Rituximab Does Not Improve Progression Free (PFS) or Overall Survival (OS) in Patients with Limited Stage Diffuse Large B Cell Lymphoma (DLBCL).

Diffuse Large B Cell Lymphoma (DLBCL) is the most common lymphoid malignancy accounting for approximately 33% of all newly diagnosed NHLs. Three randomized trials and multiple retrospective analyses have demonstrated both progression-free (PFS) and overall survival (OS) benefit to the addition of the anti-CD20 monoclonal antibody rituximab to anthracycline-containing chemotherapy in older advanced-stage patients, and in young low-risk patients with DLBCL. Approximately half of newly diagnosed patients with DLBCL present in limited stage and the benefit of rituximab containing chemotherapy regimens for these patients remains uncertain.

We used an IRB-approved clinicopathologic database, derived from comprehensive tumor registry data at the Massachusetts General Hospital, Dana Farber Cancer Institute and Brigham and Women's Hospital, to identify all patients 18 years or older diagnosed with limited stage DLBCL between 2000 and 2006. We included all patients treated with 3 or more cycles of anthracycline containing chemotherapy with curative intent. We excluded primary DLBCL of the CNS. We determined the impact of the use of rituximab on OS and PFS. PFS and OS were calculated from the date of initial diagnosis.

A total of 138 patients met eligibility criteria and are included in the analysis. Median age was 51 years (range 18-89 years). 30% of patients were above 60 years of age, and less than 3% had an IPI score of 3 or higher. One hundred and six patients received CHOP + rituximab (RCHOP) and 32 received CHOP alone. Of the 106 patients receiving RCHOP, 48 were irradiated and 58 were not. Of the 32 patients receiving CHOP, 20 received radiation and 12 did not. At a median follow-up of 35 months (range 3-109 months), PFS and OS for the entire cohort are 86.2% and 90.6%, respectively. On univariate analysis of outcome, the addition of rituximab to CHOP did not improve PFS (81.3% vs. 87.7%,p=0.817, Logrank Test) or OS (84.4% vs. 92.5%, p=0.411, Logrank Test).

The outcome of an unselected series of patients with limited stage DLBCL is excellent. In this retrospective cohort of patients with limited stage DLBCL, the use of rituximab in conjunction with standard chemotherapy did not improve PFS or OS. The results we obtained are very similar to those reported by SWOG (Persky et al. JCO 2008). The overlapping confidence intervals for PFS and OS between SWOG 0014 and 8736 patients and our data suggest that a large multicenter trial will be needed to show a benefit of rituxan in this extremely good prognosis population.

Hochberg:Genentech: Speakers Bureau; Biogen-Idec: Speakers Bureau; Enzon: Speakers Bureau; Amgen: Speakers Bureau.