CD20-TCB with obinutuzumab pretreatment as next generation treatment of hematological malignancies

Purpose: Despite promising clinical activity, T cell engaging therapies including T cell bispecific antibodies (TCBs) are associated with severe side effects requiring the use of step-up-dosing (SUD) regimens to mitigate safety. Here, we present a next generation CD20-targeting TCB (CD20-TCB) with significantly higher potency and a novel approach enabling safer administration of such potent drug. Experimental design: We developed CD20-TCB based on the 2:1 TCB molecular format and characterized its activity pre-clinically. We also applied a single administration of obinutuzumab (Gazyva pre-treatment, Gpt) prior to the first infusion of CD20-TCB as a way to safely administer such a potent drug. Results: CD20-TCB is associated with a long half-life and high potency enabled by high-avidity bivalent binding to CD20 and head-to-tail orientation of B and T cell binding domains in a 2:1 molecular format. CD20-TCB displays considerably higher potency than other CD20-TCB antibodies in clinical development and is efficacious on tumor cells expressing low levels of CD20. CD20-TCB also displays potent activity in primary tumor samples with low effector:target ratios. In vivo, CD20-TCB regresses established tumors of aggressive lymphoma models. Gpt enables profound B cell depletion in peripheral blood and secondary lymphoid organs and reduces T cell activation and cytokine release in the peripheral blood thus increasing the safety of CD20-TCB administration. Gpt is more efficacious and safer than SUD. Conclusions: CD20-TCB and Gpt represent a potent and safer approach for treatment of lymphoma patients and are currently being evaluated in Phase I, multicenter study in patients with relapsed/refractory NHL (NCT03075696).

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