I don't think that evolve is the right word here. It is not that cancers generally will develop to the point where this is no longer useful in humans. In a single human it is possible that some collection of cancer cells mutates in a way that makes them resistant or immune from this effect (e.g.: by not having the mutated PCNA), and so that strain will become the dominant cancer in that one person. It is also possible that this pathway is pretty common, and this drug does not help out much because of that. But because cancer is not spread (outside of some rare cases), this is not really going to "evolve" like viruses do.

>Even if this does prove effective in humans, eventually cancer cell defenses will evolve to get around it.

Cancer becomes tolerant to drugs separately for each patient. I.e. initially it isn't resistant, but the drug used on a patient puts evolutionary pressure on the cancer to work around the drug. What this means is that people have more months or years to live, which is great. (I am not a doctor).

It's possible that this drug doesn't wipe out all cancer cells if effective, thus leading to the possibility of the cells eventually mutating. But it's not like cancer is some bacteria that can become universally resistant.

The ABVD regime starts with the same baseline on all hodgkin's lymphoma patients, and 'cures' cancer permanently in quite a large number of them.

Goal is to die for some other reason before cancer evades this