CD33-specific chimeric antigen receptor T cells exhibit potent preclinical activity against human acute myeloid leukemia

Abstract

Patients with chemo-refractory acute myeloid leukemia (AML) have a dismal prognosis. Chimeric antigen receptor T (CART) cell therapy has produced exciting results in CD19+ malignancies and may overcome many of the limitations of conventional leukemia therapies. We developed CART cells to target CD33 (CART33) using the anti-CD33 single chain variable fragment used in gemtuzumab ozogamicin (clone My96) and tested the activity and toxicity of these cells. CART33 exhibited significant effector functions in vitro and resulted in eradication of leukemia and prolonged survival in AML xenografts. CART33 also resulted in human lineage cytopenias and reduction of myeloid progenitors in xenograft models of hematopoietic toxicity, suggesting that permanently expressed CD33-specific CART cells would have unacceptable toxicity. To enhance the viability of CART33 as an option for AML, we designed a transiently expressed mRNA anti-CD33 CAR. Gene transfer was carried out by electroporation into T cells and resulted in high-level expression with potent but self-limited activity against AML. Thus our preclinical studies show potent activity of CART33 and indicate that transient expression of anti-CD33 CAR by RNA modification could be used in patients to avoid long-term myelosuppression. CART33 therapy could be used alone or as part of a preparative regimen prior to allogeneic transplantation in refractory AML.

Toxicities of chimeric antigen receptor T cells: recognition and management

“…This mechanism of toxicity can be minimized but not eliminated by an exhaustive search for expression of a targeted antigen on normal tissues during preclinical development of a CAR. [46][47][48] Examples of this mechanism of toxicity have been reported in the literature. In one study, 3 patients with metastatic renal cell carcinoma who received infusions of autologous T cells transduced with a CAR targeting carboxyanhydrase-IX experienced grade 3-4 increases in alanine aminotransferase, aspartate aminotransferase, or total bilirubin.…”

A Tet-On Inducible System for Controlling CD19-Chimeric Antigen Receptor Expression upon Drug Administration

“…7). Previously published preclinical studies or clinical trials strongly suggest the possibility that this novel technology may also be applicable to patients with other types of hematologic malignancies such as myeloid leukemia (8), multiple myeloma (9), or certain other types of solid tumors (10)(11)(12). However, because almost no antigens are truly tumor specific, it is necessary to prepare for some degree of adverse events related to CAR T-cell therapy.…”

Recent advances in T‐cell immunotherapy for haematological malignancies

“…(Dutour et al 2012, Kenderian et al 2015) Although treatment with a CD33 CAR resulted in eradication of AML and increased survival in both MOLM14 and primary AML xenografts after a single infusion, the potent antitumour effects were accompanied by myelotoxicity. (Kenderian et al 2015) This group therefore evaluated multiple infusions of T cells modified with RNA-CAR33 with lymphodepleting chemotherapy and observed benefit.…”

“…(Dutour et al 2012, Kenderian et al 2015) Although treatment with a CD33 CAR resulted in eradication of AML and increased survival in both MOLM14 and primary AML xenografts after a single infusion, the potent antitumour effects were accompanied by myelotoxicity. (Kenderian et al 2015) This group therefore evaluated multiple infusions of T cells modified with RNA-CAR33 with lymphodepleting chemotherapy and observed benefit. (Kenderian et al 2015) Hence, although expression of CD33 and CD123 on haematopoietic cells presents a challenge for effective targeted immunotherapy, the use of short term or “biodegradable” CAR T cells equipped with safety mechanisms represents a feasible therapeutic option.…”

“…(Kenderian et al 2015) This group therefore evaluated multiple infusions of T cells modified with RNA-CAR33 with lymphodepleting chemotherapy and observed benefit. (Kenderian et al 2015) Hence, although expression of CD33 and CD123 on haematopoietic cells presents a challenge for effective targeted immunotherapy, the use of short term or “biodegradable” CAR T cells equipped with safety mechanisms represents a feasible therapeutic option.…”