Tetraspanin CD37 has recently received renewed interest as a therapeutic target for B-cell malignancies. Although complement-dependent cytotoxicity (CDC) is a powerful Fc-mediated effector function... Show moreTetraspanin CD37 has recently received renewed interest as a therapeutic target for B-cell malignancies. Although complement-dependent cytotoxicity (CDC) is a powerful Fc-mediated effector function for killing hematological cancer cells, CD37-specific antibodies are generally poor inducers of CDC. To enhance CDC, the E430G mutation was introduced into humanized CD37 monoclonal IgG1 antibodies to drive more efficient IgG hexamer formation through intermolecular Fc-Fc interactions after cell surface antigen binding. DuoHexaBody-CD37, a bispecific CD37 antibody with the E430G hexamerization-enhancing mutation targeting two non-overlapping epitopes on CD37 (biparatopic), demonstrated potent and superior CDC activity compared to other CD37 antibody variants evaluated, in particular ex vivo in patient-derived chronic lymphocytic leukemia cells. The superior CDC potency was attributed to enhanced IgG hexamerization mediated by the E430G mutation in combination with dual epitope targeting. The mechanism of action of DuoHexaBody-CD37 was shown to be multifaceted, as it was additionally capable of inducing efficient antibody-dependent cellular cytotoxicity and antibody-dependent cellular phagocytosis in vitro. Finally, potent anti-tumor activity in vivo was observed in cell line- and patient-derived xenograft models from different B-cell malignancy subtypes. These encouraging preclinical results suggest that DuoHexaBody-CD37 (GEN3009) may serve as a potential therapeutic antibody for the treatment of human B-cell malignancies. Show less
Current generation adenoviral vectors (Ads) are not suitable for those gene therapy approaches that require long-term gene expression. This is due to their high immunogenicity and transient gene... Show moreCurrent generation adenoviral vectors (Ads) are not suitable for those gene therapy approaches that require long-term gene expression. This is due to their high immunogenicity and transient gene expression in fast dividing tissue. The development of gutless Ads, also known as helper-dependent Ads, is a major improvement in reducing the immunogenicity of the vector system. Gutless Ads lack virtually all viral protein-coding sequences, thus severely limiting the viral-antigen evoked cellular immune responses that may result in the elimination of the transduced cells. Safety wise, recombinant Ads are considered safe due to their inability to replicate autonomously. However, we show in this thesis that replication of recombinant Ads can be rescued by the co-infection of wild type (wt) Ads. In this thesis studies are described that aim at the development of a new system to prevent vector mobilization. Though at its present state not directly applicable, this system could also potentially be used for the production of gutless Ads devoid of helper Ad contamination. To improve efficacy of the Ad vector in dividing tissue we also studied two integration systems for their applicability in Ads. Overall, the experiments described in this thesis aim at generating safer vectors that should result in prolonged transgene expression due to lower immunogenicity and genomic integration. Show less
