The benefit of rituximab maintenance therapy in follicular lymphoma is long lasting and evident out to at least 9 years, according to the final efficacy analysis of the PRIMA phase 3, randomized, controlled trial.
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Previously reported results of this pivotal trial showed prolongation of progression-free survival and time to next treatment with rituximab maintenance at a follow-up of 3 years and 6 years.
“Rituximab maintenance is now widely recommended for patients with follicular lymphoma responding to first-line rituximab-based immunochemotherapy,” Emmanuel Bachy, MD, PhD, of Institut National de la Santé et de la Recherche Médicale in Pierre-Bénite, France, and colleagues reported in the Journal of Clinical Oncology.
In PRIMA, patients with previously untreated high–tumor burden follicular lymphoma received any of three immunochemotherapy induction regimens. The 1,018 patients having a response were then randomly assigned to receive 2 years of rituximab (Rituxan) maintenance or observation only.
Dr. Bachy and colleagues performed the trial’s final efficacy analyses, now at a median follow-up of 9 years.
Among the 607 patients consenting to the extended follow-up, median progression-free survival was 10.5 years in the rituximab-maintenance group, compared with 4.1 years in the observation group (hazard ratio, 0.61; P less than .001).
“Subgroup analyses showed the substantial progression-free survival improvement associated with rituximab maintenance was independent of age, sex, induction immunochemotherapy regimen, response to induction, or [Follicular Lymphoma International Prognostic Index] risk score,” the investigators wrote.
Rituximab maintenance also prolonged the median time to next antilymphoma treatment (not reached vs. 6.1 years; hazard ratio, 0.66; P less than .001) and time to next chemotherapy treatment (not reached vs. 9.3 years; hazard ratio, 0.71; P less than .001).
But there was no significant difference in overall survival. Median overall survival was not reached in either group (hazard ratio, 1.04; P = .7948). The estimated 10-year overall survival rate was about 80% in both groups.
“This 9-year follow-up of the PRIMA study demonstrates that rituximab maintenance after induction immunochemotherapy provides a significant long-term [progression-free survival] benefit over observation,” the investigators wrote. “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 trial was sponsored by the Lymphoma Study Association and supported by F. Hoffmann–La Roche and Biogen. Dr. Bachy reported financial disclosures related to Roche and other companies.
SOURCE: Bachy E et al. J Clin Oncol. 2019 Nov 1;37(31):2815-24.