CellSearch system advances melanoma diagnostics

Key Points

Huntingdon Valley, Pa. - The CellSearch system (Veridex LLC) is an in vitro circulating-tumor-cell test that has shown to be of use in the management and treatment of patients with breast, colorectal and prostate cancers. Now, the system is finding its way into dermatology and may prove useful in the treatment and prognosis of melanoma.

Approved by the Food and Drug Administration for metastatic breast, colorectal and prostate cancer, the CellSearch system uses biomarkers to identify and count tumor cells, helping clinicians better determine prognosis in terms of overall and progression-free survival. Veridex has now turned its sights on circulating melanoma cells in the hopes of achieving a similar utility for their cancer-cell-counting system.

"Prior to the introduction of this kit, cell counts could not be performed in melanoma patients, and the evaluation of melanoma mostly relied upon tissue biopsies or polymerase chain reaction (PCR), which can be cumbersome and time intensive. The CellSearch approach is kind of a liquid biopsy, as the cells are taken and assessed from the blood and not tissue samples, making the process simple and reproducible," says Mark Carle Connelly, Ph.D., director of Cellular Research at Veridex LLC, a Johnson & Johnson company, Huntingdon Valley, Pa.

Study details

In a recent study, Dr. Connelly and colleagues evaluated the efficacy of the CellSearch system in melanoma patients. Of the 44 patients included in the study, 39 had metastatic melanoma and five had unresected stage III disease. In the study, CD146+ cells were immunomagnetically enriched from each patient's 7.5 mL blood sample. Isolated cells were fluorescently stained with DAPI, antimolecular weight melanoma-associated antigen (HMW-MAA), anti-CD45 and CD34 and Ki67, positively identifying and confirming them as melanoma cells. Circulating melanoma cells were identified as CD146+, HMW-MAA+, CD45-, CD34-, Ki67-/+ cells.

Results showed that 88 percent of spiked SK-MEL28 cells in 7.5 mL blood were recovered. In the retrospective analysis comparing the circulating melanoma cell (CMC) counts and overall survival in the patients' sampled blood, the CMCs ranged from 0 to 8,042 per 7.5 mL. Two or more CMCs were detected in 18 (23 percent) of the patients, and 30 to 100 percent (mean 84 percent) of the CMCs expressed the proliferation marker Ki67. Data showed that patients with ≥2 CMCs per 7.5 mL of whole blood, as compared with the group with <2 CMCs, had a shorter overall survival (2.0 vs. 12.1 months).

"Our data suggests that patients with a high number of circulating melanoma cells may have a shorter survival and faster progression of disease compared to patients who do not have circulating melanoma cells," Dr. Connelly says. "Using the CellSearch system, we can begin to generate some early data that might suggest that a change in the cell numbers may have a prognostic effect."

Though the study data shows the CellSearch kit to be effective in melanoma, Dr. Connelly says that clinical claims cannot yet be made, as multicenter clinical trials are still lacking. However, he says, the CellSearch system has the potential to significantly help researchers in a more rapid and targeted development of novel protein compounds and other investigational therapies for melanoma.

Disclosures: Dr. Connelly is an employee of Veridex LLC.