Targeting Allergies: Chimeric Antigen Receptor T cells targeting membrane-IgE successfully eliminate IgE+ cells

Tali Stauber ¹ Miri Fried ¹ Iris Dotan ¹ Alessio David Nahmad ¹ Daniel Nataf ¹ Inbal Reuveni ¹ Fred Finkelmam ² Itai Benhar ³ Irit Shefler ⁴ Yossi Mekori ⁴ National GEMM Service ⁵ Adi Barzel ¹

¹Biochemistry and Molecular Biology, Tel Aviv University, Israel
²Internal Medicine, Cincinnati Children's Hospital, USA
³Biotechnology, Tel Aviv University, Israel
⁴Laboratory of Clinical Immunology and allergy, Meir Medical Center, Israel
⁵Authority for Biological and Biomedical Models, Hebrew University, Israel

Introduction: The prevalence of IgE mediated allergies has risen dramatically in the westernized world. Current treatment for allergies fails to offer a robust cure.

Aim: To design Chimeric Antigen Receptor T cells (CAR-Ts) that will target and destroy (IgE+)-B cells, and abolish all IgE production.

Methods: We designed three 2nd generation CARs: two of the designs target IgE-C3 domain; the scFv of the first design was adopted from Omalizumab (therapeutic anti IgE antibody) and the ectodomain of the second is a mutated FcERIα IgE-Receptor. The third CAR was designed to target M1`, a domain unique to membrane bound IgE (mIgE). CARs were expressed on human primary lymphocytes via Retroviral transduction. We tested the potency of the therapy on engineered NALM-6 cell line expressing mIgE.

Results: IgE-targeting CAR-T cells successfully eliminated IgE+ expressing NALM6 cells but not wild type NALM-6. this targeted elimination was accompanied by increase of gamma interferon production by the effector cells. To test the potency of the CAR-Ts against primary IgE+ B cells, which are extremely sparse in blood, we are currently experimenting with B cells from human blood and tonsils, inducing them towards class switch to IgE production. In addition, we will assess whether the presence of free IgE will compromise the killing. The superior anti-IgE-CAR design will be tested in an in vivo transgenic mouse model.

Conclusion: CAR-Ts targeting mIgE hold promise as a curative therapy for IgE mediated allergies. We anticipate that M1`-targeting CAR-T will be the superior design in an IgE rich culture.