GTB-6550

GTB-6550 is a tri-specific immune stimulating antibody conjugate (ISAC) developed by GT Biopharma. It is designed as a trispecific killer cell engager (TriKE) that targets HER2-expressing solid tumors. The molecule combines three functional components: - An anti-HER2 targeting domain to bind tumor cells, - An interleukin 15 (IL-15) moiety to stimulate and expand natural killer (NK) cells, - A CD16-binding domain to engage NK cells for antibody-dependent cell-mediated cytotoxicity (ADCC). The mechanism of action involves antagonism of the HER2 receptor on tumor cells, replacement or mimicking of IL-15 activity to enhance NK cell proliferation and persistence, and stimulation of ADCC by recruiting NK cells via CD16 engagement. This design aims to direct the patient’s own immune system—specifically NK cells—to recognize and kill HER2-positive cancer cells more effectively. GTB-6550 is in preclinical development for solid tumors, with primary indications including breast cancer and gastrointestinal neoplasms[1][4][5]. The drug leverages the TriKE platform technology pioneered by GT Biopharma.