Evaluation of Clinical and Biological Prognostic Factors in Relapsed or Refractory Diffuse Large B-Cell Lymphoma Patients After Previous Treatment With Rituximab and Chemotherapy: Results of the PRO-R-IPI Study

Introduction Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous entity, showing a highly variable outcome. In patients with DLBCL relapsed/refractory to first-line treatment with rituximab the usefulness of the revised International Prognostic Index (R-IPI) as a prognostic tool remains unexplored. Some biological parameters (B-cell lymphoma 6 [Bcl-6], Bcl-2, p53, and multiple myeloma 1 [MUM1]) and blood populations (lymphocyte and monocyte counts) have been described as International Prognostic Index-independent prognostic factors. The objective was to evaluate the R-IPI to predict the outcome of DLBCL patients at the time of relapse after a front-line treatment with chemotherapy and rituximab and to establish in this population the relationship between biological parameters and outcome. Patients and Methods We included patients with refractory/relapsed DLBCL after first-line treatment with rituximab-containing regimens; patients must have already finished a rescue treatment also including rituximab. Immunohistochemical assessment of Bcl-2, Bcl-6, p53, and MUM1 expression were undertaken in available biopsies. R-IPI factors were identified from the clinical data at diagnosis and at relapse. Response was assessed using National Cancer Institute-sponsored Working Group guidelines. Results R-IPI prognosis at relapse was not significantly associated with overall response rate (ORR) after Rituximab-chemotherapy rescue therapy. None of the immunohistochemical parameters analyzed correlated with rescue therapy results. In contrast, patients with absolute lymphocyte count (ALC) ≥ 1 × 109/L at relapse were more likely to respond than patients with ALC < 1 × 109/L (P = .05). Conclusion The R-IPI score calculated at relapse could not predict the ORR to second-line treatment. Lymphopenia is a simple and useful predictor for outcome in relapsed/refractory DLBCL and the only prognostic factor that in our hands could predict the overall response to a second-line treatment with rituximab and chemotherapy.