Patients with untreated, high-tumor–burden follicular lymphoma had significantly improved progression-free survival (PFS) when treated with maintenance rituximab compared with observation, but long-term results from the PRIMA study indicate there is no overall survival (OS) benefit associated with the maintenance treatment.1

“Despite the lack of overall survival advantage, it is noteworthy that more than half of the patients in the rituximab maintenance arm remain free of disease progression and have not required new antilymphoma treatment beyond 10 years,” the researchers wrote in the Journal of Clinical Oncology.

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These updated results from PRIMA include 9 years of follow-up. The study included 1018 patients with untreated follicular lymphoma who were 18 years or older. Included patients had nonrandomized assignment to 1 of 3 immunochemotherapy regimens, and random assignment to 2 years of rituximab maintenance starting 8 weeks after the last induction treatment (505 individuals), or observation (513 individuals).

Prior results from the study established the PFS advantage of rituximab maintenance. These results included final PFS data and OS results.

The median PFS was more than twice as long for patients assigned to rituximab maintenance compared with observation (10.5 years vs. 4.1 years; hazard ratio [HR], 0.61; 95% CI, 0.52-0.73; P <.001).

Time to next treatment was also significantly longer in patients assigned to rituximab (not yet reached vs 6.1 years; P <.001).

However, no difference in OS was seen between the 2 groups (HR, 1.04; 95% CI, 0.77-1.40; P =.7948). The 10-year overall survival rates were aprroximately 80% in both arms.

“This finding is similar to recently published long-term follow-up studies in which prolonged PFS with the use of rituximab plus CHOP (compared with rituximab plus CVP) or rituximab plus bendamustine (compared with rituximab plus CHOP) fails to translate into prolonged overall survival and has important implications for both our understanding of the disease and future research in the field,” the researchers wrote.

Maintenance therapy was associated with a higher rate of grade 3/4 adverse events compared with observation (24.4% vs 16.9%, respectively) and serious adverse events (21.2% vs 13.4%, respectively).

Reference

Bachy E, Seymour JF, Feugier P, et al. Sustained progression-free survival benefit of rituximab maintenance in patients with follicular lymphoma: long-term results of the PRIMA study [published online July 24, 2019]. J Clin Oncol. doi: 10.1200/JCO.19.01073