Background/Purpose:

In RA patients, different randomized clinical trials have showed that the efficacy of reduced dose of RTX either initially and for subsequent courses (DANCER, SERENE MIRROR trials), or for retreatment after an initial full dose (SMART trial) did not differ from standard dose, with the advantage of a lower cost and a possible better safety.

Objective

To investigate the maintenance of RTX in patients retreated with reduced doses after an initial full-dose compared with RTX to standard doses at each infusion in real life setting.

Methods:

Patients of AIR registry (a nationwide prospective study investigating the long-term safety and efficacy of RTX in real life) were included in this specific study if they were retreated at least once with RTX for RA and had at least 6 months of follow-up. According to RTX retreatment regimen, three groups were defined. Group A: patients treated with 2 infusions of 1000 mg for all courses, group B: patients treated by 2 infusions of 1000 mg for the first course and reduced dose from the second course of RTX and thereafter and group C: patients treated by 2 infusions of 1000 mg for more than 1 course and reduced dose at a later course of RTX. Regimen of RTX was very variable in group C and will need specific analyses. Thus, this work focus on comparison of group A and B. Non maintenance was defined by the scientific committee of the registry as either death, lack of efficacy defined by introduction of a DMARD, switch to another biologic agent, increase in corticosteroid dose (≥10 mg at 2 times during follow-up), or according to physician judgment, or for side effect. Patient follow-up was censored at 3 years. Maintenance of group B was compared to that of group A using Kaplan Meier analyses and Hazard Ratio were calculated using Cox proportional Hazard model.

Results:

In total, 1233/1986 patients from the registry fulfilled inclusion criteria: group A (n=841), group B (n=175) and group C (n=217). Comparison of patient characteristics between groups did not revealed major difference. However, the patients of the group B were more likely to have erosive disease and a lower DAS28 at time of retreatment compared to group A. Maintenance of Rituximab did not significantly differ between groups A and B (median= 38 vs 40 months; hazard ratio [HR]= 0.79 [0.62-1.02], p= 0.0972). Overall, the mean time between 2 courses was lower in group B compared to group A (6.5 months vs 7.5, p< 0.001), but the cumulative RTX dose for retreatment measured in mg/year were decreased by 36% in group B compared to group A (1400 vs 2500 mg, p< 0.001). 

Conclusion:

Maintenance therapy at 3 years in RA patients treated with RTX did not differ between patients treated with full-dose at each course or with reduced dose since the second course. Also the total dose of RTX / year may be decreased by 36% leading to economic and possibly safety benefits without interfering with effectiveness.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/in-rheumatoid-arthritis-ra-patients-retreatment-with-rituximab-rtx-at-half-dose-does-not-alter-maintenance-on-drug-and-allows-one-third-reduction-of-cumulative-dose-of-drugyear-data-from-the-au/