Federico M, et al. - The impact of rituximab on the risk of histological transformation of follicular lymphoma to aggressive lymphoma and its prognosis was evaluated in the Aristotle study. Based on the findings, researchers concluded that rituximab can significantly attenuate the risk of histological transformation as a first event and this information should be shared with the patients taking rituximab.

Methods

• Researchers used data from 11 cooperative groups or institutions across Europe and included patients (≥ 18 years) with histologically confirmed follicular lymphoma grade 1, 2, or 3a, diagnosed between January 2, 1997 and December 20, 2013.
• A biopsy-proven aggressive lymphoma that occurred as a first event after first-line therapy defined histological transformation.
• The cumulative hazard of histological transformation and survival after transformation were the primary endpoints.

Results

• Data showed that information was available for a total of 10,001 patients with follicular lymphoma, 8,116 of whom were eligible for analysis.
• There were a reported 509 histological transformations.
• The estimated 10-year cumulative hazard of histological transformation was 7.7% (95% CI 6.9–8.5) following a median follow-up of 87 months (range 1–221; 2.5–97.5th percentile 5–160).
• In patients who received rituximab and in those who did not, the estimated 10-year cumulative hazard of histological transformation was 5.2% (95% CI 4.5–6.2) and 8.7% (7.2–10.6), respectively (hazard ratio [HR] 0.73, 95% CI 0.58–0.90; p=0.004).
• Findings revealed that the estimated 10-year cumulative hazard of histological transformation for patients who received induction rituximab only was 5.9% (95% CI 5.0–7.0) and was 3.6% (95% CI 2.3–5.5) for those treated with induction and maintenance rituximab (HR 0.55, 95% CI 0.37–0.81; p=0.003); multivariate analysis corroborated this finding (p=0.016).
• Out of 509 patients with histological transformation, death was reported in 287, resulting in a 10-year survival after transformation of 32% (95% CI 26–38).
• Researchers found no difference regarding survival after transformation between patients not exposed to rituximab and those who received rituximab in induction only (HR 0.94, 95% CI 0.69–1.28; p=0.70), and those who received rituximab in induction and maintenance (0.96, 0.58–1.61; p=0.88).