medwireNews: Maintenance treatment with the anti-CD20 antibody rituximab after induction immunochemotherapy and autologous hematopoietic stem-cell transplantation (HSCT) is associated with a significant survival benefit among young patients with mantle-cell lymphoma, phase III trial findings show.
At the 4-year mark, the primary endpoint of event-free survival (EFS) – where disease progression, relapse, death, allergy to rituximab, or severe infection were considered an event – was achieved by 79% of 120 patients aged less than 66 years who were randomly assigned to receive maintenance rituximab at a dose of 375 mg/m2 every 2 months for 3 years after HSCT.
This was significantly higher than the 61% EFS rate observed among their 120 counterparts who underwent observation, equating to a hazard ratio (HR) in favor of rituximab of 0.46.
The 4-year rates of progression-free and overall survival were also significantly higher in the rituximab than in the observation arm, at 83% versus 64% and 89% versus 80%, respectively, with corresponding HRs of 0.40 and 0.50.
Of note, the incidence of serious infections after transplantation was comparable across groups, with four patients in each arm experiencing a serious infection.
All study participants had received induction therapy with R-DHAP (rituximab, dexamethasone, cytarabine, and platinum derivative), achieving either complete remission or a partial response (≥75% reduction in tumor mass) before receiving conditioning with R-BEAM (rituximab, carmustine, etoposide, cytarabine, and melphalan) and undergoing HSCT.
Steven Le Gouill (University Hospital Hôtel-Dieu, Nantes, France) and team say in The New England Journal of Medicine that rituximab maintenance “prevented relapses and was associated with a low risk of major infection” in this group of patients. But they add: “Whether maintenance therapy with rituximab improves outcomes in patients who are treated with other regimens is unknown.”
Another unanswered question pertains to the utility of maintenance therapy in patients who achieve minimal residual disease, say the study authors. “Because status regarding minimal residual disease can predict outcome in patients, it could be postulated that patients with negative minimal residual disease status (i.e., those with a level of disease below the threshold of detection) after transplantation may not benefit from maintenance therapy,” they write.
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