Obinutuzumab‐Based Drug‐Free Macromolecular Therapeutics Synergizes with Topoisomerase Inhibitors

Drug‐free macromolecular therapeutics (DFMT) utilizes modified monoclonal antibodies (or antibody fragments) to generate antigen‐crosslinking‐induced apoptosis in target cells. DFMT is a two‐component system containing a morpholino oligonucleotide (MORF1) modified antibody (Ab‐MORF1) and human serum albumin conjugated with multiple copies of complementary morpholino oligonucleotide (MORF2), (HSA‐(MORF2)x). The two components recognize each other via the Watson–Crick base pairing complementation of their respective MORFs. One HSA‐(MORF2)x molecule can hybridize with multiple Ab‐MORF1 molecules on the cell surface, thus serving as the therapeutic crosslink‐inducing mechanism of action. Herein, various anti‐neoplastic agents in combination with the anti‐CD20 Obinutuzumab (OBN)‐based DFMT system are examined. Three different classes of chemotherapies are examined: DNA alkylating agents; proliferation pathway inhibitors; and DNA replication inhibitors. Chou–Talalay combination index mathematics is utilized to determine which drugs engaged synergistically with OBN‐based DFMT. It is determined that OBN‐based DFMT synergizes with topoisomerase inhibitors and DNA nucleotide analogs but is antagonistic with proliferation pathway inhibitors. Cell mechanism experiments are performed to analyze points of synergism or antagonism by investigating Ca2+ influx, mitochondrial health, lysosomal stability, and cell cycle arrest. Finally, the synergistic drug combinatorial effects of OBN‐based DFMT with etoposide in vivo are demonstrated using a human xenograft non‐Hodgkin's lymphoma mouse model. Synergistic chemotherapies to be used in combination with drug‐free macromolecular therapeutics (DFMT) technology are determined. DFMT is currently being explored as a new paradigm in treating B‐cell cancers. How DFMT behaves when administered in combination with clinically used anti‐neoplastic agents is of interest. Augmenting the technology with a synergistic chemotherapy could lead to improved anti‐cancer efficacy.