Background: The Follicular Lymphoma International Prognostic Index (FLIPI) has been developed to predict prognosis and to allow risk adapted treatment decisions in patients with follicular lymphoma (FL) before the widely use of Rituximab. However, the addition of Rituximab to standard induction chemotherapy with its long-term beneficial effects has profoundly changed the treatment outcome in patients with advanced stage FL and has become the new standard in the first line therapy of this disease. Therefore, we addressed the question, whether the prognostic value of the FLIPI could be reconfirmed in patients with advanced stage FL treated initially with a rituximab/chemotherapy combination.

Methods: The FLIPI index was tested in patients treated with Rituximab and CHOP (Cyclophosphamide, Doxorubicin, Vincristine and Prednisone, R-CHOP) in a prospective multicenter phase 3 trial of the GLSG using the time to treatment failure (TTF) as target parameter.

Results: 362 Patients treated with R-CHOP were evaluable for TTF. Of the 338 patients evaluable for all FLIPI risk factors, 14% of patients were classified as low, 41% as intermediate and 45% as high risk. After a median follow-up time of 20 months, patients with low risk and intermediate risk FLIPI had almost identical TTF (2-years TTF 92% vs 90%, 95% C.I., 83% to 100% and 84% to 96%, respectively). In contrast, the TTF was significantly shorter in the high risk FLIPI group (2-years TTF 67%, 95% C.I., 58% to 76%) as compared to the combined low/intermediate risk FLIPI group (relative risk 3.0, 95% C.I., 1.7 to 5.1; p < 0.0001). In addition, responding patients with high risk FLIPI had a significantly shorter progression free survival as compared to the low/intermediate risk group (relative risk 3.3, 95% C.I., 1.8 to 6.0; p < 0.0001). When postremission treatment was taken into account, the FLIPI separated the high risk group from the low/intermediate risk group in 65 patients treated with autologous stem cell transplantation (relative risk 6.0, 95% C.I., 1.4 to 25.2) as well as in 242 patients who had received IFN-α maintenance or no postremission therapy (relative risk 3.2, 95% C.I., 1.8 to 5.8). As the FLIPI was able to separate the high from the low/intermediate risk group in patients with advanced follicular lymphoma treated initially with Rituximab and CHOP we next performed a multivariate analysis to determine the impact of the individual parameters incorporated in the FLIPI on the TTF. The serum LDH level greater than the upper normal limit (relative risk 2.6, 95% C.I., 1.5 to 4.5) and the hemoglobin level below 12 g/dl (relative risk 2.5, 95% C.I., 1.4 to 4.3) were independently associated with a shorter TTF in these patients, whereas the age and the number of nodal areas were not discriminant.

Conclusion: Taken together, these data indicate that the FLIPI is a valid prognostic index for identifying high-risk patients in FL, also after front-line combined immuno-chemotherapy. The index will remain an important tool to adjust treatment decisions in individual patients according their risk profile and to design clinical trials for the different risk groups in the era of antibody-based therapy.

C.B. and E.H. contributed equally to the work.

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