Engineering Off-the-Shelf Gamma Delta CAR T Cells for the Treatment of Acute Myeloid Leukemia

• Published in: Blood 2023-11, Vol.142 (Supplement 1), p.4827-4827
• Main Authors: Dwivedi, Alka, Fu, Lynn, Chien, Chris Daniel, Pouzolles, Marie, Shah, Nirali N., Taylor, Naomi
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2023-190357

Chimeric antigen receptor T cell therapy (CART) therapy has shown remarkable success in the treatment of B cell acute lymphoblastic leukemias (B-ALL) and lymphomas. However, CART therapies for acute myeloid leukemia (AML), where 5-year survival rates are significantly lower than for B-ALL, are only in their infancy. CD33-CART have potent activity against AML in preclinical models and a first-in-child/first-in-human phase 1/2 CD33-CART clinical trial for AML is ongoing in the Pediatric Oncology Branch of the National Cancer Institute (NCT03971799). Nonetheless, published outcomes suggest a modest efficacy of approximately 50% (Shahzad et al., Front Immunol 2023), highlighting the critical need to develop new strategies to improve CART accessibility and a more robust anti-AML response. We hypothesized that off-the-shelf gamma delta (γδ) CD33 CART cells could potentially overcome current challenges for the treatment of AML. γδ lineage T cells are unconventional lymphocytes whose functions are not restricted to MHC-mediated antigen presentation; they are primed for immediate responses, including tumor killing. Furthermore, allogeneicγδ T cells have the potential to induce robust anti-tumor cytotoxicity without causing graft versus host disease (GVHD). Here, we generated γδ CAR T cells from healthy donor elutriated lymphocytes by activation with zoledronic acid and IL-2 for 7-14 days. Within 9 days post stimulation, the vast majority of lymphocytes were Vδ2+ and 30-40% were successfully transduced with a lentiviral CD33 CAR construct harboring the 4-1BB costimulatory domain. Importantly, and unlike conventional alpha beta (ab) T lymphocytes, >98% of these γδ CD33CAR T cells expressed IFNγ under basal conditions. This characteristic likely accounted for the efficient in vitro killing of AML cell lines by untransduced γδ T lymphocytes under conditions of high effector/target (E/T) ratios. While untransduced γδ T cells did not exhibit cytotoxicity following repeat AML stimulations, γδ CD33CAR T lymphocytes exhibited proficient in vitro cytotoxicity, with killing rates that were more rapid than those initiated by ab CD33 CART (Figure 1). These characteristics were associated with a prolonged metabolic activity of γδT cells; γδ CD33 CART expressed high levels of the GLUT1 glucose transporter for >14 days post activation whereas GLUT1 levels on ab CD33 CART returned to resting within 10 days. High GLUT1 levels were linked to efficient killing under conditions of basa