The last Seleucid king ruled in name only. Since he was a still a young child when his father Antiochus X died (88 BCE), his mother Cleopatra Selene acted as regent. Not only did she fail to gain recognition for his claim to the throne of Egypt, she lost him control of most of Syria as well. Deposed with her by Tigranes II of Armenia, Antiochus was briefly restored as a client of Rome by Lucullus (68 BCE) but was soon challenged by his second cousin Philip II. His assassination by the Arab ruler of Emesa, led Pompey to abolish the Seleucid monarchy & make Syria a Roman province.

References: Justin, Epitome 40.2.
                  Appian, History of Rome: Syrian Wars 49.

Other resources on line:

• Antiochus XIII Asiaticus - brief article in Wikipedia's  web.

• Antiochus XIII Asiaticus - Jona Lendering's biographical sketch [Livius: Articles on Ancient History].