From the St. Andrew Daily Missal (1962 Edition):-
"Peter, who was a native of Alcantara in Spain, was sixteen when he became a Franciscan at Valencia. He was a faithful follower of the primitive Rule and led a very austere life. He was one of St. Teresa [of Avila]'s spiritual directors, and encouraged her in her reformation of the Carmelite Order. His great devotion to the Passion of Our Lord found expression in his extraordinary love of penance. He died on October 1, 1592, at the age of sixty-three."
Ora pro nobis.