OUTLINE: This is a dose escalation study. Patients are treated on one of two treatment arms. In the first stage, cohorts of 1 patient each on arm I receive oral Ro 31-7453 twice daily on days 1-4, and cohorts of 1 patient each on arm II receive oral Ro 31-7453 once daily on days 1-4 at two dose levels higher than for arm I. Dose escalation ceases for each arm with the first instance of dose limiting toxicity (DLT). Two additional patients are entered at the stopping dose for each arm. If no further DLT occurs, the study proceeds to the second stage. In the second stage, dose escalation continues in increments of one dose level for each dosing schedule (arms I and II). Cohorts of 3-6 patients receive escalating doses of Ro 31-7453 in the absence of DLT. If 2 of 6 patients experience DLT at a dose level, escalation ceases and the maximum tolerated dose is defined as the previous dose level. Treatment continues every 3 weeks for 8 courses in the absence of disease progression or unacceptable toxicity. After completion of the 8 courses, patients may continue treatment until disease progression at the discretion of the investigator and the study sponsor. Patients are followed at 4 weeks.