A Systematic Review of Treatments of Relapsed/Refractory Mantle Cell Lymphoma

A systematic review was conducted to evaluate the clinical effectiveness and safety of treatments for patients with relapsed/refractory mantle cell lymphoma (MCL) unsuitable for intensive treatment. The criteria for inclusion of the trials were established before the review. A search of Medline, Embase, and the Cochrane library databases was conducted to identify phase II or III randomized controlled trials (RCTs), reported from January 1, 1994 to May 29, 2016. Relevant conference abstracts, citation lists from the included articles, published guidelines, and on-going clinical trial databases were also searched. Studies were included if they had evaluated any single agent or combination of treatments for adult patients with relapsed/refractory MCL who had received ≥ 1 previous line of therapy. Seven RCTs were identified. Only 1 treatment appeared in > 1 trial; therefore, the results from each trial could not be quantitatively pooled for meta-analysis. The lack of common comparators, differences in baseline characteristics and inclusion and exclusion criteria, and variances in the response criteria used to measure outcomes made comparison of the results difficult. Although the direction of effect for progression-free survival (PFS) and overall survival (OS) was in favor of the experimental drug in all trials, the difference in PFS was statistically significant in 5 and OS in 2. None showed statistical significance for both. A noticeable lack of RCTs evaluating treatments for patients with relapsed/refractory MCL made meaningful comparisons of effectiveness across trials rather difficult. This trend continues, because all, bar 1, of the 85 ongoing trials in this area are single-arm studies. RCTs are required to enable better evaluation of the optimal treatment regimen for this group of patients.