How does the cytotoxic component of inotuzumab ozogamicin damage tumour-cell DNA?

Nonclinical data suggest that, after inotuzumab ozogamicin binds CD22-positive tumour cells and is internalised, its linker is hydrolytically cleaved, releasing N-acetyl-gamma-calicheamicin dimethylhydrazide, whose activation induces double-stranded DNA breaks, leading to cell-cycle arrest and apoptotic cell death.