A new approach for the treatment of malignant melanoma: enhanced antitumor efficacy of an albumin-binding doxorubicin prodrug that is cleaved by matrix metalloproteinase 2.

The progression of malignant melanoma is characterized by overexpression of a number of matrix metalloproteinases (MMPs), especially MMP-2, which play a critical role in the degradation of basement membranes and the extracellular matrix. Consequently, we assessed a drug targeting strategy in which the protease activity of MMP-2 is exploited to release an anticancer agent from a macromolecular carrier, i.e., circulating albumin. For this purpose, a water-soluble maleimide derivative of doxorubicin (1) incorporating a MMP-2 specific peptide sequence (Gly-Pro-Leu-Gly-Ile-Ala-Gly-Gln) was developed that binds rapidly and selectively to the cysteine-34 position of circulating albumin. The albumin-bound form of 1 was efficiently and specifically cleaved by MMP-2 liberating a doxorubicin tetrapeptide (Ile-Ala-Gly-Gln-DOXO) and subsequently doxorubicin. In vivo, 1 was superior to the parent compound doxorubicin in the A375 human melanoma xenograft, which is characterized by a high expression of MMP-2.