- Patients with intermediate or high-risk CLL/SLL receive standard treatment with rituximab and fludarabine for six 28-day treatment cycles. Rituximab is given on day 1 and fludarabine is given on days 1-5. (For the first cycle only, fludarabine treatment starts on day 2. This delay permits blood sampling on day 1 for the effect of rituximab on white blood cells.)