Synthesis of PEGylated methotrexate conjugated with a novel CPP6, in sillico structural insights and activity in MCF-7 cells

Currently, most of the available chemotherapy has a narrow therapeutic window. This compromises the use of high-dose treatments in patients with advanced-stage cancers, who often need innovative strategies the most. Here, we present the conjugation of methotrexate with a novel cell-penetrating hexa-peptide (CPP6), a GFLG enzymatically cleavable spacer, and a short-length polyethylene glycol. The modifications added to methotrexate were rationalized to improve the drug bioavailability, specificity, and cell entry. Our final conjugate, CPGM, was successfully synthesized in solid phase and in vitro cell viability assays have shown that this conjugated form of methotrexate retains cytostatic effect towards MCF-7 breast cancer cells.