UCLA

Anti-CD20 monoclonal antibodies (mAbs) have revolutionized the therapy of B cell lymphomas, but are only partially effective. While current genetic engineering and efforts are yielding mAbs with enhanced antibody-dependent cellular functions, these improvements are largely incremental and do not result in altering the tumor microenvironment and host immune cells to favor immune-mediated tumor destruction. We hypothesize that the efficacy of anti-lymphoma mAbs can be improved by linking these precise tumor-targeting vehicles to immunomodulatory substances for release within the tumor microenvironment. Toll-like receptor 9 (TLR9) agonist CpG oligodeoxynucleotides (ODN) are prime candidates for boosting anti-lymphoma immunity. Thus we aimed to characterize the activity and mechanisms of action of anti-CD20-CpG conjugates in a syngeneic immunocompetent model for B cell lymphomas.

We confirmed that anti-CD20-CpG conjugates can be purified from unconjugated antibody and CpG while maintaining biological activity. Confocal microscopy studies with fluorescently-labeled conjugates revealed cellular uptake on human CD20 expressing mouse lymphoma cells, suggesting CpG is able to enter the cell even when targeting a non-internalizing target. Lastly, conjugates had superior normal B cell depletion efficiency compared to rituximab; even in more resistant B cell compartments such as the peritoneal cavity.