Antitumor effect of the combination of hydralazine and valproic acid plus adriamycin in a nude mice xenograft model of fibrosarcoma. Control: solid line with open squares. Tumors in animal treated with adriamycin (dotted line with closed circles) and hydralazine-valproic acid and adriamycin (broken line with open triangles) had their tumors shrinkaged at day 21, however, in animals receiving hydralazine and valproic acid tumors failed to regrowth while in those with only adriamycin tumors increased in size shortly after day 21. Saline, or adriamycin injections were performed at days 7, 14 and 21. In the group with the three-drug combination, hydralazine and valproic acid were administered daily from day 1 (seven days before the first injection of adriamycin (day 7) until sacrifice (day 35).