Compound 16 inhibits the cytolytic pore-forming activity of the perforin 1 protein [2
]. It has been developed to ascertain whether perforin inhibition can prevent early rejection of mismatched grafts in donor stem cell transplant procedures, and thereby improve successful engraftment. The acting hypothesis is based on the recognition that the natural killer (NK) cells that drive graft rejection overwhelmingly use perforin to kill non-self targets [1
]. In addition, as these NK cells are resistant to radio- and immuno-suppression, an alternative mechanism is needed to limit their activity and to achieve clinical efficacy.