Genentech drug shrinks tumors

Genentech Inc. said a charged-up version of its Herceptin drug for breast cancer shrank tumors in patients who failed to respond to other therapies.

Four out of 10 patients had their tumors shrink during a study, with minimal side effects, when taking a version of Herceptin linked to chemical toxins, researchers said at the American Society of Clinical Oncology meeting in Chicago.

The combination is in the first of three phases generally needed for U.S. marketing approval.