Medical Device Daily

Going for the hat trick. That phrase perhaps best describes Immunicon's (Huntingdon Valley, Pennsylvania) approach toward developing its cancer survival monitoring assay CellSearch.

The company had just received FDA clearance for the circulating tumor cell (CTC) kit as an aid to test in the monitoring of patients' conditions with metastatic colorectal cancer. Now hot on the heels of the colon cancer detection approval, the company has filed with the FDA to have the CellSearch test geared toward prostate cancer. The CellSearch test was originally cleared in 2004 for in vitro diagnostic use in patients with metastatic breast cancer.

"Immunicon has been working on the assay for last 10 years," Byron Hewett, president/CEO told Medical Device Daily. "Research and clinical testing have continued to prove the effectiveness and impact the Cellsearch CTC can have in the treatment of patients with metastic diseases."

He added: "With CellSearch's current FDA clearances for breast and colorectal cancers, adding the clearance for metastatic androgen-independent prostate cancer potentially will provide oncologists and pharmaceutical companies an additional tool to develop therapeutics and improve patient care for three of the top carcinomas."

This is how CellSearch works.

The assay is comprised of nanoparticles, which are able to determine the hard-to-find CTCs in the blood. The test finds one in 40 billion cells in a single blood sample. Consistent with the data in metastic breast cancer and correctal cancer, CTC's predict survival at multiple time points during the course of therapy.

Patients with three or more CTCs at any of the time points had a much higher likelihood of dying sooner than patients with less than three CTCs. Evaluation of CTC count at any time during the course of disease allows assessment of patient prognosis and is predictive of progression free survival and overall survival.

To test the effectiveness of the application, 276 patients were enrolled in the trial at 65 sites in the U.S. and Europe between 2004 and 2006. The company said that all patients had whole-body bone scans performed prior to therapy, and those with measurable disease had CT scans of the abdomen and pelvis performed prior to the initiation of therapy and at subsequent intervals following institutional guidelines.

All patients had serum samples collected for prostate-specific antigen (PSA) measurements at baseline and at about monthly intervals thereafter. CTCs also were measured at baseline and at about monthly intervals thereafter using CellTracks technology.

Patients remained in the study up to 18 months or until evidence of disease progression and/or death, whichever occurred first.

CellSearch differs from PSA tests, which measure antigens in patients. PSA is present in small quantities in the serum of normal men, and often is elevated in the presence of prostate cancer and in other prostate disorders.

"The problem with PSAs is that it's so easy to misdiagnose someone with having too many antigens or too little," Hewett said.

In addition to being more precise, the assay also has a quicker response time than imaging scans. These scans prove to be inaccurate in comparison and can only be done every 12 to 14 weeks. Because it's a blood test, Cell Search can be done every two to four weeks.

"It's a four-hour procedure," he said. "Results [from the test] can be reported as early as the next day."

A study presented at the American Society of Clinical Oncology (ASCO; Alexandria, Virginia) conference in Chicago last summer showed that CTCs are the strongest independent predictor of survival in patients and that patients with favorable CTCs after three to five weeks of therapy lived more than three times as long as those with unfavorable CTCs.

The company hopes for FDA clearance of the CellSearch for monitoring patients with metastatic androgen independent prostate cancer early next year. It has had CE-mark approval to monitor for all three cancers since 2004, Hewett said.

Although CellSearch is the primary product from the company, it isn't the only offering being developed by the company.

"We've got quite a few projects in developmental stages, but we aren't ready to comment on them at this time," he said.

Earlier last summer the company made news when it filed a universal shelf registration statement with he Securities and Exchange Commission, intended to permit the sale by Immunicon of up to $75 million of its common stock, preferred stock, debt securities, warrants, depositary shares, stock purchase contracts and stock purchase units.

The company said it has no current plans to offer the securities covered by the registration statement, with the terms of any offering to be established at the time of the offering.

Immunicon makes cell- and molecular-based human diagnostic and life science research products, with an initial focus on cancer disease management.

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