Abstract

The therapeutic antibodies constitute the most exciting group of protein therapeutics. One of the targets for cancer immunotherapy is the Notch family of receptors. Abnormal Notch signaling is associated with a number of diseases, the most prominent being cancer. To address the basic question of the mechanism of Notch receptor activation, antibodies against different regions of the Notch receptors were generated and used to study the ligand-receptor interaction and receptor activation. One of the monoclonal antibodies (MAb), specific for the ligand binding site, inhibited ligand dependent receptor activation and also depleted cancer stem cells. Several MAbs and recombinant antibodies specific for the Negatively Regulatory Region (NRR) of Notch receptors were characterized and used to map the conformational changes in the NRR upon ligand binding. One of the MAbs, which preferentially recognizes the “Gain-of-Function” mutant form of Notch associated with the hematological cancers with higher affinity, inhibited Notch signaling of the mutants at a concentration that had minimal effect on the wild type Notch. This MAb, which is being humanized, depleted the leukemia initiating cells, enhanced efficacy of the chemotherapeutic drug, inhibited tumor growth of number of cancer cells, and in presence of chemotherapeutic drugs regressed the tumors. Several human Single Chain fragment variables (ScFvs) against Notch-NRR that were characterized in the laboratory inhibited proliferation of the ovarian cancer cells suggesting their potential as cancer immunotherapeutics. Presently, the humanized MAbs and ScFvs are being hyperexpressed using the glycoengineered Pichia pastoris that produces glycoproteins such as antibodies with human-like glycan structures. In addition, a novel strategy of delivering antigens to the dendritic cells for sustained immune response for vaccines against a variety of diseases including cancer has also been developed. Thus, the basic research carried out in the laboratory has led to development of novel translational tools and strategies.