Today the Byzantine Churches keep the feast of these two saints. According to In Persona Christi:
These Saints lived during the years of Diocletian. Saint Cyrus was from Alexandria, and Saint John was from Edessa of Mesopotamia. Because of the persecution of that time, Cyrus fled to the Gulf of Arabia, where there was a small community of monks. John, who was a soldier, heard of Cyrus' fame and came to join him. Henceforth, they passed their life working every virtue, and healing every illness and disease freely by the grace of Christ; hence their title of "Unmercenaries." They heard that a certain woman, named Athanasia, had been apprehended together with her three daughters, Theodora, Theoctiste, and Eudoxia, and taken to the tribunal for their confession of the Faith. Fearing lest the tender young maidens be terrified by the torments and renounce Christ, they went to strengthen them in their contest in martryrdom; therefore they too were seized. After Cyrus and John and those sacred women had been greatly tormented, all were beheaded in the year 292. Their tomb became a renowned shrine in Egypt, and a place of universal pilgrimage. It was found in the area of the modern day resort near Alexandria named Abu Kyr.More information is available from the Orthdox Church in America.
The following antiphons are used in the Byzantine Rite office today:
Troparion: The grace of the Trinity settled in your pure hearts, most blessed Cyrus and John. You have become marvelous exorcists of impure spirits. You were doctors over hidden and visible illnesses. Now that you stand before God, heal our spiritual diseases by your unceasing prayers.
Kontakion: Receiving the gift of miracles from divine grace, you work all sorts of wonders, O holy ones. By your invisible labors you uproot all our passions, for you are heavenly doctors, O God-wise Cyrus! O glorious John!