Kathryn B. Horwitz, PhD
University of Colorado Denver
2013-2014 BCRF Project:
(The Play for P.I.N.K. Award)
If you want to know how something works, break it down into its component parts then reassemble it. The most common form of breast cancer – called luminal – grows in response to women’s hormones and is treated by hormone blockade. This assumes that all of the cancer’s cells need hormones to grow. But cell-by-cell analysis of luminal cancers finds no such uniformity. In some tumors, 90% of the cells may need hormones. But in others, 50%, 20% or even fewer cells do so. Yet remarkably, cancers are treated with hormone blockade if only 1% of the cells need hormones. Dr. Horwitz’s lab asks: what about the other cells in those cancers? Don’t we have to understand them, where they come from and how to treat them? Dr. Horwitz’s group has identified four luminal cancer-cell populations. Only one of the four is the classic hormone-dependent cell. The researchers intend to break down luminal cancer into four component cell parts, learn how to treat each component, then reassemble the tumor and prescribe rational treatment strategies.
With last year’s BCRF support, Dr. Horwitz’s team learned how to purify two of the four cell types. The first is the true “luminal” cell that requires hormones to grow. The second, called “luminobasal,” does not need hormones. Dr. Horwitz purified both, screened luminobasal cells for sensitivity to 89 non-hormone drugs already approved for oncology use, and found at least one class of drugs that strongly suppresses them.
Dr. Horwitz’s studies will show whether one luminal breast cancer cell type can morph into others. If so, suppressing it may be vitally important. In any case, the idea that all cancerous cells in a tumor need to be treated seems logical on its face. If combination therapies using already-approved cancer drugs work in the luminal cancer models, they will represent “proof of principle” for immediate Phase I/II trials.
Dr. Horwitz is a graduate of Barnard College, received a Master's degree from New York University, and a Doctoral degree from the University of Texas, Southwestern Medical School in Dallas. She then joined the Department of Medicine faculty at the University of Colorado's School of Medicine, where she was rapidly promoted to Professor. She has received many awards and recognitions for her work. The University of Colorado has recognized her extensive service to the University, and to the local, national and international community of scientists and patients, by naming her a "Distinguished Professor" of the University, an accolade reserved for only a handful of professors on the four university campuses. In addition, Dr. Horwitz received the 2010 Fred Conrad Koch Award, The Endocrine Society's highest award.