<qa>  What is fludarabine phosphate administered over 60 minutes on day 1 in cohort 1Patients receive fludarabine phosphate intravenously IV over 15-30 minutes on days 1-5 and rituximab IV over 3-4 hours on day 1. Alvocidib is administered IV over 60 minutes on day 1 in cohort 1; on days 1 and 2 in cohort 2; and on days 1, 2, and 3 in cohort 3. In cohorts 4 and 5, patients receive fludarabine phosphate and rituximab as above and alvocidib IV over 30 minutes and then IV over 4 hours on day 1 of courses 2-6. Treatment repeats every 28 days for up to 6 courses in the absence of disease progression or unacceptable toxicity. 