This article describes using lipid nanoparticles (LNPs) containing silencing RNA (siRNA) to slow or prevent the spread of cancerous multiple myeloma cells through the body.
What I found interesting about this approach is that these LNPs do not target the cancerous cells themselves, but rather targets healthy endothelial cells lining blood vessels in the body. The mechanism of action is to reduce the expression of a protein (CyPA) that cancer cells use to aid their spread through the body. So, these LNPs are simply used to help contain and localize the cancerous growth while traditional cancer treatments are used to treat the malignant cells.
A significant challenge for this approach going forward is tuning the targeting and biodistribution of the LNPs. Most LNP treatments end up in either the liver or spleen where they transfect cells in those organs and express protiens. I don't have direct experience with siRNA molecules, but transfecting epithelial cells in a lasting way could prove difficult as it scales up from mouse models.
doi: https://dx.doi.org/10.1073/pnas.2215711120