Although a low frequency of CIC structures (1–2%) was observed in MSI‐H CRC cells (Fig. S5B), the outer NK cell‐resistant, CT45A1‐expressing cancer cells in established homotypic CIC structures prevented the targeting of antibodies to inner cancer cells (Fig. 3K), indicating the formation of homotypic CIC structures may reduce the therapeutic efficacy of antibody‐conjugated oligonucleotides (ACOs), antibody‐conjugated drugs (ACDs), or ADCC. The gene discussed is CT45A1; the disease is cancer.