Development of novel synNotch CART cell therapy in adult patients with recurrent EGFRvIII+ glioblastoma

Development of safe and effective (CAR)-transduced T cell (CART) therapy for glioblastoma (GBM) needs to overcome multiple challenges, including on-target off-tumor toxicity, heterogeneity of antigen expression, and exhaustion of CART cells. There are no GBM-specific surface antigens that are uniformly present in tumor tissue.

Mutant epidermal growth factor receptor (EGFRvIII), for example, is GBM-specific but its expression is heterogenous within the tumor.

On the other hand, while non-mutant GBM-associated antigens (GAAs), such as EphA2 and IL-13R?2, are more uniformly expressed in GBM, their expression in other organs outside the central nervous system (CNS) raises concern for off-tumor toxicity.

As a way to safely and effectively target GAAs, we have adopted a novel synthetic Notch ?synNotch? receptor system and developed innovative T cells. In this system, the first antigen, which is expressed exclusively on brain or GBM cells (e.g.

EGFRvIII), primes the T cells to induce expression of a CAR that recognizes IL-13R?2 and EphA2, thereby eradicating GBM cells expressing either EphA2 or IL-13?2.

Our data show that EGFRvIII-synNotch primed IL-13R?2/EphA2 CAR are effectively but restrictedly activated by EGFRvIII as the GBM-specific signal, leading to complete eradication of patient-derived xenografts with heterogeneous EGFRvIII expression but without attacking IL-13R?2/EphA2- positive cells outside of CNS.

Furthermore, these synNotch-CAR T cells were significantly more efficacious than conventional, constitutively expressed IL-13R?2/EphA2 CAR T cells, and were associated with excellent persistence (>100 days in vivo).

Taken together, our data indicate that synNotch CAR T cells can revolutionize the CAR T therapy for solid cancers by overcoming the off-tumor toxicity, antigen heterogeneity and lack of persistence.

Our goals are to establish the process for development of Good Manufacturing Practice products of EGFRvIII-primed IL-13R?2/EphA2 CAR T cells, to obtain an Investigational New Drug (IND) approval, and to develop and conduct a phase I trial in patients with recurrent GBM.

In Aim 1, we will generate GMP-grade lentiviral vector and establish standard procedures for GMP-grade manufacturing of the EGFRvIII-primed IL-13R?2/ EphA2 CAR T cells. In Aim 2, we will complete both in vitro and in vivo studies that are required for submission of an IND.

In vitro studies include confirmation of antigen-specific priming, specific cytotoxicity, and absence of replication competent lentivirus.

In vivo, we will confirm preclinical efficacy, toxicology, tissue biodistribution, and engraftment as well as persistence of synNotch CART cells.

In Aim 3, in a first-in-human phase 1 clinical trial, we will determine safety and toxicity of the synNotch CART cells in patients with recurrent EGFRvIII+ GBM.

In a subsequent expansion cohort, in patients with recurrent EGFRvIII+ GBM, we will infuse synNotch CART cells intravenously prior to surgery, and then evaluate infiltration, priming and function of the infused cells in the resected GBM.

These studies will allow us to determine optimal dosing based not only on tolerability but also on pharmacodynamic assessments.