Michael Wolff's latest book, "Seige: Trump under Fire" reveals that Trump celebrated McCain's brain cancer and mocked his daughter Meghan. Trump used McCain's brain cancer as an exhibit of what could happen to those who cross him
"Scum bag" is too kind of a word to use to describe Trump.
https://www.azcentral.com/story/news/politics/arizona/2019/06/06/book-trump-celebrated-john-mccain-brain-cancer-mocked-meghan-mccain/1365853001/