Clinical efficacy and safety in relapsed/refractory diffuse large B-cell lymphoma: a systematic literature review

This systematic literature review was designed to assess information on the clinical efficacy and safety of interventions used in the treatment of refractory or relapsed diffuse large B-cell lymphoma (R/R DLBCL) and to perform a meta-analysis if possible. We searched databases (PubMed, EMBASE, and Cochrane Library for articles from 1997 to August 2, 2012 reported in English), conference abstracts, bibliographic reference lists, and the ClinicalTrials.gov database for phase II to IV studies with results. Studies had to report on patients with R/R DLBCL who were not eligible to receive high-dose therapy (HDT) with stem cell transplantation (SCT) (autologous or allogeneic). Mixed-type non-Hodgkin lymphoma (NHL) studies were required to report R/R DLBCL outcomes separately. We identified 55 studies that presented outcomes data separately for patients with R/R DLBCL. Of 7 comparative studies, only 4 were randomized controlled trials (RCTs). In the 2 RCTs with a common regimen, the patient populations differed too greatly to perform a valid meta-analysis. The 48 single-arm studies identified were typically small (n < 50 in most), with 31% reporting median progression-free survival (PFS) or overall survival (OS) specifically for the R/R DLBCL population. In these studies, median OS ranged from 4 to 13 months. The small number of RCTs in R/R DLBCL precludes identifying optimal treatments. Small sample size, infrequent reporting of OS and PFS separated by histologic type, and limited information on patient characteristics also hinder comparison of results. Randomized studies are needed to demonstrate which current therapies have advantages for improving survival and other important clinical outcomes in patients with R/R DLBCL.