Enhanced DR5 Agonist Activity of HexaBody-DR5/DR5 (GEN1029): C1q Dependence and Fc-gamma Receptor Independence in Preclinical Cancer Models

The study explores the use of a novel technology, HexaBody, to enhance the therapeutic potential of targeting the Death Receptor 5 (DR5) for cancer treatment. This approach involves the use of a modified immunoglobulin G (IgG) molecule that can form hexamers upon binding to cell surface antigens, thereby improving DR5 clustering on cancer cells. The HexaBody-DR5/DR5 (Hx-DR5-01/05) is a combination of two humanized monoclonal antibodies (mAbs) that have been engineered to promote hexamerization and target different epitopes of DR5.

In vitro studies have shown that Hx-DR5-01/05 exhibits enhanced DR5 agonist activity, which is dependent on both dual epitope targeting and increased Fc-Fc interactions. In vivo experiments using a mouse xenograft model have confirmed that Hx-DR5-01/05 demonstrates superior anti-tumor effects compared to single HexaBody molecules or a mixture of their wild-type counterparts.

The potency of Hx-DR5-01/05 was further evaluated in a range of human tumor cell lines and in xenograft models. The molecule was found to induce potent cytotoxicity in 104 tumor cell lines and was effective in more than ten xenograft models representing various solid cancers. Importantly, the cytotoxicity of Hx-DR5-01/05 was found to be optimal in the presence of serum or purified complement component C1q and was independent of FcγR-mediated antibody crosslinking or effector functions.

A variant of Hx-DR5-01/05 that lacks binding to both C1q and FcγR showed significantly reduced anti-tumor activity in a colon cancer xenograft model, whereas a variant that lacks FcγR binding but retains C1q binding maintained comparable anti-tumor activity to Hx-DR5-01/05. This suggests that the interaction with C1q is crucial for the cytotoxicity of Hx-DR5-01/05.

The research highlights Hx-DR5-01/05 as a promising DR5-specific HexaBody molecule with potent agonist activity across multiple preclinical models. The molecule's cytotoxicity is most effective with C1q and does not rely on FcγR binding, which is a significant finding for the development of cancer therapies. A clinical trial to evaluate the safety of Hx-DR5-01/05 in patients is currently in progress.