Fab'-MORF1

Fab'-MORF1 is a nanoconjugate composed of an antibody Fab' fragment covalently linked to a 25-base morpholino oligonucleotide (MORF1). It functions as a pre-targeting agent in a two-step drug-free macromolecular therapeutic (DFMT) system, specifically designed for the targeted crosslinking and apoptosis induction in B-cell malignancies. The Fab' portion provides antigen specificity—typically directed against B-cell antigens such as CD20, CD38, BCMA, or SLAMF7—while the MORF1 sequence serves as a hybridization site for a subsequently administered complementary oligonucleotide (MORF2) conjugated to a multivalent carrier (often human serum albumin or synthetic polymer)[1][2][3][5][8][9]. Mechanism: In the first step, Fab'-MORF1 binds the target antigen on malignant B cells. In the second step, a multivalent MORF2 construct is administered, hybridizing with cell-bound MORF1 to induce crosslinking of surface receptors, leading to direct apoptosis of the targeted cells without delivering cytotoxic drugs, toxins, or effector functions[1][3][5][9]. This system aims to achieve precise B-cell depletion, especially in diseases like non-Hodgkin lymphoma[1][3][7]. Several antigen-specific variants exist, e.g., Fab'-RTX-MORF1 (rituximab-derived, anti-CD20), Fab'-DARA-MORF1 (daratumumab-derived, anti-CD38), etc.[1][2]. Development has been conducted in academic labs (notably the Kopeček Laboratory, University of Utah), demonstrating in vitro and in vivo efficacy, but there are no indications of commercial manufacturing or clinical trials as of now[1][3][9].