Research Reports on Rituximab in Treating MCL and DLBCL

During the 2018 American Society of Clinical Oncology Annual Meeting, researchers published new findings on the use of rituximab in mantle cell lymphoma (MCL) as well as the outcomes of patients who relapse early after treatment with rituximab for diffuse large B-cell lymphoma (DLBCL).

Rituximab is not currently approved—but is sometimes used off-label—for maintenance therapy in MCL, but this use is not well studied. A systematic review and meta-analysis, published in an abstract, evaluated the outcomes of patients given rituximab maintenance versus patients not given rituximab maintenance, with outcomes of interest including progression-free survival (PFS) and overall survival (OS).¹

The researchers assessed 7 studies (including a total of 1050 patients). Three of the studies were randomized controlled trials (RCTs) and 4 were observational studies with comparative arms. Across tstudies, 455 patients received rituximab maintenance and 595 did not.

Overall, rituximab maintenance improved PFS (HR, 0.39; 95% CI, 0.31-0.50) and OS (HR, 0.47; 95% CI, 0.27-0.83), and these results persisted when assessing only patients treated after autologous stem cell transplantation for both PFS (HR, 0.34; 95% CI, 0.25-0.47) and OS (HR, 0.38; 95% CI, 0.22-0.65).

When restricting the analysis to prospective RCTs, rituximab maintenance improved PFS (HR 0.47; 95% CI, 0.34-0.65) but not OS (HR, 0.70; 95% CI, 0.46-1.08). Only 2 of the 3 RCTs reported OS, however.

Another study on rituximab discussed the biologic’s use in DLBCL, a disease that has a relapse rate of approximately 40%.² The study’s authors compared the clinical features and outcomes of patients from the Singapore lymphoma study database who experienced early relapse (within 2 years), late relapse (after 2 years), and continuous complete remission (no relapse after 5 years) following treatment with rituximab and chemotherapy received between 1992 and 2017.

Of 472 total patients, 135 had early relapse, 42 had late relapse, and 295 had continuous complete remission. In the 2 relapse groups, median survival was 1.4 years (range, 1.16-1.83), and 9.86 years (range, 6.86-13.31).

The researchers found that 98% of patients with residual disease at the end of treatment with rituximab and chemotherapy had an early relapse, and the odds of early relapse versus late relapse was higher in patients with high levels of lactate dehydrogenase, more than 1 extranodal site of disease, and stage III or stage IV disease (though age over 60 years or central nervous system involvement were not associated with early relapse).

The researchers say that, even in the era of rituximab, patients with early relapse have worse outcomes, and clinical factors predict these poor outcomes.

References

1. Hilal T, Wang Z, Almader-Douglas D, et al. Rituximab maintenance for mantle cell lymphoma: a meta-analysis. J Clin Oncol. 2018;36(suppl; Abstract e19557).

2. Koh JJ, Lim ST, Sultana R, et al. Predictors of early vs late diffuse large B cell lymphoma (DLBCL) relapses in the rituximab era. J Clin Oncol. 2018;36(suppl; Abstract e19553).