TORONTO, Aug 29 (Reuters Health) - The CD56 antigen, which is expressed on myeloid leukemia cells as well as other malignant cell types, is an important, independent predictor of poor outcome in patients with acute myeloid leukemia (AML). The finding was presented here Monday during the 28th World Congress of the International Society of Hematology.
Dr. Francesco Lauria, professor of hematology, University of Siena, Italy, and colleagues measured CD56 antigen expression as well as other immunophenotypic markers of known prognostic significance in 120 patients with newly diagnosed AML.
"Overall, 31 patients, or 26% of the group, tested positive for the CD56 antigen," Dr. Lauria reported. Patients with the M2 and M5 cytotypes were particularly likely to be CD56 positive, he added.
CD56-positive patients were also significantly more likely to overexpress the p-glycoprotein (pGP), which is associated with drug resistance. Specifically, 11 out of 15 patients who were positive for CD56 overexpressed pGP, compared with 17 out of 37 patients who were CD56-negative.
"Forty percent of CD56-positive patients also had unfavorable cytogenic patterns," Dr. Lauria reported.
The complete remission rate was 36% in CD56-positive patients compared with 67% in CD56-negative patients. Survival was also significantly shorter for CD56-positive patients, at 6 months versus with 14 months for CD56-negative patients.
"The CD56 antigen test is a very simple test to do, so we're suggesting that newly diagnosed AML patients be tested for CD56 antigen expression when identifying the antigenic pattern of these patients, because it can be very useful in helping assess their prognosis," Dr. Lauria concluded.