Minicells to target tumour cells

A difficult challenge in cancer therapeutics is to develop drugs that can overcome the heterogeneity and resistance of cancer cells. A tumor usually consist on several type of cells that contribute to tumor growth, tissue invasion and metastasis in different way. Furthermore, during a treatment drugs become ineffective because of survival of cells that escape death induced by drug.

Small minicells derived form bacteria was used to targeted delivery of drug into cancerous cells. Antibodies can target minicells to tumor cell surface receptors and release drug at the specific site. A recent publication demonstrated how it was possible to subsequently administrate short hairpin RNA and cytotoxic drug in order to firstly knock down a multidrug resistance protein, then kill the cells made vulnerable. This strategy was tested on xenograft tumor in mice model and gave the opportunity to tune the dosage of cytotoxic drug, diminishing adverse effects. Minicells were not toxic for animals and didn’t compromise their survival: this approach seems promising to specifically treat resistant tumor and the use of shRNA allows to personalize the treatment. Other important challenges in next future will be the discovery of other route to target minicells, because resistance mechanism will be early developed to decrease receptor expression on cell surface.