Karl is a board-certified medical oncologist specializing in breast cancer. Karl received his medical degree from the University of the Philippines College of Medicine and went on to pursue Internal Medicine at the National Kidney and Transplant Institute. He then finished his Medical Oncology training at the University of the Philippines - Philippine General Hospital (UP-PGH). He was the first international fellow to have been accepted in the Breast Cancer Clinical Research Fellowship program of the Chris O'Brien Lifehouse - Royal Prince Alfred Hospital, Sydney, Australia.