Uveal melanoma is associated with a high mortality rate once
metastases occur, with over >90% of metastatic patients dying within less than 1 year from
metastases to the liver. The intraarterial hepatic (iah) administration of the
alkylating agent fotemustine holds some promise with response rates of 36% and median survival of 15 months. Here, we investigated whether the DNA-repair-
protein MGMT may be involved in the variability of response to
fotemustine and
temozolomide in
uveal melanoma. Epigenetic inactivation of MGMT has been demonstrated to be a predictive marker for benefit from
alkylating agent therapy in
glioblastoma. We found a methylated MGMT promoter in 6% of liver
metastases from 34
uveal melanoma patients. The mean MGMT activity measured in liver
metastases with negligible liver tissue content was significantly lower than in liver tissue (146 versus 523 fmol/mg
protein, p = 0.002). Expression of the MGMT
protein was detectable in 50% of 88
metastases by immunohistochemistry on a tissue microarray. Expression was heterogeneous, and in accordance with MGMT activity data, usually lower than in the surrounding liver. Differential MGMT activity/expression between
metastasis and liver tissue and more efficient depletion of MGMT with higher doses of
alkylating agent therapy using iah delivery may provide the pharmacologic window for the higher response rate. However, these results do not support MGMT methylation status or
protein expression as predictive markers for treatment outcome to iah
chemotherapy with
alkylating agents.