Kristijan holds degrees in Veterinary Medicine (DVM), Veterinary Pathology (MSc) and PhD in Biochemistry and Molecular Biology. He did his post-doctoral training at the ETH-Zürich in the group of Dr H. Meyer. Between 2009 and 2013 he was Junior Group Leader and Lecturer at the Institute of Pharmacology and Toxicology-Vetsuisse, University of Zürich. In 2013 he moved to the UK to join the Oxford Institute for Radiation Oncology at the Department of Oncology as MRC Senior Group leader. From 2014 to 2019 he was Associate Professor at the Department of Oncology, University of Oxford. In 2019 Kristijan was promoted to the Full Professor of Molecular Medicine at University of Oxford.

Kristijan received the Proud of Croatia Award (Croatian Hero for 2014) for his scientific contribution in saving the life of a young boy who suffered from liver cancer caused by mutations in the SPRTN gene.