Investigating the mechanism of action of adrenotumab, a DLK1 monoclonal antibody, for the targeted treatment of adrenocortical carcinoma

Adrenocortical carcinoma is a rare malignancy with a dismal prognosis in the advanced stages. The only currently approved treatment is the drug mitotane which commonly fails to prevent progression and is poorly tolerated (1). We have previously shown that the transmembrane protein, delta-like non-canonical Notch ligand 1 (DLK1) is overexpressed in ACC and higher expression is associated with increased disease recurrence and progression (2). DLK1 is absent in most healthy tissues and therefore is an attractive target for a directed therapy in ACC (3). Using phage display, we have generated a fully human DLK1 antibody, adrenotumab, which we know to bind DLK1 with high affinity and specificity. The aim of this project is to fully characterise the mechanism of action of adrenotumab in preclinical ACC models. This will be carried out in five ACC cell and ex vivo primary ACC cultures both in 2D and 3D organoid culture. Objectives: - Assess for and characterise the internalisation of adrenotumab - Assess the effect of adrenotumab on proliferation and differentiation - Assess for antibody-dependent cell-mediated and complement-dependent cytotoxicity effects of adrenotumab The results from these experiments will inform the next steps in terms of therapeutic strategy development, being as a monoclonal antibody, antibody drug conjugate or target for CAR-T therapy. This project has the promise to provide a DLK1 targeted therapy which could provide an avenue for the development of targeted therapies for ACC and other malignancies.