Rituximab maintenance in patients with high tumor burden follicular lymphoma (FL) who have responded to rituximab plus chemotherapy induction improves progression-free survival (PFS), according to recently released results of the PRIMA study (Lancet. Dec 21, 2010. Epub ahead of print).
This randomized, controlled, phase 3 trial assigned 1019 FL patients who achieved a complete or partial response to induction therapy to either 2 years of maintenance rituximab (375 mg/m2 every 8 weeks) or observation. Patients completed quality-of-life questionnaires for functional assessment of cancer therapy-general (FACT-G).
At a median follow-up of 3 years, PFS was 74.9% (95% CI, 70.9-78.9) in the maintenance group compared with 57.6% (95% CI, 53.2-62.0) in the observation group (P <.0001). Overall survival, however, (OS) did not differ significantly (HR, 0.87; 95% CI, 0.51-1.47). The authors suggest that this may be due to the indolent nature of FL.
At the end of treatment (2-year follow-up), 71.5% of the maintenance group had complete or unconfirmed response compared with 52.2% of the observation group (P = .0001). The mean adjusted FACT-G scores, however, were similar (86.6 vs 87.2, respectively). Adverse events occurred in 24% of the maintenance group and 17% of the observation group, with infections being the most common event.
The authors concluded that these findings suggest maintenance rituximab should be considered as first-line treatment for these patients. “However, it is unclear whether the progression-free survival advantage will translate to improved overall survival,” comments Susan K. Woelich, PharmD, a clinical oncology pharmacist at Aurora Healthcare, who also notes that “based on the PRIMA trial’s preliminary results and rituximab’s favorable toxicity profile, patients with a response to induction therapy will likely receive maintenance rituximab versus the ‘watch-and-wait’ approach.”
In a commentary published with the article, Jonathan W. Friedberg of the James P. Wilmot Cancer Center recommended caution. “The scarcity of a benefit in overall survival after maintenance therapy should be emphasized,” he wrote.
Ali McBride PharmD, MS, BCPS, a clinical pharmacy specialist at Barnes-Jewish Hospital notes that the data have both positive and negative aspects. “The clear-cut benefit was seen with the R-CHOP chemotherapy induction regimen followed by rituximab maintenance, in which greater than 75% of the population were treated. Clearly, the data from this study support the use of rituximab maintenance therapy in rituximab-sensitive patients. However, cost may be a prohibitive factor in patients seeking maintenance therapy.”