ARLN and breast adenocarcinoma: The chemical synthesis scheme (Figure 8A) shows that PTX and ALN were conjugated to HPMA co-polymer via a phe-lys-p-aminobenzyl carbonate (FK-PABC), which showed a sustained release by cathepsin B. This conjugate showed the highest antitumor activity compared to free PTX or with a combination of free PTX plus ALN in 4T1-mcherry mammary adenocarcinoma in the tibia (Figure 8) [86].