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John Katzenellenbogen, PhD

Swanlund Professor of Chemistry
University of Illinois at Urbana-Champaign
Champaign, Illinois

Current Research

  • Seeking new strategies to prevent resistance to anti-estrogen therapies and extend the lives of breast cancer patients.

  • Laboratory studies are focused on the development of a new class of estrogen receptor inhibitors to block ER-dependent cell growth and tissue invasion.

  • These efforts can have a tremendous impact on preventing breast cancer deaths by developing powerful anti-estrogens that will stop the growth of recurrent ER-positive breast cancers.

Many breast cancers can be successfully treated with endocrine therapies that target the estrogen receptor. However, the cancer can sometimes recur in a form that no longer responds well to anti-estrogen therapies, such as letrozole or tamoxifen, because of mutations in the estrogen receptor. Dr. Katzenellenbogen’s team has learned how these altered receptors work and are now designing and evaluating new types of anti-estrogens that should work well to treat breast tumors with these mutant estrogen receptors.

Full Research Summary

The estrogen receptor (ER) regulates the growth of over 75 percent of human breast tumors, and many ER-positive breast cancers respond well to endocrine therapies with aromatase inhibitors or antiestrogens. However, even after a good initial response, cancer may return, often in a form more difficult to treat with endocrine therapies. 

Many of these recurrent cancers still have estrogen receptors, but they are now in activated, mutated forms that no longer need estrogen to grow. In addition, these recurrent cancers are typically resistant to aromatase-inhibitors, and much less responsive to tamoxifen (i.e., antiestrogen resistant). The goal of Dr. Katzenellebogen’s BRCF-supported research is to develop new antiestrogens that will be more powerful so they can stop the growth of recurrent breast cancers driven by these mutated estrogen receptors. 

His team has already found some compounds that show good activity and is pursuing new ideas to make them even more potent and effective. These new antiestrogens may provide great benefit for breast cancer patients with tumors containing estrogen receptors with mutations that renders them in a persistently active state.


Dr. John Katzenellenbogen, Swanlund Professor of Chemistry, directs a research program at the University of Illinois at Urbana-Champaign that spans chemistry, biology, and medical applications with a particular focus on the action of estrogens in breast cancer. He is recognized internationally as a pioneer in the development of novel diagnostic and therapeutic agents for the management of hormone-regulated cancers, including the PET imaging agents FES for estrogen receptors in breast cancers and FDHT for androgen receptor in prostate cancers, both of which are widely used in the clinical development of novel anti-hormonal agents. Through his extensive work elucidating the molecular details of estrogen action in various target tissues, he has designed novel estrogens that are being actively used to elucidate estrogen actions by numerous collaborators throughout the world.

Dr. John Katzenellenbogen has been honored as a Fellow of the American Academy of Arts and Sciences on whose National Council he served for many years, he is the recipient of the Paul Aebersold Award from the Society of Nuclear Medicine, the E. B. Hershberg Award for Important Discoveries in Medicinal Chemistry, the Esselen Award for Chemistry in the Public Service, and Portoghese Medicinal Chemistry Lectureship Award from the American Chemical Society, The Royal Society of Chemistry Centenary Award, the Leading Edge Award from the Society of Toxicology, and with Dr. Benita Katzenellenbogen the Fred Conrad Koch Lifetime Achievement Award from the Endocrine Society. He has trained more than 100 doctoral students and postdoctoral fellows, and he has published more than 500 articles.

Grid Researcher Headshot - Katzenellenbogen

BCRF Investigator Since


Donor Recognition

The Ulta Beauty Award

Area(s) of Focus