Experimental Compound Targets Molecular Cause of Leukemia

Patients with chronic myelogenous leukemia (CML) are finding new hope in an experimental oral agent developed by Oregon Health Sciences University researcher Brian Druker, MD, in collaboration with scientists at Novartis Pharmaceuticals. Early clinical trials are producing dramatic results with minimal side effects.

Unlike chemotherapy, which kills both normal and abnormal cells in an attempt to eradicate the cancer, the compound STI-571 targets an enzyme found only in leukemia cells. The result is a halt to the progression of the disease.

Complete Normalization of Blood Counts

Dr. Druker presented the results of a phase I clinical trial at the recent American Society of Hematology (ASH) conference in New Orleans. The trial, conducted at Oregon Health Sciences University in conjunction with Moshe Talpaz, MD, at M. D. Anderson Cancer Center in Houston, and Charles Sawyers, MD, at the Jonsson Cancer Center at the University of California, Los Angeles, involved CML patients who had not responded to standard antileukemia treatment. Once an STI-571 dose of 300 mg or more was established, 31 of 31 patients in the study showed a complete normalization of their blood counts, signaling a remission of the disease. Moreover, in some cases, the molecular cause of the disease seemed to disappear.

“I congratulate these investigators on pushing forward the field of rationally targeted cancer therapy,” said Richard Klausner, MD, director of the National Cancer Institute. “While too soon to evaluate the ultimate value of this agent for the standard clinical approach to CML, their early data are very encouraging.”

New Therapeutic Approach May Have Broader Applications

“The early evidence of the effectiveness of agent STI-571 heralds a new approach to leukemia therapy and perhaps that of other cancers as well, ie, the specific inactivation of the cancer-causing protein in malignant cells,” said Marshall Lichtman, MD, executive vice president for research and medical affairs of the Leukemia Society of America. “These preliminary results should engender excitement for researchers and physicians battling leukemia and new hope for affected patients. The Leukemia Society of America, on behalf of its donors and the patients we serve, is very pleased to have played an integral role in supporting this landmark research.”

“The potential significance of this type of research extends beyond leukemia,” said Dr. Druker, whose research is supported in part by the Leukemia Society and the National Cancer Institute. “One of the major goals of cancer research has been to identify differences between cancer cells and normal cells so that these differences can be targeted with more effective and less toxic treatments. That’s exactly what we’ve seen happen in these patients.”

A phase II trial, which will introduce the compound to a broader group of patients, is scheduled to begin in early 2000.