In the present study, we evaluated the potential of mACPs to inhibit two or more cancer cell lines selectively. We created CCSI, the cancer cell-line selectivity index, to distinguish selective peptides from non-selective counterparts, using the highest and the lowest pIC50 values from two CCLs for a single peptide (Eq. 1-2). A higher pIC50 value denoted a more potent mACP. A selective mACP (ACP-S) had a CCSI equal to or superior to 0.5; otherwise, the peptide was labelled as non-selective (ACP-NS). Selective peptides would exhibit different magnitudes of anticancer activity across targeted CCLs, whereas the non-selective examples inhibited cancer cell lines with similar intensity. We assembled 43 ACP-S and 95 ACP-NS with pIC50 values across 77 cancer cell lines (Figure ). Considering that SI and CCSI differ, we would not expect to observe similar features linked to the potency and selectivity of mACPs. However, we discovered weak-moderate positive relationships between CCSI and SI values against specific cancer cell lines (HeLa S3, CCRF-CEM, NCI-H157 and PC-3) -Figure .