Dr. Zakrzewski obtained an M.D. degree from the Friedrich-Alexander University (Germany) in 2000, followed by 5 years of training in Pediatrics and Pediatric Hematology/Oncology in Germany. He joined Memorial Sloan Kettering Cancer Center (MSKCC) in 2004 as a Research Fellow, studying the immunology of allogeneic hematopoietic stem cell transplantation. From 2008 – 2012 Dr. Zakrzewski was a resident in Pediatrics at SUNY Downstate Medical Center and a clinical fellow in Pediatric Hematology/Oncology at MSKCC. Dr. Zakrzewski held an appointment has an Assistant Attending Pediatrician at MSKCC from 2012 – 2017. He joined the CDI as an Associate Member in 2018 and has served as an Attending Physician in Pediatric Stem Cell Transplantation at HUMC since 2019. Dr. Zakrzewski has additional appointments as an Associate Professor of Pediatrics at Hackensack Meridian School of Medicine and as an Associate Professor of Oncology at Georgetown University School of Medicine.