In the past two decades, hundreds of thousands of nanoparticles with applications in cancer medicine have been developed. Yet very few of them have gone through clinical trials and been approved.
A panel of nanotechnology experts at the American Association for Cancer Research Annual Meeting 2021 in April discussed the issue.
Nanoparticles are particles with a size that ranges between one and 10 nanometers and are made of lipids or polymers that can self-assemble into 3D structures. Carbon nanostructures such as nanotubes and graphene sheets are also nanomaterial used in cancer research.
Nanoparticles can encapsulate therapeutics or diagnostics in their core, protecting them from biodegradation that can happen in the blood stream.
A series of targeting molecules can be attached on the surface of nanoparticles. These can be molecules that specifically interact with tumour cells, but not with healthy cells. In diagnostic tools this feature allows nanoparticles to accumulate around the tumour, making it visible on a CT scan or an X-ray. In chemotherapeutic formulations, this property allows the nanoparticle to deliver the drugs preferentially into tumour cells, reducing side effects.
Translation of nanoparticles into the clinic is more complicated than for small molecules, said Professor Jason Lewis, the director of the Centre for Molecular Imaging and Nanotechnology at the Memorial Sloan Kettering Cancer Center in New York.
Nanoparticles have to go through the same preclinical and clinical evaluation as small molecule drugs, he said, but the process is more laborious because their chemistry is more complex and reproducibility is often an issue.
Nanotechnology is also used in many ex-vivo diagnostic tools such as biosensors that pick up cancer biomarkers from a patient’s blood sample.
Professor Lewis said these types of ex-vivo nanotechnology applications are generally much easier to translate into the clinic. But, while these sensors indicate the presence of cancer in patients, they don’t locate it in the body like injectable nanodiagnostics do.
“We are seeing the transition of nanotechnology into a mass application with the COVID-19 vaccines,” said Professor Kostas Kostarelos, chair of the Nanomedicine Lab at the National Graphene Institute at the Manchester Cancer Research Centre.
“The next step forward would be to see lots of activity using nanotechnology incorporated in cancer vaccination and in particular applications such as immunotherapy.
“But cancer is not a viral infection. It is much more complex biologically, and the task is much more challenging. I do not think that they will translate as quickly as we’ve seen – luckily – with SARS-CoV2.”