By Kyla Dunn
The Scientist and the Yew Tree
Molecular pharmacologist Susan Band Horwitz realized that a small molecule found in the bark of a tree could potentially treat cancer in a new way
By Kyla Dunn
Photographs by Thomas Hoepker
The yew tree has long been associated with death and the afterlife. Druids believed the tree’s roots could talk to the dead and express their secrets, which inspired people to plant yews in graveyards. Yews appear in the mournful poetry of T. S. Eliot and Sylvia Plath, and spike the witches’ brew in Shakespeare’s Macbeth. Searching for updated references to please her grandchildren, molecular pharmacologist Susan Band Horwitz discovered that a wand made of yew (in Lord Voldemort’s hands) murdered Harry Potter’s parents and put the jagged scar on Harry’s forehead.
That same poison now extends life—as a standard chemotherapy for breast and ovarian cancer. Its brand name is Taxol (generic name paclitaxel), and three decades ago, experiments in Horwitz’s fledgling laboratory at Albert Einstein College of Medicine of Yeshiva University in the Bronx in New York City, helped to lay the groundwork for Taxol’s success. “We showed that this drug worked in a way that no other drug had worked,” she explains, “and I was very forceful in saying to the National Cancer Institute: ‘We’ve got to move forward. We have to see if this drug could be special.’ ”
When Taxol finally entered the marketplace in the early 1990s, the director of the National Cancer Institute (NCI) praised it as “the most important new drug we have had in cancer for 15 years.” Taxol has since been prescribed to well over a million people, becoming a blockbuster cancer drug. Nonetheless, “it was a fascinating story how we got to this point,” says Horwitz, now the co-chair of the department of molecular pharmacology at Einstein. “There are many times in the development of Taxol when it could have been dropped.”
An Unexpected Opportunity
Horwitz found her calling within science almost by accident. It was 1963, and Horwitz’s twin sons were born less than a week after she finished her doctoral degree in biochemistry at Brandeis University in Waltham, Mass., while her husband (a pediatrician in training) frequently had to work overnight at the hospital. Although Horwitz had lined up a postdoctoral appointment in biochemistry, she soon changed her mind. “I didn’t think I could do it: be pretty much alone with the twins and work full time in a high-powered lab,” she says. Instead, her thesis adviser pulled some strings, arranging a three-day-a-week position in the pharmacology department at Tufts University, near Boston.
Fortunately, what seemed like a career compromise proved to be an unexpected opportunity. “I had never heard of pharmacology, basically, when I was a graduate student,” she says. “I loved it. It changed my life.”