Randomized, double-blind phase III trial. A total of 211 patients (alpha 0.5, power 0.8)with cisplatin-resistant recurrent or persistent cancer will be randomized to topotecan + placebo or topotecan + hydralazine + valproate for 6 courses every 4 weeks. Patients will receive an oral dose of hydralazine of 182mg (rapid) or 83mg (slow) according to the acetylator phenotype in a single daily dose and magnesium valproate at an oral dose of 40mg/Kg t.i.d. Both drugs in a slow-release formulation. Experimental drugs or placebo will start from seven days before day 1 of chemotherapy until the end of the sixth course.
