Preliminary results showed that fludarabine plus cyclophosphamide and a double dose of ofatumumab (FC-O2) is associated with a high rate of cytometric minimal residual disease (MRD)-negative complete response and is well tolerated in young and fit patients with previously untreated chronic lymphocytic leukemia (CLL).1

Fludarabine plus cyclophosphamide and rituximab is considered the optimal first-line treatment for fit patients with CLL, but the same chemotherapy with ofatumumab has also been associated with a high complete response rate. Therefore, researchers sought to evaluate whether FC-O2 could improve the complete response rate in young and fit patients with CLL.

For the study, researchers enrolled 61 fit patients with CLL to receive fludarabine 25 mg/m2 IV on days 1-3 plus cyclophosphamide 250 mg/m2 IV on days 1-3. Ofatumumab was administered at a dose of 300 mg IV on day 14 and 1000 mg on day 21 in cycle 1, and 1000 mg on days 1 and 15 in cycles 2-6 and day 28 in cycle 6.

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Results showed that at a median follow-up of 7 months, the overall response rate in 29 evaluable patients was 90% with a complete response rate of 69%.

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Researchers observed no evidence of MRD by flow cytometry in either peripheral blood or bone marrow in 75% of patients who achieved complete responses.

In regard to safety, 7% of patients experienced grade 3-4 granulocytopenia, 7% developed a severe infection, and 8% experienced a severe infusion-related reaction during ofatumumab administration. A total of 8 patients discontinued therapy due to toxicity.


  1. Mauro FR, Zaja F, Molica S, et al. Fludarabine, cyclophosphamide, ofatumumab (FC-O2) as front-line treatment for young and fit patients with chronic lymphocytic leukemia (CLL): preliminary results of the prospective phase 2 LLC0911 Gimema study [abstract]. Blood. 2015;126(23):2946.