B2M and acute monocytic leukemia: To evaluate the potency of ImmTACs against CD1c positive and negative cell lines, β2m and CIITA genes were knocked out from the THP1 wild-type cell line (acute monocytic leukemia) using CRISPR/Cas9 (THP-DKO), abrogating cell surface expression of MHC class I and class II molecules (18).