Optimization of Grignard ring-opening of α-brominated dioxolanes for the preparation of β-hydroxy-protected vinyl ethers by a three-step one-pot procedure

PEGylation enhances the tumor selectivity of melanoma-targeted conjugates

In the development of our melanoma-selective delivery approach, three preselected conjugates of 5-iodo-2'-deoxyuridine (IUdR) to the ICF01012 melanoma-carrier were radiolabelled with iodine-125, and their in vivo distribution profile was determined. A radioiodination method for the conjugate 1a and its PEGylated derivatives 1b-c was developed via electrophilic iododestannylation in good radiochemical yield with excellent radiochemical purity (>99%). When administered to melanoma-bearing mice, the PEGylated conjugates exhibited an increased tumour uptake with a prolonged residence time. PEGylation also resulted in enhanced tumour selectivity compared with the non-PEGylated parent. These characteristics support further development of this model to achieve maximal concentration of anticancer therapeutics at the local site of action and minimize distribution to non-targeted sites.

Spacer optimization of new conjugates for a melanoma-selective delivery approach

In the search for more selective anticancer drugs, we designed and synthesized seven conjugates varying the structure of the linker connecting the 5-iodo-2'-deoxyuridine (IUdR) to the ICF 01012 melanoma-carrier for potential intratumoural specific drug release. Chemical and in vitro metabolic stability evaluations showed that, except for the ester conjugate (1), the ketal (2b), acetal (2a), carbonate (4) and carbamate (3) conjugates were compatible with our approach. The acetal (2a) and its PEGylated derivative (2c) were of particular interest for further in vivo development owing to their respective pH-dependent stability and limited metabolic degradation in order to exploit the acidic subcellular environment of malignant melanocytes to trigger the release of therapeutics upon internalization in cells.