Melanoma antigen expression in serial fine-needle aspiration samples in patients with metastatic malignant melanoma participating in immunotherapy clinical trials: a preliminary look.
BACKGROUND
MART-1 and gp100 currently are utilized as targets in immunotherapy protocols for metastatic malignant melanoma (MMM). Enrollment of patients into ongoing peptide vaccination trials at the National Cancer Institute includes immunophenotyping of samples of metastatic lesions obtained by fine-needle aspiration (FNA). As therapy progresses, immunocytochemistry is performed on serial FNAs of metastatic lesions to monitor changes in antigen expression during treatment. It is theorized that antigen expression of melanoma cells may be diminished because of selective immunodestruction of tumor cells, or perhaps intentionally, to escape immunosurveillance.


METHODS
Thirty-eight lesions from 33 patients were serially monitored for the expression of gp100 (clone HMB-45) and MART-1 (clone M2-7C10), using an avidin-biotin peroxidase technique. The staining intensity of tumor cells was scored on a scale of 0 to 3+, with the proportion of positive cells categorized as less than 25%, 25-50%, 50-75%, and greater than 75%. All lesions were examined within approximately 2 months after the start of peptide vaccination, providing a consistent timepoint for analysis.


RESULTS
Using the Wilcoxon signed rank test, the authors found that there were no significant changes from baseline compared with 2 months later for quantitative antigen expression of HMB-45 or MART-1. However, there was a trend toward a decline in staining intensity of tumor cells for HMB-45.


CONCLUSIONS
Preliminary results evaluating antigen expression during selective immunotherapy indicate a trend in the decline of staining intensity of tumor cells to HMB-45. Thus, although other studies have shown that peptide-based immunotherapy results in immune selection, this does not hinder the diagnostic utility of antibodies to HMB-45 and MART-1 in FNA samples of MMM.
Fetsch
P A
PA
Cytopathology Section, National Institutes of Health/National Cancer Institute, Bethesda, Maryland 20892-1500, USA.
Steinberg
S M
SM
Riker
A I
AI
Marincola
F M
FM
Abati
A
A
D000951:Antigens, Neoplasm; D001707:Biopsy, Needle; D002986:Clinical Trials as Topic; D003937:Diagnosis, Differential; D006801:Humans; D007150:Immunohistochemistry; D007167:Immunotherapy; D008545:Melanoma / Q000175:diagnosis / Q000188:drug therapy / Q000276:immunology*; D058950:Melanoma-Specific Antigens; D008562:Membrane Glycoproteins / Q000096:biosynthesis*; D009362:Neoplasm Metastasis; D009363:Neoplasm Proteins / Q000096:biosynthesis*; D011237:Predictive Value of Tests; D012878:Skin Neoplasms / Q000175:diagnosis / Q000188:drug therapy / Q000276:immunology*; D058951:gp100 Melanoma Antigen
D000951:Antigens, Neoplasm; C072011:MAGEA1 protein, human; D058950:Melanoma-Specific Antigens; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; C548637:PMEL protein, human; D058951:gp100 Melanoma Antigen