Anticancer peptides (ACPs) are small biologics with less than 50 residues long. The peptides are generally amphipathic and cationic due to a high proportion of basic and hydrophobic residues . These properties can be understood as many ACPs were originally discovered as broad-spectrum antimicrobial peptides. They fold into various structures, such as α-helices (full length or kinked), β-sheets, or a combination of the above, or they do not fold into any secondary structure (random coils). Although in the latter case, random-coiled ACPs may adopt a structure when approaching cell membranes . ACPs can kill cancer cell lines through different mechanisms; (i) some peptides are introduced into the cell and attack the mitochondrial membrane, triggering apoptosis (non-membranolytic ACPs), while (ii) others directly destabilise the cell membrane, generating pores and causing necrosis (membranolytic ACPs, mACPs) . Besides their intrinsic anticancer activity, many peptides such as HNP-1 possess an additional immunomodulatory function , which recruits immune cells to attack cancer cells. Others inhibit angiogenesis ; the formation of blood vessels necessary for cancer proliferation and metastasis . Furthermore, some ACPs modulate essential proteins; for example, Pep-7 cancels the activity of the E7 oncoprotein of human papillomavirus type 16 (one of those related to the development of cervical cancer) and reactivates the pRb / E2F pathway, which is necessary for the correct control of the cell cycle . Cancer cells express specific membrane lipids and proteins on their surfaces, which mACPs possibly target. These peptides are the most studied ACPs with selectivity toward cancer cells that do not induce multidrug resistance . Although the selectivity of mACPs is not yet fully understood, both the components of cancer cell membranes and the key global physicochemical properties of mACPs matter . Understanding the key characteristics of cell-line selective anticancer peptides would support their discovery and design.