Autologous Stem Cell Transplant in Recurrent Diffuse Large B- Cell Lymphoma: Prior Rituximab Therapy Has No Impact On Early Lymphocyte Recovery and Transplant Outcome.

Diffuse Large B Cell (DLBCL) is the most common histological subtype of lymphoma diagnosed in the United States. Following failure with standard Rituximab- CHOP chemotherapy, salvage therapy followed by autologous stem cell transplant is the standard treatment for those who are transplant eligible. Previous data suggest that early lymphocyte recovery is associated with superior survival after autologous stem cell transplantation (ASCT) in lymphoma. However, there are no consistent data on whether prior rituximab therapy affects lymphocyte recovery early post- transplantation. In this study we present our transplant outcome experience regarding early lymphocyte recovery in patients exposed to prior rituximab therapy.

One hundred fifteen patients undergoing autologous stem cell transplant for relapsed DLBCL at a single institution between January 2000 and December 2008 were included in our analysis after obtaining IRB approval. Descriptive statistics, Wilcoxon signed rank sum test and Kaplan-Meier analysis were performed as required using SPSS software.

Median age of patients undergoing ASCT was 50 years (range: 24-69 years). Nine patients who underwent ASCT for transformed DLBCL and 7 patients with T-cell rich B cell lymphoma were also included in the final analysis. Six patients had stage I disease, 29 patients with stage II, 33 patients with stage III and 36 patients were diagnosed with stage IV. Thirteen patients had bulky retroperitoneal adenopathy at the time of original diagnosis. Seventy one (66.3%) patients received one salvage therapy prior to transplant. Thirty six (33.7%) patients received two or more salvage therapies prior to transplant. Mobilization data was available on 89 patients. Of those, 82 patients were mobilized with chemotherapy and 5 patients underwent mobilization with GCSF alone. High dose cytclophosphamide (7200 mg/sq.m), etoposide (2000 mg/sq.m) and BCNU (400 mg/sq.m) [CBV] was the conditioning regimen in 88 (77.2%) patients. Sixty eight (59.6%) patients received pretransplant rituximab therapy. Sixty one (61.6%) patients were in radiographic complete response (CR) following salvage therapy at the time of transplant. Sixty nine (78.4%) patients continued to be in CR at day 100 evaluation. Nineteen (21.6%) patients had persistent disease requiring further therapy. The median survival of all patients was 38.7 months (range: 3 months- 186 months). At the time of the analysis, 69 (60.5%) patients were still alive. Prior rituximab therapy did not affect lymphocyte recovery on day 14 (p=0.95) or day 28 (p=0.27). Lymphocyte recovery on day 14 and day 28 (continuous and categorical variables) had no impact on transplant outcome. Other factors such as age, disease stage at presentation, presence of bulky retroperitoneal nodal disease, number of regimens, mobilization procedure, type of conditioning regimen, pre-transplant radiation therapy, pre-transplant disease status (CR vs. PR in chemo sensitive disease) had no impact on survival.

our data demonstrate that prior rituximab therapy has no impact on lymphocyte recovery on day 14 or day 28. In this group of patients, lymphocyte recovery did not impact on autologous stem cell transplant outcome. The survival benefit with early lymphocyte recovery as mentioned in prior reports may be lost with longer follow up. Prior rituximab therapy may mitigate the effect of the number of treatment regimens or disease status (CR vs. PR) on transplant outcome.

No relevant conflicts of interest to declare.