The FDA has approved updated drug labeling for fludarabine phosphate, marketed as Fludarabine Phosphate Injection, under Project Renewal, expanding its utility in treating B-cell chronic lymphocytic leukemia (CLL). This update provides clinicians with refined guidance on using fludarabine phosphate both as a monotherapy for relapsed or refractory CLL and as part of a combination regimen. The revised label incorporates recommendations for combining fludarabine phosphate with cyclophosphamide and rituximab, a common and effective treatment strategy.
The updated labeling now approves Fludarabine Phosphate Injection for use as a component of a combination regimen for the treatment of adults with B-cell CLL, and for the treatment of adults with B-cell CLL who have not responded to or whose disease has progressed during treatment with at least 1 alkylating-agent containing regimen.
Dosage and Administration
The recommended dose for adults is 25 mg/m2 administered intravenously over approximately 30 minutes daily for 5 consecutive days, with each treatment course beginning 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 demonstrated 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. The first study, conducted at The University of Texas MD Anderson Cancer Center, involved 48 patients receiving between 22 mg/m2 and 40 mg/m2 of fludarabine phosphate daily for 5 days every 28 days. The second study, by the Southwest Oncology Group (SWOG), included 31 patients receiving 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, based on the National Cancer Institute CLL Working Group criteria. Both studies reported a complete response rate of 13%, with partial response rates of 35% in the MD Anderson study and 19% in the SWOG study. The median time to response was 7 weeks (range, 1-68) and 21 weeks (range, 1-53) in the MD Anderson and SWOG studies, respectively. The median duration of disease control was 91 weeks and 65 weeks, respectively. Median survival among all patients with refractory CLL was 43 weeks and 52 weeks in the MD Anderson and SWOG studies, respectively.
Furthermore, in the MD Anderson study, Rai stage improved to stage II or better in 7 of 12 responders (58%), and in the SWOG study, it improved in 5 of 7 responders (71%) 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 anemic patients, and the average platelet count improved from 63,500/mm3 to 103,300/mm3 at the time of response in patients with 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. The FDA also removed the boxed warning, incorporating this information into the Warnings and Precautions section of the label.
