Background
T cell engagers have demonstrated success in treating hematologic malignancies, but they still face limitations for the treatment of solid tumors. ModeX has developed a novel platform termed Lymphocyte Activator and Survival Enhancement Receptor (LASER) antibodies. MDX2001 is a first-in-class tetraspecific LASER recognizing CD3 and CD28 on human T cells and c-MET and TROP2 on tumor cells. It is designed to 1) optimize T cell activation/survival by dual signaling through CD3 and CD28, and 2) overcome target expression heterogeneity and treatment escape/resistance by binding to two different tumor antigens. MDX2001 is engineered with knob-into-hole mutations to promote Fc heterodimerization, and an Fc-null format to prevent triggering of Fc-dependent immune activation. Here, we evaluate the pharmacology of MDX2001 and provide proof of concept for the proposed mechanism of action.
Methods
Binding affinity of MDX2001 was determined using biolayer interferometry. Tumor cytolytic activity was assessed by Real-Time Cell Analysis in co-cultures of human peripheral blood mononuclear cells (PBMCs) and tumor cells. T cell activation was evaluated by flow cytometry and multiplex cytokine analysis. In vivo anti-tumoral efficacy was assessed using a humanized mouse tumor model.
Results
MDX2001 binds to human CD3, CD28, c-MET and TROP2 with nanomolar affinity but does not bind to the mouse, rat, or dog orthologs. It binds to non-human primate CD28, c-MET and TROP2 but not CD3. MDX2001 demonstrates abrogated or significantly reduced binding to Fc- receptors while retaining the physiologic pH-dependent binding dynamic with human neonatal Fc receptor. When incubated with human PBMCs and tumor cells expressing TROP2 and c-MET, MDX2001 induced T cell activation as measured by secretion of interleukin (IL)-2, interferon-, and IL-6 at concentrations as low as 15 pM. In contrast, MDX2001 induced only marginal T cell activation and cytokine release in human PBMCs in the absence of tumor cells. MDX2001 induced potent in vitro anti-tumor cytolytic activity by human PBMCs against a panel of 10 human tumor cell lines of different tissue origins expressing various levels of TROP2 and c-MET, including cell lines with low TROP2 or low c-MET expression. In a humanized mouse breast cancer tumor model, MDX2001 significantly inhibited tumor growth.
Conclusions
MDX2001 is novel multispecific LASER antibody that demonstrates potent antitumor activity in vitro and in vivo, with minimal T cell activation in the absence of tumor cells. The biochemical and functional properties of MDX2001 support clinical development of this candidate for the treatment of solid tumor malignancies.
Ethics Approval
Animal study conducted at Charles River Laboratories (CRL) in compliance with CRL IACUC under IACUC No. I033.