein cells were rested in increments of 3-4 days from D4 until D25 ( Figure 7B). Since dasatinib completely suppresses CAR-T cell signaling and function ( Figure S6A) (Mestermann et al, 2019;Weber et al, 2019), whereas DD-CARs in the OFF state exhibited some leakiness in expression and function (Figures 1, S1B and S1C), we opted to utilize dasatinib to induce rest in the protracted model system. All groups of dasatinib-treated HA.28z CAR-T cells analyzed on D25 demonstrated diminished exhaustion marker expression and increased stem cell memory-associated CD62L and CD45RA expression ( Figures 7C and S6E).…”

Repeated stimulation or tonic-signaling chimeric antigen receptors drive regulatory T cell exhaustion

“…For example, even in the absence of tonic signaling, how continuous presence of an auto or alloantigen would affect a CAR-or TCRengineered Tregs will be an important consideration. The metabolic phenotype of exhausted Tregs suggests that, as for CD8 + T cells and CD4 + T convs, strategies to modulate signaling pathway activity for example by use of kinase inhibitors (Dufva et al, 2020;Mestermann et al, 2019;Weber et al, 2019;Weber et al, 2020b), or modulation of transcription factor expression Lynn et al, 2019), could be strategies to limit this risk.…”

Supercharging your CAR

“…Drugs identified in this screen as inhibitors of CAR T-cell activity, such as dasatinib, are currently under preclinical evaluation for controlling CAR T cell-mediated toxicities, which will validate the ability of this approach to identify biologically relevant drugs. 9,10 The second mitochondrial-derived activator of caspases (SMAC) mimetic birinapant was identified as enhancing CAR T-cell cytotoxicity against primary B-ALL cells. It may be of interest to evaluate birinapant for potential clinical use in combination with CAR T cells.…”