While the formulation isn't unlike the Covid-19 vaccine, which uses lipid nanoparticles to deliver the genetic instructions to the body, it is still somewhat different. Instead of the drug encoding a virus protein, it sends a message to the immune system to rally the troops. It essentially tells the body to produce certain proteins that stimulate the immune system – including a protein within cancer cells known as PD-L1 (Programmed Death-Ligand 1), which makes tumors become more visible to immune cells.

TLDR: they are finding that it’s more effective to make cancer more visible and have the body’s immune system do its thing.