Targets, structures, and recent approaches in malignant melanoma chemotherapy

Preclinical validation of a new hybrid molecule loaded in liposomes for melanoma management

The aggressiveness of melanoma and lack of effective therapies incite the discovery of novel strategies. Recently, a new dual acting hybrid molecule (HM), combining a triazene and a ʟ-tyrosine analogue, was synthesized. HM was designed to specifically be activated by tyrosinase, the enzyme involved in melanin biosynthesis and overexpressed in melanoma. HM displayed remarkable superior antiproliferative activity towards various cancer cell lines compared with temozolomide (TMZ), a triazene drug in clinical use, that acts through DNA alkylation. In B16-F10 cells, HM induced a cell cycle arrest at phase G0/G1 with a 2.8-fold decrease in cell proliferation index. Also, compared to control cells, HM led to a concentration-dependent reduction in tyrosinase activity and increase in caspase 3/7 activity. To maximize the therapeutic performance of HM in vivo, its incorporation in long blood circulating liposomes, containing poly(ethylene glycol) (PEG) at their surface, was performed for passively targeting tumour sites. HM liposomes (LIP HM) exhibited high stability in biological fluids. Preclinical studies demonstrated its safety for systemic administration and in a subcutaneous murine melanoma model, significantly reduced tumour progression. In a metastatic murine melanoma model, a superior antitumour effect was also observed for mice receiving LIP HM, with markedly reduction of lung metastases compared to positive control group (TMZ). Biodistribution studies using ¹¹¹In-labelled LIP HM demonstrated its ability for passively targeting tumour sites, thus correlating with the high therapeutic effect observed in the two experimental murine melanoma models. Overall, our proposed nanotherapeutic strategy was validated as an effective and safe alternative against melanoma.

Anticancer Triazenes: from Bioprecursors to Hybrid Molecules

Triazenes are a very useful and diverse class of compounds that have been studied for their potential in the treatment of many tumors including brain tumor, leukemia and melanoma. Novel compounds of this class continue to be developed as either anticancer compounds or even with other therapeutic applications. This review focused on several types of triazenes from the simplest ones like 1,3-dialkyl-3-acyltriazenes to the more complex ones like combi-triazenes with an emphasis on how triazenes have been developed as effective antitumor agents.

Co-delivery of Doxorubicin and Ceramide in a Liposomal Formulation Enhances Cytotoxicity in Murine B16BL6 Melanoma Cell Lines

This study reports co-delivery of doxorubicin (DOX) and ceramide in a liposomal system in B16BL6 melanoma cell lines for enhanced cytotoxic effects. Different types of ceramides (C6-ceramide, C8-ceramide, and C8-glucosylceramide) and lipids (1,2-dioleoyl-3-trimethylammonium-propane (DOTAP), 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC), 1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE)) were considered in the preparation of liposomes. DOX was encapsulated within liposome, and ceramide was used as the component of the lipid bilayer. The formulations were optimized for size and size distribution, zeta potential, and DOX encapsulation efficiency (EE). Cytotoxic effect on B16BL6 melanoma cell lines was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The ceramide based liposome formulations generally provided a mean diameter < 181 nm, a zeta potential, + 35 mV, and EE > 90% DOX EE. Co-delivery of DOX and C8-ceramide with DOTAP liposomes demonstrated significantly higher cytotoxicity as compared to DOX liposomes without ceramide (P < 0.001), and also showed enhanced cellular uptake by B16BL6 cell lines. This study provides basis for developing a co-delivery system of DOX and ceramide for lowering the dose and dose-related side effects of DOX for the treatment of melanoma.

Beyond Breast and Ovarian Cancers: PARP Inhibitors for BRCA Mutation-Associated and BRCA-Like Solid Tumors

Poly(ADP-ribose) polymerase inhibitors (PARPi) have shown clinical activity in patients with germline BRCA1/2 mutation (gBRCAm)-associated breast and ovarian cancers. Accumulating evidence suggests that PARPi may have a wider application in the treatment of cancers defective in DNA damage repair pathways, such as prostate, lung, endometrial, and pancreatic cancers. Several PARPi are currently in phase I/II clinical investigation, as single-agents and/or combination therapy in these solid tumors. Understanding more about the molecular abnormalities involved in BRCA-like phenotype in solid tumors beyond breast and ovarian cancers, exploring novel therapeutic trial strategies and drug combinations, and defining potential predictive biomarkers are critical to expanding the scope of PARPi therapy. This will improve clinical outcome in advanced solid tumors. Here, we briefly review the preclinical data and clinical development of PARPi, and discuss its future development in solid tumors beyond gBRCAm-associated breast and ovarian cancers.