This is pretty old news in the cancer biology field and even older news in the Glycobiology field but I'm happy to see it going more mainstream!

The main mechanism behind mucin/glycocalyx mediated immune evasion is increased levels of sialylation of mucin glycan structures. These densely sialylated proteins interact with a class of immune modulating proteins on immune cells called Siglecs (sialic acid binding immunoglobulin like proteins). These Siglecs bind sialylated structures and tell immune cells to ignore otherwise antigenic cells.

Researchers are trying a couple of different ways to address this, one of my favorites involves a chimeric antibody with a sialidase domain attached. I believe that one was the Bertozzi lab (a recent Nobel prize winner) and that one is already well into clinical trials.