Researchers from UCLA in the US, have created a new nanoparticle delivery system to allow water-insoluble drugs to be released into cancer cells.
The new research, to be published in later this month in the journal 'Small', used porous silica-based nanoparticles to deliver various water-insoluble drugs, such as the anticancer drug camptothecin (CPT) to human cancer cells.
The study was led by Professor Fuyu Tamanoi, professor of microbiology, immunology and molecular genetics at UCLA and Jeffrey Zink, professor of chemistry and biochemistry at UCLA.
"In order to be used on humans, current cancer therapies such as CPT or Taxol, which are poorly water soluble, must be mixed with organic solvents in order to be delivered into the body," said Tamanoi.
"These elements produce toxic side effects and in fact decrease the potency of the cancer therapy."
Various approaches to overcome the delivery problems associated with drugs with poor water solubility have included using pegylated polymers, liposomal or albumin-based nanoparticles
"Silica nanomaterials show promise for delivering CPT and other water-insoluble drugs," said Tamanoi.
"We have successfully loaded hydrophobic anticancer drugs into mesoporous nanoparticles and delivered them into human cancer cells to induce cell death."
The researchers closed the pores by constructing a structure that could be opened by external stimuli to control the release of the drug at the targeted organs.
"The beauty of our findings is that these nanoparticles are biocompatible, contain tubular pores and are relatively easy to modify," said Zink.
"Additional modification by attaching a ligand against a cancer-cell-specific receptor can make the nanoparticles recognisable by cancer cells."
By making the nanoparticles recognisable to cancer cells and functionalising them so that they only release the drugs in the vicinity of the cancerous cells, not only will the water solubility issue be overcome, but also the toxicity of the drugs should be reduced.
CPT itself has been shown to adversely affect patients by causing cystitis and many chemically related analogues that exhibit lower toxicity and enhanced therapeutic potency have been developed.
These include GlaxoSmithKline's Hycamtin (topotecan) and Pfizer's Camptostar (irinotecan) which is also known as CPT-11.