Ann: US patent issued for DEP cabazitaxel nanoparticle, page-13

is it possible as dep works with other companies products, they have been able to patent that combo, and not dep singularly.... and hence create another product? as they have MOU with thouse other companies SPL would retain the IP rights. Dep doesn't work by itself or does it have any benefit by itself? working somehow with the natural body repair and healing process.
i'm wondering why it has take so long to patent this? or SPL had it in the pipeline a long while ago... and the approval process can be slow, up to a year.