Dr. Margaret Callahan is a medical oncologist at Memorial Sloan Kettering Cancer Center (MSK), clinical director, Immune Monitoring, Parker Institute for Cancer Immunotherapy at MSK, and laboratory member in the Ludwig Center at MSK. Her research is focused on clinical and translational efforts to better understand the mechanisms that govern the clinical activity and toxicity associated with combination strategies for immunotherapeutic agents. She is involved in the research and development of novel immunotherapies to treat melanoma and other cancers, and the development of innovative approaches to monitoring patients treated with immunotherapy.