Rituximab maintenance lacks a clear overall survival benefit for Follicular Lymphoma

On 23^rd May 2017, in a letter to the editor of the British Journal of Haematology, Rie S. Bech from Regionshospitalet Nordjylland, Hjørring, and Aalborg University Hospital, Aalborg, Denmark, and colleagues outlined results of their retrospective “real world” analysis of the impact of rituximab maintenance after front line immune-chemotherapy in patients with FL.

Local investigators reviewed the medical records of patients aged 18 years or older and diagnosed with FL between 2007 and 2014 in Denmark (University Hospitals of Herlev, Odense, Aarhus, and Aalborg) or London (Guy’s and St Thomas’ Hospital).

Inclusion criteria consisted of: newly diagnosed patients; grade 1–3a disease; R-CVP, R-CHOP, or R-bendamustine upfront, or after watchful waiting; and at least PR after induction therapy.

Key Highlights:

• Overall, 239 pts included; Denmark = 208; London = 31
• Rituximab maintenance (R+) = 160 pts; without treatment (R-) = 79 pts
• After induction, 139 pts evaluated with PET/CT (R-, 35%; R+, 65%)
• Mean number of rituximab maintenance treatments = 11 (IQR, 8–12) among 92/160 R+ pts
• During follow-up, 22 pts died (R-, 13 pts; R+, 9 pts); cause of death was related to lymphoma in 5 pts (R-, 2 pts; R+, 3 pts)
• In the R- group, 5/7 deaths reported ≤2 years after FL diagnosis were unrelated to lymphoma
• 3-year PFS estimates in R+ vs. R- pts: 77% (95% CI, 70–85%) vs. 71% (95% CI, 61–82%); P = 0.35
• 3-year OS estimates in R+ vs. R- pts: 97% (95% CI, 93–100%) vs. 91% (95% CI, 85–98%); P = 0.039
• The association of better 3-year OS in R+ pts was not significant in multivariate analysis: HR = 0.33; 95% CI, 0.096–1.1; P = 0.079
• Time to Progression (TTP) was not significantly longer for R+ pts

The group then compared their results to the phase III, randomized, controlled PRIMA study (NCT00140582). Patients in the current study were administered less rituximab maintenance (11 doses) than recommended by findings of the PRIMA study (12 doses over 2 years). Moreover, specifically in patients who completed rituximab maintenance in the current analysis, 34% were treated at intervals of 3 months instead of 2 months. It was stated that it is unknown whether tighter adherence to the PRIMA trial protocol would have benefited patients in this current analysis.

Strengths of this analysis included the thorough chart review, which eliminated the impact of incomplete data, and its “real world” nature. Undoubtedly, the small sample size was a limitation. In addition, the PFS benefit in patients receiving rituximab maintenance was unclear in the present study; the authors suggest this may be due to the lack of protocolled surveillance imaging during follow-up. 

The letter concluded by stating that, based on real world data, “the value of rituximab maintenance in FL is limited and, in the absence of clear OS benefits, remains a controversial approach.”

Abstract:

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