CT26 models were treated with anti-PD-1 on days 3, 6 and 9 following subcutaneous tumor implantation generating variable responses during early tumor development . Tetramer staining was performed to determine the frequency and avidity of CD8++ T cells targeting the tumor-specific epitope GSW11 and confirmed with tetramer competition assays . In vitro studies showed that Tetlo exhibits higher cytotoxicity than Tet>hi.