There will be seven escalating doses of Valproic acid and one dose escalation step of Karenitecin. Each patient shall receive one cycle of Karenitecin alone (cycle 1 days 1 - 5) followed by the same dose of Karenitecin given in combination with VPA (cycle 2 days 1-7). Patients will receive oral VPA in divided doses for 5 days and Karenitecin starting on the 3rd day every 3 weeks (a treatment cycle).