Elli found this for Philebus, in the website of philologers/teachers in hellenic education at schools of Greece. She translated this passage:
The work was written in Plato's old age, probably between 362-360 BC and the main person is Socrates who discusses with the Protarchus and Philebus. At the beginning of the dialogue, Socrates introduces Philebus to claim that pleasure is the supreme good for all beings. Because Philebus appears to be a devotee of Aphrodite and surrendered to pleasures, he could not adopt his personal dialectical views and therefore shows confidence in his defense of his friend the Protarchus who had trained near Gorgias. Philebus may not have been an actual but imaginary person because this name did not exist in Attica, and Plato probably chose it as the sign of "friend of puberty”. In contrast, Protarchus was a real person. He was the son of Callias and a student of Gorgias and he already is mentioned some of his quotes by Aristotle in his book "The physics".
The writer here is Suzana Karakosta, who has a degree in theology and history of philosophy.