Retrospective analysis of CD5-positive diffuse large B-cell lymphoma (CD5+ DLBCL) treated with chemotherapy with or without rituximab
8551 Background: CD5+ DLBCL comprises 5–10% of DLBCL, and shows a high incidence of central nervous system (CNS) relapse. It has been included in the 4th WHO classification as an immunohistochemical subgroup. To clarify the prognosis and incidence of CNS relapse of CD5+ DLBCL in the rituximab-era, we conducted a multicenter retrospective study. Methods: We analyzed 313 patients (pts) with CD5+ DLBCL who received chemotherapy with (n=164) or without rituximab (n=149). The current series includes 107 out of 120 pts described in our previous study (Haematologica, 2008). Intravascular large B-cell lymphoma, primary CNS DLBCL, and secondary CD5+ DLBCL were excluded from the study population. Results: 313 pts showed the following clinical features: median age, 67 (range: 15–93); M:F=163:150; elevated serum LDH level, 71%; stage III/IV, 64%; IPI HI/H, 53%. No significant difference in clinical background such as the IPI and its five components, B symptom, male sex, and bone marrow involvement was found between pts who were treated with and without rituximab. Pts treated without rituximab received more dose-intensive chemotherapies (CHOP14, third-generation regimen, and high dose cytarabine-based regimen) than those treated with rituximab (24% vs. 7%, P<0.0001). The CR rate was higher in pts received rituximab than those without (81% vs. 65%; P=0.0014). The median follow-up was 28 months in pts who received rituximab (range: 7–77) and 68 months in those who did not (range: 6–187). Overall survival (OS) was significantly superior for pts with rituximab than for those without (2-yr OS: 68% vs. 54%, P=0.003). Multivariate analysis revealed that the use of rituximab was favorably associated with OS (HR=1.81, 95% CI: 1.26–2.58, P=0.001), but dose-intensive chemotherapies did not affect OS. However, the incidence of CNS relapse was not different between the two groups (2-yr CNS relapse rate: 11.9% vs. 11.4%, P=0.91). 16 of the 20 pts (80%) with CNS relapse in the rituximab group had brain parenchymal disease. Conclusions: Our data show that rituximab improves OS of pts with CD5+ DLBCL, but does not prevent CNS relapse. Future prospective studies to decrease CNS disease for CD5+ DLBCL are warranted. No significant financial relationships to disclose.