NEW ORLEANS--Increasing levels of melanoma-inhibiting activity (MIA) protein indicate increasing disease activity in melanoma patients, according to research presented at the American Association for Cancer Research meeting.
MIA is a protein produced by melanoma tumor cells, and plasma concentrations of MIA correlate with the clinical stage of the cancer. Didier Dréau, PhD, of the Carolinas Medical Center, Charlotte, NC, and his colleagues evaluated whether MIA levels could be used to monitor success and failure of immunotherapy and predict recurrences.
The subjects were 57 patients with AJCC stage II, III, or IV melanoma. Most (36) were being treated by a melanoma cell vaccine. The others were receiving repeated injections of alpha-2b-interferon (Intron A) (13 patients) or IV interleukin-2 (8 patients). Plasma MIA levels were measured before and during therapy, and various other laboratory tests and imaging exams were performed.
The 37 patients who remained free of signs of melanoma before, during, and after immunotherapy averaged low MIA values. For example, in 27 of these patients who received vaccine, the average MIA was 4.4 ng/mL before treatment and 3.8 ng/mL afterwards. Of the other 20 patients, a patient who responded to IL-2 had a drop in MIA, as did a patient whose tumor was surgically resected. In all 6 other patients treated with IL-2, the disease progressed, as did MIA levels. Twelve patients treated with either vaccine or interferon relapsed during therapy, and their average MIA level increased.
The researchers found that MIA levels paralleled disease course in most patients. Looking retrospectively at the data, they found that if they had set 4.5 ng/mL as the cut-off above which recurrence would be suspected, recurrence would have been detected earlier in 6 of the 9 relapsing patients on vaccine and in 3 of the 3 relapsing patients on interferon. In some patients, relapse would have been detected as much as 6 months earlier.
Dr. Dréau and his colleagues concluded that MIA measurements could simply and accurately diagnose progression of melanoma in most patients who are on immunotherapy. Because of the three patients who had a recurrence of melanoma without a corresponding rise in MIA, they are continuing to study MIA in other patients on immunotherapy.