FCR-3 as Frontline Therapy for Patients with Chronic Lymphocytic Leukemia (CLL).

The combination regimen of Fludarabine, Cyclophosphamide, and Rituximab (FCR) has produced high overall response (OR) rates and complete remission (CR) rates in patients receiving this as initial treatment for CLL. Earlier studies have shown that dose-dense or dose-intensified regimens of single-agent Rituximab produced higher response rates in patients with CLL. The current regimen, FCR-3, was based on the hypothesis that increasing the amount of Rituximab in the combination might improve response rates and remission duration. Doses of chemotherapy were Fludarabine 25 mg/m²/Dx3, and Cyclophosphamide 250 mg/m²/Dx3 given monthly. Rituximab was given at 375 mg/m² as the first dose and 500 mg/m² for all subsequent doses. On each day of the chemotherapy a dose of Rituximab was given so 3 doses were given monthly. With the previous FCR regimen 45% of patients achieved a CR or nPR and had <5% CD19+ 5 positive cells in the marrow at the completion of 3 cycles of therapy (rapid response, RR). The median time to progression (TTP) in that group has not been reached; it was 3 years in patients who did not achieve that endpoint (p<.001). The current protocol aimed to increase that response rate from 45% to 60%. Sixty-five patients were treated. Eighty percent were men. The median age was 59 years (27–82). Rai Stage 3–4 disease was present in 25% of patients. Median WBC count was 92.4 x 10³/ul (7.9–363). Median B₂-microglobulin was 3.8 (1.6–10.1). Unfavorable FISH abnormalities were present in 35% of 52 evaluable patients. Somatic hypermutation status was available for 44 patients; 61% were unmutated. ZAP-70 expression analysis performed by immunostaining or flow cytometry was positive in 62% of 47 evaluable patients. Results of FCR-3 in comparison to FCR are shown in the table.

PCR negativity using consensus primer PCR was achieved in 49% of patients at the end of therapy. Median number of days between courses ranges from 29–35 per course (overall range 27–95). Eighty-five percent of patients completed 6 cycles. No patient has progressed with a median follow-up of 10 months. With limited follow-up the addition of 3 doses of Rituximab to FC chemotherapy does not appear to provide greater benefit than one dose.