Along with Albert Cornelis (before 1513–1531) and Ambrosius Benson (before 1518–1550), a painter from Lombardy, he worked in the workshop of Bruges' leading painter Gerard David, while he was already a master at that time. Isenbrandt is mentioned in the book "De Gandavensibus et Brugensibus eruditionis laude claris libri duo" by the priest Antonius Sanderus, published in Amsterdam in 1624. This writer refers to texts of the Florentine Lodovico Guicciardini, the Schilderboeck of Karel van Mander and the (lost) notes of the Ghent jurist Dionysius Hardwijn (or Harduinus, 1530–1604). The latter, who had spent several years in Bruges about 1550, mentions Isenbrandt as a disciple of the old Gerard David, who excelled "in nudes and in portraits". He may have travelled to Genoa in 1511 together with Joachim Patinir and Gerard David. The influence of Gerard David shows clearly in the composition and the landscape background of the works attributed to Isenbrandt.