157P Phase I expansion of IMC-C103C, a MAGE-A4×CD3 ImmTAC bispecific protein, in ovarian carcinoma

ImmTAC® bispecific proteins redirect polyclonal T cells to target intra/extracellular proteins using a T cell receptor as targeting domain. IMC-C103C (MAGE-A4 × CD3) is an ImmTAC against MAGE-A4, which is expressed in several tumors including ovarian carcinoma (OC). ≥ 90 μg IMC-C103C was demonstrated as the clinically active range (Davar 2021). Pre-selection for MAGE-A4 expression was not required as a majority of OC express MAGE-A4 (H score ≥ 1) and tebentafusp demonstrated OS benefit and ctDNA reductions regardless of H score, although RECIST responses were enriched at higher H scores (Leach 2021).