Prognostic significance of programmed cell death-1-positive cells in follicular lymphoma patients may alter in the rituximab era.

Programmed cell death-1 (PD-1) is involved in one of the inhibitory pathways of the B7-cluster of differentiation (CD) 28 family; this pathway is known to be involved in the attenuation of T-cell responses and promotion of T-cell tolerance. PD-1 is known to negatively regulate T-cell receptor-mediated proliferation and cytokine production, lead to alternation in the tumor microenvironment. Although several studies have shown that high levels of PD-1-positive cells in follicular lymphoma (FL) patients influence their prognosis, those studies included patients treated without rituximab, and the prognostic impact of PD-1 positivity in the rituximab era (R-era) has not yet been elucidated. We retrospectively studied 82 patients with FL uniformly treated with standard R-CHOP therapy at six institutions between 2001 and 2009 (median follow-up for survivors: 55 months). We also collected and examined biopsy specimens for diagnosis with respect to PD-1 positivity. The PD-1 positivity was significantly higher in male patients and patients with high beta-2 microglobulin (B2M ≥ 3.0) (P = 0.03 and 0.003, respectively). Three-year progression free survival (PFS) and overall survival (OS) were 60% and 86%, respectively. By univariate analysis, elevated LDH (P = 0.07) worsened PFS. Male gender (P = 0.03), high FLIPI score (P = 0.05), and high B2M levels (P = 0.08) worsened OS. Multivariate analysis detected no significant prognostic factors, including PD-1 positivity. However, in male subgroup, high levels of PD-1-positive cells were found to be a prognostic factor for PFS. Addition of rituximab might have altered the prognostic impact of PD-1-positive cells.