Dr. Pfeifer earned his MS in pharmacology in 1981 and his PhD in biochemistry in 1984 from Goethe University in Frankfurt, Germany. In 1988, he joined Beckman Research Institute at City of Hope where most recently he held the Lester M. and Irene C. Finkelstein Chair in Biology.

In 2014 he joined the Van Andel Research Institute within the Center for Epigenetics. The laboratory studies epigenetic mechanisms of disease, focusing on DNA methylation and the role of 5-hydroxymethylcytosine in cancer and other diseases. Specifically, the lab studies hypermethylation in cancer genes with the intent of elucidating the mechanisms and significance of CpG island methylation, and continues work on the tumor suppressor RASSF1A, discovered by his laboratory.

Over the years, he has mentored and trained young scholars including 10 graduate students and over 20 postdoctoral fellows and clinical oncologists in various aspects of cancer biology and epigenetics.