A monoclonal antibody directed against the Notch receptor with potential antineoplastic activity. Anti-Notch receptor monoclonal antibody OMP-59R5 binds to Notch on the cell surface, thereby inhibiting Notch-mediated signalling and gene transcription, which may impede tumour angiogenesis. Notch receptors are important for cell-cell communication, which involves gene regulation mechanisms that control multiple cell differentiation processes during embryonic and adult life. Dysregulated Notch signalling is implicated in many diseases including T-ALL (T-cell acute lymphoblastic leukemia), CADASIL (cerebral autosomal dominant arteriopathy with sub-cortical infarcts and leukoencephalopathy), MS (multiple sclerosis), and many other disease states.