West Coast Editor

Diagnostics-focused Immunicon Corp.'s belt-tightening two summers ago continues to pay off, most recently with success in a pivotal trial testing its CellSearch Circulating Tumor Cell Kit for measuring prostate cancer cells.

Byron Hewett, president and CEO of Huntingdon Valley, Pa.-based Immunicon, said the company likely will ask the FDA around mid-year for clearance to market the test in the new indication.

"What we offer, for the first time, is an objective measure that tells the clinician when the patient has failed therapy" without relying solely on symptoms and imaging, Hewett said. Symptoms can mislead, and imaging only shows the size of the tumor, not its virulence - a given subject might have a large but indolent tumor, or a small but much more aggressive one.

"In a lot of ways, [doctors] are flying blind in managing these patients," Hewett told BioWorld Today.

In the next three to four months, the company will ask regulators' go-head for CellSearch in colorectal cancer, where the product hit its endpoints in a pivotal trial this fall. (See BioWorld Today, Sept. 27, 2006.)

Already approved for use in breast cancer, CellSearch now has met its primary endpoint in predicting overall survival of prostate-cancer patients by measuring circulating tumor cell (CTC) levels three to five weeks after chemotherapy started.

Immunicon's stock (NASDAQ:IMMC) closed Thursday at $3.19, up 1 cent.

The trial was designed to number CTCs in metastatic, androgen-independent patients about to start either their first or later line of chemo. At 65 sites in the U.S. and Europe, 276 patients were enrolled between October 2004 and February 2006. All had whole-body bone scans performed before therapy began, and those with measurable disease had CT scans of the abdomen and pelvis as well, with more scans at intervals according to institutional guidelines.

Prostate specific antigen measurements were made at baseline and about every month after, along with CTCs. Patients stayed with the study and provided blood for up to 18 months or until documented evidence of disease progression and/or death, whichever happened first.

CellSearch, approved in 2004 for use in metastatic breast cancer, is the first diagnostic technology to automatically identify and count CTCs in a tube of blood. The product is partnered with Johnson & Johnson unit Veridex LLC, of Warren, N.J.

In August 2005, Immunicon laid off one-fourth of its work force to strengthen its balance sheet, narrowing its research and development work to projects that would boost near-term revenue. (See BioWorld Today, Aug. 30, 2005.)

"Since then, we've continued to make a lot of great progress, and studies like [the latest in prostate cancer] are certainly a major way to drive that forward," Hewett said. As of the end of 2006's third quarter, the company had about $29 million in cash, cash equivalents and short-term investments.

"We're building a body of evidence here," he said. "The statistical significance we achieve in our studies is always phenomenal, not just barely significant."

How often CTC tests might be done for cancer patients is "up to the physician, but certainly you want to do it at baseline and first follow up," Hewett said. "Eventually, we hope that by measuring CTCs, we'll also be able to interrogate them for other proteins or genes."

Such work is already under way. Intriguing news from Immunicon's partner Pfizer Inc., of New York, emerged from last year's meeting of the American Society of Clinical Oncology. CTC testing became part of a Phase I study with CP-751,871, Pfizer's monoclonal antibody targeting insulin-like growth factor 1 receptor (IGF-1R) in combination with docetaxel.

Of those patients that were positive for IGF-1R on circulating cells, almost 60 percent responded to therapy, compared to a 15 percent response rate for those that were negative. Investigators "were thrilled, of course, with that data," Hewett said. "It showed we've identified the right target. A 60 percent response rate in oncology is pretty much unheard of."

Such results, he noted, could ultimately open the door to diagnostic tests paired with drugs, such as the HER2 test for women potentially eligible for Herceptin (trastuzumab), the breast cancer drug from South San Francisco-based Genentech Inc.