The approval of maintenance with rituximab (MR) for 2 years following response to an induction with rituximab-chemotherapy (R-chemotherapy) for patients with newly diagnosed follicular lymphoma was based on results of the PRIMA study (ClinicalTrials.gov Identifier: NCT00140582).1
Rituximab maintenance has been shown to improve progression-free survival, though overall survival results are inconclusive. A recent meta-analysis including patients from 7 trials shows, however, that MR improves overall survival (vs observation) among all patients regardless of patient and disease characteristics.2
The trials contributed data from 2315 patients for this meta-analysis. Most patients received R-chemotherapy (74%) or chemotherapy as induction therapy followed by MR or observation. Induction chemotherapy included cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) among 62% of patients, cyclophosphamide, vincristine, and prednisone (CVP) among 23% of patients, and fludarabine among 15% of patients. Of the included patients, 1145 patients received MR and 1170 patients did not.
The median follow-up was 6 years; overall survival was significantly improved for patients on MR, reducing the risk of death by 21%. Median overall survival in the MR and observation groups was 12 years and 11.5 years, respectively.
Significant overall survival improvements were not seen among patients receiving MR after first-line induction versus observation. With a hazard ratio of 1.049, patients who received first-line rituximab in their induction regimen were likely to have similar overall survival rates from MR compared with observation only.
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Among patients receiving MR after second-line induction with chemoimmunotherapy or chemotherapy, however, there was a significant benefit in overall survival, with a 30% reduced risk for death. Similar results were seen with patients who received only chemotherapy as induction therapy.