SCOTT SHEPARD

Dr. Lee S. Schwartzberg is pictured with the CellSearch system.

Despite 50 years of advances in cancer treatment the dread fear is always that a cell — a single cancer cell — may escape the tumor, survive the immune system and start its work again.

But a new technology at West Cancer Clinic aims to monitor those circulating tumor cells, both as a way of assessing tumor treatment and to calculate the risk of metastasizing elsewhere in the body.

The system is CellSearch, developed and marketed by Veridex, a division of Johnson & Johnson. Just approved by the FDA in December for breast cancer, the system is so new, and novel, that West Clinic is the first to have anything like it. Using three different markers that distinguish cancerous epithelial T-cells from others, CellSearch can detect a single cell in 7.5 cubic centimeters of blood: one target cell among 1 billion others.

“Cells from breast tumors and other epithelial cells have surfaces that look different; with this technology we can identify those unique proteins,” said medical oncologist Dr. Lee S. Schwartzberg, medical director of West Clinic, and president of Accelerated Community Oncology Research Network (ACORN).

There has been a decades-long quest to find a technology that looks for such cells, with most of the effort going into bone marrow studies. Harvesting marrow is painful and expensive, while blood can be drawn by a phlebotomist.

The test is far more sensitive than a Positron Emission Tomography test. In a PET scan radioactive isotopes are married to glucose, which is devoured by hungry-and-fast-growing cancer cells. The cells light up like Christmas lights under the scanner. It can cost as much as $4,000.

“For an accurate PET scan you need billions of cells in one area,” Schwartzberg said. “CellSearch is much easier and less expensive.”

In CellSearch a blood specimen is treated with magnetic reagents and fluorescent markers, with the target cells lighting up under scrutiny.

The system costs $125,000 to buy. Each test is about $900, including interpretation. With FDA approval, Medicare has begun reimbursing for the procedure, with private insurance companies inching in that direction.

Of the 180,000 new cases of breast cancer each year reported by the American Cancer Society about 40,000 will eventually die, mainly because cancer cells escaped to the blood stream, only to reestablish in the breast. Circulating cells can also colonize new tumors in other parts of the body, such as the liver or brain.

The device is both prognostic and predictive, Schwartzberg said. First, it plays a sentinel role. The number of circulating cells indicates the effectiveness of tumor treatment; because chemotherapy is systemic, a high cell count indicates that the tumor cells are not being killed off.

“This aids me in learning how to treat a patient,” he said. “If there are many cells I may become more aggressive.”

Secondly, subsequent tests can show the number of circulating cells and their risk of metastasizing.

“The clearance of CellSearch as a routine monitoring diagnostic tool validates its efficacy as a critical part of the resources used to manage patients with metastatic breast cancer,” said Mark Myslinski, general manager of Veridex. “With CellSearch, oncologists can clearly and consistently monitor the number of circulating tumor cells present in a patient’s blood, an indication of disease progression.”

CellSearch has already been validated in colon cancer, and is expected to win approval within six months. Next on the list is a third type of epithelial cells: prostate cancer. As an early adopter of the technology, Schwartzberg would like to use ACORN to extend CellSearch studies to other community oncology practices across the United States.

West Clinic now operates an American-style oncology practice in Singapore, and is working on comparable clinics in China, Indonesia and the Philippines, where wealthy and middle class self-pay patients are diagnosed, and then treated close to home. Since blood specimens are easily shipped, and the strategy is to replicate Memphis medicine in Asian clinics, Schwartzberg says it’s likely that foreign patients will also get CellSearch tests.

CellSearch is still a technology searching for wider acceptance. Although West Clinic and Baptist Memorial Health Care Corp. have close ties, Baptist has opted not to purchase CellSearch. After evaluating the technology, it was declined, said nurse Gordon Lintz, director of Baptist’s cancer services. Likewise, Baptist Memorial Hospital for Women has also chosen not to pursue it.

Schwartzberg is chairman of the Baptist Cancer Institute’s Breast Cancer Research Committee and medical director of the Myelosuppression Unit of Baptist Hospital

Medical oncologists with UT Medical Group, Inc., say they have heard about CellSearch but don’t know enough about it to make a decision.

There is a calculated risk in investing in technology that is first to be approved, Schwartzberg concedes. While Veridex is improving software a competitor could leapfrog CellSearch. But that has to balanced against patients that can benefit from the technology today. And even if another company develops a more sensitive test, he said, having a one-in-a-billion gauge is still quite effective.



October 2007