Soluble interleukin-2 receptor level predicts survival in patients with follicular lymphoma treated with cyclophosphamide, doxorubicin, vincristine and prednisone chemotherapy in the rituximab era

Abstract

This study analyzed the prognostic significance of soluble interleukin-2 receptor α (sIL-2Rα) levels in 100 prospectively enrolled patients with previously untreated follicular lymphoma. It showed that sIL-2Rα level ≥ 115 pmol/L at the time of treatment initiation correlated with a high Follicular Lymphoma International Prognostic Index-2 (FLIPI-2), bulky disease, advanced clinical stage, number of involved lymph nodes, bone marrow involvement and elevated β2-microglobulin (B2M) level. When testing all patients, sIL-2Rα ≥ 115 pmol/L was associated with significantly shorter progression-free (PFS; p < 0.03, hazard ratio [HR] 2.04) but not overall (OS; p = 0.06, HR 2.36) survival rates. Subanalysis of patients receiving cyclophosphamide, doxorubicin, vincristine and prednisone (CHOP) ± rituximab showed higher predictive power for both PFS (HR 2.75, 95% confidence interval [CI] 1.24-6.11, p = 0.01) and OS (HR 3.33, 95% CI 1.15-9.63, p = 0.02). In the whole population (n = 100), only B2M proved a significant univariate predictor (p = 0.007, HR = 2.8) of PFS. When testing patients treated with CHOP ± rituximab, sIL-2Rα was found to be the best univariate predictor for PFS among all FLIPI-2 factors (HR = 2.68, p = 0.015). Serum IL-2Rα levels may help to refine risk assessment in the modern immunotherapy era complementary to FLIPI-2 factors.