 Eligible patients after signing informed consent will undergo study evaluation and acetylation status typing before being treated. Patients will begin treatment day -7 with a daily dose of a slow-release formulation of hydralazine tablets containing either 182 mg for rapid-acetylators or 83 mg for slow-acetylators and slow-release tablets containing 700mg of magnesium valproate at a dose of 40mgKb t.i.d. Both hydralazine and magnesium valproate will be administered from day -7 until the last day of the last chemotherapy cycle. Chemotherapy will initiate at day 1 after seven days of being taken hydralazine and magnesium valproate with the same pre-study protocol regimen at which patients showed tumor progression. Toxicity will be evaluated after each course of chemotherapy. Response will be evaluated at the third course of chemotherapy. Promoter of selected genes will be evaluated by methylation-specific PCR in serum DNA before and after 7 days of treatment with hydralazine and valproate. 