Though 2006 is not even half over, it’s already a year to remember for Joseph Schlessinger, Ph.D., chair and William H. Prusoff Professor of Pharmacology. In late January, a new drug based on Schlessinger’s research was approved by the U.S. Food and Drug Administration (FDA) for advanced kidney cancer and a rare type of stomach cancer. A month later, Schlessinger learned that he would share a $1 million prize for his scientific discoveries from the Dan David Foundation.

Schlessinger, known to friends as “Yossi,” is a leading figure in the field of signal transduction by receptor tyrosine kinases, enzymes that are located on the cell surface and function as receptors for growth factor proteins. When growth factors activate these receptors, their associated tyrosine kinases send out intracellular signals that cause cells to divide and grow. In research spanning more than three decades, Schlessinger and his colleagues have elucidated the mechanism of action of these receptors and demonstrated how dysfunctions in certain kinases can lead to the rampant cell growth seen in cancer.

In 1991, together with Axel Ullrich, Ph.D., of the Max Planck Institute of Biochemistry in Germany, Schlessinger formed the pharmaceutical company Sugen—the “S” and “U” in the company’s name stand for the two founders’ last names—to develop drugs that inhibit faulty tyrosine kinases. The company was acquired by Pfizer in 2003, and in subsequent clinical trials, Pfizer showed the Sugen-developed drug SU11248 to be effective in treating advanced kidney cancer as well as a stomach cancer known as gastrointestinal stromal tumor, or GIST. According to the American Cancer Society, 32,000 Americans are diagnosed with advanced kidney cancer each year, and there are 5,000 new cases of GIST. With January’s FDA approval in hand, Pfizer is now marketing the drug under the tradename Sutent.

In 2001, Schlessinger co-founded Berkeley, Calif.-based Plexxikon, a drug-discovery firm focused on the role of kinases and other enzymes in diverse diseases, including cardiovascular disease, diabetes and cancer. He also serves on the scientific advisory boards of several other companies.

The Dan David Foundation, with headquarters at Tel Aviv University in Israel, awards three $1 million prizes annually for cultural, scientific, social or technological impact in three time dimensions—“past,” “present” and “future.” Dan David, a native of Romania who invented and marketed a variety of photographic technologies including automatic photo booths, inaugurated the prizes in 2001. Schlessinger shares the 2006 award in the Future category with John Mendelsohn, M.D., president of the M.D. Anderson Cancer Center at the University of Texas, who did the science behind the kinase-inhibiting anti-cancer drug Erbitux. Renowned cellist Yo-Yo Ma won in the Past category for preserving cultural heritage through his Silk Road project, and four journalists from around the world shared the Present prize.

Schlessinger says he was “thrilled” when he learned about the prize. “It recognizes the idea that hypothesis-driven research can lead to new understanding of how cells are activated and eventually that such knowledge can lead to new and better drugs,” he says. Since coming to Yale from New York University five years ago, Schlessinger has overseen the building of new quarters for the pharmacology department and has recruited six new faculty members. “It takes a long time to build science,” he says. “It takes patience.”

Schlessinger says that he will attend the Dan David awards ceremony at Tel Aviv University in May, and he adds that he intends to donate a portion of the prize money to further research and education in his department. “This is a recognition of a career,” he says of the prize, “one which I hope is not over yet.”