With LibreOffice Draw you can edit the PDF (modify the text, move or change images, etc), then save as pdf, but it can't parse and save it as .odt, .doc, .html or similar.
LibreOffice has some really perplexing functionality gaps.
The one that baffles me is that it doesn't understand its own graphics format, so you have to export drawings to TIFF or something (if I remember correctly).
