Since 2018, Prof Gillessen has been Genitourinary Cancer Systemic Therapy Research Chair at the University of Manchester and Honorary Consultant at The Christie Hospital, while continuing to work as Consultant in the Department of Oncology/Haematology at the Kantonsspital St. Gallen, Switzerland.
In January 2020 Prof Gillessen was appointed Head of the Department of Medical Oncology, full professor at the Università della Svizzera Italiana (USI) in Lugano and Director of the Oncology Institute of Southern Switzerland (IOSI) in Bellinzona, Switzerland.