The FDA has approved updated drug labeling for fludarabine phosphate, a medication used in the treatment of B-cell chronic lymphocytic leukemia (CLL), as part of the agency's Project Renewal. This update expands the drug's approved uses and provides clearer guidance on its administration, potentially improving outcomes for CLL patients.
Updated Labeling Details
Fludarabine Phosphate Injection is now approved for use as a component of a combination regimen for the treatment of adults with B-cell CLL. This includes patients who have not responded to or whose disease has progressed during treatment with at least one alkylating-agent containing regimen. The FDA also amended the existing label to include the recommended dosage for use in combination with cyclophosphamide and rituximab. Previously included as a boxed warning, information has been incorporated into the Warnings and Precautions section.
The recommended dose in adults is 25 mg/m2 administered intravenously over approximately 30 minutes daily for 5 consecutive days. Each treatment course should begin every 28 days. The label advises dose reduction for patients with creatinine clearance between 30 and 70 mL/min/1.73 m2 and contraindicates its use in patients with severe renal impairment.
Clinical Efficacy
The efficacy of fludarabine phosphate was evaluated in two single-arm, open-label studies involving adult patients with CLL who were refractory to at least one prior standard alkylating agent–containing regimen. In a study at The University of Texas MD Anderson Cancer Center, 48 patients received between 22 mg/m2 and 40 mg/m2 of fludarabine phosphate daily for 5 days every 28 days. A second study by the Southwest Oncology Group (SWOG) involved 31 patients who received between 15 mg/m2 and 25 mg/m2 of fludarabine phosphate daily for 5 days every 28 days.
The objective response rates were 48% and 32% in the MD Anderson and SWOG studies, respectively, according to response criteria developed by the National Cancer Institute CLL Working Group. The complete response rate in both studies was 13%, while the partial response rate was 35% in the MD Anderson study and 19% in the SWOG study. The median time to response in the MD Anderson and SWOG studies was 7 weeks (range, 1-68) and 21 weeks (range, 1-53), respectively. The median duration of disease control was 91 weeks and 65 weeks in the MD Anderson and SWOG studies, respectively. The median survival among all patients with refractory CLL who received fludarabine phosphate in the MD Anderson and SWOG studies was 43 weeks and 52 weeks, respectively.
In the MD Anderson study, Rai stage improved to stage II or better in 7 of 12 responders (58%) and in 5 of 7 responders (71%) in the SWOG study who had stage II or IV disease at baseline. The mean hemoglobin concentration improved from 9.0 g/dL at baseline to 11.8 g/dL at the time of response in a subgroup of patients with anemia. Additionally, the average platelet count improved from 63,500/mm3 to 103,300/mm3 at the time of response in a subgroup of patients who had thrombocytopenia at baseline.
Safety Profile
Common adverse effects associated with fludarabine phosphate include myelosuppression, fever and chills, fatigue, weakness, infection, pneumonia, cough, nausea, vomiting, and diarrhea. Other frequently reported events include malaise, mucositis, and anorexia. Healthcare providers should monitor patients closely for these and other potential side effects during treatment.
