Chimeric Antigen Receptors Incorporating D Domains Targeting CD123 Direct Potent Mono- and Bi-specific Antitumor Activity of T Cells.

Chimeric antigen receptor (CAR) T cell therapies have demonstrated impressive initial response rates in hematologic malignancies. However, relapse rates are significant, and robust efficacies in other indications, such as solid tumors, will likely require novel therapeutic strategies and CAR designs. To that end, we sought to develop simple, highly selective targeting domains (D domains) that could be incorporated into complex, multifunctional therapeutics. Herein, we describe the identification and characterization of D domains specific for CD123, a therapeutic target for hematologic malignancies, including acute myelogenous leukemia (AML). CARs comprised of these D domains mediate potent T cell activation and cytolysis of CD123-expressing target cells and induce complete durable remission in two AML xenograft models. We describe a strategy of engineering less immunogenic D domains through the identification and removal of putative T cell epitopes and investigate the binding kinetics and affinity requirements of the resultant D domain CARs. Finally, we extended the utility of D domains by generating functional, bi-specific CARs comprised of a CD123-specific D domain and a CD19-specific scFv. The properties of D domains suggest that this class of targeting domain may facilitate the development of multi-functional CARs where conventional, scFv-based designs may be suboptimal.

Qin H ，Edwards JP ，Zaritskaya L ，Gupta A ，Mu CJ ，Fry TJ ，Hilbert DM ，LaFleur DW ... -  《-》

Redirecting Specificity of T cells Using the Sleeping Beauty System to Express Chimeric Antigen Receptors by Mix-and-Matching of VL and VH Domains Targeting CD123+ Tumors.

Thokala R ，Olivares S ，Mi T ，Maiti S ，Deniger D ，Huls H ，Torikai H ，Singh H ，Champlin RE ，Laskowski T ，McNamara G ，Cooper LJ ... -  《PLoS One》

T cells expressing CD123-specific chimeric antigen receptors exhibit specific cytolytic effector functions and antitumor effects against human acute myeloid leukemia.

Mardiros A ，Dos Santos C ，McDonald T ，Brown CE ，Wang X ，Budde LE ，Hoffman L ，Aguilar B ，Chang WC ，Bretzlaff W ，Chang B ，Jonnalagadda M ，Starr R ，Ostberg JR ，Jensen MC ，Bhatia R ，Forman SJ ... -  《-》

Engineering CAR-NK cells to secrete IL-15 sustains their anti-AML functionality but is associated with systemic toxicities.

The prognosis of patients with recurrent/refractory acute myelogenous leukemia (AML) remains poor and cell-based immunotherapies hold promise to improve outcomes. Natural Killer (NK) cells can elicit an antileukemic response via a repertoire of activating receptors that bind AML surface ligands. NK-cell adoptive transfer is safe but thus far has shown limited anti-AML efficacy. Here, we aimed to overcome this limitation by engineering NK cells to express chimeric antigen receptors (CARs) to boost their anti-AML activity and interleukin (IL)-15 to enhance their persistence. We characterized in detail NK-cell populations expressing a panel of AML (CD123)-specific CARs and/or IL-15 in vitro and in AML xenograft models. CARs with 2B4.ζ or 4-1BB.ζ signaling domains demonstrated greater cell surface expression and endowed NK cells with improved anti-AML activity in vitro. Initial in vivo testing revealed that only 2B4.ζ Chimeric Antigen Receptor (CAR)-NK cells had improved anti-AML activity in comparison to untransduced (UTD) and 4-1BB.ζ CAR-NK cells. However, the benefit was transient due to limited CAR-NK-cell persistence. Transgenic expression of secretory interleukin (sIL)-15 in 2B4.ζ CAR and UTD NK cells improved their effector function in the setting of chronic antigen simulation in vitro. Multiparameter flow analysis after chronic antigen exposure identified the expansion of unique NK-cell subsets. 2B4.ζ/sIL-15 CAR and sIL-15 NK cells maintained an overall activated NK-cell phenotype. This was confirmed by transcriptomic analysis, which revealed a highly proliferative and activated signature in these NK-cell groups. In vivo, 2B4.ζ/sIL-15 CAR-NK cells had potent anti-AML activity in one model, while 2B4.ζ/sIL-15 CAR and sIL-15 NK cells induced lethal toxicity in a second model. Transgenic expression of CD123-CARs and sIL-15 enabled NK cells to function in the setting of chronic antigen exposure but was associated with systemic toxicities. Thus, our study provides the impetus to explore inducible and controllable expression systems to provide cytokine signals to AML-specific CAR-NK cells before embarking on early-phase clinical testing.

Christodoulou I ，Ho WJ ，Marple A ，Ravich JW ，Tam A ，Rahnama R ，Fearnow A ，Rietberg C ，Yanik S ，Solomou EE ，Varadhan R ，Koldobskiy MA ，Bonifant CL ... -  《Journal for ImmunoTherapy of Cancer》

Improved Activity against Acute Myeloid Leukemia with Chimeric Antigen Receptor (CAR)-NK-92 Cells Designed to Target CD123.

Morgan MA ，Kloos A ，Lenz D ，Kattre N ，Nowak J ，Bentele M ，Keisker M ，Dahlke J ，Zimmermann K ，Sauer M ，Heuser M ，Schambach A ... -  《Viruses-Basel》