Leticia De Mattos-Arruda is a medical oncologist, clinician-scientist and group leader at the IrsiCaixa Foundation, Barcelona, Spain. After obtaining a Ph.D. from the Universitat Autonoma de Barcelona, Spain, she completed a Fellowship in Vall d’Hebron in 2014, after which she took up a position as a Visiting Scientist at the Memorial Sloan Kettering Cancer Center, New York, US. From 2015 to 2016, she was a Visiting Scientist at the Cancer Research UK Cambridge Institute. Dr. De Mattos-Arruda subsequently returned to Spain where, in 2016, she was appointed Principal Investigator at the Vall d'Hebron Institute of Oncology. She is a member of ESMO, ASCO, EACR, AACR. She is a faculty member for breast cancer field for ESMO, part of the Editorial Board in the field of Breast Cancer of "ESMO Open - Cancer Horizons", and a member of the “ESMO Translational Research and Precision Medicine Working Group”. Dr. De Mattos-Arruda’s main research interest is the genomic and immune characterization of tumours and liquid biopsies to accomplish the goals of precision oncology.