I assume Docetaxel had the best result. This being their first combo trial, it would not make sense to take any chances by using a less efficacious drug. Having it be off patent is a big plus. It's an older drug (since it's off patent) and so the safety and dosing parameters would be extremely well known. That's an important consideration too -- you want to be able to have a reasonable idea of what side effects are to be expected from the Docetaxel itself. There must be tons of data about that.