Some patients receive an initial dose of alvocidib IV over 1-7 hours on day 1 (course 0). Beginning 1 week later and for all subsequent courses, all patients receive gemcitabine hydrochloride IV over 60-150 minutes on days 1 and 15 and alvocidib IV over 1-7 hours on days 2 and 16. Courses repeat every 28 days in the absence of disease progression or unacceptable toxicity.