Efficacy and safety of rituximab in auto-immune hemolytic anemia: A meta-analysis of 21 studies

Abstract

Objective: This study aims to evaluate the response to rituximab (RTX) treatment in auto-immune hemolytic anemia (AIHA) patients.

Methods: Studies were selected from MEDLINE up to March 2014. Two investigators independently extracted data on study design, patient characteristics, clinical features (AIHA type, disease duration, previous treatments), dose-schedule of rituximab, duration of treatment follow-up, and toxicities. Pooled overall response rate (ORR) and complete response (CR) rates were evaluated to determine RTX efficacy and toxicity by calculating the weighted mean proportion with fixed or random-effects models in case of heterogeneity (p<0.1 or I(2)>50%).

Results: Twenty-one studies encompassing 409 patients were included in the meta-analysis. The characteristics of the entire analyzed cohort reported were as follows: mean male proportion: 43%, mean age: 50 years, splenectomized patients range: 0-50%. Warm AIHA, primary AIHA and adults were mostly represented. With the random-effect model, the overall response rate (ORR) was 73% (95% CI 64-81%, 20 studies encompassing 402 patients). CR rate was 37% (95% CI 26-49%, 20 studies including 397 patients). The ORRs were close to 70% for warm AIHA (79%, 95% CI 60-90%, 11 studies, 154 patients), primary AIHA (67%, 95% CI 49-81%, 10 studies, 161 patients), and secondary AIHA (72%, 95% CI 60-82%, 8 studies, 66 patients). The ORR was 57% (95% CI 47-66%, 6 studies, 109 patients) for cold agglutinin disease (CAD). The CR rate was 42% (95% CI 27-58%, 11 studies, 154 patients) for warm AHAI, 32% (95% CI 17-51%, 11 studies, 176 patients) for primary AIHA, 46% (95% CI 30-62%, 9 studies, 87 patients) for secondary AIHA and only 21% (95% CI 6-51%, 7 studies, 118 patients) for CAD. Definitive response rates were evaluated during follow-up. CR rate was the highest within 2 to 4 months after RTX (13 studies, 203 patients, CR=70% [57-80%]). As for toxicities, 38 adverse events in 364 patients were noted (14% (95% CI 9-21%)). Sixteen events were infusion-linked side effects, mostly chills and fever, whereas twenty-two were severe. Only one opportunistic Pneumocystis jiroveci pneumonia was reported. Seventeen patients out of 364 (4.6%) died during follow-up. In univariate mixed-effect meta-regressions, ORR and CR were significantly associated with warm AIHA (p=0.002) and mean age (p<0.001), and marginally associated with disease type (p=0.06 and 0.005, respectively).

Conclusions: Rituximab seems to be a safe and effective therapy for AIHA in this meta-analysis of observational studies. The authors suggest that it could be used at an earlier point in therapy, before more toxic immunosuppressive drugs, or in place of splenectomy in some cases.

Keywords: Autoimmune hemolytic anemia; Cold agglutinin disease; Complete response; Overall response rate; Rituximab; Warm autoimmune hemolytic anemia.