Philoxenos was an officer under Alexander the Great and later was given a satrapy. This is much the same story as a dozen others on this list, and like them, we know very little about Philoxenos.
We know that he was neither given a satrapy under Alexander, nor immediately after his death. However, in the fallout he must have taken the side of Perdikkas, since he was given the satrapy of Silicia by him in 321 BCE. Afterwards, he must have used brown-nosing to a sufficient degree to keep his satrapy after the partition of Triparidisus, since Perdikkas was murdered by his own troops along the Nile.
After that, we know nothing about Philoxenos. Was he removed by Antigonos? Did he get drunk and fall off a cliff? Did he start his own bakery with branded cupcakes? Because so much information has been lost, these are all equally likely.