Background
Multispecific T cell adhesion scaffolds have become effective anticancer therapies for hematologic malignancies. Strategies are needed to modulate cancer cell targeting and provide personalized, multispecific immunotherapy. The effectiveness of T cell recruitment strategies depends on the expression of target antigens on cancer cells. Downregulation of target antigens on cancer cells impairs the effectiveness of T cell therapy and prevents cancer cell destruction. Dual- and multi-target T cell recruitment strategies hold promise for addressing relapse by expanding cancer cell targeting. Simultaneously targeting two or more antigens on the cancer cell surface can increase selective therapeutic pressure and reduce the incidence of antigen-negative relapses.
On August 16, 2024, researchers from the Center for Controlled Chemical Delivery and the Department of Molecular Pharmacy at the University of Utah published an article titled "Multiantigen T-Cell Hybridizers: A Two-Component T-Cell-Activating Therapy" in ACS nano. The study reports a modular, split-antibody-like approach consisting of Fab' fragments modified with complementary morpholino oligonucleotides (MORFs), a technology named Multi-Antigen T-Cell Hybridization (MATCH). A library of B cell-targeting Fab'-MORF1 conjugates was synthesized, which self-assembled with complementary T cell-binding Fab'-MORF2 conjugates via Watson-Crick base pairing hybridization.
Using MATCH, the authors achieved cancer-specific T cell recruitment by targeting four B cell antigens: CD20, CD38, BCMA, and SLAMF7. Antigen expression profiles of various malignant B cell lines were generated, and these diverse antigen expression profiles were used to activate cell-specific T cells against lymphoma, leukemia, and multiple myeloma cell lines in vitro. The self-assembling MATCH conjugates resemble bispecific T cell-binding constructs. The two-component nature of MATCH enables a modular and customizable approach to design bispecific and multispecific T cell recruitment therapies.
Synthesis and Characterization of Fab'-MORF Conjugates
Based on their uniqueness on malignant B cells, the availability of FDA-approved antibodies, and their potential use for major hematologic cancers, four antigens—CD20, CD38, BCMA, and SLAMF7—were selected to generate a library of targeting motifs targeting various malignant B cell lines. The authors constructed a T cell engagement molecule based on the α-CD3 antibody. Two complementary morpholino oligonucleotides, MORF1 and MORF2, functionalized with primary amines at their 3' ends, served as recognition motifs between the T cell and B cell conjugates. The oligonucleotides were linked to the desired Fabs via a bifunctional SM ( PEG ) 2 linker. MORF1 was conjugated to cancer antigen Fabs, while MORF2 was conjugated to CD3-targeting Fabs. A Fab'B cell-MORF1 species complemented a Fab'CD3-MORF2 molecule through Watson-Crick base pairing to form heterodimers.
B cell antigen expression profiles and lineage-specific T cell activation
Three representative cell lines of major hematological cancers are HL-60 (leukemia), Raji (lymphoma), and MMIS (myeloma). Each cell type has a distinct target antigen expression profile. T cells are activated only when the target cells express the corresponding antigen. Raji cells were killed by effector T cells when treated with Fab 'CD38-MORF1' or Fab 'CD20-MORF1', but not when treated with Fab 'BCMA-MORF1' or Fab 'SLAMF7-MORF1-targeting motifs. The same T cells were exposed to three different cancers and activated using cancer-specific targeting motifs to kill each cancer.
MATCH-induced T cell cytotoxicity in target cells
MATCH functions similarly to BsAbs, forming a bridge between target cancer cells and effector cytotoxic T cells, creating an immune synapse. Binding of the Fab's CD3-MORF2 to the TCR initiates TCR-like activation of the T cell, leading to polarization and degranulation of cytotoxic components toward the target cell at the interface. Cytotoxic cell death is rapid, occurring in the order of 1-6 hours. One hour after exposure to CD20-directed MATCH-induced T cell activation against Raji cells, significant increases in mitochondrial depolarization, caspase activity, and cytosolic reactive oxygen species were observed.
A single dose of CD20-targeted MATCH eliminates NHL tumors in vivo
CD20-directed MATCH therapy was used to treat non-Hodgkin lymphoma (NHL) in a mouse model. A two-step administration approach was used, with the B cell-targeting Fab ' RTX-MORF1' first administered, followed by the T cell engager Fab ' CD3-MORF2, administered 5 hours apart. The study found that mice treated with MATCH had a trend toward increased survival compared to mice treated with blinatumomab. A single 60 μg dose of CD20-targeted MATCH resulted in three out of three mice surviving to the endpoint of the experiment, 75 days. After 75 days, the mice were sacrificed, and bone marrow was obtained for staining for human B cell markers. No residual disease was observed in the three surviving mice.
T cell to target cell ratio for CD20 -directed MATCH in NRG mice
Through in vivo NRG mouse model experiments, it was found that 1 hour after vaccination, when the MATCH dose was 60 μg, the optimal ratio of T cells to target cells was 5:1, which had a better delaying effect on disease onset.
Summarize
MATCH technology is an innovative two-component T cell activation therapy that achieves highly effective treatment of a variety of hematological malignancies by specifically binding to cancer cells and T cells. The two-component system allows for the construction of modular bispecific structures with high throughput compared to BiTEs or other related recombinant strategies. The platform capabilities of MATCH provide a method for simultaneous cancer-specific optimization and effector cell identification to achieve long-term responses to treatment and greater resistance to antigen-negative relapse. Personalized targeted therapy will provide better prognosis for patients, while tunable effector cell activation will enable physicians to better control unnecessary and dangerous effector cell side effects.
