IDEALIZED SOLID TUMOR has been partly cut away to reveal some of its blood vessels. Before a blood-borne drug can begin to attack malignant cells in a tumor, it must accomplish three critical tasks (detail). It has to make its way into a microscopic blood vessel lying near malignant cells in the tumor (1), exit from the vessel into the surrounding matrix (the interstitium)(2) and,‘nally, migrate through the matrix to the cells (3). Unfortunately, tumors often develop in ways that hinder each of these steps.

RAKESH K. JAIN, who was born in India, is Andrew Werk Cook Professor of Tumor Biology in the department of radiation oncology at Harvard Medical School. He is also professor in the Harvard University «Massachusetts Institute of Technology division of health sciences and technology and director of the Edwin L. Steele Laboratory at Massachusetts General Hospital. Before moving to Boston, he was a professor of chemical engineering at Carnegie Mellon University for more than a decade. JainÃs research uniquely combines engineering science with tumor biology. He has received many awards for his contributions to the understanding of tumor pathophysiology, recently including a National Cancer Institute Outstanding Investigator Grant.