However, the high affinity (KD = 0.54 or 46 nM) due to the slow koff from HER2 antigen limited the depth of intratumoral penetration of HCT-mono-mIL12 and the consequent tumor infiltration of T cells, resulting in inferior antitumor activity compared with that of HCT-mono-mIL12 with moderate affinity of (KD = 130 nM) and a faster koff. The gene discussed is ERBB2; the disease is neoplasm.