Ellsasser is a graduate of the Sackler School of Medicine at Tel Aviv University and of Drake University. He completed a residency in psychiatry and a fellowship in palliative and hospice medicine at Montefiore Medical Center.
Before his career in medicine, he worked in research at Columbia University for both the department of biological psychiatry and the department of neurological surgery.
Ellsasser is a published author and community activist who has served on the advisory committee for the World AIDS Institute. He also has varied experience with LGBT, AIDS and nonprofit organizations.
He was also instrumental with the creation, launch and management of a community-based media company before changing his career focus to mental health and palliative care.