1137 EVOLVE205, a highly potent 2:1 CD20-targeted CD2 co-stimulatory T cell engager engineered for the treatment of B cell malignancies and B cell autoimmune diseases

<h3>Background</h3> T cell engager CD3-bispecifics have improved the treatment of patients with B cell lymphomas leading to recent approvals of the CD20-targeted CD3 bispecifics Glofitamab, Mosunetuzumab, and Epcoritamab for patients with relapsed, refractory diseases. Glofitamab with its 2:1 molecular format has the potential for increased CD20 binding and superior antitumor response compared to conventional 1:1 bispecifics. Recently, drug combinations of CD3-bispecifics and tumor-targeted costimulatory agonists, CD19-4-1BBL and CD19-CD28, have shown to be an attractive strategy in preclinical models to enhance Glofitamab’s efficacy, and are being investigated in the clinic but have challenges to establish optimal dose scheduling and dose levels which ensure simultaneous CD3 and costimulatory pathway activation. T cell costimulation using CD2 is an alternative strategy which may have significant benefits compared to 4-1BB and CD28. <h3>Methods</h3> Here we report on the development of a next-generation 2:1 format EVOLVE with integrated CD2-costimulation to improve CD3-mediated T cell receptor activation and sustain T cell-mediated cytotoxicity by increasing avidity-driven binding and the potential for the formation of alternative tumor-T cell synapses, to achieve superior performance to clinical benchmarks. <h3>Results</h3> EVOLVE205 with 2:1 molecular format and integrated CD2-costimulatory agonist shows superior cytotoxicity in both high and low CD20 expressing cell lines, representative of human B lineage sub-population found in lymphoid tissues. In an in vitro co-culture assay with tumor cells and Human PBMCs, EVOLVE205 displays improved human T cell activation, increased T cell expansion, and superior tumor cell killing without a substantial increase in cytokine release compared to 1:1 and 2:1 clinical benchmark bispecifics. Importantly, the tumor-killing potency of EVOLVE205 was improved by up to 60-fold compared to clinical benchmarks, and by over 1,000-fold compared to B cell depleting therapeutics (BCDTs) such as Rituximab. These data suggest the potential of EVOLVE205 to establish an improved therapeutic index relative to these clinical benchmarks. In a PBMC-engrafted xenograft NSG mouse model with WSU-DLCL2 large B cell lymphoma cell line, EVOLVE205 demonstrated superior tumor control to Glofitamab biosimilar. <h3>Conclusions</h3> CD2 costimulation integrated EVOLVE205 may provide sustained and potent T cell activation potentially to induce durable anti-tumor response in patients, while demonstrating good developability and favorable IgG-like pharmacokinetics in mice. EVOLVE205 is a highly differentiated CD20-targeted immunotherapy capable of providing deep and durable tissue and peripheral B cell depletion with favorable cytokine release profile compared to clinically available CD20-targeted TCE therapies and BCDTs for the treatment of B cell lymphomas and B cell-mediated autoimmune diseases.