MART-1/Melan-A and tyrosinase transcripts in peripheral blood of melanoma patients: PCR analyses and follow-up testing in relation to clinical stage and disease progression

The use of tyrosinase-based polymerase chain reaction (PCR) tests for the d etection of circulating tumour cells in the blood of melanoma patients has led to highly controversial results. We here report on the analysis of 120 blood samples from 76 stage I to IV melanoma patients using a new MART-1/Me lan-A PCR system in conjunction with the tyrosinase-specific assay reported in the literature. While there were no positive results in localized disea se (stages I and II), identification of specific PCR products in stage IH m elanoma patients was restricted to the MART-1/Melan-A tests, with positive results in 11% (two out of 19) of the blood specimens analysed. Stage IV me lanoma patients presented with the highest incidence of detectable mRNA lev els, with positive results for tyrosinase in 38% (12 out of 32) and for MAR T-1/Melan-A in 22% (seven out of 32). By delineating 64 follow-up specimens covering sampling periods of up to 33 weeks, stable mRNA expression profil es were identified in nearly 95%. Four patients, however, showed PCR change s towards positive MART-1/Melan-A expression that were linked to metastatic melanoma progression, Taken together, PCR tests for tyrosinase and MART-1/ Melan-A seem to lack sufficient detection frequencies for the routine monit oring of melanoma disease. Regarding the link between MART-1/Melan-A seroco nversion and the development of metastatic disease, further studies are nee ded to clarify the clinical value of this observation. (C) 2001 Lippincott Williams & Wilkins.