- Patients who have had chemotherapy or radiotherapy within 4 weeks (6 weeks for nitrosoureas or mitomycin C) prior to entering the study or those who have not recovered (=< grade 1) from clinically significant adverse events due to agents administered more than 4 weeks earlier; prior palliative radiotherapy is allowed if greater than 2 weeks have elapsed and patient has also recovered to baseline or grade < 1 from any treatment adverse effects